Note: This page contains sample records for the topic inert gas dilution from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Purification of Inert Gas  

Microsoft Academic Search

The rate of removal of oxygen from inert gas by metallic getter is measured continuously, and the dilution model is adopted for explaining the rate of purification. The rate of removal of oxygen increases with flow rate. It is found that hydrogen and water vapor present in the inert gas contributes very effectively to reducing the oxygen partial pressure. The

Keiji NAITO; Toshihide TSUJI; Tsuneo MATSUI; Katsumi UNE

1974-01-01

2

Inert gas ion thruster  

NASA Technical Reports Server (NTRS)

Inert gas performance with three types of 12 cm diameter magnetoelectrostatic containment (MESC) ion thrusters was tested. The types tested included: (1) a hemispherical shaped discharge chamber with platinum cobalt magnets; (2) three different lengths of the hemispherical chambers with samarium cobalt magnets; and (3) three lengths of the conical shaped chambers with aluminum nickel cobalt magnets. The best argon performance was produced by a 8.0 cm long conical chamber with alnico magnets. The best xenon high mass utilization performance was obtained with the same 8.0 cm long conical thruster. The hemispherical thruster obtained 75 to 87% mass utilization at 185 to 205 eV/ion of singly charged ion equivalent beam.

Ramsey, W. D.

1980-01-01

3

Inert gas thrusters  

NASA Technical Reports Server (NTRS)

Inert gas thrusters have continued to be of interest for space propulsion applications. Xenon is of interest in that its physical characteristics are well suited to propulsion. High atomic weight and low tankage fraction were major factors in this choice. If a large amount of propellant was required, so that cryogenic storage was practical, argon is a more economical alternative. Argon was also the preferred propellant for ground applications of thruster technology, such as sputter etching and deposition. Additional magnetic field measurements are reported. These measurements should be of use in magnetic field design. The diffusion of electrons through the magnetic field above multipole anodes was studied in detail. The data were consistent with Bohm diffusion across a magnetic field. The theory based on Bohm diffusion was simple and easily used for diffusion calculations. Limited startup data were obtained for multipole discharge chambers. These data were obtained with refractory cathodes, but should be useful in predicting the upper limits for starting with hollow cathodes.

Kaufman, H. R.

1978-01-01

4

Mechanisms of Inert Gas Narcosis.  

National Technical Information Service (NTIS)

Experiments describing the mechanism of inert gas narcosis are reported. A strain of mice, genetically altered to increase susceptibility to botulin poisoning (synaptic response) appears to increase metabolic rates while breathing argon; this infers a gen...

1973-01-01

5

46 CFR 154.906 - Inert gas generators.  

Code of Federal Regulations, 2010 CFR

...Inert gas generators. The inert gas generator must: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device...station that alarms when the inert gas contains 5% or more oxygen by...

2010-10-01

6

Apparatus for manufacturing high pressure inert gas  

Microsoft Academic Search

At the present time, one of the biggest usages of inert gas is in the petroleum industry, wherein such gas is utilized in the recovery of petroleum. An apparatus is described for manufacturing high pressure inert gas utilizing hydrocarbon fuel. The gas is produced by the burning of hydrocarbon fuel in an internal combustion engine, the exhaust gases therefrom being

Gower

1971-01-01

7

Mechanisms of inert gas narcosis  

NASA Technical Reports Server (NTRS)

Experiments describing the mechanism of inert gas narcosis are reported. A strain of mice, genetically altered to increase susceptibility to botulin poisoning (synaptic response) appears to increase metabolic rates while breathing argon; this infers a genetically altered synaptic response to both botulin toxin and narcotic gases. Studies of metabolic depression in human subjects breathing either air or a 30% mixture of nitrous oxide indicate that nitrous oxide narcosis does not produce pronounced metabolic depression. Tests on mice for relative susceptibilities to narcosis and oxygen poisoning as a function of fatty membrane composition show that alteration of the fatty acid composition of phospholipids increases resistance to metabolically depressant effects of argon but bas no effect on nitrous oxide narcosis. Another study suggests that acclimatization to low tension prior to high pressure oxygen treatment enhances susceptibility of mice to convulsions and death; developing biochemical lesions cause CNS metabolite reductions and pulmonary damage.

1973-01-01

8

Inert gas transport in blood and tissues.  

PubMed

This article establishes the basic mathematical models and the principles and assumptions used for inert gas transfer within body tissues-first, for a single compartment model and then for a multicompartment model. From these, and other more complex mathematical models, the transport of inert gases between lungs, blood, and other tissues is derived and compared to known experimental studies in both animals and humans. Some aspects of airway and lung transfer are particularly important to the uptake and elimination of inert gases, and these aspects of gas transport in tissues are briefly described. The most frequently used inert gases are those that are administered in anesthesia, and the specific issues relating to the uptake, transport, and elimination of these gases and vapors are dealt with in some detail showing how their transfer depends on various physical and chemical attributes, particularly their solubilities in blood and different tissues. Absorption characteristics of inert gases from within gas cavities or tissue bubbles are described, and the effects other inhaled gas mixtures have on the composition of these gas cavities are discussed. Very brief consideration is given to the effects of hyper- and hypobaric conditions on inert gas transport. PMID:23737195

Baker, A Barry; Farmery, Andrew D

2011-04-01

9

Fast, Nonspattering Inert-Gas Welding  

NASA Technical Reports Server (NTRS)

Proposed welding technique combines best features of metal (other than tungsten)/inert-gas welding, plasma arc welding, and tungsten/inert-gas welding. Advantages include: wire fed to weld joint preheated, therefore fed at high speed without spattering; high-frequency energy does not have to be supplied to workpiece to initiate welding; size of arc gap not critical, power-supply control circuit adjusts voltage across gap to compensate for changes; only low gas-flow rate needed; welding electrode replaced easily as prefabricated assembly; external wire-feeding manipulator not needed; and welding process relatively forgiving of operator error.

Gilbert, Jeffrey L.

1991-01-01

10

Inflatable, Inert Gas-Purged, Welding Chamber.  

National Technical Information Service (NTIS)

An inflatable, inert-gas purged welding chamber assembly ideally suited for use in welding workpieces made of a metal (e.g., titanium), or of an alloy, which is susceptible to atmospheric contamination during welding. The welding chamber of the assembly i...

J. M. MacFarland

1981-01-01

11

Portable spectrometer monitors inert gas shield in welding process  

NASA Technical Reports Server (NTRS)

Portable spectrometer using photosensitive readouts, monitors the amount of oxygen and hydrogen in the inert gas shield of a tungsten-inert gas welding process. A fiber optic bundle transmits the light from the welding arc to the spectrometer.

Grove, E. L.

1967-01-01

12

46 CFR 154.908 - Inert gas generator: Location.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Inert gas generator: Location. 154.908 Section 154...Containment Systems § 154.908 Inert gas generator: Location. (a) Except as allowed...paragraph (b) of this section, an inert gas generator must be located in the main...

2013-10-01

13

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2011-07-01

14

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2000-07-01

15

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2010-07-01

16

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2012-07-01

17

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2001-07-01

18

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2002-07-01

19

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2008-07-01

20

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2004-07-01

21

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2007-07-01

22

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2003-07-01

23

Refractory metals welded or brazed with tungsten inert gas equipment  

NASA Technical Reports Server (NTRS)

Appropriate brazing metals and temperatures facilitate the welding or brazing of base metals with tungsten inert gas equipment. The highest quality bond is obtained when TIG welding is performed in an inert atmosphere.

Wisner, J. P.

1965-01-01

24

46 CFR 153.501 - Requirement for dry inert gas.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Requirement for dry inert gas. 153.501 Section 153.501 Shipping COAST...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment...

2013-10-01

25

46 CFR 153.500 - Inert gas systems.  

Code of Federal Regulations, 2013 CFR

... 5 2013-10-01 2013-10-01 false Inert gas systems. 153.500 Section 153.500 Shipping...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment...

2013-10-01

26

Inert gas diffusion in DLC–Si films  

Microsoft Academic Search

Inert-gas diffusion in DLC–Si films was studied by thermal effusion experiments. It is shown that the motion of inert gases in the films is controlled by diffusion, greatly depending on the size of the diffusing species. The results provide qualitative information on the microstructure size in agreement with the doorway diffusion model, in which the mechanical stiffness of the material

S. S. Camargo; J. C. Damasceno; W. Beyer

2002-01-01

27

Economic Feasibility of Inert Cushions in Underground Gas Storage.  

National Technical Information Service (NTIS)

The physical properties of storage reservoirs and the economics of three major processes for generating inert gases (cryogenic nitrogen, engine exhaust gas and boiler flue gases) have been investigated and compared to the current practice of using natural...

1980-01-01

28

33 CFR 157.164 - Use of inert gas system.  

Code of Federal Regulations, 2010 CFR

... § 157.164 Use of inert gas system. (a) The master...tank is crude oil washed, the oxygen content in the tank is measured...crude oil washed: (i) A gas or a mixture of gases with an oxygen content of 8 percent or...

2010-07-01

29

Heaterless ignition of inert gas ion thruster hollow cathodes  

NASA Technical Reports Server (NTRS)

Heaterless inert gas ion thruster hollow cathodes were investigated with the aim of reducing ion thruster complexity and increasing ion thruster reliability. Cathodes heated by glow discharges are evaluated for power requirements, flowrate requirements, and life limiting mechanisms. An accelerated cyclic life test is presented.

Schatz, M. F.

1985-01-01

30

Spectral analysis of inert gas elimination data: resolution limits.  

PubMed

A new method of analyzing inert gas data for recovery of the pulmonary ventilation-perfusion ration (VA/Q) distribution is proposed. It is shown that the conventional inert gas elimination equation takes the form of a convolution integral, and the relationship between VA/Q distribution and inert gas elimination resembles that of a noncausal low-pass filter with infinite zero-frequency gain. With the use of this formulation, characteristic features of VA/Q distribution may be represented in the frequency domain in terms of the corresponding energy spectrum. It is shown that the lack of resolution associated with finite data samples and measurement error is caused by distortions in the high-frequency contents of the resulting VA/Q distribution. With six inert gases, the technique cannot resolve a log SD less than 0.21 decade and a modal separation less than 0.87 decade. In the presence of measurement error, the degree of resolution is even less. It is suggested that for maximum resolution the number of discrete and duplicate data samples should be chosen so that the resulting noise and sampling cutoff frequencies are approximately equal. PMID:3379004

Poon, C S

1988-04-01

31

Inert gas analysis of ventilation-perfusion matching during hemodialysis.  

PubMed Central

The mechanism of hypoxemia during hemodialysis was investigated by the multiple inert gas elimination technique in anesthetized, paralyzed, mechanically ventilated dogs. Profound leukopenia occurred in the first hour of a 2-h hemodialysis with a cuprophan membrane and dialysate that contained acetate. Arterial partial pressure of O2 and CO2 and oxygen consumption remained unchanged during dialysis. Pulmonary carbon dioxide elimination and lung respiratory exchange ratio decreased with the initiation of dialysis, remained depressed throughout the duration of dialysis, and returned to predialysis levels after the cessation of dialysis. Cardiac output diminished during dialysis but did not return to base-line levels after dialysis. Multiple indices calculated from inert gas analysis revealed no ventilation-perfusion mismatching during dialysis. The shunt and perfusion to regions of low alveolar ventilation-to-perfusion ratio (VA/Q) were unchanged during dialysis. There was no change in the mean or standard deviation of the profile of the percentage of total perfusion to regions of the lung that had VA/Q near 1.0; nor was there any increase in the directly calculated arterial-alveolar partial pressure differences for the inert gases during dialysis. Dead space became mildly elevated during dialysis. These results show that during dialysis with controlled ventilation there is no ventilation-perfusion mismatching that leads to hypoxemia. During spontaneous ventilation any hypoxemia must occur due to hypoventilation secondary to the CO2 exchange by the dialyzer and subsequent reduction in pulmonary CO2 exchange.

Ralph, D D; Ott, S M; Sherrard, D J; Hlastala, M P

1984-01-01

32

Nuclear Technology. Course 28: Welding Inspection. Module 28-3, Tungsten Inert Gas (TIG), Metal Inert Gas (MIG) and Submerged Arc Welding.  

ERIC Educational Resources Information Center

This third in a series of ten modules for a course titled Welding Inspection presents the apparatus, process techniques, procedures, applications, associated defects, and inspection for the tungsten inert gas, metal inert gas, and submerged arc welding processes. The module follows a typical format that includes the following sections: (1)…

Espy, John

33

Iron nitride nanoparticles synthesized by inert gas condensation  

NASA Astrophysics Data System (ADS)

Inert gas condensation (IGC) is a highly versatile technique to synthesize monodisperse nanoparticles (NP). Earlier research done in our group on iron oxide nanoparticles and Fe- and Co- based fluids suggests that these NP's are well suited for magnetic drug delivery, however, their utility would be dramatically enhanced if they exhibited higher saturation magnetization. Iron-oxide nanoparticles are the most commonly studied system; however, the saturation magnetization (70-90 emu/g) is considerably lower than pure Fe (210 emu/g). Fe NPs tend to oxidize easily, so we are exploring Fe-N and Fe-C alternatives. We have used IGC to synthesize Fe-N nanoparticles (mean sizes ˜ 10-20 nm) using Fe deposition followed by gaseous nitrogenation, and via reactive inert-gas condensation. Post-deposition nitrogenation does not form Fe-N phases, nor protect the nanoparticles from oxidation. By reactive sputtering with varying relative concentration of N:Ar, we can produce FexN phases ranging from x=1 (non-magnetic ?-FeN) x=4. A systematic study of nitride phase formation as a function of Ar/N2 ratio during sputtering will be reported.

Shah, Prasanna; Ford, Brent; Dean, Andrew; Pelecky, Diandra

2009-10-01

34

Cytogenetic studies of stainless steel welders using the tungsten inert gas and metal inert gas methods for welding.  

PubMed

Cytogenetic damage was studied in lymphocytes from 23 welders using the Tungsten Inert Gas (TIG), and 21 welders using the Metal Inert Gas (MIG) and/or Metal Active Gas (MAG) methods on stainless steel (SS). A matched reference group I, and a larger reference group II of 94 subjects studied during the same time period, was established for comparison. Whole blood conventional cultures (CC), cultures in which DNA synthesis and repair were inhibited (IC), and the sister chromatid exchange (SCE) assay were applied in the study. For the CC a statistically significant decrease in chromosome breaks and cells with aberrations was found for both TIG/SS and MIG/MAG/SS welders when compared with reference group II. A non-significant decrease was found for the corresponding parameters for the two groups of welders when compared with their matched referents. A statistically significant negative association was found between measurements of total chromium (Cr) in inhaled air and SCE, and a weaker negative correlation with hexavalent Cr (Cr(VI)) in air. In conclusion, no cytogenetic damage was found in welders exposed to the TIG/SS and MIG/MAG/SS welding fumes with low content of Cr and Ni. On the contrary, a decline in the prevalence of chromosomal aberrations was indicated in the TIG/SS and MIG/MAG/SS welders, possibly related to the suggested enhancement of DNA repair capacity at slightly elevated exposures. PMID:7885396

Jelmert, O; Hansteen, I L; Langård, S

1995-03-01

35

Odorization of inert gas for occupational safety: psychophysical considerations.  

PubMed

Odorization of inert gas can serve to warn workers in an enclosed space about gas leaking into the space. This psychophysical investigation, performed under conditions of directed attention, examined two candidates for possible odorization of argon:pyridine and cis-3-hexen-1-ol. Detection thresholds for pyridine and cis-3-hexen-1-ol in argon were 106 ppb and 19 ppb, respectively. Practice over four days yielded modest improvement in the detection of both odorants. For cis-3-hexen-1-ol, smokers had marginally lower thresholds than nonsmokers and older participants had slightly higher thresholds than younger participants. Gender, smoking status and age had no reliable influence on threshold for pyridine. This outcome indicated desirable perceptual stability for pyridine. Additional experiments dealt with the perceived intensity of pyridine and cis-3-hexen-1-ol over time in the realistic setting of an environmental chamber. Visitors to the chamber and occupants in the chamber assessed perceived magnitude at 5-min intervals for up to 60 min during injections of odorized argon into the chamber. Participants could gauge and track the concentration of pyridine much better than that of cis-3-hexen-1-ol. This held true for occupants almost to the same degree as visitors, though occupants inevitably exhibited some olfactory adaptation. Hence, the suprathreshold measurements also gave strong relative endorsement to pyridine. Calculations based on the experimental results indicated that odorization of the inert gas stream with 3 to 10 ppm (v/v) pyridine should suffice to warn occupants or visitors of an argon buildup of any severity. Field studies should permit a definitive judgment of the best concentration to use in practice. PMID:3031973

Cain, W S; Leaderer, B P; Cannon, L; Tosun, T; Ismail, H

1987-01-01

36

Development of advanced inert-gas ion thrusters  

NASA Technical Reports Server (NTRS)

Inert gas ion thruster technology offers the greatest potential for providing high specific impulse, low thrust, electric propulsion on large, Earth orbital spacecraft. The development of a thruster module that can be operated on xenon or argon propellant to produce 0.2 N of thrust at a specific impulse of 3000 sec with xenon propellant and at 6000 sec with argon propellant is described. The 30 cm diameter, laboratory model thruster is considered to be scalable to produce 0.5 N thrust. A high efficiency ring cusp discharge chamber was used to achieve an overall thruster efficiency of 77% with xenon propellant and 66% with argon propellant. Measurements were performed to identify ion production and loss processes and to define critical design criteria (at least on a preliminary basis).

Poeschel, R. L.

1983-01-01

37

46 CFR 153.462 - Static discharges from inert gas systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Static discharges from inert gas systems. 153.462 Section 153.462 Shipping...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment...

2013-10-01

38

Molecular dissociation in dilute gas  

NASA Astrophysics Data System (ADS)

The charge state distributions (CSD) produced during molecular dissociation are important to both Trace Element Accelerator Mass Spectrometry (TEAMS) and the ion implantation industry. The CSD of 1.3-1.7 MeV SiN+, SiMg+, SiMn+, and SiZn+ molecules have been measured for elements that do not form atomic negative ions (N, Mg, Mn, and Zn) using a NEC Tandem Pelletron accelerator. The molecules were produced in a Cs sputter negative ion source, accelerated, magnetically analyzed, and then passed through an N2 gas cell. The neutral and charged breakups where analyzed using an electrostatic deflector and measured with particle detectors. Equilibrium CSD were determined and comparisons made between molecular and atomic ion data.

Renfrow, S. N.; Duggan, J. L.; McDaniel, F. D.

1999-06-01

39

Inert-gas welding and brazing enclosure fabricated from sheet plastic  

NASA Technical Reports Server (NTRS)

Custom-fabricated plastic bag maintains an inert-gas atmosphere for welding and brazing certain metals. The bag fits over part of the workpieces and the welding and brazing tools. It is also used for metal brazing and fusion plating which require an inert-gas atmosphere.

Wisner, J. P.

1965-01-01

40

Visual/vestibular effects of inert gas narcosis.  

PubMed

Divers breathing compressed air at depths beyond 30 m experience a type of behavioural impairment known as inert gas narcosis. This condition degrades performance on a wide range of tasks and has the potential to compromise safety. Symptoms associated with narcosis include slowed response time, amnesia, and euphoria. Studies have also found disturbances to mechanisms regulating ocular control in response to vestibular stimulation; however, these experiments have been limited to very low frequency head movement (0.2 Hz). Thus, to further examine the effects of narcosis on visual/vestibular mechanisms, the vestibular ocular reflex (VOR) was assessed across a range of higher frequencies more representative of natural head movement (2.0-4.7 Hz). Seven subjects were tested prior to, during and after exposure to narcosis which was induced using 30% nitrous oxide. Standard room air was breathed as a control. The results indicated that narcosis decreased the velocity of compensatory eye movements in response to head rotation (decrease in VOR-gain), with more pronounced decreases occurring at the higher frequencies. The lag between eye and head position (phase lag) was also decreased by nitrous oxide; an effect that was again more pronounced at higher frequencies. These results indicate that narcosis disrupts ocular regulatory mechanisms which help to stabilize images on the retina during head movement. PMID:8365388

Hamilton, K; Laliberte, M F; Heslegrave, R; Khan, S

1993-08-01

41

Simplified power processing for inert gas ion thrusters  

NASA Technical Reports Server (NTRS)

Significant simplifications to power processors for inert gas ion thrusters in the 1 to 5 kW range have been identified. They include elimination of all but three power supplies - one each for the neutralizer, main discharge, and beam. The neutralizer and discharge power supplies would provide both cathode heating and plasma generating functions. This dual-use power supply concept was validated via integration tests with a 30 cm diameter xenon ion thruster. The beam/accelerator power supply would have positive and negative outputs to allow a single power supply to provide both functions. The discharge and beam power supplies would incorporate full-bridge inverters similar to those proven for flight-ready arcjet propulsion systems. Operation of this simplified power processing scheme at an inverter frequency of 50 kHz results in a projected power processor design with low mass and high efficiency. A 2 kW reference point design has estimated values of specific mass of 5.4 kg/kW and an efficiency of 93 percent.

Rawlin, V. K.; Pinero, L. R.; Hamley, J. A.

1993-01-01

42

Oxygen carrier for gas chromatographic analysis of inert gases in propellants  

NASA Technical Reports Server (NTRS)

Gas chromatographic determination of small quantities of inert gases in reactive propellants is discussed. Operating conditions used for specific analyses of helium in diborane and nitrogen in oxygen difluoride are presented in tabular form.

Cannon, W. A.

1972-01-01

43

Problems in the modelling of inert gas kinetics.  

PubMed

The models used to describe the kinetics of inert gases during underwater diving are inadequate. Medical practitioners and scientists interested in such diving have attempted to quantitatively describe the behaviour of nitrogen in compressed air diving since 1908, with little success. The problems encountered during this diving research are relevant to anaesthesia theory and practice. PMID:7793591

Gorman, D

1995-04-01

44

Noninvasive Cardiac Output Determination for Children by the Inert Gas-Rebreathing Method  

Microsoft Academic Search

Standard methods for determination of cardiac output (CO) are either invasive or technically demanding. Measurement of CO\\u000a by the inert gas–rebreathing (IGR) method, applied successfully in adults, uses a low-concentration mixture of an inert and\\u000a a blood-soluble gas, respectively. This study tested the feasibility of this method for determining CO during exercise for\\u000a pediatric patients with complete congenital atrioventricular block

Gesa Wiegand; Gunter Kerst; Winfried Baden; Michael Hofbeck

2010-01-01

45

Operation of the J-series thruster using inert gas  

NASA Technical Reports Server (NTRS)

Electron bombardment ion thrusters using inert gases are candidates for large space systems. The J-Series 30 cm diameter thruster, designed for operation up to 3 k-W with mercury, is at a state of technology readiness. The characteristics of operation with xenon, krypton, and argon propellants in a J-Series thruster with that obtained with mercury are compared. The performance of the discharge chamber, ion optics, and neutralizer and the overall efficiency as functions of input power and specific impulse and thruster lifetime were evaluated. As expected, the discharge chamber performance with inert gases decreased with decreasing atomic mass. Aspects of the J-Series thruster design which would require modification to provide operation at high power with insert gases were identified.

Rawlin, V. K.

1982-01-01

46

Lifting of heavy oil with inert-gas-operated chamber pumps  

SciTech Connect

A description is given of an unconventional gas lift system which can replace rod pumping for shallow (<3,000 ft.) heavy oil production. The heart of this system is an insert chamber downhole, whose only moving parts are two standing valves. Produced fluid entering the chamber is periodically expelled into a production annulus by pressurized gas injected from the surface down a small injection string. Natural gas, inert gas, or even air can be used for pumping. This study analyzes the operation of the chamber lifting system and shows how to optimize the system design and the operating variables to obtain maximum production at minimum cost. With the close spacing of thermal wells (2-5 acres), the combination of a single inert gas generator and associated compressor to supply a large number of wells equipped with chamber pumps is feasible. Several types of inert gas generators are described. 7 refs.

Dewan, J.T.; Elfarr, J.

1981-01-01

47

INVESTIGATION ON THE OSCILLATING GAS FLOW ALONG AN INERTANCE TUBE BY EXPERIMENTAL AND CFD METHODS  

SciTech Connect

To investigate the oscillating gas flow along an inertance tube used in pulse tube coolers, a CFD model is set up for FLUENT and an experimental measuring cell is designed and optimized by CFD results. Some characteristics of oscillating flow are demonstrated and discussed. Then, the flow status along an inertance tube is measured by the optimized measuring cell. The experimental results validate the simulating results.

Chen Houlei; Zhao Miguang; Yang Luwei; Cai Jinghui; Hong Guotong; Liang Jingtao [Technical Institute of Physics and Chemistry, CAS, Beijing, 100190 (China)

2010-04-09

48

Evaporation and Condensation of Large Droplets in the Presence of Inert Admixtures Containing Soluble Gas  

Microsoft Academic Search

In this study the mutual influence of heat and mass transfer during gas absorption and evaporation or condensation on the surface of a stagnant droplet in the presence of inert admixtures containing noncon- densable soluble gas is investigated numerically. The performed analysis is pertinent to slow droplet evapo- ration or condensation. The system of transient conjugate nonlinear energy and mass

T. Elperin; A. Fominykh; B. Krasovitov

2007-01-01

49

Carbothermic Reduction of Chromite Ore Under Different Flow Rates of Inert Gas  

NASA Astrophysics Data System (ADS)

The reduction of chromite ore with carbon has been studied extensively in many laboratories. Inert gases have been used in these investigations to control the experimental conditions. However, little information is available in the literature on the influence of the gas flow rate on the rate of reduction. Experiments were carried out to study the influence of the flow rate of inert gas on the reducibility of chromite ore. The experiments showed that the rate of reduction increased with the increasing flow rate of argon up to an optimum flow rate. At higher flow rates, the rate of reduction decreased. The influence of the proportion of reductant on the extent of reduction depended on the rate of flow rate of inert gas. The experimental results are interpreted on the basis of a model that postulates that the mechanism of reduction changes with the flow rate of argon.

Chakraborty, Dolly; Ranganathan, S.; Sinha, S. N.

2010-02-01

50

Continuous injection of an inert gas through a drill rig for drilling into potentially hazardous areas  

DOEpatents

A drill rig for drilling in potentially hazardous areas includes a drill having conventional features such as a frame, a gear motor, gear box, and a drive. A hollow rotating shaft projects through the drive and frame. An auger, connected to the shaft is provided with a multiplicity of holes. An inert gas is supplied to the hollow shaft and directed from the rotating shaft to the holes in the auger. The inert gas flows down the hollow shaft, and then down the hollow auger and out through the holes in the bottom of the auger into the potentially hazardous area. 3 figs.

McCormick, S.H.; Pigott, W.R.

1997-12-30

51

Continuous injection of an inert gas through a drill rig for drilling into potentially hazardous areas  

DOEpatents

A drill rig for drilling in potentially hazardous areas includes a drill having conventional features such as a frame, a gear motor, gear box, and a drive. A hollow rotating shaft projects through the drive and frame. An auger, connected to the shaft is provided with a multiplicity of holes. An inert gas is supplied to the hollow shaft and directed from the rotating shaft to the holes in the auger. The inert gas flows down the hollow shaft, and then down the hollow auger and out through the holes in the bottom of the auger into the potentially hazardous area.

McCormick, Steve H. (Idaho Falls, ID); Pigott, William R. (Idaho Falls, ID)

1997-01-01

52

Role of Carbon Dioxide in Inert Gas Narcosis.  

National Technical Information Service (NTIS)

The role of carbon dioxide and oxygen in high pressure narcosis was studied by exposing animals to hyperbaric conditions while maintaining them normoxic and normocapnic. Chickens were the experimental animals. Heated, humidified gas entered the lung via a...

H. S. Weiss

1977-01-01

53

Inert gas rejection device for zinc-halogen battery systems  

DOEpatents

An electrolytic cell for separating chlorine gas from other (foreign) gases, having an anode, a cathode assembly, an aqueous electrolyte, a housing, and a constant voltage power supply. The cathode assembly is generally comprised of a dense graphite electrode having a winding channel formed in the face opposing the anode, a gas impermeable (but liquid permeable) membrane sealed into the side of the cathode electrode over the channel, and a packing of graphite particles contained in the channel of the cathode electrode. The housing separates and parallelly aligns the anode and cathode assembly, and provides a hermetic seal for the cell. In operation, a stream of chlorine and foreign gases enters the cell at the beginning of the cathode electrode channel. The chlorine gas is dissolved into the electrolyte and electrochemically reduced into chloride ions. The chloride ions disfuse through the gas impermeable membrane, and are electrochemically oxidized at the anode into purified chlorine gas. The foreign gases do not participate in the above electrochemical reactions, and are vented from the cell at the end of the cathode electrode channel.

Hammond, Michael J. (Sterling Heights, MI); Arendell, Mark W. (Warren, MI)

1981-01-01

54

Study on DC Double Pulse Metal Inert Gas (MIG) Welding of Magnesium Alloy  

Microsoft Academic Search

This article gives a preliminary research on direct current (DC) double pulse metal inert gas (MIG) welding of magnesium alloys. It will be an effort for broadening the application of this new MIG welding process. The unique parameters of DC double pulse MIG welding are selected to investigate their effects on weld bead geometry size and appearance of AZ31B Mg

Zhaodong Zhang; Xiangyu Kong

2012-01-01

55

Superparamagnetic Nanocomposite of Silver\\/Iron-Oxide by Inert Gas Condensation  

Microsoft Academic Search

A superparamagnetic nanocomposite of silver and iron oxide was synthesized by gas condensation. The procedure involved (1) coevaporation of silver and iron, (2) in situ oxidation of iron particles, (3) in situ compaction, and (4) post-annealing in an inert or an oxidizing atmosphere. The magnetization plots against H\\/T fell on a single curve from room temperature to 160 K, thereby

Takao Yamamoto; Robert D. Shull; Prabhakar R. Bandaru; Frederic Cosandey; Horst W. Hahn

1994-01-01

56

Relationship Between Arc Voltage Current and Arc Length in TIG (Tungsten Inert Gas) Welding.  

National Technical Information Service (NTIS)

The report investigates the relationship between arc voltage, arc length and current in Tungsten Inert Gas welding. It concludes that using these parameters is not the best method to use in developing a system to control the arc length. (Copyright (c) Cen...

P. N. Drew R. T. Deam

1989-01-01

57

TIG (Tungsten Inert Gas) Welding for Dry Storage Containers,  

National Technical Information Service (NTIS)

The single pass plasma welding technique, developed to meet the original GDCD specification for sealing the AGR dry storage containers, has been shown to contain ineradicable gas pores of up to two-thirds of the wall thickness at the points of keyhole clo...

C. J. Smith E. J. Morgan-Warren

1987-01-01

58

Inert gas clearance from tissue by co-currently and counter-currently arranged microvessels  

PubMed Central

To elucidate the clearance of dissolved inert gas from tissues, we have developed numerical models of gas transport in a cylindrical block of tissue supplied by one or two capillaries. With two capillaries, attention is given to the effects of co-current and counter-current flow on tissue gas clearance. Clearance by counter-current flow is compared with clearance by a single capillary or by two co-currently arranged capillaries. Effects of the blood velocity, solubility, and diffusivity of the gas in the tissue are investigated using parameters with physiological values. It is found that under the conditions investigated, almost identical clearances are achieved by a single capillary as by a co-current pair when the total flow per tissue volume in each unit is the same (i.e., flow velocity in the single capillary is twice that in each co-current vessel). For both co-current and counter-current arrangements, approximate linear relations exist between the tissue gas clearance rate and tissue blood perfusion rate. However, the counter-current arrangement of capillaries results in less-efficient clearance of the inert gas from tissues. Furthermore, this difference in efficiency increases at higher blood flow rates. At a given blood flow, the simple conduction-capacitance model, which has been used to estimate tissue blood perfusion rate from inert gas clearance, underestimates gas clearance rates predicted by the numerical models for single vessel or for two vessels with co-current flow. This difference is accounted for in discussion, which also considers the choice of parameters and possible effects of microvascular architecture on the interpretation of tissue inert gas clearance.

Lu, Y.; Michel, C. C.

2012-01-01

59

Comparison of Inert-Gas-Fusion and Modified Kjeldahl Techniques for Determination of Nitrogen in Niobium Alloys.  

National Technical Information Service (NTIS)

This report compares results obtained for the determination of nitrogen in a selected group of niobium-base alloys by the inert-gas-fusion and the Kjeldahl procedures. In the inert-gas-fusion procedure the sample is heated to approximately 2700 C in a hel...

E. J. Merkle J. W. Graab W. F. Davis

1974-01-01

60

Influence of inert gas species on the growth of silver and molybdenum films via a magnetron discharge  

Microsoft Academic Search

Argon is the process gas of choice for most magnetron sputtering applications due to its large atomic mass, inert chemistry, and relatively low cost. Other inert gases are available for use in sputtering deposition that have varying mass and hence different momentum behaviour during ion bombardment of solid surfaces — affecting sputter yield, particle implantation and incorporation of process gas

G. T. West; P. J. Kelly

61

Comments on ``Behaviour of inert gas bubbles under chemical concentration gradients'' by G.P. Tiwari  

NASA Astrophysics Data System (ADS)

The motion of inert gas bubbles induced by thermal vacancy gradients has previously been used by the present authors to understand gas bubble release in UO 2 and metals. This approach has been recently questioned by Tiwari. In the present letter, a critical discussion of his viewpoint is presented, together with an analysis of the important experimental results of Marachov et al. There appears to be good evidence for the disputed effect.

Evans, J. H.; van Veen, A.

1998-01-01

62

Effectiveness of Various Concentrations of an Inert Gas Mixture for Preventing and Suppressing Mining Equipment Cab Fires: Development of a Dual Cab Fire Inerting System.  

National Technical Information Service (NTIS)

The National Institute for Occupational Safety and Health (NIOSH/PRL) conducted a series of large-scale experiments to evaluate the effectiveness and safety of various concentrations of an inert gas mixture (CO2, 8%; N2, 50%; Ar, 42%) for preventing and s...

C. D. Litton M. I. De Rosa

2008-01-01

63

Effect of High-Pressure Inert Gas Annealing on AlON/Ge Gate Stacks  

NASA Astrophysics Data System (ADS)

We investigated germanium (Ge) metal--insulator--semiconductor (MIS) gate stacks with aluminum oxynitride (AlON) thin dielectric film. We found that high-pressure inert gas post deposition annealing (PDA) using N2 or Ar gas dramatically improved the electrical properties of AlON/Ge MIS gate stacks. The advantage of this process over high-pressure O2 oxidation or annealing, which produce excellent Ge gate stacks, is that no further interface layer growth in the N2 or Ar PDA is expected. We expect that thin AlON films combined with high-pressure inert gas PDA will provide a new way to achieve excellent Ge-MIS gate stacks with scalable equivalent oxide thickness.

Tabata, Toshiyuki; Nagashio, Kosuke; Toriumi, Akira

2012-09-01

64

Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures  

NASA Technical Reports Server (NTRS)

Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 < r* < 0.83. These smooth tube data may serve as a reference to the heat transfer and pressure drop performance in annuli, tubes, and channels having helixes or spacer ribs, or other surfaces.

Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

2007-01-01

65

Onboard Inert Gas Generation System/Onboard Oxygen Gas Generation System (OBIGGS/OBOGS) Study. Part 1; Aircraft System Requirements  

NASA Technical Reports Server (NTRS)

The purpose of this technology assessment is to define a multiphase research study program investigating Onboard Inert Gas Generation Systems (OBIGGS) and Onboard Oxygen Generation Systems (OBOGS) that would identify current airplane systems design and certification requirements (Subtask 1); explore state-of-the-art technology (Subtask 2); develop systems specifications (Subtask 3); and develop an initial system design (Subtask 4). If feasible, consideration may be given to the development of a prototype laboratory test system that could potentially be used in commercial transport aircraft (Subtask 5). These systems should be capable of providing inert nitrogen gas for improved fire cargo compartment fire suppression and fuel tank inerting and emergency oxygen for crew and passenger use. Subtask I of this research study, presented herein, defines current production aircraft certification requirements and design objectives necessary to meet mandatory FAA certification requirements and Boeing design and performance specifications. These requirements will be utilized for baseline comparisons for subsequent OBIGGS/OBOGS application evaluations and assessments.

Reynolds, Thomas L.; Bailey, Delbert B.; Lewinski, Daniel F.; Roseburg, Conrad M.; Palaszewski, Bryan (Technical Monitor)

2001-01-01

66

Research on inert gas narcosis and air velocity effects on metabolic performance  

NASA Technical Reports Server (NTRS)

The effects of air velocity on metabolic performance are studied by using high forced airflow in a closed environment as a mechanism to control the concentration of volatile animal wastes. Air velocities between 100 and 200 ft/min are without significant effects on the metabolism of rats. At velocities of 200 ft/min and above, oxygen consumption and CO2 production as well as food consumption increase. In most instances, the changes are on the order of 5-10%. At the same time, the RQ for the animals increases slightly and generally correlates well with oxygen consumption and CO2 production. Experiments on the nature of inert gas narcosis show that halothane and methoxyflurane are rather potent inhibitors of the NADH:O2 oxidoreductase system in rats. These experiments suggest that the mechanism of inert gas narcosis is not mandatorily related to a membrane surface phenomenon.

1974-01-01

67

Optimization of pyrolysis conditions of scrap tires under inert gas atmosphere  

Microsoft Academic Search

A pyrolysis system was designed for the production of activated carbon and other products from scrap tires. The system allows work under inert atmosphere (N2 gas). The pyrolysis experiments were carried out in a fixed-bed batch reactor of (1.25m length and 0.03m o.d.) which was heated by an electric furnace. The feed material used was scrap tires supplied from General

Mahmood M. Barbooti; Thamer J. Mohamed; Alaa A. Hussain; Falak O. Abas

2004-01-01

68

X-ray characterization of inert gas atomized low carbon astroloy powder  

Microsoft Academic Search

X-ray studies were carried out on an inert gas atomized low carbon (LC) astroloy powder. The as-atomized powder was sieved into different fractions of narrow size using suitable combination of sieves to study the effect of particle size on the compositional homogeneity and lattice parameter. Using a slow scanning X-ray diffraction technique, the lattice parameter of the sample and broadening

Mahendra Kumar; S. V. Nagender Naidu

2004-01-01

69

Microstructure and magnetic properties of inert gas atomized rare earth permanent magnetic materials  

Microsoft Academic Search

Several permanent magnet alloys based on the ternary NdâFeââB (2-14-1) composition have been prepared by inert gas atomization (IGA). The microstructure and magnetic properties of these alloys have been studied as a function of particle size, both before and after heat treatment. Different particle sizes have characteristic properties due to the differences in cooling rate experienced during solidification from the

C. H. Sellers; T. A. Hyde; D. J. Branagan; L. H. Lewis; V. Panchanathan

1997-01-01

70

Microstructure and magnetic properties of inert gas atomized rare earth permanent magnetic materials  

Microsoft Academic Search

Several permanent magnet alloys based on the ternary Nd2Fe14B (2-14-1) composition have been prepared by inert gas atomization (IGA). The microstructure and magnetic properties of these alloys have been studied as a function of particle size, both before and after heat treatment. Different particle sizes have characteristic properties due to the differences in cooling rate experienced during solidification from the

C. H. Sellers; T. A. Hyde; D. J. Branagan; L. H. Lewis; V. Panchanathan

1997-01-01

71

BRIEF COMMUNICATIONS: Experimental investigation of a gasdynamic laser utilizing mixtures of carbon monoxide and an inert gas  

Microsoft Academic Search

Stimulated emission was obtained from mixtures of CO molecules with inert gases (He, Ne, Ar, Kr) expanding supersonically in a planar nozzle 4 cm long (the expansion ratio at the edge of the nozzle was 100). The influence of the nature of the inert gas and of the initial pressure of the mixture on the output power of the stimulated

V. F. Gavrikov; A. P. Dronov; V. K. Orlov; A. K. Piskunov

1975-01-01

72

Bose–Einstein transition temperature in a dilute repulsive gas  

Microsoft Academic Search

We discuss certain specific features of the calculation of the critical temperature of a dilute repulsive Bose gas. Interactions modify the critical temperature in two different ways. First, for gases in traps, temperature shifts are introduced by a change of the density profile, arising itself from a modification of the equation of state of the gas (reduced compressibility); these shifts

Markus Holzmann; Jean-Noel J. N. Fuchs; Gordon A. Baym; Jean-Paul J. P. Blaizot; Franck F. Laloe

2004-01-01

73

Condensate fluctuations in the dilute Bose gas  

SciTech Connect

The fluctuations of a number of particles in the Bose-Einstein condensate are studied in the grand canonical ensemble with an effective single-mode Hamiltonian, which is derived from an assumption that the mode corresponding to the Bose-Einstein condensate does not asymptotically correlate with other modes. The fluctuations are evaluated in the dilute limit with a proposed simple method, which is beyond the mean-field approximation. The accuracy of the latter is estimated; it is shown that the mean-field scheme does not work for the single-mode Hamiltonian, while for the Hartree Hamiltonian it allows us to estimate the condensate fluctuations up to a numerical factor. As a hypothesis, a formula is proposed that relates the fluctuations in the canonical ensemble with that of the grand canonical one.

Cherny, Alexander Yu. [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Strasse 38, D-01187 Dresden (Germany); and Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980, Dubna (Russian Federation)

2005-04-01

74

Evaluation of two gas-dilution methods for instrument calibration  

NASA Technical Reports Server (NTRS)

Two gas dilution methods were evaluated for use in the calibration of analytical instruments used in air pollution studies. A dual isotope fluorescence carbon monoxide analyzer was used as the transfer standard. The methods are not new but some modifications are described. The rotary injection gas dilution method was found to be more accurate than the closed loop method. Results by the two methods differed by 5 percent. This could not be accounted for by the random errors in the measurements. The methods avoid the problems associated with pressurized cylinders. Both methods have merit and have found a place in instrument calibration work.

Evans, A., Jr.

1977-01-01

75

TIG WELDER LOCATED IN THE CLEAN ROOM OF THE TECHNICAL SERVICES BUILDING TSB - THE INERT GAS WELDING  

NASA Technical Reports Server (NTRS)

TIG WELDER LOCATED IN THE CLEAN ROOM OF THE TECHNICAL SERVICES BUILDING TSB - THE INERT GAS WELDING FACILITY IS USED FOR WELDING REFRACTORY METALS IN CONNECTION WITH THE COLUMBIUM LIQUID SODIUM LOOP PROJECT

1963-01-01

76

A Model for Surface Induced Growth of Inert Gas Bubbles in Irradiated Copper-Boron Alloys  

SciTech Connect

A matrix containing inert gas bubbles dilates in direct proportion to the growth experienced by the gas bubbles. This phenomenon is termed as swelling. A model for the swelling induced by the growth of the helium gas bubbles in irradiated copper-boron alloys is presented. The bubbles grow by acquiring vacancies from the external surface, which acts as a source of vacancies. The vacancies reach the surface of the bubbles mainly via lattice diffusion and to a limited extent via diffusion through short-circuiting paths such as grain boundaries and dislocation pipes. The model predicts that overall swelling of the matrix varies as 1.5 power of time. Another consequence of the present model is that the growth rate of a gas bubble varies inversely as the cube of its distance from the external surface. The model has been applied to the data on irradiated copper-boron alloys and found to be in accord with the experimental results. The model is general and can be applied to the growth of all kinds of stationary inert gas bubbles trapped within a crystalline matrix. (authors)

Tiwari, G.P.; Ramadasan, E. [Post Irradiation Examination Division, Bhabha Atomic Research Division (India)

2006-07-01

77

Validation of myocardial blood flow estimation with nitrogen-13 ammonia PET by the argon inert gas technique in humans  

Microsoft Academic Search

We simultaneously determined global myocardial blood flow (MBF) by the argon inert gas technique and by nitrogen-13 ammonia positron emission tomography (PET) to validate PET-derived MBF values in humans. A total of 19 patients were investigated at rest (n=19) and during adenosine-induced hyperaemia (n=16). Regional coronary artery stenoses were ruled out by angiography. The argon inert gas method uses the

Jörg Kotzerke; Gerhard Glatting; Jörg van den Hoff; Martin Höher; Bernd Neumaier; Jochen Wöhrle; Sven N. Reske

2001-01-01

78

A new gas dilution method for measuring body volume.  

PubMed Central

This study was designed to examine the validity of a new gas dilution method (GD) for measuring human body volume and to compare its accuracy with the results obtained by the underwater weighing method (UW). We measured the volume of plastic bottles and 16 subjects (including two females), aged 18-42 years with each method. For the bottles, the volume measured by hydrostatic weighing was correlated highly (r = 1.000) with that measured by the new gas dilution method. For the subjects, the body volume determined by the two methods was significantly correlated (r = 0.998). However, the subject's volume measured by the gas dilution method was significantly larger than that by underwater weighing method. There was significant correlation (r = 0.806) between GD volume-UW volume and the body mass index (BMI), so that UW volume could be predicted from GD volume and BMI. It can be concluded that the new gas dilution method offers promising possibilities for future research in the population who cannot submerge underwater.

Nagao, N; Tamaki, K; Kuchiki, T; Nagao, M

1995-01-01

79

Modelling the transient behaviour of pulsed current tungsten-inert-gas weldpools  

NASA Astrophysics Data System (ADS)

A three-dimensional model is established to simulate the pulsed current tungsten-inert-gas (TIG) welding process. The goal is to analyse the cyclic variation of fluid flow and heat transfer in weldpools under periodic arc heat input. To this end, an algorithm, which is capable of handling the transience, nonlinearity, multiphase and strong coupling encountered in this work, is developed. The numerical simulations demonstrate the transient behaviour of weldpools under pulsed current. Experimental data are compared with numerical results to show the effectiveness of the developed model.

Wu, C. S.; Zheng, W.; Wu, L.

1999-01-01

80

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

81

The Diffusion of Oxygen, Carbon Dioxide, and Inert Gas in Flowing Blood  

PubMed Central

Measurements were made of exchange rates of oxygen, carbon dioxide, and krypton-85 with blood at 37.5°C. Gas transfer took place across a 1 mil silicone rubber membrane. The blood was in a rotating disk boundary layer flow, and the controlling resistance to transfer was the concentration boundary layer. Measured rates were compared with rates predicted from the equation of convective diffusion using velocities derived from the Navier-Stokes equations and diffusivities calculated from the theory for conduction in a heterogeneous medium. The measured absorption rate of krypton-85 was closely predicted by this model. Significant deposition of material onto the membrane surface, resulting in an increased transfer resistance, occurred in one experiment with blood previously used in a nonmembrane type artificial lung. The desorption rate of oxygen from blood at low Po21 was up to four times the corresponding transfer rate of inert gas. This effect is described somewhat conservatively by a local equilibrium form of the convective diffusion equation. The carbon dioxide transfer rate in blood near venous conditions was about twice that of inert gas, a rate significantly greater than predicted by the local equilibrium theory. It should be possible to apply these theoretical methods to predict exchange rates with blood flowing in systems of other geometries.

Spaeth, E. E.; Friedlander, S. K.

1967-01-01

82

Quantitative analysis of trace bulk oxygen in silicon wafers using an inert gas fusion method.  

PubMed

This paper describes a method for removing oxide film from the surface of silicon wafers using an inert gas fusion impulse furnace and precise determination of bulk oxygen within the wafer. A silicon wafer was cut to about 0.35 g (6 x 13 x 2 mm) and dropped into a graphite crucible. The sample was then heated for 40 s at 1300 degrees C. The wafer's oxide film was reduced by carbon and removed as carbon monoxide. The treated silicon sample was taken out of the graphite crucible and maintained again with the holder of the oxygen analyzer. The graphite crucible was then heated to 2100 degrees C. The treated silicon sample was dropped into the heated graphite crucible and the trace bulk oxygen in the wafer was measured using the inert gas fusion infrared absorption method. The relative standard deviations of the oxygen in silicon wafer samples with the removed surface oxide film were determined to be 0.8% for 9.8 x 10(17) atoms/cm3, and 2.7% for 13.0 x 10(17) atoms/cm3. PMID:14640456

Uchihara, Hiroshi; Ikeda, Masahiko; Nakahara, Taketoshi

2003-11-01

83

Experimental observations of effects of inert gas on cavity formation during irradiation  

SciTech Connect

Cavity (void) formation and swelling in non-fissile materials during neutron irradiation and charged particle bombardments are reviewed. Helium is the most important inert gas and is primarily active as a cavity nucleant. It also enhances formation of dislocation structure. Preimplantation of helium overstimulates cavity nucleation and gives a different temperature response of swelling than when helium is coimplanted during the damage process. Helium affects, and is affected by, radiation-induced phase instability. Many of these effects are explainable in terms of cavity nucleation on submicroscopic critical size gas bubbles, and on the influence of the neutral sink strength of such bubbles. Titanium and zirconium resist cavity formation when vacancy loops are present.

Farrell, K.

1980-04-01

84

Lecture 2: Bogoliubov theory of a dilute Bose gas  

Microsoft Academic Search

Second quantization for bosons is reviewed. Bose-Einstein condensation for non-interacting bosons is interpreted as an example of spontaneous symmetry breaking. The spectrum of a dilute Bose gas with hardcore repulsion is calculated within Bogoliubov mean-field theory. It is shown that a Goldstone mode, an acoustic phonon, emerges in association with spontaneous symmetry breaking. Landau criterion for superfluidity is presented.

Christopher Mudry

85

Measuring Diffusivity in Supercooled Liquid Nanoscale Films using Inert Gas Permeation: I. Kinetic Model and Scaling Methods  

SciTech Connect

We describe in detail a diffusion model used to simulate inert gas transport through supercooled liquid overlayers. In recent work, the transport of the inert gas has been shown to be an effective probe of the diffusivity of supercooled liquid methanol in the experimentally challenging regime near the glass transition temperature. The model simulations accurately and quantitatively describe the inert gas permeation desorption spectra. The simulation results are used to validate universal scaling relationships between the diffusivity, overlayer thickness, and the temperature ramp rate for isothermal and temperature programmed desorption. From these scaling relationships we derive simple equations from which the diffusivity can be obtained using the peak desorption time or temperature for an isothermal or set of TPD experiments respectively without numerical simulation. The results presented here demonstrate that the permeation of gases through amorphous overlayers has the potential to be a powerful technique to obtain diffusivity data in deeply supercooled liquids.

Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

2010-11-07

86

Comparison of inert-gas-fusion and modified Kjeldahl techniques for determination of nitrogen in niobium alloys  

NASA Technical Reports Server (NTRS)

This report compares results obtained for the determination of nitrogen in a selected group of niobium-base alloys by the inert-gas-fusion and the Kjeldahl procedures. In the inert-gas-fusion procedure the sample is heated to approximately 2700 C in a helium atmosphere in a single-use graphite crucible. A platinum flux is used to facilitate melting of the sample. The Kjeldahl method consisted of a rapid decomposition with a mixture of hydrofluoric acid, phosphoric acid, and potassium chromate; distillation in the presence of sodium hydroxide; and highly sensitive spectrophotometry with nitroprusside-catalyzed indophenol. In the 30- to 80-ppm range, the relative standard deviation was 5 to 7 percent for the inert-gas-fusion procedure and 2 to 8 percent for the Kjeldahl procedure. The agreement of the nitrogen results obtained by the two techniques is considered satisfactory.

Merkle, E. J.; Graab, J. W.; Davis, W. F.

1974-01-01

87

Gap states in pentacene thin film induced by inert gas exposure.  

PubMed

We studied gas-exposure effects on pentacene (Pn) films on SiO2 and Au(111) substrates by ultrahigh sensitivity photoelectron spectroscopy, which can detect the density of states of ?10(16) states eV-1?cm-3 comparable to electrical measurements. The results show the striking effects for Pn/SiO2: exposure to inert gas (N2 and Ar) produces a sharp rise in gap states from ?10(16) to ?10(18) states eV-1?cm-3 and pushes the Fermi level closer to the valence band (0.15-0.17 eV), as does exposure to O2 (0.20 eV), while no such gas-exposure effect is observed for Pn/Au(111). The results demonstrate that these gap states originate from small imperfections in the Pn packing structure, which are induced by gas penetration into the film through the crystal grain boundaries. PMID:23848923

Bussolotti, Fabio; Kera, Satoshi; Kudo, Kazuhiro; Kahn, Antoine; Ueno, Nobuo

2013-06-28

88

Structural and optical properties of PbSe nanostructure thin films prepared by inert gas condensation  

NASA Astrophysics Data System (ADS)

Lead Selenide (PbSe) nanostructure thin films synthesized via inert gas condensation (IGC) technique. The structure of as-prepared PbSe nanostructure thin films, were studied using Grazing incident in-plane X-ray diffraction (GIIXD). The study reveals that all films crystallized in cubic structure. The particle size (Ps) of the films, were calculated from X-ray diffraction to be ~5, 8 and 11 nm for film thicknesses 20, 46 and 87 nm respectively which have been confirmed with those determined from transmission electron microscope (TEM) micrographs. The optical energy gap was found to be increases from 2.22 eV to 2.37 eV as particle size decreases from 11 nm to 5.5 nm. In addition, the band tail width increased with decreasing the particle size but the refractive index increases with increasing the particle size of the prepared films.

Mahdy, Manal A.; Mahdy, Iman A.; Mahmoud, E. A.

2014-05-01

89

Electron temperature and density measurement of tungsten inert gas arcs with Ar-He shielding gas mixture  

NASA Astrophysics Data System (ADS)

The diagnostics of atmospheric welding plasma is a well-established technology. In most cases the measurements are limited to processes using pure shielding gas. However in many applications shielding gas is a mixture of various components including metal vapor in gas metal arc welding (GMAW). Shielding gas mixtures are intentionally used for tungsten inert gas (TIG) welding in order to improve the welding performance. For example adding Helium to Argon shielding gas allows the weld geometry and porosity to be influenced. Yet thermal plasmas produced with gas mixtures or metal vapor still require further experimental investigation. In this work coherent Thomson scattering is used to measure electron temperature and density in these plasmas, since this technique allows independent measurements of electron and ion temperature. Here thermal plasmas generated by a TIG process with 50% Argon and 50% Helium shielding gas mixture have been investigated. Electron temperature and density measured by coherent Thomson scattering have been compared to the results of spectroscopic measurements of the plasma density using Stark broadening of the 696.5 nm Argon spectral line. Further investigations of MIG processes using Thomson scattering technique are planned.

Kühn-Kauffeldt, M.; Marques, J.-L.; Forster, G.; Schein, J.

2013-10-01

90

Fusao a arco sob atmosfera de gas inerte da esponja de zirconio. (Arc melting in inert gas atmosphere of zirconium sponge).  

National Technical Information Service (NTIS)

The obtainment of metallic zirconium in laboratory scale with commercial and nuclear quality is the objective of the Metallurgy Department of IEN/CNEN - Brazil, so a melting procedure of zirconium sponge in laboratory scale using an arc furnace in inert a...

O. Julio Junior A. H. P. Andrade

1991-01-01

91

Noninvasive Determination of Cardiac Output by the Inert-Gas-Rebreathing Method – Comparison with Cardiovascular Magnetic Resonance Imaging  

Microsoft Academic Search

Background: An easy, noninvasive and accurate technique for measuring cardiac output (CO) would be desirable for the diagnosis and therapy of cardiac diseases. Innocor, a novel inert-gas-rebreathing (IGR) system, has shown promising results in smaller studies. An extensive evaluation in a larger, less homogeneous patient collective is lacking. Methods: We prospectively assessed the accuracy and reproducibility of CO measurements obtained

Joachim Saur; Stephan Fluechter; Frederik Trinkmann; Theano Papavassiliu; Stefan Schoenberg; Joerg Weissmann; Dariusch Haghi; Martin Borggrefe; Jens J. Kaden

2009-01-01

92

Non-Invasive Measurement of Cardiac Output during Atrial Fibrillation: Comparison between Cardiac Magnetic Resonance Imaging and Inert Gas Rebreathing  

Microsoft Academic Search

Objectives: Atrial fibrillation (AF) is one of the most frequent heart rhythm disorders. It potentially influences cardiac function and its measurement. Cardiac magnetic resonance imaging (CMR) has become the new gold standard for non-invasive assessment of cardiac output (CO). A novel inert gas rebreathing (IGR) device based on the Fick Principle also proved promising in patients in sinus rhythm (SR).

J. Saur; F. Trinkmann; C. Doesch; J. Weissmann; K. Hamm; S. O. Schoenberg; M. Borggrefe; D. Haghi; J. J. Kaden

2010-01-01

93

Non-invasive assessment of pulmonary blood flow using an inert gas rebreathing device in fibrotic lung disease  

Microsoft Academic Search

Background and aimsPulmonary hypertension (PH) is increasingly recognised in patients with diffuse lung disease, and is associated with increased mortality. Cardiac output (CO) is a prognostic marker in PH. Non-invasive assessment of pulmonary blood flow (PBFINNOCOR) with the inert gas rebreathing Innocor device has been validated against CO in PH, but not in PH associated with parenchymal lung disease. PBFINNOCOR

Tamera J Corte; Athol U Wells; Michael A Gatzoulis; Derek Cramer; Simon Ward; Peter S Macdonald; Konstantinos Dimopoulos; Stephen J Wort

2010-01-01

94

Combustion of Cr 2 O 3 + Al powder mixtures in a coflow of inert gas: 5. Effect of green density  

Microsoft Academic Search

Combustion of Cr2O3 + Al powder mixtures in a coflow of inert gas (Ar) was investigated upon variation in green density in the presence\\/absence\\u000a of blowing agents (borax, baking soda). The results were rationalized in terms of the convection-conduction theory for combustion\\u000a in heterogeneous condensed systems.

B. S. Seplyarskii; G. B. Brauer; A. G. Tarasov

2009-01-01

95

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

Microsoft Academic Search

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

Stephan Kaufmann; Karl Hilfiker

1999-01-01

96

Requirements for long-life operation of inert gas hollow cathodes - Preliminary results  

NASA Technical Reports Server (NTRS)

An experimental investigation was initiated to establish conditioning procedures for reliable hollow cathode operation via the characterization of critical parameters in a representative cathode test facility. From vacuum pumpdown rates, it was found that approximately 1.5 hours were required to achieve pressure levels within 5 percent of the lowest attainable pressure for this facility, depending on the purge conditions. The facility atmosphere was determined by a residual gas analyzer to be composed of primarily air and water vapor. The effects of vacuum pumping and inert gas purging were evaluated. A maximum effective leakage rate of 2.0 x 10 (exp -3) sccm was observed and its probable causes were examined. An extended test of a 0.64 cm diameter Mo-Re hollow cathode was successfully completed. This test ran for 504 hours at an emission current of 23.0 amperes and a xenon flow rate of 6.1 sccm. Discharge voltage rose continuously from 15 to 21 volts over the course of the test. The temperature of the cathode body during the test was relatively stable at 1160 C. Post-test examination revealed ion-bombardment texturing of the orifice plate to be the only detectable sign of wear on the hollow cathode.

Verhey, Timothy R.; Macrae, Gregory S.

1990-01-01

97

Requirements for long-life operation of inert gas hollow cathodes: Preliminary report  

NASA Technical Reports Server (NTRS)

An experimental investigation was initiated to establish conditioning procedures for reliable hollow cathode operation via the characterization of critical parameters in a representative cathode test facility. From vacuum pumpdown rates, it was found that approximately 1.5 hours were required to achieve pressure levels within 5 percent of the lowest attainable pressure for this facility, depending on the purge conditions. The facility atmosphere was determined by a residual gas analyzer to be composed of primarily air and water vapor. The effects of vacuum pumping and inert gas purging were evaluated. A maximum effective leakage rate of 2.0 x 10(exp -3)sccm was observed and its probable causes were examined. An extended test of a 0.64 cm diameter Mo-Re hollow cathode was successfully completed. This test ran for 504 hours at an emission current of 23.0 amperes and a xenon flow rate of 6.1 sccm. Discharge voltage rose continuously from 15 to 21 volts over the course of the test. The temperature of the cathode body during the test was relatively stable at 1160 C. Post-test examination revealed ion-bombardment texturing of the orifice plate to be the only detectable sign of wear on the hollow cathode.

Verhey, Timothy R.; Macrae, Gregory S.

1990-01-01

98

Ground state asymptotics of a dilute, rotating gas  

NASA Astrophysics Data System (ADS)

We investigate the ground state properties of a gas of interacting particles confined in an external potential in three dimensions and subject to rotation around an axis of symmetry. We consider the Gross-Pitaevskii (GP) limit of a dilute gas. Analysing both the absolute and the bosonic ground states of the system, we show, in particular, their different behaviour for a certain range of parameters. This parameter range is determined by the question whether the rotational symmetry in the minimizer of the GP functional is broken or not. For the absolute ground state, we prove that in the GP limit a modified GP functional depending on density matrices correctly describes the energy and reduced density matrices, independent of symmetry breaking. For the bosonic ground state this holds true if and only if the symmetry is unbroken.

Seiringer, Robert

2003-09-01

99

Formation of inorganic electride thin films via site-selective extrusion by energetic inert gas ions  

NASA Astrophysics Data System (ADS)

Inert gas ion implantation (acceleration voltage 300 kV) into polycrystalline 12CaO.7Al2O3 (C12A7) films was investigated with fluences from 1×1016 to 1×1017 cm-2 at elevated temperatures. Upon hot implantation at 600 °C with fluences greater than 1×1017 cm-2, the obtained films were colored and exhibited high electrical conductivity in the as-implanted state. The extrusion of O2- ions encaged in the crystallographic cages of C12A7 crystal, which leaves electrons in the cages at concentrations up to ~1.4×1021 cm-3, may cause the high electrical conductivity. On the other hand, when the fluence is less than 1×1017 cm-2, the as-implanted films are optically transparent and electrically insulating. The conductivity is enhanced and the films become colored by irradiating with ultraviolet light due to the formation of F+-like centers. The electrons forming the F+-like centers are photo released from the encaged H- ions, which are presumably derived from the preexisting OH- groups. The induced electron concentration is proportional to the calculated displacements per atom, which suggests that nuclear collision effects of the implanted ions play a dominant role in forming the electron and H- ion in the films. The hot ion implantation technique provides a nonchemical process for preparing electronic conductive C12A7 films.

Miyakawa, Masashi; Toda, Yoshitake; Hayashi, Katsuro; Hirano, Masahiro; Kamiya, Toshio; Matsunami, Noriaki; Hosono, Hideo

2005-01-01

100

Precipitation in nanocrystalline Al-Ag prepared by inert gas condensation and by mechanical alloying  

SciTech Connect

One of the well-investigated model systems for precipitation reactions is the Al-Ag system on the Al-rich side of the phase diagram. When the supersaturated homogeneous alloy is aged within the miscibility gap, coherent Ag-rich regions form, the so-called Guinier-Preston (GP) zones. Upon further aging, Ag{sub 2}Al develops in two steps: first, precipitates of the semicoherent {gamma}{prime}-phase nucleate and grow. Second, incoherent precipitates of the equilibrium {gamma}-phase develop. There is general agreement in the literature that GP zones in Al-Ag are roughly spherical, but their exact shape and composition is the subject of ongoing research. GP-zones form homogeneously within the host matrix while Ag{sub 2}Al preferentially precipitates on defects such as dislocations and grain boundaries. Because of the high electron density contrast between Al and Ag, spatial variations of the alloy concentration on a scale of 1 nm--100 nm cause strong small-angle X-ray scattering (SAS). Therefore, SAS has been used extensively to study the decomposition of single-crystal or coarse-grained Al-Ag. In the present work, the precipitation of Ag in nanocrystalline Al-Ag is studied by small- and wide-angle X-ray scattering (WAS). Nanocrystalline samples were prepared by two different methods: inert gas condensation and mechanical alloying.

Hoeckel, P.G.; Weissmueller, J. [Univ. des Saarlandes, Saarbruecken (Germany)] [Univ. des Saarlandes, Saarbruecken (Germany)

1996-09-01

101

Energy balance in disk and CO2 laser beam inert gas fusion cutting  

NASA Astrophysics Data System (ADS)

Experimental, numerical and analytical investigations were performed to give a possible explanation of the differences in cutting quality detected for inert gas laser beam cutting process performed with disk and CO2 laser sources. Cutting experiments were carried out at maximum cutting speed on cold work steel test specimens with different sheet thicknesses. The particular feature of the applied experimental setup was the similar geometry of both the CO2 and the disk laser beam with comparable values of the focus diameter and the Rayleigh length. The thermodynamic analysis was based on experimentally primary losses evaluation by means of polymethylmethacrylate (PMMA) blocks, on numerical computation of conductive power losses and analytical calculation of the remaining terms of energy balance. Energy balance allowed the evaluation of secondary losses and proportion of vaporized kerf volume used for justifying the lower quality of disk laser cuts. The lower proportion of vaporized kerf volume detected for disk laser cuts results in an increased process temperature, thus an increase of viscosity of molten material and the subsequent more difficult ejection of the melted material from the cut kerf.

Scintilla, Leonardo Daniele; Tricarico, Luigi; Wetzig, Andreas; Beyer, Eckhard

2012-02-01

102

Effect of inert cover gas on performance of radioisotope Stirling space power system  

NASA Astrophysics Data System (ADS)

This paper describes an updated Orbital design of a radioisotope Stirling power system and its predicted performance at the beginning and end of a six-year mission to the Jovian moon Europa. The design is based on General Purpose Heat Source (GPHS) modules identical to those previously developed and safety-qualified by the Department of Energy (DOE) which were successfully launched on missions to Jupiter and Saturn by the Jet Propulsion Laboratory (JPL). In each generator, the heat produced by the decay of the Pu-238 isotope is converted to electric power by two free-piston Stirling engines and linear alternators developed by Stirling Technology Company (STC), and their rejected waste heat is transported to radiators by heat pipes. The principal difference between the proposed system design and previous Orbital designs (Or et al., 2000) is the thermal insulation between the heat source and the generator's housing. Previous designs had employed multifoil insulation, whereas the design described here employs Min-K-1800 thermal insulation. Such insulation had been successfully used by Teledyne and GE in earlier RTGs (Radioisotope Thermoelectric Generators). Although Min-K is a much poorer insulator than multifoil in vacuum and requires a substantially greater thickness for equivalent performance, it offers compensating advantages. Specifically it makes it possible to adjust the generator's BOM temperatures by filling its interior volume with inert cover gas. This makes it possible to meet the generator's BOM and EOM performance goals without exceeding its allowable temperature at the beginning of the mission. .

Carpenter, R.; Kumar, V.; Or, C.; Schock, A.

2001-02-01

103

Analysis of cracks in stainless steel TIG (tungsten inert gas) welds  

SciTech Connect

This report contains the results of a combined experimental and analytical study of ductile crack growth in tungsten inert gas (TIG) weldments of austenitic stainless steel specimens. The substantially greater yield strength of the weld metal relative to the base metal causes more plastic deformation in the base metal adjacent to the weld than in the weld metal. Accordingly, the analytical studies focused on the stress-strain interaction between the crack tip and the weld/base-metal interface. Experimental work involved tests using compact (tension) specimens of three different sizes and pipe bend experiments. The compact specimens were machined from a TIG weldment in Type 304 stainless steel plate. The pipe specimens were also TIG welded using the same welding procedures. Elastic-plastic finite element methods were used to model the experiments. In addition to the J-integral, different crack-tip integral parameters such as ..delta..T/sub p/* and J were evaluated. Also, engineering J-estimation methods were employed to predict the load-carrying capacity of the welded pipe with a circumferential through-wall crack under bending.

Nakagaki, M.; Marschall, C.; Brust, F.

1986-12-01

104

Thorium-232 exposure during tungsten inert gas arc welding and electrode sharpening.  

PubMed

To assess the exposure of welders to thorium-232 (232Th) during tungsten inert gas arc (TIG) welding, airborne concentrations of 232Th in the breathing zone of the welder and background levels were measured. The radioactive concentrations were 1.11 x 10(-2) Bq/m3 during TIG welding of aluminum (TIG/Al), 1.78 x 10(-4) Bq/m3 during TIG welding of stainless steel (TIG/SS), and 1.93 x 10(-1) Bq/m3 during electrode sharpening, with 5.82 x 10(-5) Bq/m3 background concentration. Although the annual intake of 232Th estimated using these values did not exceed the annual limit intake (ALI, 1.6 x 10(2) Bq), we recommend reducing 232Th exposure by substituting thoriated electrodes with a thorium-free electrodes, setting up local ventilation systems, and by using respiratory protective equipment. It is also necessary to inform workers that thoriated tungsten electrodes contain radioactive material. PMID:12916759

Saito, Hiroyuki; Hisanaga, Naomi; Okada, Yukiko; Hirai, Shoji; Arito, Heihachiro

2003-07-01

105

MOX and MOX with 237Np/241Am Inert Fission Gas Generation Comparison in ATR  

SciTech Connect

The treatment of spent fuel produced in nuclear power generation is one of the most important issues to both the nuclear community and the general public. One of the viable options to long-term geological disposal of spent fuel is to extract plutonium, minor actinides (MA), and potentially long-lived fission products from the spent fuel and transmute them into short-lived or stable radionuclides in currently operating light-water reactors (LWR), thus reducing the radiological toxicity of the nuclear waste stream. One of the challenges is to demonstrate that the burnup-dependent characteristic differences between Reactor-Grade Mixed Oxide (RG-MOX) fuel and RG-MOX fuel with MA Np-237 and Am 241 are minimal, particularly, the inert gas generation rate, such that the commercial MOX fuel experience base is applicable. Under the Advanced Fuel Cycle Initiative (AFCI), developmental fuel specimens in experimental assembly LWR-2 are being tested in the northwest (NW) I-24 irradiation position of the Advanced Test Reactor (ATR). The experiment uses MOX fuel test hardware, and contains capsules with MOX fuel consisting of mixed oxide manufactured fuel using reactor grade plutonium (RG-Pu) and mixed oxide manufactured fuel using RG-Pu with added Np/Am. This study will compare the fuel neutronics depletion characteristics of Case-1 RG-MOX and Case-2 RG-MOX with Np/Am.

G. S. Chang; M. Robel; W. J. Carmack; D. J. Utterbeck

2006-06-01

106

Joining titanium materials with tungsten inert gas welding, laser welding, and infrared brazing.  

PubMed

Titanium has a number of desirable properties for dental applications that include low density, excellent biocompatibility, and corrosion resistance. However, joining titanium is one of the practical problems with the use of titanium prostheses. Dissolved oxygen and hydrogen may cause severe embrittlement in titanium materials. Therefore the conventional dental soldering methods that use oxygen flame or air torch are not indicated for joining titanium materials. This study compared laser, tungsten inert gas, and infrared radiation heating methods for joining both pure titanium and Ti-6Al-4V alloy. Original rods that were not subjected to joining procedures were used as a control method. Mechanical tests and microstructure analysis were used to evaluate joined samples. Mechanical tests included Vickers microhardness and uniaxial tensile testing of the strength of the joints and percentage elongation. Two-way analysis of variance and Duncan's multiple range test were used to compare mean values of tensile strength and elongation for significant differences (p < or = 0.05). Tensile rupture occurred in the joint region of all specimens by cohesive failure. Ti-6Al-4V samples exhibited significantly greater tensile strength than pure titanium samples. Samples prepared by the three joining methods had markedly lower tensile elongation than the control titanium and Ti-6Al-4V rods. The changes in microstructure and microhardness were studied in the heat-affected and unaffected zones. Microhardness values increased in the heat-affected zone for all the specimens tested. PMID:8809260

Wang, R R; Welsch, G E

1995-11-01

107

[Hydrogen and oxidative stress injury--from an inert gas to a medical gas].  

PubMed

Oxidative stress is intensive cellular oxidation caused by redundant reactive oxygen species (ROS) or free radicals. Redundant ROS causes DNA fracture, lipid peroxidation and protein inactivation, thus leading to severe cell damage. Recent studies have shown that hydrogen is a good anti-oxidant. It selectively reduces the hydroxyl radical, the most cytotoxic of ROS; however, it does not react with other ROS, which play physiological roles. As a result, it could protect tissues against oxidative stress injuries, such as ischemia/reperfusion injury of the heart, liver and intestine, cisplatin nephrotoxicity, sepsis and colon inflammation. As a medical gas, hydrogen may have a prospect for far-reaching clinical application. PMID:21503133

Zhang, Qiao-li; Du, Jun-bao; Tang, Chao-shu

2011-04-18

108

Casting particulate and fibrous metal-matrix composites by vacuum infiltration of a liquid metal under an inert gas pressure  

Microsoft Academic Search

A new method of making metal-matrix composites is reported. This method combines the essentials of three liquid-phase fabrication\\u000a methods: (i) vacuum infiltration, (ii) infiltration under an inert gas pressure, and (iii) squeeze casting. In this method,\\u000a the particulate or fibrous preform is placed in a mould and the matrix alloy is placed above the preform. The matrix alloy\\u000a is heated

Jingyu Yang; D. D. L. Chung

1989-01-01

109

Analysis of residual stress in metal-inert-gas-welded Al2024 using neutron and synchrotron X-ray diffraction  

Microsoft Academic Search

A combination of neutron and synchrotron X-ray diffraction was used to measure and map the full three-dimensional state of residual stress across the cross-section in coupon samples of metal-inert-gas (MIG)-welded 2024 aluminium alloy. Samples were analysed both as-welded and following a post-welding skim which served to remove the weld flash and reduce the plate thickness. The profile of the residual

S. Ganguly; V. Stelmukh; L. Edwards; M. E. Fitzpatrick

2008-01-01

110

A study of thorium exposure during tungsten inert gas welding in an airline engineering population.  

PubMed

To investigate the theoretic possibility of excessive exposure to thorium during the process of tungsten inert gas (TIG) welding using thoriated rods we carried out a cross-sectional study of TIG welders and an age- and skill-matched group. We measured the radiation doses from inhaled thorium that was retained in the body and investigated whether any differences in health or biologic indices could have been attributable to the welding and tip-grinding process. Sixty-four TIG welders, 11 non-TIG welders, and 61 control subjects from an airline engineering population participated. All of the subjects were interviewed for biographic, occupational history and morbidity details. All of the welders and eight control subjects carried out large-volume urine sampling to recover thorium 232 and thorium 228; this group also had chest radiographs. All of the subjects had a blood sample taken to estimate liver enzymes, and they provided small-volume urine samples for the estimation of retinol-binding protein and beta 2-microglobulin. We found no excess of morbidity among the TIG or non-TIG welding groups, and the levels of retinol-binding protein and beta 2-microglobulin were the same for both groups. There was a higher aspartate aminotransferase level in the control group. The internal radiation doses were estimated at less than an annual level of intake in all cases, and considerably less if the exposure (as was the case) was assumed to be chronic over many years. Some additional precautionary measures are suggested to reduce further any potential hazard from this process. PMID:8396174

McElearney, N; Irvine, D

1993-07-01

111

Comparison of methods for separating small quantities of hydrogen isotopes from an inert gas  

SciTech Connect

It is frequent within tritium processing systems that a small amount of hydrogen isotopes (Q{sub 2}) must be separated from an inert gas such as He, Ar and N{sub 2}. Thus, a study of presently available technologies for effecting such a separation was performed. A base case and seven technology alternatives were identified and a simple design of each was prepared. These technologies included oxidation-adsorption-metal bed reduction, oxidation-adsorption-palladium membrane reactor, cryogenic adsorption, cryogenic trapping, cryogenic distillation, hollow fiber membranes, gettering and permeators. It was found that all but the last two methods were unattractive for recovering Q{sub 2} from N{sub 2}. Reasons for technology rejection included (1) the method unnecessarily turns the hydrogen isotopes into water, resulting in a cumbersome and more hazardous operation, (2) the method would not work without further processing, and (3) while the method would work, it would only do so in an impractical way. On the other hand, getters and permeators were found to be attractive methods for this application. Both of these methods would perform the separation in a straightforward, essentially zero-waste, single step operation. The only drawback for permeators was that limited low-partial Q{sub 2} pressure data is available. The drawbacks for getters are their susceptibility to irreversible and exothermic reaction with common species such as oxygen and water, and the lack of long-term operation of such beds. More research is envisioned for both of these methods to mature these attractive technologies.

Willms, R.S.; Tuggle, D.; Birdsell, S.; Parkinson, J.; Price, B. [Los Alamos National Lab., NM (United States); Lohmeir, D. [Savannah River Site, Aiken, SC (United States)

1998-03-01

112

Mobility of Supercooled liquid Toluene, Ethylbenzene, and Benzene near their Glass Transition Temperatures Investigated using Inert Gas Permeation  

SciTech Connect

We investigate the mobility of supercooled liquid toluene, ethylbenzene, and benzene near their respective glass transition temperatures (Tg). The permeation rate of Ar, Kr, and Xe through the supercooled liquid created when initially amorphous overlayers heated above their glass transition temperature is used to determine the diffusivity. Amorphous benzene crystallizes at temperatures well below its Tg and as a result the inert gas underlayer remains trapped until the onset of benzene desorption. In contrast, for toluene and ethylbenzene the onset of inert gas permeation is observed at temperatues near Tg. The inert gas desorption peak temperature as a function of the heating rate and overlayer thickness is used to quantify the diffusivity of supercooled liquid toluene and ethylbenzene from 115 K to 135 K. In this temperature range, diffusivities are found to vary across five orders of magnitude (~10-14 to 10-9 cm2/s). These data are compared to viscosity measurements and used to determine the low temperature fractional Stokes-Einstein exponent. Efforts to determine the diffusivity of a mixture of benzene and ethylbenzene are detailed, and the effect of mixing these materials on benzene crystallization is explored using infrared spectroscopy.

May, Robert A.; Smith, R. Scott; Kay, Bruce D.

2013-11-21

113

Compatibility of Space Nuclear Power Plant Materials in an Inert He/Xe Working Gas Containing Reactive Impurities  

SciTech Connect

A major materials selection and qualification issue identified in the Space Materials Plan is the potential for creating materials compatibility problems by combining dissimilar reactor core, Brayton Unit and other power conversion plant materials in a recirculating, inert He/Xe gas loop containing reactive impurity gases. Reported here are results of equilibrium thermochemical analyses that address the compatibility of space nuclear power plant (SNPP) materials in high temperature impure He gas environments. These studies provide early information regarding the constraints that exist for SNPP materials selection and provide guidance for establishing test objectives and environments for SNPP materials qualification testing.

MM Hall

2006-01-31

114

Irreversible wall collisions and thermalization of a gas of inert atoms  

Microsoft Academic Search

Reflection of inert, charge-neutral, spherical atoms from a fixed solid wall with cubic symmetry at low temperature is considered. Working in the limit of classical trajectories, a condition is stated for the irreversibility of reflections, in terms of inelastic energy exchange with wall phonons, from which two classes of atomic energies are implied: I and R. It is found that

Richard L Liboff

1995-01-01

115

Quantum hydrodynamics in dilute-gas Bose-Einstein condensates  

NASA Astrophysics Data System (ADS)

The peculiar dynamics of superfluids are a fascinating research topic. Since the first generation of a dilute gas Bose-Einstein condensate (BEC) in 1995, quantum degenerate atomic gases have taken the investigation of quantum hydrodynamics to a new level. The atomic physics toolbox has grown tremendously and now provides unique and powerful ways to explore nonlinear quantum systems. As an example, pioneering results have recently revealed that the counterflow between two superfluids can be used as a well controlled tool to access the rich dynamics of vector systems. New structures, such as beating dark-dark solitons which only exist in multicomponent systems and have never been observed before, can now be realized in the lab for the first time. Furthermore, the field of nonlinear quantum hydrodynamics is entering new regimes by exploiting Raman dressing as a tool to directly modify the dispersion relation. This leads to the generation of spin-orbit coupled BECs, artificial gauge fields, etc. that are currently receiving tremendous interest due to their parallels to complex condensed-matter systems. Studies of quantum hydrodynamics help to develop a profound understanding of nonlinear quantum dynamics, which is not only of fundamental interest but also of eminent importance for future technological applications, e.g. in telecommunication applications using optical solitons in fibers. This talk will showcase some ``classic'' hallmark results and highlight recent advances from the forefront of the field.

Engels, Peter

2012-10-01

116

Method for extending the useful shelf-life of refrigerated red blood cells by flushing with inert gas  

DOEpatents

A method is disclosed using oxygen removal for extending the useful shelf-life of refrigerated red blood cells. A cost-effective, 4 C storage procedure that preserves red cell quality and prolongs post-transfusion in vivo survival is described. Preservation of adenosine triphosphate levels and reduction in hemolysis and in membrane vesicle production of red blood cells stored at 4 C for prolonged periods of time is achieved by removing oxygen from the red blood cells at the time of storage; in particular, by flushing with an inert gas. Adenosine triphosphate levels of the stored red blood cells are boosted in some samples by addition of ammonium phosphate. 4 figs.

Bitensky, M.W.; Yoshida, Tatsuro

1997-04-29

117

Method for extending the useful shelf-life of refrigerated red blood cells by flushing with inert gas  

DOEpatents

Method using oxygen removal for extending the useful shelf-life of refrigerated red blood cells. A cost-effective, 4.degree. C. storage procedure that preserves red cell quality and prolongs post-transfusion in vivo survival is described. Preservation of adenosine triphosphate levels and reduction in hemolysis and in membrane vesicle production of red blood cells stored at 4.degree. C. for prolonged periods of time is achieved by removing oxygen therefrom at the time of storage; in particular, by flushing with an inert gas. Adenosine triphosphate levels of the stored red blood cells are boosted in some samples by addition of ammonium phosphate.

Bitensky, Mark W. (Los Alamos, NM); Yoshida, Tatsuro (Los Alamos, NM)

1997-01-01

118

Changing inert gas mixing ratios on Mars using the York Mars GCM  

NASA Astrophysics Data System (ADS)

The current version of the York Mars model, GEM-MARS, is currently undergoing revision, and is being re-developed and assessed to be used in a semi-operational mode for planetary missions. GEM-Mars is based on the dynamical core of the Canadian Weather Forecast GEM (Global Environment Multi-scale) Model and our current version of GEM-MARS uses version 3.3.0. (Experiments are continuing at BIRA with a version which has a staggered vertical grid.) This study intends to focus on the condensation aspects of CO2 and its impact on the mixing ratios of inert (on a seasonal time scale) species for example such as Ar, and CO. As CO2 floods the polar atmosphere in the springtime the mixing ratios of the inert species decrease until mixing from lower latitudes adjusts the balance. In winter time the opposite sequence is obtained. We use straightforward CO2 condensation based on the work of Forget (1998) and adjust the 4D mixing ratio of the species in the column to ensure mass conservation for the basic species which make up the Martian atmosphere.

Beagley, S. R.; Fomichev, V. I.; Semeniuk, K.; Kaminski, J. W.; Wu, D.; Lupu, A.; Fazel-Rastgar, F.; McConnell, J. C.; Daerden, F.; Neary, L.

2012-12-01

119

Effects of oxygen cover gas and NaOH dilution on gas generation in tank 241-SY-101 waste  

SciTech Connect

Laboratory studies are reported of gas generation in heated waste from tank 241-SY-101. The rates of gas generation and the compositions of product gas were measured. Three types of tests are compared. The tests use: undiluted waste, waste diluted by a 54% addition of 2.5 M NaOH, and undiluted waste with a reactive cover gas of 30% Oxygen in He. The gas generation rate is reduced by dilution, increased by higher temperatures (which determines activation energies), and increased by reactions of Oxygen (these primarily produce H{sub 2}). Gases are generated as reduction products oxidation of organic carbon species by nitrite and oxygen.

Person, J.C.

1996-05-30

120

A method for calculating regional cerebral blood flow from emission computed tomography of inert gas concentrations  

SciTech Connect

Emission tomography of positron or gamma emitting inert gases allows calculation of regional cerebral blood flow (rCBF) in cross-sectional slices of human brain. An algorithm is presented for rCBF calculations from a sequence of time averaged tomograms using inhaled 133Xe. The approach is designed to avoid loss of information in brain areas with low flow rates. It is based on linearizing and scaling the early isotope distribution picture (recorded from 0 to 2 min) in rCBF units of ml/100 g/min. This is done by calculating the time constant ki for pixels with high count rate using the entire sequence of four 1 min pictures and using a fixed value for the brain:blood partition coefficient, lambda. The method is essentially based on the bolus distribution principle, and it allows the estimation of blood flow in ischemic areas. Application to positron emission tomography is discussed.

Celsis, P.; Goldman, T.; Henriksen, L.; Lassen, N.A.

1981-10-01

121

Highly size-controlled synthesis of metal nanoclusters by inert-gas condensation for nano-devices.  

PubMed

Metal nanoclusters were fabricated by inert-gas condensation in a sputtering reactor. From transmission electron microscopy, it was confirmed that copper nanoclusters with a high degree of monodispersity in size of about 5 nm were successfully produced. The conductance of the percolated nanocluster film was measured. In order to incorporate nano-scale arrangement characterizations in nano-devices being operated in air, aging experiments of the specimen after long time in air were carried. Negative temperature coefficient of resistance suggests that surface native copper oxide in core-shell structured nanoclusters was mainly responsible for the conductance, because copper oxide is known as semiconductor. After aged at higher than 100 degrees C, the conductance at room temperature didn't return to the original value. This irreversible phenomenon might be due to coarsening and/or coalescence of copper nanoclusters. PMID:20359024

Kang, Il-Suk; Seo, Hyun-Sang; Kim, Deuk-Han; Lee, Taek-Yeong; Yang, Jun-Mo; Hwang, Wook-Jung; Ahn, Chi Won

2010-05-01

122

Microstructural investigations of rapidly solidified Cu-Nb alloy powders produced by inert-gas atomization. Technical report  

SciTech Connect

This study presents a metallographic technique which enables the microstructural examination of the cross-sections of individual, fine-scale (10-75 um) powder particles. The technique was developed to permit characterization of the as-solidified features of Cu-based powders produced by high pressure inert gas atomization in order to relate the microstructures to processing history. In order to perform the necessary microscopy to elucidate the microstructural features, a metallographic technique was developed to permit characterization of the as-atomized microstructures within the individual powder particles. This technique involved classifying, mounting, and polishing through the diameters of individual powder particles and then using an attack etch to remove some of the copper matrix. This enabled characterization of the niobium-rich second phase. Secondary electron imaging on a scanning electron microscope provided the necessary resolution to characterize the second phase morphologies as a function powder-particle size, ultimately relating the microstructures to processing conditions.

Zeik, K.L.; Anderson, I.E.; Koss, D.A.; Howell, P.R.

1991-04-30

123

Computation of decompression schedules for single inert gas-oxygen dives using a hand-held programmable calculator.  

PubMed

An algorithm for on-site computation with a hand-held programmable calculator (TI-59, Texas Instruments) of single inert-gas decompression schedules is described. This program is based on Workman's 'M-value' method. It can compute decompression schedules with changes in the oxygen content of the breathing mixture and extension of stay at any decompression stop. The features of the program that enable calculation of atypical dive profiles, along with the portability of small calculators, would make such an algorithm suitable for on-site applications. However, since dive profiles generated by the program have not yet been tested, divers are warned not to generate schedules until their safety has been established by field tests. PMID:6257447

Ranade, A; Peterson, R E

1980-08-01

124

Federal helium program: The reaction over an inert gas. Final report  

SciTech Connect

Helium, present in relatively high concentrations in only a few natural gas fields, is released to the atmosphere and wasted when the natural gas is burned as fuel. Government involvement in helium conservation dates to the Helium Act of 1925 which authorized the Bureau of Mines to build and operate a large-scale helium extraction and purification plant. From 1929 until 1960 the federal government was the only domestic helium producer. In 1960, Congress amended the Helium Act to provide incentives to natural gas producers for stripping natural gas of its helium, for purchase of the separated helium by the government, and for its long-term storage. With over 960 million cubic meters (34.6 billion cubic feet) of helium in government storage and a large private helium recovery industry, questions arise as to the need for either the federal helium extraction program or the federally maintained helium stockpile.

Mielke, J.E.

1996-10-09

125

Effects of inert species in the gas phase in a model for the catalytic oxidation of CO.  

PubMed

We study by kinetic Monte Carlo simulations the catalytic oxidation of carbon monoxide on a surface in the presence of contaminants in the gas phase. The process is simulated by a Ziff-Gulari-Barshad (ZGB) model that has been modified to include the effect of the contaminants and to eliminate an unphysical oxygen poisoned phase at very low CO partial pressures. The impurities can adsorb and desorb on the surface but otherwise remain inert. We find that if the impurities cannot desorb, no matter how small their proportion in the gas mixture, the reactive window and discontinuous transition to a CO poisoned phase at high CO pressures that characterize the original ZGB model disappear. The coverages become continuous, and once the surface has reached a steady state there is no production of CO(2). This is quite different from the behavior of systems in which the surface presents a fixed percentage of impurities. When the contaminants are allowed to desorb, the reactive phase appears again for CO pressures below a value that depends on the proportion of contaminants in the gas and on their desorption rate. PMID:22587074

Buendía, G M; Rikvold, P A

2012-03-01

126

Inert gas stratigraphy of Apollo 15 drill core sections 15001 and 15003  

NASA Technical Reports Server (NTRS)

Rare gase contents were studied in Apollo 15 drill core sections corresponding to 207 to 238 and 125 to 161-cm depths, with respect to layering of the core, turnover on a centimeter scale, and cosmic proton bombardment history. Trapped gas abundance was established in all samples, the mean grain size being a major factor influencing the absolute rare gas contents. Analysis of the results suggests that the regolith materials were exposed to galactic and solar cosmic rays long before their deposition.

Huebner, W.; Kirsten, T.; Heymann, D.

1973-01-01

127

Combustion of bulk density powder mixtures in a coflow of inert gas: 6*(Fe 2 O 3 + 2Al) + 30% Al 2 O 3 mixtures  

Microsoft Academic Search

Investigated was the combustion of bulk density (Fe2O3 + 2Al) + 30% Al2O3 mixtures in a coflow of inert gas (Ar) in the presence\\/absence of blowing agents (borax, baking soda) and applied pressure\\u000a difference ?P. The results have been rationalized in terms of the conduction-convection theory for combustion in heterogeneous systems.

G. B. Brauer; A. G. Tarasov; B. S. Seplyarskii

2009-01-01

128

Observation of the trapping of radioactive inert gas radon on oxide glass surfaces: Macroporous scintillating-glass-fiber bundler alpha detector  

Microsoft Academic Search

We report the observation of the trapping of radioactive inert gas radon (222Rn) on oxide glass under ambient air temperature and pressure of 300 K and 760 Torr, respectively. Radon diffuses from the source, through two macroporous scintillating-glass-fiber bundle alpha detectors in series, to the end of the linear closed system filled with ambient air. The strategy is to provide

I. S. Kim; A. Appleby; G. H. Sigel

1997-01-01

129

Observation of the trapping of radioactive inert gas radon on oxide glass surfaces: Macroporous scintillating-glass-fiber bundle alpha detector  

Microsoft Academic Search

We report the observation of the trapping of radioactive inert gas radon (222Rn) on oxide glass under ambient air temperature and pressure of 300 K and 760 Torr, respectively. Radon diffuses from the source, through two macroporous scintillating-glass-fiber bundle alpha detectors in series, to the end of the linear closed system filled with ambient air. The strategy is to provide

I. S. Kim; A. Appleby; G. H. Sigel Jr.

1997-01-01

130

Modeling and analyzing the effects of heat treatment on the characteristics of magnesium alloy joint welded by the tungsten-arc inert gas welding  

Microsoft Academic Search

The objective of this paper is to present the mathematical models for modeling and analysis of the effects of heat treatment on the characteristics of magnesium alloy joint welded by the tungsten-arc inert gas (TIG) welding. The process of heat treatment adopts the tempering process with varying processing parameters, including tempering temperature and tempering time. The microstructure and mechanical properties

Te-Chang Tsai; Chih-Chung Chou; Deng-Maw Tsai; Ko-Ta Chiang

2011-01-01

131

EFFECT OF VENTILATION AND PERFUSION IMBALANCE ON INERT GAS REBREATHING VARIABLES  

EPA Science Inventory

The effects of ventilation-to-perfusion (Va/Qc) maldistribution within the lungs on measured multiple gas rebreathing variables were studied in 14 dogs. The rebreathing method (using He, C18C, and C2H2) allows for measurements of pulmonary capillary blood flow (Qc), diffusing cap...

132

The effect of dilution on the gas retention behavior of Tank 241-SY- 103 waste  

SciTech Connect

Twenty-five of the 177 underground waste storage tanks on the Hanford Site have been placed on the Flammable Gas watch list. These 25 tanks, containing high-level waste generated during plutonium and uranium processing, have been identified as potentially capable of accumulating flammable gases above the lower flammability limit (Babad et al. 1991). In the case of Tanks 241-SY-101 and 241-SY-103, it has been proposed that diluting the tank waste may mitigate this hazard (Hudson et al. 1995; Stewart et al. 1994). The effect of dilution on the ability of waste from Tank 241-SY-103 to accumulate gas was studied at Pacific Northwest National Laboratory. A similar study has been completed for waste from Tank 241-SY-101 (Bredt et al. 1995). Because of the additional waste-storage volume available in Tank 241-SY-103 and because the waste is assumed to be similar to that currently in Tank 241-SY-101, Tank 241-SY-103 became the target for a demonstration of passive mitigation through in-tank dilution. In 1994, plans for the in-tank dilution demonstration were deferred pending a decision on whether to pursue dilution as a mitigation strategy. However, because Tank 241-SY-103 is an early retrieval target, determination of how waste properties vary with dilution will still be required.

Bredt, P.R.; Tingey, S.M.

1996-01-01

133

Comparison of water-based foam and inert-gas mass emergency depopulation methods.  

PubMed

Current control strategies for avian influenza (AI) and other highly contagious poultry diseases include surveillance, quarantine, depopulation, disposal, and decontamination. Selection of the best method of emergency mass depopulation involves maximizing human health and safety while minimizing disease spread and animal welfare concerns. Proper selection must ensure that the method is compatible with the species, age, housing type, and disposal options. No one single method is appropriate for all situations. Gassing is one of the accepted methods for euthanatizing poultry. Whole-house, partial-house, or containerized gassing procedures are currently used. The use of water-based foam was developed for emergency mass depopulation and was conditionally approved by the United States Department of Agriculture in 2006. Research has been done comparing these different methods; parameters such as time to brain death, consistency of time to brain death, and pretreatment and posttreatment corticosterone stress levels were considered. In Europe, the use of foam with carbon dioxide is preferred over conventional water-based foam. A recent experiment comparing CO2 gas, foam with CO2 gas, and foam without CO2 gas depopulation methods was conducted with the use of electroencephalometry results. Foam was as consistent as CO2 gassing and more consistent than argon-CO2 gassing. There were no statistically significant differences between foam methods. PMID:20521728

Alphin, R L; Rankin, M K; Johnson, K J; Benson, E R

2010-03-01

134

Ferronematic ground state of the dilute dipolar Fermi gas.  

PubMed

It is shown that a homogeneous two-component Fermi gas with (long-range) dipolar and short-range isotropic interactions has a ferronematic phase for suitable values of the dipolar and short-range coupling constants. The ferronematic phase is characterized by having a nonzero magnetization and long-range orientational uniaxial order. The Fermi surface of the spin-up (-down) component is elongated (compressed) along the direction of the magnetization. PMID:20365988

Fregoso, Benjamin M; Fradkin, Eduardo

2009-11-13

135

Ferronematic Ground State of the Dilute Dipolar Fermi Gas  

SciTech Connect

It is shown that a homogeneous two-component Fermi gas with (long-range) dipolar and short-range isotropic interactions has a ferronematic phase for suitable values of the dipolar and short-range coupling constants. The ferronematic phase is characterized by having a nonzero magnetization and long-range orientational uniaxial order. The Fermi surface of the spin-up (-down) component is elongated (compressed) along the direction of the magnetization.

Fregoso, Benjamin M.; Fradkin, Eduardo [Department of Physics, University of Illinois, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States)

2009-11-13

136

A van der Waals Equation of State for a Dilute Boson Gas  

ERIC Educational Resources Information Center

An equation of state of a system is a relationship that connects the thermodynamic variables of the system such as pressure and temperature. Such equations are well known for classical gases but less so for quantum systems. In this paper we develop a van der Waals equation of state for a dilute boson gas that may be used to explain the occurrence…

Deeney, F. A.; O'Leary, J. P.

2012-01-01

137

Synchrotron X-ray measurement and finite element analysis of residual strain in tungsten inert gas welded aluminum alloy 2024  

NASA Astrophysics Data System (ADS)

Residual strains have been measured in a tungsten inert gas (TIG) butt-welded 2024 aluminum alloy plate using synchrotron X-ray diffraction. Novel two-dimensional strain maps spanning the entire plate reveal steep gradients in residual stress and provide detailed validation data for finite element (FE) analysis. Two variants of a FE model have been used to predict the residual strain distributions, incorporating different levels of plate constraint. The model uses decoupled thermal and elastic-plastic mechanical analyses and successfully predicts the longitudinal and transverse residual strain field over the entire weld. For butt weld geometries, the degree of transverse constraint is shown to be a significant boundary condition, compared to simpler bead-on-plate analyses. The importance of transverse residual strains for detailed model validation is highlighted, together with the need for care in selecting the location for line scans. The residual stress is largest in the heat-affected zone (HAZ), being equal to the local postweld yield stress, though the strength increases subsequently by natural aging. In addition, a halving of the diffraction line width has been observed local to the weld, and this correlates with the microstructural changes in the region.

Preston, R. V.; Shercliff, H. R.; Withers, P. J.; Hughes, D. J.; Smith, S. D.; Webster, P. J.

2006-12-01

138

Precipitate microstructures and resulting properties of Al-Zn-Mg metal inert gas-weld heat-affected zones  

NASA Astrophysics Data System (ADS)

Using the combination of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), the precipitate microstructure is quantitatively investigated in the heat-affected zones (HAZs) of Al-Zn-Mg metal inert gas (MIG)-welds, and the resulting mechanical properties are determined by hardness measurements. Three initial states prior to welding (T4, T6, and T7) are investigated, and the subsequent microstructure evolution during natural aging and postwelding heat treatments (PWHTs) is assessed. The critical part of the HAZ is shown to be the transition region where partial dissolution of the initially present precipitates occurs. In this transition zone, precipitate coarsening is shown to occur for the T6 and T7 initial states, contrarily to the T4 material. After PWHT, the T6 and T7 materials experience a weak region related to this coarsening behavior, whereas the T4 material HAZ is able to recover a homogeneous microstructure after a suitably chosen PWHT. Simple model ramp heat treatments are shown to describe the main phenomena involved in the HAZ. Finally, a precipitation hardening model is successfully applied to the microstructural data to describe the hardness profiles in the various HAZs.

Nicolas, M.; Deschamps, A.

2004-05-01

139

Abnormal distribution of microhardness in tungsten inert gas arc butt-welded AZ61 magnesium alloy plates  

SciTech Connect

In this study, the effects of heat input on the distribution of microhardness of tungsten inert gas (TIG) arc welded hot-extruded AZ61 magnesium alloy joints were investigated. The results show that with an increase of heat input, the distributions of microhardness at the top and bottom of the welded joints are different because they are determined by both the effect of grain coarsening and the effect of dispersion strengthening. With an increase of the heat input, the microhardness of the heat-affected zone (HAZ) at the top and bottom of welded joints and the fusion zone (FZ) at the bottom of welded joints decreased gradually, while the microhardness of the FZ at the top of welded joints decreased initially and then increased sharply. The reason for the abnormal distribution of microhardness of the FZ at the top of the welded joints is that this area is close to the heat source during welding and then large numbers of hard {beta}-Mg{sub 17}(Al,Zn){sub 12} particles are precipitated. Hence, in this case, the effect of dispersion strengthening dominated the microhardness.

Xu Nan [College of Material Science and Engineering, Chongqing University, Chongqing 400044 (China); Shen Jun, E-mail: shenjun2626@163.com [College of Material Science and Engineering, Chongqing University, Chongqing 400044 (China); Xie Weidong; Wang Linzhi; Wang Dan; Min Dong [College of Material Science and Engineering, Chongqing University, Chongqing 400044 (China)

2010-07-15

140

Energy barrier enhancement by weak magnetic interactions in Co/Nb granular films assembled by inert gas condensation  

NASA Astrophysics Data System (ADS)

A series of nanogranular Co/Nb samples has been prepared using an unfiltered beam of Co nanoparticles preformed by inert gas condensation. The preparation technique is shown to be a simple and effective method for fabricating, in a single deposition step, a sample series across which both particle size and concentration vary. We estimate the presence of weak interparticle (dipole-dipole) interactions ranging from 7 to 19% in strength (normalized to the median anisotropy energy barrier) across the present series. With the aim of elucidating the effect of such interactions on the blocking behavior of such nanogranular material, we have studied the field and temperature dependence of the magnetization in the films. For each sample, the temperature of the maximum in the zero-field-cooled magnetization curve (TMAX) is found to lie between the values of blocking (TB) and freezing (TF) temperature estimated from the experimentally determined particle size and concentration; i.e., TB

de Toro, J. A.; González, J. A.; Normile, P. S.; Muñiz, P.; Andrés, J. P.; López Antón, R.; Canales-Vázquez, J.; Riveiro, J. M.

2012-02-01

141

Ultrasonic and resistive hydrogen sensors for inert gas-water vapour atmospheres  

NASA Astrophysics Data System (ADS)

Hydrogen concentration measurements were developed for a series of experiments in which a molten oxide is mixed with water to study vapour explosion phenomena. The gas mixture to be analysed consisted of hydrogen with water vapour and either helium or argon. Two types of sensor have been developed for these tests. The first is an ultrasonic sensor, which detects variations in the acoustic velocity within a 0.4 mm-diameter palladium wire. The sensor measures hydrogen concentrations in the range 0.1-100%, at atmospheric pressure, over an operating temperature range of 200-400 °C. The response time (for 0-90% of the final response) is about 30 s at 180 °C and 8 s at 380 °C. The second sensor consists of a palladium coil, constructed with 0.05 mm-diameter wire that is wound around a ceramic tube. Measurements of wire resistance were used to detect partial pressure of hydrogen. This sensor operates at 150-300 °C and measures hydrogen concentrations of 1-100%. The response time is short, 1-2 s for a temperature of 300 °C.

Lomperski, S.; Anselmi, M.; Huhtiniemi, I.

2000-05-01

142

Effects of ventilation on cardiac output determined by inert gas rebreathing.  

PubMed

One of the most important methodological problems of the foreign gas rebreathing technique is that outcome of the measurements depends on procedural variables such as rebreathing frequency (RF), rebreathing bag volume (V(reb)), lung volume at start of rebreathing and intervals between measurements. Therefore, in 10 healthy males we investigated the effects of changes in ventilation pattern on cardiac output (CO) estimated by an N(2)O-rebreathing technique. Reducing the rebreathing volume (V(reb)) from 1.5 to 1.0 l diminished CO by 0.5 +/- 0.2 l min(-1), whereas an increase in V(reb) from 1.5 to 2.5 l had no effects. CO was 1.0 +/- 0.2 l min(-1) higher when, rebreathing was performed after a forced expiration than following a normal tidal expiration. Serial determinations of CO required a 3-min interval between the measurements to avoid effects of recirculation of N(2)O. Changing RF from 15 to 30 breaths min(-1) or adding serial dead space by up to 600 ml did not affect the determination of CO. In conclusion, the rebreathing procedure for determination of CO at rest should be performed following a normal tidal expiration with a rebreathing bag volume of between 1.5 and 2.5 l and with manoeuvres separated by at least 3-5 min. Variations in RF within the physiological range from 15 to 30 breaths min(-1) do not affect outcome of the measurements. PMID:15888093

Damgaard, Morten; Norsk, Peter

2005-05-01

143

Reaction of trace mercury in natural gas with dilute polysulfide solutions in a packed column  

SciTech Connect

This paper reports that the natural gas produced around the world can contain traces of mercury which have to be removed. It is difficult to purify gas to desired mercury levels using conventional techniques. By scrubbing with dilute polysulfide solution, the residual mercury in the gas can be removed from about 0.1 to below 0.01 ppb, a reduction of 90%. In this system, the gas is passed through a packed tower wetted with a solution containing 3 ppm of polysulfide salt. Stainless steel packings are effective for this application. In addition to promoting gas-liquid contact, the stainless steel packings adsorb and concentrate polysulfides which react with Hg in the gas to form insoluble HgS, and thus remove Hg from the gas.

Not Available

1991-12-01

144

Interfacial microstructure and mechanical properties of aluminium–zinc-coated steel joints made by a modified metal inert gas welding–brazing process  

Microsoft Academic Search

The microstructure and properties of aluminium–zinc coated steel lap joints made by a modified metal inert gas CMT welding–brazing process was investigated. It was found that the nature and the thickness of the high-hardness intermetallic compound layer which formed at the interface between the steel and the weld metal during the welding process varied with the heat inputs. From the

H. T. Zhang; J. C. Feng; P. He; H. Hackl

2007-01-01

145

Brazability of dissimilar metals tungsten inert gas butt welding–brazing between aluminum alloy and stainless steel with Al–Cu filler metal  

Microsoft Academic Search

Dissimilar metals tungsten inert gas butt welding–brazing between 5A06 aluminum alloy and SUS321 stainless steel was carried out using Al–Cu6 filler metal and non-corrosive flux. A thin intermetallic compound layer has formed in welded seam\\/steel interface and the average thickness of the whole layer is 3–5?m, which is less than the limited value of 10?m. The intermetallic compound layer consists

S. B. Lin; J. L. Song; C. L. Yang; C. L. Fan; D. W. Zhang

2010-01-01

146

46 CFR 154.1848 - Inerting.  

Code of Federal Regulations, 2010 CFR

...air is admitted; and (4) When gas free cargo tanks are to be filled...is purged from the tank by inert gas until the oxygen concentration in the tank is 8 percent...vapor is introduced. (b) Inert gas must be supplied from the shore...

2010-10-01

147

Effect of strong electromagnetic fields on dilute-gas spectra: The three-level system  

Microsoft Academic Search

The effect of a strong perturbing radiation field on spectral lines is studied using an extension of the Kubo-Zwanzig-Fano relaxation formalism. The problem of a dilute gas interacting with a strong perturbing field and a weak probe field is solved, assuming a separation of collisional and radiative processes, by introducing a classical-field renormalization technique. The solution is formulated entirely in

Lewis Klein; Michel Giraud; Abraham Ben-Reuven

1974-01-01

148

Theory of light and atom scattering in the Bose-Einstein condensate of a dilute gas  

SciTech Connect

A semiclassical theory of superradiant light scattering from a Bose-Einstein condensate of a dilute gas is developed without recourse to the mean field approximation. The dynamics and spectrum of superradiant field, as well as the kinetics of formation of coherent atomic states with various translational momenta are calculated. The results are qualitatively consistent with experimental data for atoms scattered in the backward direction relative to that of the exciting laser beam propagation.

Avetisyan, Ya. A. [Russian Academy of Sciences, Institute of Problems of Fine Mechanics and Control (Russian Federation); Trifonov, E. D. [Herzen State Pedagogical University (Russian Federation)], E-mail: thphys@herzen.spb.ru

2006-11-15

149

INVESTIGATING THE POTENTIAL DILUTION OF THE METAL CONTENT OF HOT GAS IN EARLY-TYPE GALAXIES BY ACCRETED COLD GAS  

SciTech Connect

The measured emission-weighted metal abundance of the hot gas in early-type galaxies has been known to be lower than theoretical expectations for 20 years. In addition, both X-ray luminosity and metal abundance vary significantly among galaxies of similar optical luminosities. This suggests some missing factors in the galaxy evolution process, especially the metal enrichment process. With Chandra and XMM-Newton, we studied 32 early-type galaxies (kT {approx}< 1 keV) covering a span of two orders of L{sub X,gas}/L{sub K} to investigate these missing factors. Contrary to previous studies that X-ray faint galaxies show extremely low Fe abundance ({approx}0.1 Z{sub Sun }), nearly all galaxies in our sample show an Fe abundance at least 0.3 Z{sub Sun }, although the measured Fe abundance difference between X-ray faint and X-ray bright galaxies remains remarkable. We investigated whether this dichotomy of hot gas Fe abundances can be related to the dilution of hot gas by mixing with cold gas. With a subset of 24 galaxies in this sample, we find that there is virtually no correlation between hot gas Fe abundances and their atomic gas content, which disproves the scenario that the low metal abundance of X-ray faint galaxies might be a result of the dilution of the remaining hot gas by pristine atomic gas. In contrast, we demonstrate a negative correlation between the measured hot gas Fe abundance and the ratio of molecular gas mass to hot gas mass, although it is unclear what is responsible for this apparent anti-correlation. We discuss several possibilities including that externally originated molecular gas might be able to dilute the hot gas metal content. Alternatively, the measured hot gas Fe abundance may be underestimated due to more complex temperature and abundance structures and even a two-temperature model might be insufficient to reflect the true value of the emission weighted mean Fe abundance.

Su, Yuanyuan; Irwin, Jimmy A., E-mail: ysu@crimson.ua.edu [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States)

2013-03-20

150

Manifestation of quantum resonances and antiresonances in a finite-temperature dilute atomic gas  

SciTech Connect

We investigate the effect of temperature on resonant and antiresonant dynamics in a dilute atomic gas kicked periodically by a standing-wave laser field. Our numerical calculations are based on a Monte Carlo method for an incoherent mixture of noninteracting plane waves, and show that the atomic dynamics are highly sensitive to the initial momentum width of the gas. We explain this sensitivity by examining the time evolution of individual atomic center-of-mass momentum eigenstates with varying quasimomentum, and we determine analytic expressions for the evolution of the second-order momentum moment to illustrate the range of behaviors.

Saunders, M.; Halkyard, P. L.; Challis, K. J.; Gardiner, S. A. [Department of Physics, Durham University, Rochester Building, South Road, Durham DH1 3LE (United Kingdom)

2007-10-15

151

Manifestation of quantum resonances and antiresonances in a finite-temperature dilute atomic gas  

NASA Astrophysics Data System (ADS)

We investigate the effect of temperature on resonant and antiresonant dynamics in a dilute atomic gas kicked periodically by a standing-wave laser field. Our numerical calculations are based on a Monte Carlo method for an incoherent mixture of noninteracting plane waves, and show that the atomic dynamics are highly sensitive to the initial momentum width of the gas. We explain this sensitivity by examining the time evolution of individual atomic center-of-mass momentum eigenstates with varying quasimomentum, and we determine analytic expressions for the evolution of the second-order momentum moment to illustrate the range of behaviors.

Saunders, M.; Halkyard, P. L.; Challis, K. J.; Gardiner, S. A.

2007-10-01

152

First and second sound in a weakly interacting dilute Bose gas  

NASA Astrophysics Data System (ADS)

An explicit expression for the density response function in the hydrodynamic region has been given by Hohenberg and Martin, starting from the two-fluid equations of motion for a superfluid. We use their results to calculate the first and second sound resonances in a weakly interacting, dilute Bose-condensed gas. We only consider the intermediate temperature region, where the effect of the interactions may be treated as a small correction ( nV 0« k B T). We use the transport coefficients obtained by Kirkpatrick and Dorfman. As expected for a gas, the second sound mode has appreciable weight in the density-fluctuation spectrum.

Gay, Colin; Griffin, Allan

1985-03-01

153

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

154

Pair condensation in a dilute Bose gas with Rashba spin–orbit coupling  

NASA Astrophysics Data System (ADS)

We show that in a two-component Bose gas with Rashba spin–orbit coupling (SOC), two atoms can form bound states (Rashbons) with any intra-species scattering length. At zero center-of-mass momentum, there are two degenerate Rashbons due to time-reversal symmetry, but the degeneracy is lifted at finite in-plane momentum with two different effective masses. A stable Rashbon condensation can be created in a dilute Bose gas with attractive intra-species and repulsive inter-species interactions. The critical temperature of Rashbon condensation is about six times smaller than the Bose–Einstein condensation transition temperature of an ideal Bose gas. Due to the Rashba SOC, excitations in the Rashbon condensation phase are anisotropic in momentum space.

Li, Rong; Yin, Lan

2014-05-01

155

Fluid-dynamical and poro-elastic coupling of gas permeability of inert and sorbing gases on an Australian sub-bituminous coal  

NASA Astrophysics Data System (ADS)

The interaction and the coupling of slip-flow, a fluid dynamic phenomenon, and the cleat volume compressibility which is a poroelastic phenomenon has been investigated on two samples from the Taroom coal measure, Surat Basin, Queensland Australia. Measurements were performed using inert (helium and argon) and sorbing gases (nitrogen, methane and carbon dioxide) at controlled effective stress. We observed the following regular sequence of permeability coefficients for the different gases: Helium >> argon => nitrogen > methane >> CO2 Even after slip-flow correction, different intrinsic permeability coefficients are obtained for the same sample if different gases are used in the tests. The permeability values determined with helium are largest while those measured with CO2 are lowest. Inert gases like helium and argon show higher apparent- and even slip flow-corrected permeability coefficients than sorbing gases like methane or carbon dioxide. This observation is contrary to the prediction that the slip-flow corrected permeability have to be the same for all gases. The cleat volume compressibility cf was evaluated using the 'matchstick approach' [1, 2]. The cleat volume compressibility coefficients cf are almost identical for the two samples taken from the same well. However, for one sample a strong dependence of the cf with the mean pore pressure was observed. This is attributed to a strong slip-flow effect caused by a narrow cleat system as compared to the sister sample. The cleat volume compressibility coefficient cf is almost the same for inert and sorbing gases. We conclude that the occurrence of slip-flow in coals is able to compensate the permeability reduction resulting from increasing effective stress. This should lead to a much higher productivity of coal bed methane reservoirs in the third production phase (pseudo-steady state phase; [3]). This conclusion appears to be also valid for shale gas and tight gas reservoirs, where the gas transport takes place in meso- and micropores, as well.

Gensterblum, Y.; Krooss, B. M.

2013-12-01

156

Nonequilibrium effects on the rate of bimolecular chemical reaction in a dilute gas  

NASA Astrophysics Data System (ADS)

The perturbation solution of the Boltzmann equation in a dilute gas shows that the rate constant of chemical reaction A+ A ? B+ B is diminished due to nonequilibrium effects. For the line-of-centers model, the relative decrease ? of the reaction rate can reach even nearly 45% (for a small reduced threshold energy ?* and a large molar fraction xB). For slow reactions this method is valid and ? does not depend on xB. The appropriate equilibrium expressions for reaction rate (with: (a) the temperature of the system T, (b) the nonequilibrium Shizgal-Karplus temperatures TA and TB) are used for this analysis.

Cukrowski, A. S.; Fritzsche, S.; Fort, J.

2001-06-01

157

Calculation of the relaxation properties of a dilute gas consisting of Lennard-Jones chains  

NASA Astrophysics Data System (ADS)

The relaxation properties in the dilute-gas limit have been calculated by the classical trajectory (CT) method for a gas consisting of chain-like molecules that are rigid and interact through site-site Lennard-Jones 12-6 potentials. Results are reported for volume viscosity ?V, rotational collision number ?rot and the ratio of the rotational to self-diffusion coefficient Drot/D. The results indicate that the volume viscosity increases with temperature and decreases with chain length. The rotational relaxation of chains is efficient, as it takes of the order of 1.75-2.7 collisions to attain equilibrium. The rotational collision number is only weakly temperature dependent.

Hellmann, Robert; Riesco, Nicolas; Vesovic, Velisa

2013-06-01

158

Defect effect on tribological behavior of diamond-like carbon films deposited with hydrogen diluted benzene gas in aqueous environment  

NASA Astrophysics Data System (ADS)

This study examined the friction and wear behavior of diamond-like carbon (DLC) films deposited from a radio frequency glow discharge using a hydrogen diluted benzene gas mixture. The DLC films were deposited on Si (1 0 0) and polished stainless steel substrates by radio frequency plasma-assisted chemical vapor deposition (r.f.-PACVD) at hydrogen to benzene ratios, or the hydrogen dilution ratio, ranging from 0 to 2.0. The wear test was carried out in both ambient and aqueous environments using a homemade ball-on-disk type wear rig. The stability of the DLC coating in an aqueous environment was improved by diluting the benzene precursor gas with hydrogen, suggesting that hydrogen dilution during the deposition of DLC films suppressed the initiation of defects in the film and improved the adhesion of the coating to the interface.

Yi, Jin Woo; Park, Se Jun; Moon, Myoung-Woon; Lee, Kwang-Ryeol; Kim, Seock-Sam

2009-05-01

159

Headspace solid phase microextraction and gas chromatography-olfactometry dilution analysis of young and aged Chinese "Yanghe Daqu" liquors.  

PubMed

The aroma compounds of young and aged Chinese "Yanghe Daqu" liquor samples were extracted by solid phase microextraction (SPME) and analyzed by gas chromatography (GC)-olfactometry dilution analysis. The original liquor samples were diluted with deionized water to give a final alcohol content of 14% (v/v). The samples were stepwise diluted (1:1) with 14% (by volume) ethanol-water solution and then extracted by headspace SPME. The samples were preequilibrated at 50 degrees C for 15 min and extracted with stirring at the same temperature for 30 min prior to injection into GC. The aroma compounds were identified by both GC-MS and GC-olfactometry using DB-Wax and DB-5 columns. The results suggested that esters were the major contributors to Yanghe Daqu liquor aroma. Ethyl hexanoate, ethyl butanoate, and ethyl pentanoate had very high flavor dilution values in both young and aged liquors (FD > 8192). Methyl hexanoate, ethyl heptanoate, ethyl benzoate, and butyl hexanoate could also be very important because of their high flavor dilution values (FD > or = 256). Moreover, two acetals, 1,1-diethoxyethane and 1,1-diethoxy-3-methylbutane, also were shown high flavor dilution values in Yanghe Daqu liquors (FD > or = 256). Other aroma compounds having moderate flavor dilution values included acetaldehyde, 3-methylbutanol, and 2-pentanol (FD > or = 32). Comparing young and aged liquors, the aroma profiles were similar, but the aroma compounds in the aged sample had higher flavor dilution values than in the young ones. PMID:16190652

Fan, Wenlai; Qian, Michael C

2005-10-01

160

Computational modeling of dilute gas-particle flows in an ultrasonic gas flowmeter  

Microsoft Academic Search

A computational procedure is presented to predict particle-laden turbulent gas flows in an ultrasonic flowmeter using curvilinear coordinates. The Eulerian-Lagrangian hybrid model is used for the two-phase flow predictions. The turbulent gas phase is formulated using the Eulerian governing equations whereas the particle phase is formulated using the Lagrangian governing equations. The effect of the gas turbulence on discrete particle

X.-Q. Chen; J. C. F. Pereira

1998-01-01

161

Elliptic flow of the dilute Fermi gas: From kinetics to hydrodynamics  

SciTech Connect

We use the Boltzmann equation in the relaxation-time approximation to study the expansion of a dilute Fermi gas at unitarity. We focus, in particular, on the approach to the hydrodynamic limit. Our main findings are the following: (i) In the regime that has been studied experimentally hydrodynamic effects beyond the Navier-Stokes approximation are small. (ii) Mean-field corrections to the Boltzmann equation are not important. (iii) Experimental data imply that freezeout occurs very late, which means that the relaxation time remains smaller than the expansion time during the entire evolution of the system. (iv) The experimental results also imply that the bulk viscosity is significantly smaller than the shear viscosity of the system.

Dusling, K.; Schaefer, T. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

2011-07-15

162

Dissipative fluid dynamics for the dilute Fermi gas at unitarity: Free expansion and rotation  

SciTech Connect

We investigate the expansion dynamics of a dilute Fermi gas at unitarity in the context of dissipative fluid dynamics. Our aim is to quantify the effects of shear viscosity on the time evolution of the system. We compare exact numerical solutions of the equations of viscous hydrodynamics to various approximations that have been proposed in the literature. Our main findings are (i) shear viscosity leads to characteristic features in the expansion dynamics; (ii) a quantitative description of these effects has to include reheating; (iii) dissipative effects are not sensitive to the equation of state P(n,T) as long as the universal relation P=(2/3)E is satisfied; (iv) the expansion dynamics mainly constrains the cloud average of the shear viscosity.

Schaefer, T. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

2010-12-15

163

Correlation effects on plasmon dispersion of a dilute two-dimensional electron gas at finite temperature  

NASA Astrophysics Data System (ADS)

We have studied theoretically the effect of correlations on the plasmon dispersion of a dilute two-dimensional electron gas, realized in a narrow GaAs quantum well and probed recently using inelastic light scattering experiments by Hirjibehedin et al. The plasmon energy is obtained from the poles of the electron density response function determined by employing the finite temperature version of the self-consistent mean-field theory of Singwi et al. Our results show an excellent agreement with the experimental data, but it is vital to incorporate the exchange-correlation effects and their dependence on the temperature. Interestingly, plasmon energy shows a blue shift with increasing temperature, and the correlation effects which grow with decreasing electron density, introduce a red shift. These findings may be of practical importance in the design of plasmonic devices.

Bhukal, Nisha; Singh, Gurvinder; Moudgil, R. K.

2013-06-01

164

Dilute-gas properties of some systems containing CO/sub 2/  

SciTech Connect

The SSR-MPA potential model is used to correlate and extrapolate the dilute-gas properties of some systems containing CO/sub 2/. With parameters determined from a consistent set of second virial and Joule-Thomson data, the third virial coefficient of CO/sub 2/ as well as the second virial coefficients of various mixtures containing CO/sub 2/ can be predicted very well. The Mason-Monchik approximation fails for a complicated molecule such as CO/sub 2/, although at least a viscosity prediction of technical accuracy is obtained. If parameters fitted to the CO/sub 2/ viscosity are used, excellent predictions can be made for the viscosity of gaseous mixtures containing CO/sub 2/.

Ameling, W.; Lucas, K.

1987-05-01

165

Electron spin resonance in a dilute magnon gas as a probe of magnon scattering resonances  

NASA Astrophysics Data System (ADS)

We study the electron spin resonance in a dilute magnon gas that is realized in a ferromagnetic spin system at low temperature. A quantum cluster expansion is developed to show that the frequency shift of the single-magnon peak changes its sign and the linewidth reaches its maximum across a scattering resonance between magnons. Such characteristic behaviors are universal and can be used to experimentally locate the two-magnon resonance when an external parameter such as pressure is varied. Future achievement of the two-magnon resonance may have an impact comparable to the Feshbach resonance in ultracold atoms and will open up a rich variety of strongly correlated physics such as the recently proposed Efimov effect in quantum magnets. We also suggest how the emergence of an Efimov state of three magnons and its binding energy may be observed with the electron spin resonance.

Nishida, Yusuke

2013-12-01

166

A large nonequilibrium effect of decrease of the bimolecular chemical reaction rate in a dilute gas  

NASA Astrophysics Data System (ADS)

The perturbation solution of the Boltzmann equation is used to analyze the relative decrease ?( T) of the rate constant k( T) of a chemical reaction in a dilute gas in the temperature T. The Prigogine-Xhrouet model of the reactive cross-section is introduced for the reaction A+A?B+B. A large effect for ?( T) equal even nearly 75% ( for a small reduced threshold energy ?0 and a large molar fraction xB) follows from the analytical solution for k( T). A replacement of T by the Shizgal-Karplus nonequilibrium temperatures TA and TB in the equilibrium rate constants (for the forward and reverse reactions) gives ?( TA, TB) confirming this effect.

Cukrowski, A. S.; Fritzsche, S.; Cukrowski, M. J.

2003-09-01

167

Simple Models for Nonequilibrium Effects in Bimolecular Chemical Reaction in a Dilute Gas  

NASA Astrophysics Data System (ADS)

Two models for reactive cross sections are introduced to analyze non-equilibrium effects connected with proceeding of the bimolecular chemical reaction A+A ? B+B in a dilute gas: 1. Line-of-Centers model LC, 2. the reverse model rLC leading to negative values of the Arrhenius activation energy. The perturbation method of solution of the Boltzmann equation is used to obtain analytical expressions for the rate constant of chemical reaction and for the nonequilibrium Shizgal--Karplus temperatures. It is shown that if the molar fraction of product is large enough the relative change of the rate of chemical reaction is constant, i.e. does not depend on the molar fraction. Replacing the equilibrium temperature by the nonequilibrium one (depending on the molar fraction) in the equilibrium equations for forward and reverse rate constants confirms these results.

Cukrowski, Andrzej S.; Fort, Joaquim; Fritzsche, Siegfried

2002-04-01

168

Ground-State Energy and Condensate Density of a Dilute Bose Gas Revisited  

NASA Astrophysics Data System (ADS)

The ground-state energy per particle E/N and condensate density n0 of a dilute Bose gas are studied with a self-consistent perturbation expansion satisfying the Hugenholtz--Pines theorem and conservation laws simultaneously. A class of Feynman diagrams for the self-energy, which has escaped consideration so far, is shown to add an extra constant cip˜ O(1) to the expressions reported by Lee et al. [Phys. Rev. 106 (1957) 1135] as E/N=(2?\\hbar2an/m)[1+(128/15\\sqrt?+16cip/5)\\sqrt{a3n}] and n0/n=1-(8/3\\sqrt?+cip)\\sqrt{a3n}, where a, n, and m are are the s-wave scattering length, particle density, and particle mass, respectively. We present a couple of estimates for cip; the third-order perturbation expansion yields cip=0.412.

Tsutsui, Kazumasa; Kita, Takafumi

2013-06-01

169

Radiographic, scintigraphic, and gas-dilution estimates of individual lung and lobar volumes in man.  

PubMed Central

We describe a method of separately determining the volumes of the right and left lungs from conventional chest radiographs and of determining the volumes of individual lobes and pathological spaces, whenever their boundaries are visible radiologically or can be displayed scintigraphically--for example, during fibreoptic bronchoscopy. Scintigrams of individual lungs, lobes, and segments are obtained by deflecting a stream of air marked with 81m krypton down the suction channel of the bronchoscope into the appropriate bronchus during inspiration, followed by a breath-hold during which the image is recorded with a gamma camera. Both radiographic and scintigraphic methods have been validated by comparison with argon dilution estimates of individual lung and lobar volumes also obtained at bronchoscopy, and results for the three methods in normal subjects are presented. Used in conjunction with bronchoscopic soluble gas uptake studies, these volume measurements permit precise estimation of effective perfusion, tissue and water volume, and gas transfer at lobar and segmental level. Individual lung and lobar volumes can be used to quantify lung and lobar collapse and compression, mediastinal shift, regional ventilation and gas trapping, and phrenic paresis. Images

Pierce, R J; Brown, D J; Denison, D M

1980-01-01

170

Effect of Inert Gas Additive Species on Cl(2) High Density Plasma Etching of Compound Semiconductors: Part 1. GaAs and GaSb  

SciTech Connect

The role of the inert gas additive (He, Ar, Xe) to C12 Inductively Coupled Plasmas for dry etching of GaAs and GaSb was examined through the effect on etch rate, surface roughness and near-surface stoichiometry. The etch rates for both materials go through a maximum with Clz 0/0 in each type of discharge (C12/'He, C12/Ar, C12/Xc), reflecting the need to have efficient ion-assisted resorption of the etch products. Etch yields initially increase strongly with source power as the chlorine neutral density increases, but decrease again at high powers as the etching becomes reactant-limited. The etched surfaces are generally smoother with Ax or Xe addition, and maintain their stoichiometry.

Abernathy, C.R.; Cho, H.; Hahn, Y.B.; Hays, D.C.; Jung, K.B.; Pearton, S.J.; Shul, R.J.

1998-12-23

171

Wide-band exciplex halogen lamps operating on inert gas mixtures with chlorine and Freon-12 molecules  

NASA Astrophysics Data System (ADS)

The results of analysis of the spectral characteristics of short-wave radiation sources operating on transitions in argon, krypton, and xenon monohalogenides, as well as chlorine molecules, excited by a longitudinal low-pressure glow discharge are considered. Radiation emitted by ArCl*, KrCl*, XeCl*, Cl{2/**}, and Cl{2/*} molecules in a spectral range of 170-350 nm is optimized using complex working mixtures of Ar-Kr-(Xe)-Cl2 in the lamps. The average radiation power of the lamps ranges from 1 to 10 W for an efficiency of ?25%. Optimization of wide-band lamps on transitions in chlorine molecules and the decay products of Freon-12 molecules (CF2Cl2) is carried out on mixtures of helium with chlorine and Freon-12 molecules. This makes it possible to develop lamps emitting in a spectral range of 140-270 nm and containing no costly inert gases (Xe or Kr) in their working mixtures. Exciplex halogen lamps with a wide-band emission spectrum in the VUV-UV range can be used in spectrometers as radiation sources in experiments with absorption and in high-energy chemistry, ecology, and medicine.

Shuaibov, A. K.; Shevera, I. V.

2007-09-01

172

Calculation of the transport properties of a dilute gas consisting of Lennard-Jones chains.  

PubMed

The transport properties in the dilute gas limit have been calculated by the classical-trajectory method for a gas consisting of chain-like molecules. The molecules were modelled as rigid chains consisting of spherical segments that interact through a combination of site-site Lennard-Jones 12-6 potentials. Results are reported for shear viscosity, self-diffusion, and thermal conductivity for chains consisting of 1, 2, 3, 4, 5, 6, 7, 8, 10, 13, and 16 segments in the reduced temperature range of 0.3-50. The results indicate that the transport properties increase with temperature and decrease with chain length. At high temperatures the dependence of the transport properties is governed effectively by the repulsive part of the potential. No simple scaling with chain length has been observed. The higher order correction factors are larger than observed for real molecules so far, reaching asymptotic values of 1.019-1.033 and 1.060-1.072 for viscosity and thermal conductivity, respectively. The dominant contribution comes from the angular momentum coupling. The agreement with molecular dynamics calculations for viscosity is within the estimated accuracy of the two methods for shorter chains. However, for longer chains differences of up to 7% are observed. PMID:23464153

Hellmann, Robert; Riesco, Nicolas; Vesovic, Velisa

2013-02-28

173

[Determination of indicator toxaphene in soil by isotope dilution-gas chromatography-tandem mass spectrometry].  

PubMed

Although toxaphene is now banned in use, the analysis of toxaphene has attracted increasing interest due to its persistence and widespread atmospheric transport in the environment. A new method based on isotope dilution-gas chromatography-tandem mass spectrometry (ID-GC-MS/MS) has been developed for the determination of three toxaphene specific congeners comprised of Parlar No. 26 (P26), Parlar No. 50 (P50) and Parlar No. 62 (P62) in soil. (13)C10-labeled indicator toxaphene solution was added to the sample prior to pretreatment. Then the sample was extracted using pressurized liquid extraction (PLE) followed by purification on multilayer acidic silica column and neutral silica column. The eluent was concentrated under gentle nitrogen gas flow and spiked with the injection of internal standard of (13)C10-chlordane. Identification and quantification of the analytes were carried out in the multiple reaction monitoring (MRM) mode after the GC separation. The linear range was 20-800 microg/L for three congeners, limits of detection (LOD) ranged from 3.0 to 6.0 pg. The five point calibration curves showed a good linearity for all the congeners (R2 > 0.99). The relative standard deviations (RSDs) were below 11% for and the spiked recoveries were in the range of 55%-110%. The developed analytical method is suitable for the determination of toxaphene specific congeners in soil. PMID:20812620

Zhang, Bing; Wu, Jiajia; Liu, Guorui; Gao, Lirong; Zheng, Minghui

2010-05-01

174

Inert electrode connection  

DOEpatents

An inert electrode connection is disclosed wherein a layer of inert electrode material is bonded to a layer of conductive material by providing at least one intermediate layer of material therebetween comprising a predetermined ratio of inert material to conductive material. In a preferred embodiment, the connection is formed by placing in a die a layer of powdered inert material, at least one layer of a mixture of powdered inert material and conductive material, and a layer of powdered conductive material. The connection is then formed by pressing the material at 15,000-20,000 psi to form a powder compact and then densifying the powder compact in an inert or reducing atmosphere at a temperature of 1200.degree.-1500.degree. C.

Weyand, John D. (Greensburg, PA); Woods, Robert W. (New Kensington, PA); DeYoung, David H. (Plum Boro, PA); Ray, Siba P. (Plum Boro, PA)

1985-01-01

175

Inert electrode connection  

DOEpatents

An inert electrode connection is disclosed wherein a layer of inert electrode material is bonded to a layer of conductive material by providing at least one intermediate layer of material therebetween comprising a predetermined ratio of inert material to conductive material. In a preferred embodiment, the connection is formed by placing in a die a layer of powdered inert material, at least one layer of a mixture of powdered inert material and conductive material, and a layer of powdered conductive material. The connection is then formed by pressing the material at 15,000--20,000 psi to form a powder compact and then densifying the powder compact in an inert or reducing atmosphere at a temperature of 1,200--1,500 C. 5 figs.

Weyand, J.D.; Woods, R.W.; DeYoung, D.H.; Ray, S.P.

1985-02-19

176

Microemulsion Prepared Pt in Ceria: Catalytically Active for Water Gas Shift Reaction but Totally Inert for Methanation  

Microsoft Academic Search

A core–shell Pt in ceria type of catalyst prepared by a microemulsion technique shows high activity for both water gas shift\\u000a and reverse water gas shift reactions but it does not catalyze methanation from carbon oxides and hydrogen feeds at all, whereas\\u000a Pt-ceria catalysts prepared by traditional methods are effective for all these reactions under comparable reaction conditions.\\u000a This clearly

Connie Mei Yu Yeung; Shik Chi Tsang

2009-01-01

177

Response of electrochemical oxygen sensors to inert gas-air and carbon dioxide-air mixtures: measurements and mathematical modelling.  

PubMed

Electrochemical oxygen gas sensors are widely used for monitoring the state of inertisation of flammable atmospheres and to warn of asphyxiation risks. It is well established but not widely known by users of such oxygen sensors that the response of the sensor is affected by the nature of the diluent gas responsible for the decrease in ambient oxygen concentration. The present work investigates the response of electrochemical sensors, with either acid or alkaline electrolytes, to gas mixtures comprising air with enhanced levels of nitrogen, carbon dioxide, argon or helium. The measurements indicate that both types of sensors over-read the oxygen concentrations when atmospheres contain high levels of helium. Sensors with alkaline electrolytes are also shown to underestimate the severity of the hazard in atmospheres containing high levels of carbon dioxide. This deviation is greater for alkaline electrolyte sensors compared to acid electrolyte sensors. A Computational Fluid Dynamics (CFD) model is developed to predict the response of an alkaline electrolyte, electrochemical gas sensor. Differences between predicted and measured sensor responses are less than 10% in relative terms for nearly all of the gas mixtures tested, and in many cases less than 5%. Extending the model to simulate responses of sensors with acid electrolytes would be straightforward. PMID:21112151

Walsh, P T; Gant, S E; Dowker, K P; Batt, R

2011-02-15

178

Quantifying gross fluxes of nitrous oxide and dinitrogen gas using a novel isotope pool dilution technique  

NASA Astrophysics Data System (ADS)

One of the existing challenges in trace gas biogeochemistry lies in understanding the environmental controls on the net and gross fluxes of soil-derived compounds. This is because gross production and consumption fluxes of these gases often occur simultaneously or in close spatial proximity, making it difficult to make inferences about the effects of environmental variables (e.g. temperature, soil water content, porosity, redox, etc.) on gross fluxes based on bulk concentration measurements alone. One novel approach for quantifying gross fluxes of N2O and N2 is 'stable isotope pool dilution;' a technique that has been successfully applied to study bidirectional fluxes of other biogenic compounds, such as CH4 and halocarbons. To evaluate the efficacy of this method for quantifying gross N2O and N2 fluxes, we conducted a combined field and laboratory test of the pool dilution technique along side conventional measures of nitrification and denitrification. Experiments were conducted in a N-rich managed peatland pasture in the Sacramento-San Joaquin Delta, California, USA. Field and laboratory measurements were performed in a broad range of microforms and microtopes spanning a range of hydrologic and environmental conditions. Field experiments focussed on gross fluxes of N2O and N2 in upper soil horizons; the soil layers that exchange most rapidly with the atmosphere. Laboratory experiments indicated that 15N pool dilution compares favourably with more conventional measures of N2O and N2 flux, such as acetylene inhibition or the 15NO3- pulse-trace approach. Gross N2O fluxes greatly exceeded N2 fluxes by as much as an order of magnitude or more, and averaged 6.1 ± 2.2 mg N m-2 d-1, with a range from 0.06 to 63.13 mg N m-2 d-1. N2O:N2 emissions ratios generally exceeded 1 except along slopes, with an overall range of 0.2 to 30.9. NH4+ concentrations and denitrifying enzyme activity were the best predictors of gross N2O fluxes in the field (r2 = 0.65). Net N2O production rates explained 53 percent of the variability in gross N2 fluxes, whereas N2O:N2 ratios were best predicted by the combination of water-filled pore space and mineral N concentration (r2 = 0.44). This research highlights the potential of the pool dilution approach for quantifying gross fluxes of N2O and N2 from surface soils under both field and laboratory conditions. Future experiments will couple these measures of soil surface fluxes with push-pull methods for determining gross N2O and N2 fluxes at depth, and natural abundance isotopomer measurements to determine sources of N2O.

Arn Teh, Yit; Yang, Wendy; Silver, Whendee L.

2010-05-01

179

Transformation of a beta gamma Hot-Cell under Air in a Tight Hot-Cell under Inert Gas.  

National Technical Information Service (NTIS)

For several years now, fuel elements from graphite gas reactors have been stored in pools at the Cadarache Center after having been subjected (in general) to laboratory examinations. The CEA has adopted the following re-transfer procedure for these fuel e...

G. Lambert

1981-01-01

180

Itinerant ferromagnetism in a Fermi gas with contact interaction: Magnetic properties in a dilute Hubbard model  

NASA Astrophysics Data System (ADS)

Motivated by recent experiments addressing the issue of itinerant ferromagnetism in a dilute ultra-cold Fermi gas with contact interaction, we examine ground state properties of the repulsive Hubbard model on a cubic lattice [1] by means of a very accurate auxiliary-field quantum Monte Carlo method [2]. We focus on low-density systems with varying on-site interaction U/t, in the range relevant to the experiments. Twist-averaged boundary conditions are used to eliminate open-shell effects and large lattice sizes are studied to reduce finite-size effects. The sign problem is controlled by a generalized constrained path approximation [2]. We find no ferromagnetic phase transition in this model. The ground-state correlations are consistent with those of a paramagnetic Fermi liquid. [4pt] [1] Chia-Chen Chang, Shiwei Zhang, and David M. Ceperley, arXiv:1009.1409[0pt] [2] Chia-Chen Chang and Shiwei Zhang, Phys. Rev. B 78, 165101 (2008).

Chang, Chia-Chen; Zhang, Shiwei; Ceperley, David M.

2011-03-01

181

Analysis of Nonequilibrium Effects in a Bimolecular Chemical Reaction in a Dilute Gas  

NASA Astrophysics Data System (ADS)

We analyze a thermally activated bimolecular reaction in a dilute gas proceeding with introduction of the Prigogine--Xhrouet model (PX) for the reactive cross section. We use the Shizgal--Karplus perturbation method of solution of the Boltzmann equation for reactions A + A ? B + B and A + A ? B + B to obtain the analytical expressions for the nonequilibrium temperatures of reagents and for the rate of chemical reaction. We present the results obtained within one and two Sonine polynomials approximations. The rate constant of chemical reaction depends on concentration of products for the first reaction only and for the second reaction is constant. The analytical results for the temperature of the reagent A and its value in the beginning of reaction for the product B are compared with those obtained from the Monte Carlo computer simulations with use of the Bird method. It is shown that the nonequilibrium effects in Shizgal--Karplus temperatures and in decrease of the chemical constant rate are more pronounced than for the lines-of-centers model. For the PX model the rate constant can be decreased even 4 times.

Cukrowski, Andrzej S.; Fritzsche, Siegfried

2003-07-01

182

Laws of the DC arc in an inert gas during melting in furnaces with a tungsten electrode  

NASA Astrophysics Data System (ADS)

The I-V and voltage-baric characteristics of the dc arc glowing in argon between a tungsten cathode and a molten anode made of titanium, chromium, or manganese are studied at various gas pressures, arc currents, and arc lengths. The arc is probed to establish the relation between the voltage drop across the arc and its regions on the anode material and the melting conditions.

Belyanchikov, L. N.

2012-06-01

183

Mixed aqueous solutions as dilution media in the determination of residual solvents by static headspace gas chromatography.  

PubMed

Static headspace (HS) sampling has been commonly used to test for volatile organic chemicals, usually referred to as residual solvents (RS) in pharmaceuticals. If the sample is not soluble in water, organic solvents are used. However, these seriously reduce the sensitivity in the determination of some RS. Here, mixed aqueous dilution media (a mixture of water and an organic solvent like dimethyl formamide, dimethyl sulfoxide or dimethyl acetamide) were studied as alternative media for static HS-gas chromatographic analysis. Although it has been known that mixed aqueous dilution media can often improve sensitivity for many RS, this study used a systematic approach to investigate phase volumes and the organic content in the HS sampling media. Reference solutions using 18 different class 1, 2 and 3 RS were evaluated. The effect of salt addition was also studied in this work. A significant increase in the peak area was observed for all RS using mixed aqueous dilution media, when compared with organic solvents alone. Matrix effects related to the mixed aqueous dilution media were also investigated and reported. Repeatability and linearity obtained with mixed aqueous dilution media were found to be similar to those observed with pure organic solvents. PMID:21538876

D'Autry, Ward; Zheng, Chao; Wolfs, Kris; Yarramraju, Sitaramaraju; Hoogmartens, Jos; Van Schepdael, Ann; Adams, Erwin

2011-06-01

184

Experimental investigation on fiber and CO2 inert gas fusion cutting of AZ31 magnesium alloy sheets  

NASA Astrophysics Data System (ADS)

The influence of processing parameters and laser source type on cutting edge quality of AZ31 magnesium alloy sheets and differences in cutting efficiency between fiber and CO2 lasers were studied. A first part of the cutting experiments compared a fiber and CO2 laser source when cutting 1 mm thick sheets in continuous wave mode and using Argon as an assist gas. The effects of cutting speed and assist gas pressure were investigated and optimal conditions were identified. In the second part of the experimental investigation, 3.3 mm thick sheets were cut using fiber laser. Focal position and cutting speed were varied in order to detect the optimal combination of processing parameters to obtain the best edge quality. For both sheet thicknesses investigated, surface roughness, dross height, and striation pattern inclination were measured. Cutting quality assessment and classification was carried out according to UNI EN ISO 9013 standard. Results showed that productivity, process efficiency and cutting edges quality obtained using fiber lasers outperform CO2 laser performances and therefore are considered suitable for application like sheet metal trimming.

Scintilla, L. D.; Tricarico, L.

2013-03-01

185

Characterisation of the surface thermodynamic properties of cement components by inverse gas chromatography at infinite dilution  

SciTech Connect

The surface thermodynamic properties of three main inorganic compounds formed during hydration of Portland cement: calcium hydroxide (Ca(OH){sub 2}), ettringite (3CaO.Al{sub 2}O{sub 3}.3CaSO{sub 4}.32H{sub 2}O) and calcium-silicate-hydrates (C-S-H), respectively, and one mineral filler: calcium carbonate (CaCO{sub 3}), have been characterised by inverse gas chromatography at infinite dilution (IGC-ID) at 35 deg. C. The thermodynamic properties have been investigated using a wide range of non-polar (n-alkane series), Lewis acidic (CH{sub 2}Cl{sub 2} and CHCl{sub 3}), Lewis basic (diethyl ether) and aromatic (benzene) and n-alkene series molecular probes, respectively. The tested samples are fairly high surface energy materials as judged by the high dispersive contribution to the total surface energy (the dispersive components {gamma} {sub s} {sup d} range from 45.6 up to 236.2 mJ m{sup -2} at 35 deg. C) and exhibit amphoteric properties, with a predominant acidic character. In the case of hydrated components (i.e. ettringite and C-S-H), the surface thermodynamic properties have been determined at various temperatures (from 35 up to 120 deg. C) in order to examine the influence of the water content. The changes of both dispersive and specific components clearly demonstrate that the material surface properties are activated with temperature. The changes in the acid-base properties are correlated with the extent of the overall water loss induced by the thermal treatment as demonstrated by thermogravimetric analysis (TGA). The elemental surface composition of these compounds has been determined by X-ray photoelectron spectroscopy (XPS)

Perruchot, Christian [Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS) Universite Paris 7- Denis. Diderot, 1 Rue Guy de la Brosse, 75005 Paris (France); Chehimi, Mohamed M. [Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS) Universite Paris 7- Denis. Diderot, 1 Rue Guy de la Brosse, 75005 Paris (France); Vaulay, Marie-Josephe [Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS) Universite Paris 7- Denis. Diderot, 1 Rue Guy de la Brosse, 75005 Paris (France); Benzarti, Karim [Laboratoire Central des Ponts et Chaussees (LCPC), 58 Boulevard Lefevre, 75732 Paris Cedex 15 (France)]. E-mail: benzarti@lcpc.fr

2006-02-15

186

Maxwell-Schroedinger equations for a dilute gas Bose-Einstein condensate coupled to an electromagnetic field  

SciTech Connect

We give a general formulation of the semiclassical approach to solving the problem of interaction between a Bose-Einstein condensate of dilute gas and electromagnetic radiation without using the commonly applied mean-field approximation. We suggest variants of the systems of Maxwell-Schroedinger equations whose solution describes such effects as superradiant light scattering, light beam amplification, atomic wave (atomic laser) amplification, induced transparency, and reduction in the group velocity of light.

Avetisyan, Yu. A. [Russian Academy of Sciences, Institute of Problems of Precise Mechanics and Control (Russian Federation); Trifonov, E. D. [Herzen Russian State Pedagogical University (Russian Federation)], E-mail: thphys@herzen.spb.ru

2008-03-15

187

Determination of part-per-trillion levels of atmosphere dimethyl sulfide by isotope dilution gas chromatography/mass spectrometry  

NASA Astrophysics Data System (ADS)

Stable isotopic dilution was applied to the determination of dimethyl sulfide (DMS) in ambient air at the low part-per-trillion by volume (pptrv) levels. Perdeuterated DMS was used as an internal standard in the gas chromatography/mass spectrometry determination. The isotopically labelled internal standard provided insensitivity to possible losses of DMS in sampling and analysis. The lower limit of detection (LLD) was 1 pptrv with a sample acquisition time of 2 min.

Thornton, Donald C.; Bandy, Alan R.; Ridgeway, Robert G.; Driedger, Arthur R., III; Lalevic, Marija

1990-11-01

188

Absolute quantification of peptides by isotope dilution liquid chromatography-inductively coupled plasma mass spectrometry and gas chromatography\\/mass spectrometry  

Microsoft Academic Search

Absolute quantitation of peptides\\/proteins in dilute calibration solutions used in various diagnostic settings is a major challenge. Here we report the absolute quantitation of peptides by non-species-specific isotope dilution liquid chromatography-inductively coupled plasma mass spectrometry (ID LC-ICPMS) based on stoichiometric Eu tagging. The method was validated by species-specific isotope dilution gas chromatography\\/mass spectrometry (GC\\/MS) analysis of constituent amino acids of

R. a b c Liu; X. b Hou; Y. b Lv; M. a McCooeye; L. a Yang; Z.a Mester

2013-01-01

189

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C  

NASA Astrophysics Data System (ADS)

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled ? (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

2014-04-01

190

The Role of Spraying Parameters and Inert Gas Shrouding in Hybrid Water-Argon Plasma Spraying of Tungsten and Copper for Nuclear Fusion Applications  

NASA Astrophysics Data System (ADS)

Tungsten-based coatings have potential application in the plasma-facing components in future nuclear fusion reactors. By the combination of refractory tungsten with highly thermal conducting copper, or steel as a construction material, functionally graded coatings can be easily obtained by plasma spraying, and may result in the development of a material with favorable properties. During plasma spraying of these materials in the open atmosphere, oxidation is an important issue, which could have adverse effects on their properties. Among the means to control it is the application of inert gas shrouding, which forms the subject of this study and represents a lower-cost alternative to vacuum or low-pressure plasma spraying, potentially applicable also for spraying of large surfaces or spacious components. It is a continuation of recent studies focused on the effects of various parameters of the hybrid water-argon torch on the in-flight behavior of copper and tungsten powders and the resultant coatings. In the current study, argon shrouding with various configurations of the shroud was applied. The effects of torch parameters, such as power and argon flow rate, and powder morphology were also investigated. Their influence on the particle in-flight behavior as well as the structure, composition and properties of the coatings were quantified. With the help of auxiliary calculations, the mass changes of the powder particles, associated with oxidation and evaporation, were assessed.

Mat?jí?ek, J.; Kavka, T.; Bertolissi, G.; Ctibor, P.; Vilémová, M.; Mušálek, R.; Nevrlá, B.

2013-06-01

191

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C  

NASA Astrophysics Data System (ADS)

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled ? (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

2014-06-01

192

Controlled inert gas environment for enhanced chlorine and fluorine detection in the visible and near-infrared by laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Efficient quantitative detection for halogens is necessary in a wide range of applications, ranging from pharmaceutical products to air polluting hazardous gases or organic compounds used as chemical weapons. Detection of the non-metallic elements such as fluorine (F) and chlorine (Cl) presents particular difficulty, because strong emission lines originating from their resonance states lie in the VUV spectral range (110-190 nm). In the present work we detect F and Cl in the upper visible and in the near IR (650-850 nm) under controlled inert gas ambient atmosphere. Investigation of the controlled atmosphere effects suggests that there exists an optimum pressure range that optimizes signal strength and quality. Ablation and ionization were achieved with a UV laser at 355 nm, and a gated GaAs photocathode-based detector was used for detection with quantum efficiency in the range of 20% in the wavelengths of interest. Our results indicate that our approach provides quantitative detection with linearity over at least two orders of magnitude that is achieved without the need for Internal Standardization Method, and improved limits of detection. In particular, fluorine has been detected for concentration values down to 0.03 wt.% Definite spectral assignment revealing all major emission lines centered around 837 nm for F and 687 nm for Cl has been obtained for the first time in Laser-induced breakdown spectroscopy application.

Asimellis, George; Hamilton, Stephen; Giannoudakos, Aggelos; Kompitsas, Michael

2005-08-01

193

Effects of CaF2 Coating on the Microstructures and Mechanical Properties of Tungsten Inert Gas Welded AZ31 Magnesium Alloy Joints  

NASA Astrophysics Data System (ADS)

The effects of CaF2 coating on the macromorphologies of the welded seams were studied by morphological analysis. Microstructures and mechanical properties of butt joints welded with different amounts of CaF2 coatings were investigated using optical microscopy and tensile tests. The welding defects formed in the welded seams and the fracture surfaces were analyzed by scanning electron microscopy. An increase in the amount of CaF2 coating deteriorated the appearances of the welded seams but it improved the weld penetration depth and the depth/width ( D/ W) ratio of the tungsten inert gas (TIG) welded joints. The ?-Mg grains and Mg17(Al,Zn)12 intermetallic compound (IMC) were coarser in the case of a higher amount of CaF2 coating. The increase in the amount of CaF2 coating reduced the porosities and total length of solidification cracks in the fusion zone (FZ). The ultimate tensile strength (UTS) value and elongation increased at first and then decreased sharply.

Shen, Jun; Wang, Linzhi; Peng, Dong; Wang, Dan

2012-11-01

194

Investigation of At-Vent Dynamics and Dilution of Gas Puffing Using Thermal Infrared Radiometers at Masaya Volcano, Nicaragua  

NASA Astrophysics Data System (ADS)

In order to develop a detailed understanding of the dynamics of gas puffing (gas release as a series of discrete clouds) and more sustained degassing (steady plumes of gas) during persistent volcanic degassing, measurements of gas mass flux are required in the vicinity of the volcanic vent. Masaya Volcano (Nicaragua), a persistently degassing system, is an ideal location for measuring the dynamics of releases of volcanic gas in the first few seconds of their propagation. We carried out two field experiments during February 2002 and March 2003, during which thermal infrared thermometers were targeted into the degassing vent at Masaya to record thermal variations related to variations in the at-vent gas emission over short (on the order of seconds) timescales. The thermometers recorded an oscillating signal as gas puffs passed through the field of view, detailing variations in the degassing process developing over time scales of seconds. These data were processed to extract puff frequencies, amplitudes, durations, emission velocities and volumes. These data showed that, over time periods of hours, the total gas flux was stable with little variation in the puffing frequency. However, between 2002 and 2003 we noted a systematic increase in mean plume temperature, puffing frequency, puff emission velocity and puff volume, as well as a decrease in mean puff duration. While the first 4 parameters respectively increased from 105 to 157°C, 6 to 7 puffs per minute, 2 to 3 m s^{- 1} and ~2300 to ~2900 m3, puff duration decreased from 10 to 8.5 seconds. These changes were consistent with a thermal-data-derived increase in emitted gas volume from 1.1 x 107 m3 d-1 to 1.6 x 107 m3 d-1 between 2002 and 2003. Turbulent gas puffs entrain surrounding air, and quantifying the magnitude of air entrainment, or dilution, represents a major challenge for the measurement of total volcanic gas emissions. Our observations of small gas puffs suggest that they behave as turbulent buoyant thermals, and we use equations for mass, momentum and buoyancy, coupled with the standard entrainment assumption for turbulent buoyant flows, to estimate the gas puff dilution. The theoretically calculated entrainment rate of 40% dilution between emission and detection yields total SO2 mass fluxes of 450 t d-1 and 640 t d-1 for 2002 and 2003, respectively. This compares well with UV-spectrometer SO2 fluxes of 470 and 680 t d-1 for February 2002 and March 2003, respectively.

Branan, Y. K.; Harris, A.; Watson, I.; Phillips, J.; Horton, K.; Williams-Jones, G.; Garbeil, H.

2006-12-01

195

Dilute, Dense-Phase and Maximum Solid-Gas Transport. Third Quarterly Report.  

National Technical Information Service (NTIS)

A multiparticle size, transient, two-dimensional computer program was developed that has the potential of predicting flow behavior in all flow regimes including hopper flow, fluidization, dense and dilute pneumatic transport with a minimum of empirical in...

D. Gidaspow

1985-01-01

196

Inert Carbon Free Radicals.  

National Technical Information Service (NTIS)

The first inert carbon free radicals, completely dissociated and with both chemical and thermal stability, are described. These compounds belong to the perchlorocarbon class and are exemplified by perchlorotriphenylmethyl, perchlorodiphenylmethyl, and rel...

M. Ballester

1968-01-01

197

Hot nanoindentation in inert environments  

NASA Astrophysics Data System (ADS)

An instrument capable of performing nanoindentation at temperatures up to 500 °C in inert atmospheres, including partial vacuum and gas near atmospheric pressures, is described. Technical issues associated with the technique (such as drift and noise) and the instrument (such as tip erosion and radiative heating of the transducer) are identified and addressed. Based on these considerations, preferred operation conditions are identified for testing on various materials. As a proof-of-concept demonstration, the hardness and elastic modulus of three materials are measured: fused silica (nonoxidizing), aluminum, and copper (both oxidizing). In all cases, the properties match reasonably well with published data acquired by more conventional test methods.

Trenkle, Jonathan C.; Packard, Corinne E.; Schuh, Christopher A.

2010-07-01

198

Inert gas ion source program  

NASA Technical Reports Server (NTRS)

THe original 12 cm hexagonal magneto-electrostatic containment discharge chamber has been optimized for argon and xenon operation. Argon mass utilization efficiencies of 65 to 77 percent were achieved at keeper-plus-main discharge energy consumptions of 200 to 458 eV/ion, respectively. Xenon performance of 84 to 96 percent mass utilization was realized at 203 to 350 eV/ion. The optimization process and test results are discussed.

Ramsey, W. D.

1978-01-01

199

Inert gas ion thruster development  

NASA Technical Reports Server (NTRS)

Two 12 cm magneto-electrostatic containment (MESC) ion thrusters were performance mapped with argon and xenon. The first, hexagonal, thruster produced optimized performance of 48.5to 79 percent argon mass utilization efficiencies at discharge energies of 240 to 425 eV/ion, respectively, Xenon mass utilization efficiencies of 78 to 95 percent were observed at discharge energies of 220 to 290 eV/ion with the same optimized hexagonal thruster. Changes to the cathode baffle reduced the discharge anode potential during xenon operation from approximately 40 volts to about 30 volts. Preliminary tests conducted with the second, hemispherical, MESC thruster showed a nonuniform anode magnetic field adversely affected thruster performance. This performance degradation was partially overcome by changes in the boundary anode placement. Conclusions drawn the hemispherical thruster tests gave insights into the plasma processes in the MESC discharge that will aid in the design of future thrusters.

Ramsey, W. D.

1980-01-01

200

Hydrogen\\/dust explosion hazard in ITER: Effect of nitrogen dilution on explosion behavior of hydrogen\\/tungsten dust\\/air mixtures  

Microsoft Academic Search

The work is aimed at supporting inert-gas dilution method proposed to mitigate hydrogen\\/dust explosion hazard in ITER in case of severe accidents. A standard method of 20-l sphere is used to study the effect of nitrogen dilution on the explosion behavior of 0.5-?m tungsten dust dispersed in hydrogen-containing air atmospheres. The oxygen content varied from normal 21 to 10vol.%. The

A. Denkevits

2010-01-01

201

10 cm x 10 cm Single Gas Electron Multiplier (GEM) X-ray Fluorescence Detector for Dilute Elements  

NASA Astrophysics Data System (ADS)

We have built and tested a 10 cm × 10 cm single Gas Electron Multiplier (GEM) X-ray detector to probe dilute amounts of Fe in a prepared sample. The detector uses Argon/Carbon Dioxide (75/25) gas mixture flowing at a slow rate through a leak proof Plexi-glass enclosure held together by O-rings and screws. The Fluorescence X-ray emitted by the element under test is directed through a Mylar window into the drift region of the detector where abundant gas is flowing. The ionized electrons are separated, drifted into the high electric field of the GEM, and multiplied by impact ionization. The amplified negatively charged electrons are collected and further amplified by a Keithley amplifier to probe the absorption edge of the element under test using X-ray absorption spectroscopy technique. The results show that the GEM detector provided good results with less noise as compared with a Silicon drift detector (SDD).

Shaban, E. H.; Siddons, D. P.; Seifu, D.

2014-03-01

202

Particles dispersed in a dilute gas. II. From the Langevin equation to a more general kinetic approach  

NASA Astrophysics Data System (ADS)

In the attempt to solve the age-old problem of unifying Langevin, Fokker-Planck and Boltzmann theories for test particles in a dilute gas, the Uhlenbeck and Ornstein's theory relating Langevin and Fokker-Planck equations is critically analyzed. Agreement and discrepancies between such theory and the results following from the Boltzmann one are also examined. It is concluded that the currently assumed form of the fluctuating-force autocorrelation function, which is extremely successful for Brownian particles in dense fluids, cannot generally guarantee an accurate (or acceptable) relaxation law for the mean square velocity components of generic test particles in dilute gases. This difficulty can be overcome in the framework of a more general kinetic approach which is shown to consistently include Langevin, Fokker-Planck, and Boltzmann theories. The advantages of such approach in interpreting experimental results are particularly evident when the test particles move in a (homogeneous) gas in non-equilibrium conditions and when correlations exist between test- and gas-particle velocities.

Ferrari, Leonardo

2014-01-01

203

Methanol Droplet Combustion in Oxygen-Inert Environments in Microgravity  

NASA Technical Reports Server (NTRS)

The Flame Extinguishment (FLEX) experiment that is currently underway in the Combustion Integrated Rack facility onboard the International Space Station is aimed at understanding the effects of inert diluents on the flammability of condensed phase fuels. To this end, droplets of various fuels, including alkanes and alcohols, are burned in a quiescent microgravity environment with varying amounts of oxygen and inert diluents to determine the limiting oxygen index (LOI) for these fuels. In this study we report experimental observations of methanol droplets burning in oxygen-nitrogen-carbon dioxide and oxygen-nitrogen-helium gas mixtures at 0.7 and 1 atmospheric pressures. The initial droplet size varied between approximately 1.5 mm and 4 mm to capture both diffusive extinction brought about by insufficient residence time at the flame and radiative extinction caused by excessive heat loss from the flame zone. The ambient oxygen concentration varied from a high value of 30% by volume to as low as 12%, approaching the limiting oxygen index for the fuel. The inert dilution by carbon dioxide and helium varied over a range of 0% to 70% by volume. In these experiments, both freely floated and tethered droplets were ignited using symmetrically opposed hot-wire igniters and the burning histories were recorded onboard using digital cameras, downlinked later to the ground for analysis. The digital images yielded droplet and flame diameters as functions of time and subsequently droplet burning rate, flame standoff ratio, and initial and extinction droplet diameters. Simplified theoretical models correlate the measured burning rate constant and the flame standoff ratio reasonably well. An activation energy asymptotic theory accounting for time-dependent water dissolution or evaporation from the droplet is shown to predict the measured diffusive extinction conditions well. The experiments also show that the limiting oxygen index for methanol in these diluent gases is around 12% to 13% oxygen by volume.

Nayagam, Vedha; Dietrich, Daniel L.; Hicks, Michael C.; Williams, Forman A.

2013-01-01

204

Some aspects of the distribution of polycyclic aromatic hydrocarbons (pah) between particles and gas phase from diluted gasoline exhausts generated with the use of a dilution tunnel, and its validity for measurement in ambient air  

NASA Astrophysics Data System (ADS)

The composition of particle associated polycyclic aromatic hydrocarbons (PAH) originating from diluted gasoline exhausts is compared with that of ambient air samples. The dilution technique used for sampling of vehicle exhausts generates particles with a PAH profile similar to that of ambient air particles. It is demonstrated that 2-4-ring PAH originating from gasoline-fueled vehicle exhausts are mainly in the gas phase in the urban street environment. In the case of diesel vehicles, a substantial part of the low molecular weight PAH are adsorbed on the exhaust particles.

Westerholm, Roger; Stenberg, Ulf; Alsberg, Tomas

205

Method of producing hydrogen, and rendering a contaminated biomass inert  

DOEpatents

A method for rendering a contaminated biomass inert includes providing a first composition, providing a second composition, reacting the first and second compositions together to form an alkaline hydroxide, providing a contaminated biomass feedstock and reacting the alkaline hydroxide with the contaminated biomass feedstock to render the contaminated biomass feedstock inert and further producing hydrogen gas, and a byproduct that includes the first composition.

Bingham, Dennis N. (Idaho Falls, ID) [Idaho Falls, ID; Klingler, Kerry M. (Idaho Falls, ID) [Idaho Falls, ID; Wilding, Bruce M. (Idaho Falls, ID) [Idaho Falls, ID

2010-02-23

206

New absorption liquids for the removal of CO 2 from dilute gas streams using membrane contactors  

Microsoft Academic Search

A new absorption liquid based on amino acid salts has been studied for CO2 removal in membrane gas–liquid contactors. Unlike conventional gas treating solvents like aqueous alkanolamines solutions, the new absorption liquid does not wet polyolefin microporous membranes. The wetting characteristics of aqueous alkanolamines and amino acid salt solutions for a hydrophobic membrane was studied by measuring the surface tension

P. S. Kumar; J. A. Hogendoorn; P. H. M. Feron; G. F. Versteeg

2002-01-01

207

Two-phase flow equations for a dilute dispersion of gas bubbles in liquid  

Microsoft Academic Search

Equations of motion correct to the first order of the gas concentration by volume are derived for a dispersion of gas bubbles in liquid through systematic averaging of the equations on the microlevel. First, by ensemble averaging, an expression for the average stress tensor is obtained, which is non-isotropic although the local stress tensors in the constituent phases are isotropic

A. Biesheuvel; L. van Wijngaarden

1984-01-01

208

Inert gases in Sea of Fertility regolith  

NASA Technical Reports Server (NTRS)

The content and isotopic composition were studied of inert gases -- He, Ne, Ar, Kr, and Xe -- in samples of lunar regolith returned by the Luna 16 automatic station. The samples were taken from depths of about 12 and 30 cm. The high concentrations of inert gases exceed by several orders their concentrations observed in ordinary stony meteorites. The gases in lunar regolith were a complex mixture of gases of different origins: Solar, cosmogenic, radiogenic, and so on. Solar wind gases predominated, distributed in the thin surficial layer of the regolith grains. The concentrations of these gases in the surficial layer is several cubic centimeters per gram. The isotopic composition of the inert gases of solar origin approaches their composition measured in gas-rich meteorites.

Vinogradov, A. P.; Zadorozhnyy, I. K.

1974-01-01

209

Efficient gas-separation process to upgrade dilute methane stream for use as fuel  

DOEpatents

A membrane-based gas separation process for treating gas streams that contain methane in low concentrations. The invention involves flowing the stream to be treated across the feed side of a membrane and flowing a sweep gas stream, usually air, across the permeate side. Carbon dioxide permeates the membrane preferentially and is picked up in the sweep air stream on the permeate side; oxygen permeates in the other direction and is picked up in the methane-containing stream. The resulting residue stream is enriched in methane as well as oxygen and has an EMC value enabling it to be either flared or combusted by mixing with ordinary air.

Wijmans, Johannes G. (Menlo Park, CA); Merkel, Timothy C. (Menlo Park, CA); Lin, Haiqing (Mountain View, CA); Thompson, Scott (Brecksville, OH); Daniels, Ramin (San Jose, CA)

2012-03-06

210

Effect of Kr Gas Dilution on O Atom Density in Inductively Coupled Kr/O2 Plasma  

NASA Astrophysics Data System (ADS)

Oxygen-based plasmas have been used for the low temperature oxidation of materials. It has been reported that the high quality SiO2 film was formed at a low temperature by Kr dilution O2 plasma. From the viewpoint of developing the low temperature oxidation processes used for the gate dielectric film in LCD devices, a quantitative study on the behavior of O atom in the Kr/O2 mixture plasma is strongly required. In this study, we measured the absolute O atom and metastable Kr atom densities in an inductively coupled Kr/O2 plasma using vacuum ultraviolet absorption spectroscopy technique. The transition lines used for absorption measurements were ^3S0 - ^3P_2, ^3S0 - ^3P1 and ^3S0 - ^3P0 at 130.2 nm for O atom and ^3D3 - ^3P2 at 811.3 nm for metastable Kr atom. The absolute O atom density was almost constant on 4×10^13 cm-3 although the Kr dilution ratio was increased from 0 to 99% at an RF power of 200W, a pressure of 107 Pa, and a total gas flow rate of 100 sccm. The effect of metastable Kr atom on the production of the O atom has been discussed.

Hori, Masaru; Ikuma, Soichi; Goto, Toshio

2003-10-01

211

Determination of lead in urine and whole blood by stable isotope dilution gas chromatography-mass spectrometry.  

PubMed

A stable isotope dilution gas chromatography-mass spectrometry (GC-MS) method is described for the determination of lead (Pb) in urine and whole blood. The use of lithium bis(trifluoroethyl)dithiocarbamate Pb(FDEDTC) as a chelating agent showed strong memory effect, restricting the range of Pb isotope ratios that can be measured in unknown samples. To overcome this carryover problem, we further derivatized the Pb(FDEDTC)2 chelate with 4-fluorophenyl magnesium bromide to form Pb(FC6H4)4. The sequential analyses of solutions of natural Pb and enriched 204Pb with Pb(FC6H4)4 chelate by GC-MS demonstrated no observable memory effect. Precision and accuracy of Pb isotope ratio measurements with Pb(FC6H4)4 were established, and the isotope dilution GC-MS method was validated by determining Pb concentrations in urine standards from the National Institute of Standards and Technology, urine and blood reference materials from the New York State Department of Health, and blood Pb survey samples from the College of American Pathologists. PMID:8044988

Aggarwal, S K; Kinter, M; Herold, D A

1994-08-01

212

Study of Fuel Dilution of Diesel Lubricating Oil by Gas Chromatography/Mass Spectrometry.  

National Technical Information Service (NTIS)

A method for the detection and identification of fuel components in diesel lubricating oil is described. The method uses a capillary gas chromatograph coupled to a quadrupole mass spectrometer to separate, detect and identify diluents in the oil. A typica...

D. E. Veinot J. A. Hiltz R. D. Haggett

1989-01-01

213

Effect of lattice discreteness on the statistical mechanics of a dilute gas of kinks  

Microsoft Academic Search

We apply the collective-variable projection-operator approach based on the Dirac-bracket theory of constrained Hamiltonian systems to the calculation of the Helmholtz free energy of discrete nonlinear Klein-Gordon systems in the ideal-kink-gas limit. The kinks in the continuum nonlinear Klein-Gordon systems in the ideal-gas limit behave as free particles and the phonon density of states changes due to the presence of

C. R. Willis; R. Boesch

1990-01-01

214

Simultaneous determination of alachlor, metolachlor, atrazine, and simazine in water and soil by isotope dilution gas chromatography/mass spectrometry  

SciTech Connect

A multiresidue method was developed for the simultaneous determination of low parts per billion (ppb) concentrations of the herbicides alachlor, metolachlor, atrazine, and simazine in water and soil using isotope dilution gas chromatography/mass spectrometry (GC/MS). Known amounts of /sup 15/N,/sup 13/C-alachlor and /sup 2/H/sub 5/-atrazine were added to each sample as internal standards. The samples were then prepared by a solid phase extraction with no further cleanup. A high resolution GC/low resolution MS system with data acquisition in selected ion monitoring mode was used to quantitate herbicides in the extract. The limit of detection was 0.05 ppb for water and 0.5 ppb for soil. Accuracy greater than 80% and precision better than 4% was demonstrated with spiked samples.

Huang, L.Q.

1989-03-01

215

46 CFR 154.1740 - Vinyl chloride: Inhibiting and inerting.  

Code of Federal Regulations, 2010 CFR

...FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Special Design and Operating Requirements § 154...met; or (b) Section 154.1710 is met, and the oxygen content of inert gas is less than 0.1% by...

2010-10-01

216

New microscopic model for dilute alpha-gas states and its extension  

NASA Astrophysics Data System (ADS)

We show a road map of the microscopic ?-condensation model, which fully takes into account the Pauli principle between all the constituent nucleons and effective inter-nucleon forces simultaneously, and which can play an important role in reproducing an ?-gas-like nature thanks to ?-condensation.

Tohsaki, Akihiro

2011-09-01

217

The quantification of synthetic corticosteroids using isotope dilution gas chromatography negative chemical ionization mass spectrometry.  

PubMed

Prednisolone, dexamethasone and betamethasone were labelled with deuterium via a simple synthetic procedure and used as internal standards in the gas chromatographic/mass spectrometric analysis of the corresponding undeuterated compounds. The mass spectrometer was used in the negative chemical ionization mode, which gave fragmentation of the methoxime trimethylsilyl ether derivatives favourable for their quantification. The method was applicable to the quantification of synthetic corticosteroids contained in human aqueous humour in the 0.1-10-ng range. PMID:3382802

Midgley, J M; Watson, D G; Healey, T; Noble, M

1988-05-01

218

Dilute, dense-phase and maximum solid-gas transport. Sixth quarterly report  

Microsoft Academic Search

The objective of this investigation is to develop an experimentally verified theory of gas-solid transport that will permit scale-up and design of many coal feeding and transport systems. This report presents our data for pressure drop and hold-up of glass beads transported in the vertical pneumatic apparatus described in the Proceedings of the Advanced Research And Development Direct Utilization Contractors

Gidespow

1986-01-01

219

Determination of atmospheric carbonyl sulfide by isotope dilution gas chromatography/mass spectrometry  

SciTech Connect

A gas chromatography/mass spectrometry (GB/MS) method for determining atmospheric carbonyl sulfide (OCS) with a precision better than 2% is reported. High precision and insensitivity to sample loss and changes in detector response were achieved by using isotopically labeled OCS as an internal standard. Tenax, Molecular Sieve 5A, Carbosieve B, and Carbosieve S were evaluated for collecting atmospheric OCS. Molecular Sieve 5A provided the best trapping and recovery efficiencies.

Lewin, E.E.; Taggart, R.L.; Lalevic, M.; Bandy, A.R.

1987-05-01

220

Thermochemical Data of Organic Ions Obtained from Investigations in the More or Less "Diluted" Gas Phase.  

PubMed

How is a proton bound to an arene, how mobile is it in such a complex, and how much energy is required to remove it-these questions have been of fundamental interest in physical organic chemistry for half a century. The experimental determination of quantitative thermochemical data of organic elementary processes in the gas phase is discussed for recent examples, such as the alpha-acidification of tertiary amines by complexation with boranes (see reaction) and the "local" C(alpha)-H acidities of alpha,alpha,alpha-trifluoromethylbenzene and higher analogues. PMID:10649351

Kuck

2000-01-01

221

Activity Coefficients at Infinite Dilution of Organic Compounds in Trihexyl(tetradecyl)phophonium Bis(trifluoromethylsulfonyl)imide Using Inverse Gas Chromatography  

SciTech Connect

Activity coefficients at infinite dilution of organic compounds in the ionic liquid (IL) trihexyl(tetradecyl) phosphonium bis(trifluoromethylsulfonyl)imide were determined using inverse gas chromatography at three temperatures, T ) (302.45, 322.35, and 342.45) K. Linear free energy relationship (LFER) correlations have been obtained for describing the gas-to-IL and water-to-IL partition coefficients.

Revelli, Anne-Laure [Laboratoire de Thermodynamique des Milieux Polyphases, Nancy-Universite, Nancy, France; Sprunger, Laura [University of North Texas; Gibbs, Jennifer [University of North Texas; Acree, William [University of North Texas; Baker, Gary A [ORNL; Mutelet, Fabrice [Laboratoire de Thermodynamique des Milieux Polyphases, Nancy-Universite, Nancy, France

2009-01-01

222

PAFC performance loss due to CO2 dilution effect  

NASA Astrophysics Data System (ADS)

The sensitivity of dilution effects in anode fuel has been extensively examined for Westinghouse Phosphoric Acid Fuel Cells (PAFCs). These fuel cells were designed to be operated with reformed fuel generated from natural gas and other H2 rich fuels. The main nonhydrogen constituents of the studied fuels are CO2 and CO. This work was performed to study the real effect of CO2 diluting losses on these cells in various anode fuel mixtures with the CO2 concentration varying from 0 percent to as high as 53 percent by mole. Cell performance losses were evaluated over a utilization range of 40-85 percent and two current levels, 150 A and 320 A. The results obtained confirm that the Westinghouse PAFC could operate with high inert (CO2 or similar gases) concentration fuel.

Le, M. T.

223

Implications of hydrodynamic fluctuations for the minimum shear viscosity of the dilute Fermi gas at unitarity  

NASA Astrophysics Data System (ADS)

We confirm and expand on work by Chafin and Schäfer [Phys. Rev. A1050-294710.1103/PhysRevA.87.023629 87, 023629 (2013)] on hydrodynamic fluctuations in the unitary Fermi gas. Using the result for the equation of state from a recent MIT experiment, we derive lower bounds for ?/n and ?/s as a function of temperature. Reanalyzing recent quantum Monte Carlo data for the shear-viscosity spectral function, we point out a possible resolution for the tension between the viscosity bound ?/n?0.3 from Chafin and Schäfer and the quantum Monte Carlo results ?/n?0.2 from Wlazlowski, Magierski, and Drut [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.109.020406 109, 020406 (2012)] near the critical temperature.

Romatschke, Paul; Young, Ryan Edward

2013-05-01

224

Analysis of N-nitrosamines in water by isotope dilution gas chromatography-electron ionisation tandem mass spectrometry.  

PubMed

A method has been developed for the determination of eight N-nitrosamines in drinking water and treated municipal effluent. The method uses solid phase extraction (SPE), gas chromatography (GC) and analysis by tandem mass spectrometry (MS-MS) with electron ionization (EI). The target compounds are N-nitrosodimethylamine (NDMA), N-nitrosomethyethylamine (NMEA), N-nitrosodiethylamine NDEA), N-nitrosodipropylamine (NDPA), N-nitrosodi-n-butylamine (NDBuA), N-nitrosodiphenylamine (NDPhA), N-nitrosopyrrolidine (NPyr), N-nitrosopiperidine (NPip), N-nitrosomorpholine (NMorph). The use of direct isotope analogues for isotope dilution analysis of all analytes ensures accurate quantification, accounting for analytical variabilities that may occur during sample processing, extraction and instrumental analysis. Method detection levels (MDLs) were determined to describe analyte concentrations sufficient to provide a signal with 99% certainty of detection. The established MDLs for all analytes were 0.4-4 ng L(-1) in a variety of aqueous matrices. Sample matrices were observed to have only a minor impact on MDLs and the method validation confirmed satisfactory method stability over intra-day and inter-day analyses of tap water and tertiary treated effluent samples. PMID:22967534

McDonald, James A; Harden, Nick B; Nghiem, Long D; Khan, Stuart J

2012-09-15

225

Isotope dilution determination of polycyclic aromatic hydrocarbons in olive pomace oil by gas chromatography-mass spectrometry.  

PubMed

A gas chromatographic (GC) method with mass spectrometry detection (MS) for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in olive pomace oil has been developed. The oil was diluted with n-pentane and extracted by liquid-liquid partition with dimethyl sulphoxide (DMSO). After water addition and back-extraction with cyclohexane, a thin-layer chromatography on silica gel was performed as a further purification step. The PAHs spot was scraped off from the plate and the final extract was concentrated and analysed by GC-MS in full scan mode. The eight PAHs under investigation were determined in the presence of the corresponding labelled compounds added as internal standards to the sample at the beginning of the analytical process. The identified PAHs were then quantified by the isotope dilution methodology assuring the compensation of the concentration of each analyte for any variation in the sample preparation. The method precision was satisfactory with relative standard deviation (R.S.D.) values in the range 3.6-12.7% for all PAHs. The average recovery rates ranged from 69.0 to 97.5%. Accuracy was also calculated for benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene by analysing a certified reference material (CRM 458, coconut oil) with adequate results. All response curves exhibited a linear fit from 0.1 to 10 microg ml(-1) and the determination coefficients R2 were better than 0.9942. The limits of detection (0.1-0.4 microg kg(-1)) were acceptable when compared with the maximum permitted limit of 2 microg kg(-1) for each of the eight considered PAHs and 5 microg kg(-1) for the sum of the eight PAHs established by the Italian legislation. Measurement uncertainty was finally calculated identifying and quantifying the uncertainty components of the analytical process. The relative expanded uncertainties (Uc), expressed as percent values were in the range 8.5-11.4% thus appropriate for residues quantification in the range of concentrations considered in the present study. PMID:15679162

Diletti, Gianfranco; Scortichini, Giampiero; Scarpone, Rossana; Gatti, Giuseppe; Torreti, Luigi; Migliorati, Giacomo

2005-01-14

226

Simultaneous detection of multiple hydroxylated polychlorinated biphenyls from a complex tissue matrix using gas chromatography/isotope dilution mass spectrometry.  

PubMed

In this study, we developed a comprehensive, highly sensitive, and robust method for determining 53 congeners of three to eight chlorinated OH-PCBs in liver and brain samples by using isotope dilution gas chromatography (GC) coupled with electron capture negative ionization mass spectrometry (ECNI-MS). These results were compared with those from GC coupled with electron ionization high-resolution mass spectrometry (EI-HRMS). Clean-up procedures for analysis of OH-PCBs homologs in liver and brain samples involve a pretreatment step consisting of acetonitrile partition and 5% hydrated silica-gel chromatography before derivatization. Recovery rates of tri- and tetra-chlorinated OH-PCBs in the acetonitrile partition method followed by the 5% hydrated silica-gel column (82% and 91%) were higher than conventional sulfuric acid treatment (2.0% and 3.5%). The method detection limits of OH-PCBs for each matrix obtained by GC/ECNI-MS and GC/EI-HRMS were 0.58-2.6 pg g(-1) and 0.36-1.6 pg g(-1) wet wt, respectively. Recovery rates of OH-PCB congeners in spike tests using sample matrices (10 and 50 pg) were 64.7-117% (CV: 4.7-14%) and 70.4-120% (CV: 2.3-12%), respectively. This analytical method may enable the simultaneous detection of various OH-PCBs from complex tissue matrices. Furthermore, this method allows more comprehensive assessment of the biological effects of OH-PCB exposure on critical organs. PMID:24274296

Eguchi, Akifumi; Nomiyama, Kei; Ochiai, Mari; Mizukawa, Hazuki; Nagano, Yasuko; Nakagawa, Katsuhiro; Tanaka, Kouki; Miyagawa, Haruhiko; Tanabe, Shinsuke

2014-01-15

227

Diagnosis of inborn errors of metabolism using filter paper urine, urease treatment, isotope dilution and gas chromatography-mass spectrometry.  

PubMed

This review will be concerned primarily with a practical yet comprehensive diagnostic procedure for the diagnosis or even mass screening of a variety of metabolic disorders. This rapid, highly sensitive procedure offers possibilities for clinical chemistry laboratories to extend their diagnostic capacity to new areas of metabolic disorders. The diagnostic procedure consists of the use of urine or filter paper urine, preincubation of urine with urease, stable isotope dilution, and gas chromatography-mass spectrometry. Sample preparation from urine or filter paper urine, creatinine determination, stable isotope-labeled compounds used, and GC-MS measurement conditions are described. Not only organic acids or polar ones but also amino acids, sugars, polyols, purines, pyrimidines and other compounds are simultaneously analyzed and quantified. In this review, a pilot study for screening of 22 target diseases in newborns we are conducting in Japan is described. A neonate with presymptomatic propionic acidemia was detected among 10,000 neonates in the pilot study. The metabolic profiles of patients with ornithine carbamoyl transferase deficiency, fructose-1,6-bisphosphatase deficiency or succinic semialdehyde dehydrogenase deficiency obtained by this method are presented as examples. They were compared to those obtained by the conventional solvent extraction methods or by the tandem mass spectrometric method currently done with dried filter blood spots. The highly sensitive, specific and comprehensive features of our procedure are also demonstrated by its use in establishing the chemical diagnosis of pyrimidine degradation defects in order to prevent side effects of pyrimidine analogs such as 5-flurouracil, and the differential diagnosis of three types of homocystinuria, orotic aciduria, uraciluria and other urea cycle disorders. Evaluation of the effects of liver transplantation or nutritional conditions such as folate deficiency in patients with inborn errors of metabolism is also described. PMID:11482733

Kuhara, T

2001-07-01

228

Simultaneous analysis of urinary phthalate metabolites of residents in Korea using isotope dilution gas chromatography-mass spectrometry.  

PubMed

Phthalates are used in industry products, household items, and medical tools as plasticizers. Human exposure to phthalates has raised concern about its toxicity. In the present study, optimization was conducted for the simultaneous analysis of eight kinds of phthalate metabolites using gas chromatography-mass spectrometry (GC-MS): MEP, MiBP, MnBP, MBzP, MiNP, MEHP, MEOHP, and MEHHP. In order to minimize the matrix effect and to do quantitative analysis, isotope dilution and LLE-GC-MS methods were performed. Urine samples were enzymatically hydrolyzed, extracted with a mixture of n-hexane and ethyl ether (8:2; v:v), and subsequently derivatized with trimethylsilylation. All eight kinds of analytes showed clear resolution and high reproducibility in GC-MS results. The method detection limit ranged from 0.05 ng/mL to 0.2 ng/mL. Calibration curves were found to be linear from 0.2 to 100 ng/mL with -(2)>0.992. The relative standard deviation of the intraday precision using water and urine ranged from 2.1% to 16.3%. The analysis was performed with urine samples that were collected from adults residing in the Republic of Korea. The analyzed concentration results were compared according to gender and region. As a result, DEHP metabolites showed the highest detected concentration (75.92 ?g/g creatinine, 100%), and MiNP, a metabolite of DiNP, showed the lowest detected concentration (0.42 ?g/g creatinine, 22.5%). On average, female urine (200.76 ?g/g creatinine) had a higher detected concentration of ?8 phthalate metabolites than male urine. Samples from rural regions (211.96 ?g/g creatinine) had higher levels than samples from urban regions. PMID:23928369

Kim, Miok; Song, Na Rae; Choi, Jong-Ho; Lee, Jeongae; Pyo, Heesoo

2014-02-01

229

Measurement of dialkyl phosphate metabolites of organophosphorus pesticides in human urine using lyophilization with gas chromatography-tandem mass spectrometry and isotope dilution quantification  

Microsoft Academic Search

Urinary dialkylphosphate (DAP) metabolites have been used to estimate human exposure to organophosphorus pesticides. We developed a method for quantifying the six DAP urinary metabolites of at least 28 organophosphorus pesticides using lyophilization and chemical derivatization followed by analysis using isotope-dilution gas chromatography–tandem mass spectrometry (GC–MS\\/MS). Urine samples were spiked with stable isotope analogues of the DAPs and the water

Roberto Bravo; Lisa M Caltabiano; Gayanga Weerasekera; Ralph D Whitehead; Carolina Fernandez; Larry L Needham; Asa Bradman; Dana B Barr

2004-01-01

230

Quantification of carcinogenic 4- to 6-ring polycyclic aromatic hydrocarbons in human urine by solid-phase microextraction gas chromatography–isotope dilution mass spectrometry  

Microsoft Academic Search

Polycyclic aromatic hydrocarbons (PAHs) are pollutants found in living and working environments. The aim of this study was\\u000a to develop a solid-phase microextraction (SPME) gas chromatography (GC)–isotope dilution mass spectrometry method for the\\u000a quantification of 10 four- to six-ring PAHs in urine samples. Seven of the selected PAHs have been classified as carcinogenic.\\u000a Under the final conditions, analytes were sampled

Laura Campo; Silvia Fustinoni; PierAlberto Bertazzi

231

Application of isotope dilution to the determination of methylmercury in fish tissue by solid-phase microextraction gas chromatography-mass spectrometry  

Microsoft Academic Search

Species-specific isotope dilution (ID) calibration using solid-phase microextraction (SPME) in combination with gas chromatography-mass spectrometry (GC-MS) for separation and detection of methylmercury (MeHg) in fish tissue is described. Samples were digested with methanolic potassium hydroxide. Analytes were propylated and headspace sampled with a polydimethylsiloxane-coated SPME fused-silica fiber. ID analysis was performed using a laboratory-synthesized 198Hg-enriched methylmercury (Me198Hg) spike. Using selective

Lu Yang; Vanessa Colombini; Paulette Maxwell; Zoltán Mester; Ralph E. Sturgeon

2003-01-01

232

Validation of a gas chromatography-mass spectrometry isotope dilution method for the determination of 2-butoxyethanol and other common glycol ethers in consumer products.  

PubMed

A gas chromatography-mass spectrometry isotope dilution (GC-MS ID) method was developed and tested for the determination of 14 common glycol ethers in consumer products. Stable isotope labelled standards, 2-methoxyethanol-D(7) and 2-butoxyethanol-(13)C(2) (CDN isotopes) were employed to enhance the accuracy and precision of the glycol ethers determination. A 1000-fold sample dilution with methanol was applied to avoid column overload and contamination. At this dilution matrix effects were in most cases negligible and did not interfere with the analysis. The instrument detection limit (IDL) for analysed compounds varied from 0.01 to 1 ?g/mL; while the estimated limit of quantification (LoQ) varied between different glycol ethers from 0.02 to 3.4 ?g/mL. Calibration was tested in the range of 0.1-200 ?g/mL and showed that the linear fit is upheld from 0.1 to 10 ?g/mL, and extends beyond this range for some of the analytes. Recoveries of glycol ethers from products with different matrices were similar. The recoveries varied from 87% to 116% between the analysed compounds, while measurements precision varied between 2% and 14%. The method is applicable to products with glycol ether concentrations above 0.002-0.2% (w/w). The concentration range can be extended below the specified limits by decreasing the dilution factor; however, with lower dilution the sample matrix effect is expected to be stronger. Products with very high concentrations of glycol ether (>20%) may need to be further diluted prior to injection to avoid column overload. The method can be used for testing liquid and aerosol products designed for household use, such as cleaners, paints, solvents and paint stripers, for compliance and enforcement of regulations which limit glycol ethers content. PMID:20855078

Tokarczyk, Ryszard; Jiang, Ying; Poole, Gary; Turle, Richard

2010-10-29

233

Aroma quality assessment of Korean fermented red pepper paste (gochujang) by aroma extract dilution analysis and headspace solid-phase microextraction-gas chromatography-olfactometry.  

PubMed

The objective of this study was to assess aroma quality of gochujang using purge and trap, simultaneous steam distillation and solvent extraction (SDE), and headspace solid-phase microextraction (HS-SPME), followed by gas chromatography-olfactometry (GC-O). Nineteen and 28 aroma-active compounds were detected by aroma extract dilution analysis of purge and trap and SDE, respectively. Diallyl disulfide and 3-isobutyl-2-methoxypyrazine played a significant role in the aroma quality of gochujang. Twelve aroma-active compounds were detected by HS-SPME-GC-O based on sample dilution analysis. Methional, diallyl disulfide, and 3-isobutyl-2-methoxypyrazine were the most intense aroma-active compounds. 3-Isobutyl-2-methoxypyrazine was identified for the first time in gochujang. PMID:24128505

Kang, Kyung-Mo; Baek, Hyung-Hee

2014-02-15

234

Examination of charge dilution with EGR to reduce NO{sub x} emissions from a natural gas-fuelled 16 valve DOHC four-cylinder engine  

SciTech Connect

Charge dilution is commonly used to reduce emissions of nitrogen oxides (NO{sub x}) from internal combustion engine exhaust gas. The question of whether to use air or exhaust gas recirculation (EGR) as a charge diluent for the natural gas-fuelled test engine is addressed first. The decision to use EGR is based on the potentially lower NO{sub x} and unburned hydrocarbon emissions that could be achieved if a three-way catalyst were applied to the engine. The effect of EGR on the spark advance for maximum brake torque (MBT), NO{sub x}, and unburned hydrocarbon emissions is then examined in detail. The effect on fuel efficiency is discussed briefly. 37 refs., 16 figs., 3 tabs.

Jaeaeskelaeinen, H.E.; Wallace, J.S.

1994-10-01

235

Transient Thermometry with Inert Thermometers.  

National Technical Information Service (NTIS)

A thermometer in contact with a test specimen is inert, if its heat capacity is not small compared with the heat capacity of the test specimen. The response of the thermometer to a transient temperature of the specimen can then be described by a transfer ...

J. C. Erdmann J. A. Jahoda

1966-01-01

236

Relations Between the Arrhenius Activation Energy and Threshold Energy for Simple Models of the Reactive Cross Sections in a Dilute Gas  

NASA Astrophysics Data System (ADS)

The Arrhenius activation energy for the reaction A + A leftrightarrows B + B in a dilute gas is calculated from a temperature dependence of the rate constant obtained from the perturbation solution of the Boltzmann equation. The first and the second approximation to the velocity distribution function are used in an analysis of nonequilibrium effects. Results obtained for the line-of-centers model and the Prigogine--Xhrouet model of reactive differential cross sections are presented. The Arrhenius activation energy is represented as a function of appropriate threshold energies.

Cukrowski, A. S.

2006-06-01

237

Bénard instabilities in a binary-liquid layer evaporating into an inert gas: Stability of quasi-stationary and time-dependent reference profiles  

NASA Astrophysics Data System (ADS)

This study treats an evaporating horizontal binary-liquid layer in contact with the air with an imposed transfer distance. The liquid is an aqueous solution of ethanol (10% wt). Due to evaporation, the ethanol mass fraction can change and a cooling occurs at the liquid-gas interface. This can trigger solutal and thermal Rayleigh-Bénard-Marangoni instabilities in the system, the modes of which corresponding to an undeformable interface form the subject of the present work. The decrease of the liquid-layer thickness is assumed to be slow on the diffusive time scales (quasi-stationarity). First we analyse the stability of quasi-stationary reference profiles for a model case within which the mass fraction of ethanol is assumed to be fixed at the bottom of the liquid. Then this consideration is generalized by letting the diffusive reference profile for the mass fraction in the liquid be transient (starting from a uniform state), while following the frozen-time approach for perturbations. The critical liquid thickness below which the system is stable at all times quite expectedly corresponds to the one obtained for the quasi-stationary profile. As a next step, a more realistic, zero-flux condition is used at the bottom in lieu of the fixed-concentration one. The critical thickness is found not to change much between these two cases. At larger thicknesses, the critical time at which the instability first appears proves, as can be expected, to be independent of the type of the concentration condition at the bottom. It is shown that solvent (water) evaporation plays a stabilizing role as compared to the case of a non-volatile solvent. At last, an effective approximate Pearson-like model is invoked making use in particular of the fact that the solutal Marangoni is by far the strongest as an instability mechanism here.

Machrafi, H.; Rednikov, A.; Colinet, P.; Dauby, P. C.

2011-02-01

238

Dilution Confusion: Conventions for Defining a Dilution  

ERIC Educational Resources Information Center

Two conventions for preparing dilutions are used in clinical laboratories. The first convention defines an "a:b" dilution as "a" volumes of solution A plus "b" volumes of solution B. The second convention defines an "a:b" dilution as "a" volumes of solution A diluted into a final volume of "b". Use of the incorrect dilution convention could affect…

Fishel, Laurence A.

2010-01-01

239

Dilution-based emissions sampling from stationary sources: Part 2--Gas-fired combustors compared with other fuel-fired systems.  

PubMed

With the recent focus on fine particle matter (PM2.5), new, self-consistent data are needed to characterize emissions from combustion sources. Such data are necessary for health assessment and air quality modeling. To address this need, emissions data for gas-fired combustors are presented here, using dilution sampling as the reference. The dilution method allows for collection of emitted particles under conditions simulating cooling and dilution during entry from the stack into the air. The sampling and analysis of the collected particles in the presence of precursor gases, SO2 nitrogen oxide, volatile organic compound, and NH3 is discussed; the results include data from eight gas fired units, including a dual-fuel institutional boiler and a diesel engine powered electricity generator. These data are compared with results in the literature for heavy-duty diesel vehicles and stationary sources using coal or wood as fuels. The results show that the gas-fired combustors have very low PM2.5 mass emission rates in the range of approximately 10(-4) lb/million Btu (MMBTU) compared with the diesel backup generator with particle filter, with approximately 5 x 10(-3) lb/MMBTU. Even higher mass emission rates are found in coal-fired systems, with rates of approximately 0.07 lb/MMBTU for a bag-filter-controlled pilot unit burning eastern bituminous coal. The characterization of PM2.5 chemical composition from the gas-fired units indicates that much of the measured primary particle mass in PM2.5 samples is organic or elemental carbon and, to a much less extent, sulfate. Metal emissions are quite low compared with the diesel engines and the coal- or wood-fueled combustors. The metals found in the gas-fired combustor particles are low in concentration, similar in concentration to ambient particles. The interpretation of the particulate carbon emissions is complicated by the fact that an approximately equal amount of particulate carbon (mainly organic carbon) is found on the particle collector and a backup filter. It is likely that measurement artifacts, mostly adsorption of volatile organic compounds on quartz filters, are positively biasing "true" particulate carbon emission results. PMID:17269233

England, Glenn C; Watson, John G; Chow, Judith C; Zielinska, Barbara; Chang, M C Oliver; Loos, Karl R; Hidy, George M

2007-01-01

240

Gas chromatography-combustion-mass spectrometry with postcolumn isotope dilution for compound-independent quantification: its potential to assess HS-SPME procedures.  

PubMed

A quadrupole GC-MS instrument with an electron ionization (EI) source has been modified to enable application of postcolumn isotope dilution analysis for the standardless quantification of organic compounds injected in the gas chromatograph. Instrumental modifications included the quantitative conversion of the separated compounds into CO(2), using a postcolumn combustion furnace, and the subsequent mixing of the gas with a constant flow of (13)CO(2) diluted in helium. The online measurement of the (12)CO(2)/(13)CO(2) (44/45) ratio in the EI-MS allowed us to obtain quantitative data without resorting to compound-specific standards. Validation of the procedure involved the analysis of standard solutions containing different families of organic compounds (C(9)-C(20) linear hydrocarbons, BTEX and esters) obtaining satisfactory results in all cases in terms of absolute errors (<6%) and precision (<4% RSD). The developed procedure showed excellent linearity over the range assayed (2 orders of magnitude) and adequate detection limits for carbon containing compounds (0.8 pg C s(-1)). The generic value of this compound-independent calibration approach was assessed by studying the quantitative performance of Head Space-Solid Phase Microextraction (HS-SPME). The proposed compound-independent quantification by EI-MS permits comparison of the performance of different fibers by assessing analyte recoveries with extreme robustness, simplicity, and precision. PMID:20704376

Cueto Díaz, Sergio; Ruiz Encinar, Jorge; Sanz-Medel, Alfredo; García Alonso, J Ignacio

2010-08-15

241

Inert anodes for aluminum smelting  

SciTech Connect

The use of nonconsumable or inert anodes for replacement of consumable carbon anodes in Hall electrolysis cells for the production of aluminum has been a technical and commercial goal of the aluminum industry for many decades. This report summarizes the technical success realized in the development of an inert anode that can be used to produce aluminum of acceptable metal purity in small scale Hall electrolysis cells. The inert anode material developed consists of a cermet composition containing the phases: copper, nickel ferrite and nickel oxide. This anode material has an electrical conductivity comparable to anode carbon used in Hall cells, i.e., 150 ohm {sup {minus}1}cm{sup {minus}1}. Metal purity of 99.5 percent aluminum has been produced using this material. The copper metal alloy present in the anode is not removed by anodic dissolution as does occur with cermet anodes containing a metallic nickel alloy. Solubility of the oxide phases in the cryolite electrolyte is reduced by: (1) saturated concentration of alumina, (2) high nickel oxide content in the NiO-NiFe{sub 2}O{sub 4} composition, (3) lowest possible cell operating temperature, (4) additions of alkaline or alkaline earth fluorides to the bath to reduce solubilities of the anode components, and (5) avoiding bath contaminants such as silica. Dissolution rate measurements indicate first-order kinetics and that the rate limiting step for dissolution is mass transport controlled. 105 refs., 234 figs., 73 tabs.

Weyand, J.D.; Ray, S.P.; Baker, F.W.; DeYoung, D.H.; Tarcy, G.P.

1986-02-01

242

Trace analysis of acidic pharmaceutical residues in waters with isotope dilution gas chromatography-mass spectrometry via methylation derivatization.  

PubMed

Acidic pharmaceutical residues are pollutants of emerging concern and are generally monitored by HPLC-MS/MS. However, due to the limited separation efficiency of HPLC column and lack of suitable mass transition for confirmation analysis, some interference may not be separated completely and differentiated from ibuprofen, which may cause the results with interference, especially in sample with complex matrix. The objective of this study is to develop a sensitive and reliable method for the determination of acidic pharmaceutical residues in water samples by GC-MS with better resolution by using methylation derivatization and isotope dilution techniques. TMSDM, a mild reagent, was used as the derivatization reagent coupling with the isotope dilution technique, for the first time, to improve the precision and accuracy of the analytical method to determine the pharmaceutical residues in water. The MDLs for the five acidic organic compounds: ibuprofen, gemfibrozil, naproxen, ketoprofen and diclofenac were from 0.7 to 1.1 ng/L, with recoveries ranging from 93 to 110%. Alternative to the HPLC-MS/MS method, the developed GC-MS protocols provides an additional option for the analysis of acidic pharmaceutical residues in water, with better separation efficiency in reducing interferences from complicated sample matrix, for determination of ibuprofen residues. PMID:21872014

Hu, Ruikang; Yang, Zhaoguang; Zhang, Lifeng

2011-09-30

243

Nonlinear Pressure Shifts of Rubidium in Inert Gases  

Microsoft Academic Search

Vapor-cell atomic frequency standards are based on the hyperfine (microwave) magnetic-resonance frequencies of optically pumped alkali-metal atoms in inert buffer gas. Through the hyperfine-shift interaction, buffer gas induces pressure shift and broadening in these microwave resonances. Previous work uncovered nonlinear dependence in the pressure shifts of ^87Rb and Cs atoms to the pressure of buffer gases Ar and Kr, but

Bart McGuyer; Yuan-Yu Jau; William Happer

2009-01-01

244

Developing a scalable inert gas ion thruster  

NASA Technical Reports Server (NTRS)

Analytical studies to identify and then design a high performance scalable ion thruster operating with either argon or xenon for use in large space systems are presented. The magnetoelectrostatic containment concept is selected for its efficient ion generation capabilities. The iterative nature of the bounding magnetic fields allows the designer to scale both the diameter and length, so that the thruster can be adapted to spacecraft growth over time. Three different thruster assemblies (conical, hexagonal and hemispherical) are evaluated for a 12 cm diameter thruster and performance mapping of the various thruster configurations shows that conical discharge chambers produce the most efficient discharge operation, achieving argon efficiencies of 50-80% mass utilization at 240-310 eV/ion and xenon efficiencies of 60-97% at 240-280 eV/ion. Preliminary testing of the large 30 cm thruster, using argon propellant, indicates a 35% improvement over the 12 cm thruster in mass utilization efficiency. Since initial performance is found to be better than projected, a larger 50 cm thruster is already in the development stage.

James, E.; Ramsey, W.; Steiner, G.

1982-01-01

245

Modelling of non-catalytic reactions in a gas-solid trickle flow reactor: dry, regenerative flue gas desulphurization using a silica-supported copper oxide sorbent  

Microsoft Academic Search

A one-dimensional, two-phase dispersed plug flow model has been developed to describe the steady-state performance of a relatively new type of reactor, the gas-solid trickle flow reactor (GSTFR). In this reactor, an upward-flowing gas phase is contacted with as downward-flowing dilute solids phase over an inert packing. The model is derived from the separate mass heat balances for both the

J. H. A. Kiel; W. Prins; Swaaij van W. P. M

1992-01-01

246

An experimental and numerical investigation on the influence of external gas recirculation on the HCCI autoignition process in an engine: Thermal, diluting, and chemical effects  

SciTech Connect

In order to contribute to the solution of controlling the autoignition in a homogeneous charge compression ignition (HCCI) engine, parameters linked to external gas recirculation (EGR) seem to be of particular interest. Experiments performed with EGR present some difficulties in interpreting results using only the diluting and thermal aspect of EGR. Lately, the chemical aspect of EGR is taken more into consideration, because this aspect causes a complex interaction with the dilution and thermal aspects of EGR. This paper studies the influence of EGR on the autoignition process and particularly the chemical aspect of EGR. The diluents present in EGR are simulated by N{sub 2} and CO{sub 2}, with dilution factors going from 0 to 46 vol%. For the chemically active species that could be present in EGR, the species CO, NO, and CH{sub 2}O are used. The initial concentration in the inlet mixture of CO and NO is varied between 0 and 170 ppm, while that of CH{sub 2}O alters between 0 and 1400 ppm. For the investigation of the effect of the chemical species on the autoignition, a fixed dilution factor of 23 vol% and a fixed EGR temperature of 70 C are maintained. The inlet temperature is held at 70 C, the equivalence ratios between 0.29 and 0.41, and the compression ratio at 10.2. The fuels used for the autoignition are n-heptane and PRF40. It appeared that CO, in the investigated domain, did not influence the ignition delays, while NO had two different effects. At concentrations up until 45 ppm, NO advanced the ignition delays for the PRF40 and at higher concentrations, the ignition delayed. The influence of NO on the autoignition of n-heptane seemed to be insignificant, probably due to the higher burn rate of n-heptane. CH{sub 2}O seemed to delay the ignition. The results suggested that especially the formation of OH radicals or their consumption by the chemical additives determines how the reactivity of the autoignition changed. (author)

Machrafi, Hatim; Cavadias, Simeon [UPMC Universite Paris 06, LGPPTS, Ecole Nationale Superieure de Chimie de Paris, 11, rue de Pierre et Marie Curie, 75005 Paris (France); UPMC Universite Paris 06, FRT, Institut Jean Le Rond D'Alembert, 2, place de la Gare de Ceinture, 78210 St Cyr l'Ecole (France); Guibert, Philippe [UPMC Universite Paris 06, FRT, Institut Jean Le Rond D'Alembert, 2, place de la Gare de Ceinture, 78210 St Cyr l'Ecole (France)

2008-11-15

247

Improving gas chromatographic determination of residual solvents in pharmaceuticals by the combined use of headspace solid-phase microextraction and isotopic dilution.  

PubMed

Cyclohexane and toluene were gas chromatographically determined via headspace solid-phase microextraction both in ketoprofen drug substance and ketoprofen capsules by a procedure relying on isotopic dilution (ID), an analytical tool derived from mass spectrometry (MS). This approach, using an internal standard method, gave mean precision and accuracy (RSD 2.56%, 2.97% and bias 0.21%, -0.99% for cyclohexane and toluene, respectively) not obtainable by the more commonly used external standard ones in the presence of real sample matrices. Optimisation of the operative conditions was also supported by experimental design. More generally, the proposed method, exploiting ID without resort to the costly MS instrumentation, could be recommended whenever opportune deuterated analogues of the target analytes and GC capillary columns able to separate all the peaks involved are ready available on the market. PMID:11358250

Coran, S A; Giannellini, V; Furlanetto, S; Bambagiotti-Alberti, M; Pinzauti, S

2001-04-27

248

The role of products and a reverse reaction in analysis of nonequilibrium effects in a bimolecular chemical reaction in a dilute gas  

NASA Astrophysics Data System (ADS)

A thermally activated bimolecular reaction in a dilute gas is analyzed. The Shizgal-Karplus perturbation method of solution of the Boltzmann equation for reactions A+A?B+B and A+A?B+B is used to obtain the analytical expressions for the nonequilibrium temperatures of reactants and for the rate of chemical reaction. For both the reactions the temperatures of components obtained within one and two Sonines approximations depend on concentration of products. The rate constant of chemical reaction depends on concentration of products for the first reaction only and for the second reaction is constant. The analytical results for the temperature of the reactant A are compared with those obtained from the Monte Carlo computer simulations with use of the Bird method. It is shown that all analytical expressions simplify to those previously discussed if the concentration of products is negligible.

Cukrowski, A. S.

2000-01-01

249

Ultrasonication extraction and gel permeation chromatography clean-up for the determination of polycyclic aromatic hydrocarbons in edible oil by an isotope dilution gas chromatography–mass spectrometry.  

PubMed

An analytical method for the determination of US EPA priority pollutant 16 polycyclic aromatic hydrocarbons (PAHs) in edible oil was developed by an isotope dilution gas chromatography-mass spectrometry (GC-MS). Extraction was performed with ultrasonication mode using acetonitrile as solvent, and subsequent clean-up was applied using narrow gel permeation chromatographic column. Three deuterated PAHs surrogate standards were used as internal standards for quantification and analytical quality control. The limits of quantification (LOQs) were globally below 0.5 ng/g, the recoveries were in the range of 81-96%, and the relative standard deviations (RSDs) were lower than 20%. Further trueness assessment of the method was also verified through participation in international cocoa butter proficiency test (T0638) organised by the FAPAS with excellent results in 2008. The results obtained with the described method were satisfying (z ? 2). The method has been applied to determine PAH in real edible oil samples. PMID:20627308

Wang, Jian-Hua; Guo, Cui

2010-07-01

250

Determination of atrazine, lindane, pentachlorophenol, and diazinon in water and soil by isotope dilution gas chromatography/mass spectrometry  

SciTech Connect

This paper describes an isotope dilution GC/MS technique for the analysis of low-parts-per-billion concentrations of atrazine, lindane, pentachlorophenol, and diazinon in water and soil. Known amounts of stable-labeled isotopes such as atrazine-d/sub 5/, lindane-d/sub 6/, pentachlorophenol-/sup 13/C/sub 6/, and diazinon-d/sub 10/ are spiked into each sample prior to extraction. Water samples are extracted with methylene chloride; soil samples are extracted with acetone/hexane. Analysis is performed by high-resolution GC/MS with the mass spectrometer operated in the selected ion monitoring mode. Accuracy greater than 86% and precision better than 8% were demonstrated by use of spiked samples. This technique has been used successfully in the analysis of over 300 water and 300 soil samples. Detection limits of 0.1-1.0 ppb were achieved for the test compounds by selected ion monitoring GC/MS. 8 references, 2 figures, 4 tables.

Lopez-Avila, V.; Hirata, P.; Kraska, S.; Flanagan, M.; Taylor, J.H. Jr.; Hern, S.C.

1985-12-01

251

Interactions of Inert Confiners with Explosives  

Microsoft Academic Search

The deformation of an inert confiner by a steady detonation wave in an adjacent explosive is investigated for cases where\\u000a the confiner is sufficiently strong (or the explosive sufficiently weak) such that the overall change in the sound speed of\\u000a the inert is small. A coupling condition which relates the pressure to the deflection angle along the explosive-inert interface\\u000a is

G. J. Sharpe; J. B. Bdzil

2006-01-01

252

Characterization of the major odor-active compounds in Thai durian ( Durio zibethinus L. 'Monthong') by aroma extract dilution analysis and headspace gas chromatography-olfactometry.  

PubMed

An aroma extract dilution analysis applied on the volatile fraction isolated from Thai durian by solvent extraction and solvent-assisted flavor evaporation resulted in 44 odor-active compounds in the flavor dilution (FD) factor range of 1-16384, 41 of which could be identified and 24 that had not been reported in durian before. High FD factors were found for ethyl (2S)-2-methylbutanoate (fruity; FD 16384), ethyl cinnamate (honey; FD 4096), and 1-(ethylsulfanyl)ethanethiol (roasted onion; FD 1024), followed by 1-(ethyldisulfanyl)-1-(ethylsulfanyl)ethane (sulfury, onion), 2(5)-ethyl-4-hydroxy-5(2)-methylfuran-3(2H)-one (caramel), 3-hydroxy-4,5-dimethylfuran-2(5H)-one (soup seasoning), ethyl 2-methylpropanoate (fruity), ethyl butanoate (fruity), 3-methylbut-2-ene-1-thiol (skunky), ethane-1,1-dithiol (sulfury, durian), 1-(methylsulfanyl)ethanethiol (roasted onion), 1-(ethylsulfanyl)propane-1-thiol (roasted onion), and 4-hydroxy-2,5-dimethylfuran-3(2H)-one (caramel). Among the highly volatile compounds screened by static headspace gas chromatography-olfactometry, hydrogen sulfide (rotten egg), acetaldehyde (fresh, fruity), methanethiol (rotten, cabbage), ethanethiol (rotten, onion), and propane-1-thiol (rotten, durian) were found as additional potent odor-active compounds. Fourteen of the 41 characterized durian odorants showed an alkane-1,1-dithiol, 1-(alkylsulfanyl)alkane-1-thiol, or 1,1-bis(alkylsulfanyl)alkane structure derived from acetaldehyde, propanal, hydrogen sulfide, and alkane-1-thiols. Among these, 1-(propylsulfanyl)ethanethiol, 1-{[1-(methylsulfanyl)ethyl]sulfanyl}ethanethiol, and 1-{[1-(ethylsulfanyl)ethyl]sulfanyl}ethanethiol were reported for the first time in a natural product. PMID:23088286

Li, Jia-Xiao; Schieberle, Peter; Steinhaus, Martin

2012-11-14

253

Flammability limits of dusts: Minimum inerting concentrations  

SciTech Connect

A new flammability limit parameter has been defined as the Minimum Inerting Concentration (MIC). This is the concentration of inertant required to prevent a dust explosion regardless of fuel concentration. Previous experimental work at Fike in a 1-m{sup 3} spherical chamber has shown this flammability limit to exist for pulverized coal dust and cornstarch. In the current work, inerting experiments with aluminum, anthraquinone and polyethylene dusts as fuels were performed, using monoammonium phosphate and sodium bicarbonate as inertants. The results show that an MIC exists only for anthraquinone inerted with sodium bicarbonate. The other combustible dust and inertant mixtures did not show a definitive MIC, although they did show a strong dependence between inerting level and suspended fuel concentration. As the fuel concentration increased, the amount of inertant required to prevent an explosion decreased. Even though a definitive MIC was not found for most of the dusts an effective MIC can be estimated from the data. The use of MIC data can aid in the design of explosion suppression schemes.

Dastidar, A.G.; Amyotte, P.R. [Dalhousie Univ., Halifax, Nova Scotia (Canada). Dept. of Chemical Engineering] [Dalhousie Univ., Halifax, Nova Scotia (Canada). Dept. of Chemical Engineering; Going, J.; Chatrathi, K. [Fike Corp., Blue Springs, MO (United States)] [Fike Corp., Blue Springs, MO (United States)

1999-05-01

254

Airborne measurements of sulfur dioxide, dimethyl sulfide, carbon disulfide, and carbonyl sulfide by isotope dilution gas chromatography/mass spectrometry  

NASA Technical Reports Server (NTRS)

A gas chromatograph/mass spectrometer is described for determining atmospheric sulfur dioxide, carbon disulfide, dimethyl sulfide, and carbonyl sulfide from aircraft and ship platforms. Isotopically labelled variants of each analyte were used as internal standards to achieve high precision. The lower limit of detection for each species for an integration time of 3 min was 1 pptv for sulfur dioxide and dimethyl sulfide and 0.2 pptv for carbon disulfide and carbonyl sulfide. All four species were simultaneously determined with a sample frequency of one sample per 6 min or greater. When only one or two species were determined, a frequency of one sample per 4 min was achieved. Because a calibration is included in each sample, no separate calibration sequence was needed. Instrument warmup was only a few minutes. The instrument was very robust in field deployments, requiring little maintenance.

Bandy, Alan R.; Thornton, Donald C.; Driedger, Arthur R., III

1993-01-01

255

A dynamic inert metal anode.  

SciTech Connect

A new concept for a stable anode for aluminum electrowinning is described. The anode consists of a cup-shaped metal alloy container filled with a molten salt that contains dissolved aluminum. The metal alloy can be any of a number of alloys, but it must contain aluminum as a secondary alloying metal. A possible alloy composition is copper with 5 to 15 weight percent aluminum. In the presence of oxygen, aluminum on the metal anode's exterior surface forms a continuous alumina film that is thick enough to protect the anode from chemical attack by cryolite during electrolysis and thin enough to maintain electrical conductivity. However, the alumina film is soluble in cryolite, so it must be regenerated in situ. Film regeneration is achieved by the transport of aluminum metal from the anode's molten salt interior through the metal wall to the anode's exterior surface, where the transported aluminum oxidizes to alumina in the presence of evolving oxygen to maintain the protective alumina film. Periodic addition of aluminum metal to the anode's interior keeps the aluminum activity in the molten salt at the desired level. This concept for an inert anode is viable as long as the amount of aluminum produced at the cathode greatly exceeds the amount of aluminum required to maintain the anode's protective film.

Hryn, J. N.

1998-11-09

256

Inert matrix fuel behaviour in test irradiations  

NASA Astrophysics Data System (ADS)

Among others, three large irradiation tests on inert matrix fuels have been performed during the last five years: the two irradiation tests IFA-651 and IFA-652 in the OECD Halden Material Test Reactor and the OTTO irradiation in the High Flux Reactor in Petten. While the OTTO irradiation is already completed, the other two irradiations are still ongoing. The objectives of the experiments differ: for OTTO, the focus was on the comparison of different concepts of IMF, i.e. homogeneous fuel versus different types of heterogeneous fuel. In IFA-651, single phase yttria stabilized zirconia (YSZ) doped with Pu is compared with MOX. In IFA-652, the potential of calcia stabilized zirconia (CSZ) as a matrix with and without thoria is evaluated. The design of the three experiments is explained and the current status is reviewed. The experiments show that the homogeneous, single phase YSZ-based or CSZ-based fuel show good and stable irradiation behaviour. It can be said that homogeneous stabilized zirconia based fuel is the most promising IMF concept for an LWR environment. Nevertheless, the fuel temperatures were relatively high due to the low thermal conductivity, potentially leading to high fission gas release, and must be taken into account in the fuel design.

Hellwig, Ch.; Streit, M.; Blair, P.; Tverberg, T.; Klaassen, F. C.; Schram, R. P. C.; Vettraino, F.; Yamashita, T.

2006-06-01

257

Regional water-quality analysis of 2,4-D and dicamba in river water using gas chromatography-isotope dilution mass spectrometry  

USGS Publications Warehouse

Gas chromatography with isotope dilution mass spectrometry (GC-MS) and enzyme-linked immunosorbent assay (ELISA) were used in regional National Water Quality Assessment studies of the herbicides, 2,4-D and dicamba, in river water across the United States. The GC-MS method involved solid-phase extraction, derivatized with deutemted 2,4-D, and analysis by selected ion monitoring. The ELISA method was applied after preconcentration with solid-phase extraction. The ELISA method was unreliable because of interference from humic substances that were also isolated by solid-phase extraction. Therefore, GC-MS was used to analyzed 80 samples from river water from 14 basins. The frequency of detection of dicamba (28%) was higher than that for 2,4-D (16%). Concentrations were higher for dicamba than for 2,4-D, ranging from less than the detection limit (<0.05 ??g/L) to 3.77 ??g/L, in spite of 5 times more annual use of 2,4-D as compared to dicamba. These results suggest that 2,4-D degrades more rapidly in the environment than dicamba.

Thurman, E. M.; Zimmerman, L. R.; Aga, D. S.; Gilliom, R. J.

2001-01-01

258

Determination of nerve agent metabolites in human urine by isotope-dilution gas chromatography-tandem mass spectrometry after solid phase supported derivatization.  

PubMed

A simple and sensitive method has been developed and validated for determining ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA), isobutyl methylphosphonic acid (iBuMPA), and pinacolyl methylphosphonic acid (PMPA) in human urine using gas chromatography-tandem mass spectrometry (GC-MS/MS) coupled with solid phase derivatization (SPD). These four alkyl methylphosphonic acids (AMPAs) are specific hydrolysis products and biomarkers of exposure to classic organophosphorus (OP) nerve agents VX, sarin, RVX, and soman. The AMPAs in urine samples were directly derivatized with pentafluorobenzyl bromide on a solid support and then extracted by liquid-liquid extraction. The analytes were quantified with isotope-dilution by negative chemical ionization (NCI) GC-MS/MS in a selected reaction monitoring (SRM) mode. This method is highly sensitive, with the limits of detection of 0.02 ng/mL for each compound in a 0.2 mL sample of human urine, and an excellent linearity from 0.1 to 50 ng/mL. It is proven to be very suitable for the qualitative and quantitative analyses of degradation markers of OP nerve agents in biomedical samples. PMID:24633564

Lin, Ying; Chen, Jia; Yan, Long; Guo, Lei; Wu, Bidong; Li, Chunzheng; Feng, Jianlin; Liu, Qin; Xie, Jianwei

2014-08-01

259

Simultaneous analysis of phthalates, adipate and polycyclic aromatic hydrocarbons in edible oils using isotope dilution-gas chromatography-mass spectrometry.  

PubMed

A method for simultaneous determination of 12 priority phthalates, adipate and polycyclic aromatic hydrocarbons (PAHs) in edible oils by isotope dilution-gas chromatography-mass spectrometry (ID-GC-MS) was developed for fast, accurate and trace analysis. The extraction and clean-up procedures were optimised, and using stable isotope-labelled internal standards for each analyte, relative standard deviations (RSDs) of 0.92-10.6% and spiked sample recoveries of 80.6-97.8% were obtained. Limits of detection for PAHs were in the range of 0.15-0.77 µg/kg and those for phthalates were in the range of 4.6-10.0 µg/kg. The calibration curves exhibited good linearities with regression coefficients of R(2) ? 0.99. Twelve edible oils were examined to evaluate the efficiency of this method. Among the 12 analytes, dibutyl phthalates (DBP), diethylhexyl phthalates (DEHP), diethylhexyl adipate (DEHA), benzo[a]anthracene (B[a]A), chrysene (Chry) and benzo[b]fluoranthene (B[b]F) were detected in the range of 1.17-806 µg/kg. PMID:25029399

Oh, Min-Seok; Lee, Seon-Hwa; Moon, Myeong Hee; Lee, Dong Soo; Park, Hyun-Mee

2014-09-01

260

Quantification of 2-acetyl-1-pyrroline in rice by stable isotope dilution assay through headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry.  

PubMed

A new and convenient synthesis of 2-acetyl-1-pyrroline (2AP), a potent flavor compound in rice, and its ring-deuterated analog, 2-acetyl-1-d(2)-pyrroline (2AP-d(2)), was reported. A stable isotope dilution assay (SIDA), involving headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-positive chemical ionization-ion trap-tandem mass spectrometry (GC-PCI-IT-MS-MS), was developed for 2AP quantification. A divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was used for HS-SPME procedure and parameters affecting analytes recovery, such as extraction time and temperature, pH and salt, were studied. The repeatability of the method (n=10) expressed as relative standard deviation (RSD) was 11.6%. A good linearity was observed from 5.9 to 779 ng of 2AP (r(2)=0.9989). Limits of detection (LOD) and quantification (LOQ) for 2AP were 0.1 and 0.4 ng g(-1) of rice, respectively. The recovery of spiked 2AP from rice matrix was almost complete. The developed method was applied to the quantification of 2AP in aerial parts and grains of scented and non-scented rice cultivars. PMID:20800726

Maraval, Isabelle; Sen, Kemal; Agrebi, Abdelhamid; Menut, Chantal; Morere, Alain; Boulanger, Renaud; Gay, Frédéric; Mestres, Christian; Gunata, Ziya

2010-08-24

261

Liquid paraffin as new dilution medium for the analysis of high boiling point residual solvents with static headspace-gas chromatography.  

PubMed

Residual solvents are volatile organic compounds which can be present in pharmaceutical substances. A generic static headspace-gas chromatography analysis method for the identification and control of residual solvents is described in the European Pharmacopoeia. Although this method is proved to be suitable for the majority of samples and residual solvents, the method may lack sensitivity for high boiling point residual solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and benzyl alcohol. In this study, liquid paraffin was investigated as new dilution medium for the analysis of these residual solvents. The headspace-gas chromatography method was developed and optimized taking the official Pharmacopoeia method as a starting point. The optimized method was validated according to ICH criteria. It was found that the detection limits were below 1?g/vial for each compound, indicating a drastically increased sensitivity compared to the Pharmacopoeia method, which failed to detect the compounds at their respective limit concentrations. Linearity was evaluated based on the R(2) values, which were above 0.997 for all compounds, and inspection of residual plots. Instrument and method precision were examined by calculating the relative standard deviations (RSD) of repeated analyses within the linearity and accuracy experiments, respectively. It was found that all RSD values were below 10%. Accuracy was checked by a recovery experiment at three different levels. Mean recovery values were all in the range 95-105%. Finally, the optimized method was applied to residual DMSO analysis in four different Kollicoat(®) sample batches. PMID:21549541

D'Autry, Ward; Zheng, Chao; Bugalama, John; Wolfs, Kris; Hoogmartens, Jos; Adams, Erwin; Wang, Bochu; Van Schepdael, Ann

2011-07-15

262

Dilute Oxygen Combustion; Phase I Final Report  

Microsoft Academic Search

A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NOx through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting

H. M. Ryan; M. F. Riley; H. Kobayashi

1997-01-01

263

Dilute Oxygen Combustion; Phase 2 Final Report  

Microsoft Academic Search

A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NOx through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting

H. M. Ryan; M. F. Riley; H. Kobayashi

2005-01-01

264

Dilute Oxygen Combustion, Phase 2 Final Report.  

National Technical Information Service (NTIS)

A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) ...

Y. Wang H. Kobayashi

2005-01-01

265

Isentropic Compression of Multicomponent Mixtures of Fuels and Inert Gases  

NASA Technical Reports Server (NTRS)

In selected aerospace applications of the fuels hydrazine and monomethythydrazine, there occur conditions which can result in the isentropic compression of a multicomponent mixture of fuel and inert gas. One such example is when a driver gas such as helium comes out of solution and mixes with the fuel vapor, which is being compressed. A second example is when product gas from an energetic device mixes with the fuel vapor which is being compressed. Thermodynamic analysis has shown that under isentropic compression, the fuels hydrazine and monomethylhydrazine must be treated as real fluids using appropriate equations of state. The appropriate equations of state are the Peng-Robinson equation of state for hydrazine and the Redlich-Kwong-Soave equation of state for monomethylhydrazine. The addition of an inert gas of variable quantity and input temperature and pressure to the fuel compounds the problem for safety design or analysis. This work provides the appropriate thermodynamic analysis of isentropic compression of the two examples cited. In addition to an entropy balance describing the change of state, an enthalpy balance is required. The presence of multicomponents in the system requires that appropriate mixing rules are identified and applied to the analysis. This analysis is not currently available.

Barragan, Michelle; Julien, Howard L.; Woods, Stephen S.; Wilson, D. Bruce; Saulsberry, Regor L.

2000-01-01

266

Monitoring urinary metabolites resulting from sulfur mustard exposure in rabbits, using highly sensitive isotope-dilution gas chromatography-mass spectrometry.  

PubMed

A highly sensitive method for the determination of sulfur mustard (SM) metabolites thiodiglycol (TDG) and thiodiglycol sulfoxide (TDGO) in urine was established and validated using isotope-dilution negative-ion chemical ionization (NICI) gas chromatography-mass spectrometry (GC-MS). TDGO in the samples was reduced with TiCl3, and then determined together with TDG as a single analyte. The sample preparation procedures, including two solid-phase-extraction (SPE) clean-up steps, were optimized to improve the sensitivity of the method. The limits of detection (LOD) for both TDG and TDG plus TDGO (TDG + TDGO) were 0.1 ng mL(-1), and the limits of quantitation (LOQ) for both were 0.3 ng mL(-1). The method was used in a rabbit cutaneous SM exposure model. Domestic rabbits were exposed to neat liquid SM at three dosage levels (0.02, 0.05, and 0.15 LD50), and the urinary excretion of four species of hydrolysis metabolites, namely free TDG, free plus conjugated TDG (total TDG), free TDG + TDGO, and free plus conjugated TDG + TDGO (total TDG + TDGO), was evaluated to investigate the metabolic processes. The total urinary excretion profiles of the metabolites, including the peak time, time window, and dose-response and time-response relationships, were clarified. The results revealed that the concentrations of TDG and TDG + TDGO in the urine increased quickly and then decreased rapidly in the first two days after SM exposure. The cumulative amount of total TDG + TDGO excreted in urine during the first five days accounted for 0.5-1 % of the applied dose of SM. It is also concluded that TDG and TDGO in urine existed mainly in free form, the levels of glucuronide and of sulfate conjugates of TDG or TDGO were very low, and most hydrolysis metabolites were present in the oxidized form (TDGO). The study indicates that the abnormal increase of TDG and TDGO excretion levels can be used as a diagnostic indicator and establishes a reference time-window for retrospective analysis and sampling after SM exposure. PMID:24924210

Nie, Zhiyong; Zhang, Yajiao; Chen, Jia; Lin, Ying; Wu, Bidong; Dong, Yuan; Feng, Jianlin; Liu, Qin; Xie, Jianwei

2014-08-01

267

Determination of 11-deoxycortisol (Reichstein's compound S) in human plasma by clinical isotope dilution mass spectrometry using benchtop gas chromatography-mass selective detection.  

PubMed

A first assay based on stable isotope dilution/gas chromatography-mass spectrometry (ID/GC-MS) has been developed for plasma 11-deoxycortisol (Reichstein's compound S), the leading hormonal marker of 11beta-hydroxylase deficiency. A suitable internal standard being unavailable, we synthesized dideuterated 11-deoxycortisol according to a newly devised synthetic procedure. 17,21-Dihydroxy-pregna-1,4-diene-3,20-dione underwent selective deuteration using Wilkinson's catalyst. Our product [1alpha,2alpha-2H2]11-deoxycortisol was obtained in good yield (35.6%) and high isotopic purity (0.1% 2H0, 99.9% 2H2). Structural confirmation was done by MS and NMR. Our plasma work up consisted of equilibration of plasma with internal standard ([1alpha,2alpha-2H2]11-deoxycortisol), solid phase extraction with Extrelut NT columns, a clean up step using Sephadex LH-20 mini columns and preparation of heptafluorobutyrates as derivatives. Quantification was achieved by selected ion monitoring of m/z 465.40 (analyte) and m/z 467.40 (internal standard). One hundred twenty picograms of 11-deoxycortisol gave a signal to noise ratio of 10. Calibration plot was linear. Spiking experiments showed good accuracy with relative errors <3.0%. Intraassay precision CV was 4.78% and interassay precision CV was 4.56%. We succeeded in integrating our new analyte into our already existing multisteroid ID/GC-MS plasma assay, which now, in its expanded version, is capable of determining all major diagnostic steroids of androgen related disorders in a single profile: 11-deoxycortisol, 17alpha-hydroxyprogesterone, testosterone, 4-androstenedione, 17alpha-hydroxypregnenolone, dehydroepiandrosterone, androstanediol and 5alpha-dihydrotestosterone. The diagnostic potential of our multisteroid ID/GC-MS assay, the small amounts of plasma (0.5 ml) required, the rapid and convenient sample work up, the application of benchtop GC-MS instrumentation, and highest specificity offered by mass spectrometric detection prove our assay suitable for routine clinical use, especially in pediatric endocrinology. PMID:12231120

Wudy, Stefan A; Hartmann, Michaela; Homoki, Janos

2002-09-01

268

Live and Inert Fascine Streambank Erosion Control.  

National Technical Information Service (NTIS)

Live fascines (LF) and inert fascines (IF) are sausage-shaped bundle structures made from cuttings of living woody plant material. In the LF, the cut branches are expected to grow producing roots and top growth, (performing additional soil reinforcement v...

R. B. Sotir C. Fischenich

2001-01-01

269

Microfluidic serial dilution ladder.  

PubMed

Serial dilution is a fundamental procedure that is common to a large number of laboratory protocols. Automation of serial dilution is thus a valuable component for lab-on-a-chip systems. While a handful of different microfluidic strategies for serial dilution have been reported, approaches based on continuous flow mixing inherently consume larger amounts of sample volume and chip real estate. We employ valve-driven circulatory mixing to address these issues and also introduce a novel device structure to store each stage of the dilution process. The dilution strategy is based on sequentially mixing the rungs of a ladder structure. We demonstrate a 7-stage series of 1?:?1 dilutions with R(2) equal to 0.995 in an active device area of 1 cm(2). PMID:24231765

Ahrar, Siavash; Hwang, Michelle; Duncan, Philip N; Hui, Elliot E

2014-01-01

270

The mathematics of dilution.  

PubMed

The major objection to homeopathic medicine is that the doses of medicine prescribed in some cases are too dilute for any active ingredient to be present. The medicines would hence be rendered inactive, necessitating novel explanations for the action. A further examination of dilution in the light of the Langmuir equation shows that homeopathic medicines may not be as dilute as a simplistic application of Avogadro's Principle suggests, due to surface effects. PMID:24685420

Chatterjee, Barun Kumar

2014-04-01

271

Generation and induced emission on transitions in Xe2Cl* exciplex molecules in Xe-CCl4 and Ar-Xe-CCl4 "Dilute" gas mixtures pumped by pulsed electron beam  

NASA Astrophysics Data System (ADS)

We have experimentally studied spontaneous and induced emission from Xe2Cl* triplex molecules in Xe-CCl4 and Ar-Xe-CCl4 "dilute" gas mixtures excited by a pulsed high-energy electron beam. For an energy of about 0.004 J/pulse deposited in a 4-cm-long cavity, a regime of spontaneous emission amplification in a wavelength range of 430-550 nm is realized on transitions from 22B2 and 42? states of Xe2Cl* molecules.

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

2013-04-01

272

Stable-isotope dilution gas chromatography–mass spectrometric measurement of 3-hydroxyglutaric acid, glutaric acid and related metabolites in body fluids of patients with glutaric aciduria type 1 found in newborn screening  

Microsoft Academic Search

We developed a simple and sensitive stable-isotope dilution method for the quantification of 3-hydroxyglutaric acid (3HGA) and glutaric acid (GA) in body fluids. In our method, tert-butyldimethylsilyl (tBDMS) derivatives of 3HGA and GA were measured with a conventional electron-impact ionization (EI) mode in gas chromatography–mass spectrometry (GC–MS). The control values for 3HGA in nmol\\/ml were 0.15±0.08 (serum; n=10) and 0.07±0.03

Yosuke Shigematsu; Ikue Hata; Yukie Tanaka; Go Tajima; Nobuo Sakura; Etsuo Naito; Toru Yorifuji

2005-01-01

273

Mechanisms controlling the global oceanic distribution of the inert gases argon, nitrogen and neon  

Microsoft Academic Search

Dissolved inert gas measurements in the ocean yield important information about processes that occur during water mass formation. We present argon, nitrogen, and neon data from the subtropical and subpolar North Pacific and the subtropical North Atlantic. All three gases were supersaturated at the surface. In the deep ocean, Ar and N2 were undersaturated while Ne re- mained supersaturated. All

Roberta C. Hamme; Steven R. Emerson

2002-01-01

274

Light-soaking in aSiC:H films grown by PECVD in undiluted and hydrogen diluted SiH 4 + CH 4 gas mixtures  

Microsoft Academic Search

Amorphous silicon carbon alloys having an energy gap in the range 2.0–2.5 eV were deposited by plasma enhanced chemical vapor deposition (PECVD) from undiluted and hydrogen diluted SiH4 + CH4 mixtures. The optoelectronic and compositional properties of the samples were measured. Light soaking till saturation was performed on the samples and the effect on defect densities and photoconduction was investigated

M. Fathallah; R. Gharbi; G. Crovini; F. Demichelis; F. Giorgis; C. F. Pirri; E. Tresso; P. Rava

1996-01-01

275

46 CFR 154.1740 - Vinyl chloride: Inhibiting and inerting.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Vinyl chloride: Inhibiting and inerting. 154...Requirements § 154.1740 Vinyl chloride: Inhibiting and inerting. When a vessel is carrying vinyl chloride, the master shall ensure that:...

2013-10-01

276

Trilepton signals in the inert doublet model  

SciTech Connect

In this work, we investigate the prospects for detecting the Inert Doublet Model via the trilepton channel at the LHC. We present a set of representative benchmark scenarios in which all applicable constraints are satisfied, and show that in some of these scenarios, it is possible to obtain a signal at the 5{sigma} significance level or better with integrated luminosity of 300 fb{sup -1}.

Miao, Xinyu; Su, Shufang [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); Thomas, Brooks [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

2010-08-01

277

mJ Mixing in Oriented 42P12 Potassium Atoms, Induced by Collisions with Inert Gases  

Microsoft Academic Search

A modified Zeeman scanning method was used to excite selectively the magnetic substates of the 42P12 potassium atoms mixed with inert gases and placed in a strong magnetic field. The resulting potassium-inert-gas atomic collisions induced mJ mixing in potassium, which manifested itself by the depolarization of the potassium resonance fluorescence. The polarization measurements yielded the following disorientation cross sections: K-He:

W. Berdowski; L. Krause

1968-01-01

278

mJ Mixing in Oriented 42P32 Potassium Atoms Induced by Collisions with Inert Gases  

Microsoft Academic Search

The cross sections for the decay of circular and of linear polarization in oriented 42P32 potassium atoms, induced in collision with inert-gas atoms, were determined in a series of fluorescence experiments. A modified Zeeman scanning method was used to populate selectively the mJ sublevels of the 2P32 potassium atoms mixed with inert gases and placed in a strong magnetic field.

W. Berdowski; T. Shiner; L. Krause

1971-01-01

279

Pressure Effect of Various Inert Gases on the Phase Behavior of Polystyrene-block-Poly(n-pentyl methacrylate) Copolymer  

NASA Astrophysics Data System (ADS)

We investigated the pressure effect of three inert gases (nitrogen, helium and argon) on the phase behavior of polystyrene-block-poly(n-pentylmethacrylate) copolymer (PS-b-PnPMA) showing closed-loop phase behavior and baroplasticity. Helium gas pressure enhanced the miscibility between PS and PnPMA blocks similar to the hydrostatic pressure. Very interestingly, however, with increasing nitrogen and argon gas pressure, the miscibility between the two blocks decreased even though these two are also considered as inert gases. To explain these unexpected results, we measured the amount of gas absorption into each block. The experimentally measured gas absorption results are consistent with the theoretical ones based on the Sanchez-Lacombe theory. The results in this study imply that well-known and widely employed inert gases such as nitrogen and argon could significantly affect the phase behavior of a weakly interacting block copolymer at high pressures.

Moon, Hong Chul; Kim, Hye Jeong; Cho, Junhan; Kim, Jin Kon

2013-03-01

280

Absorption removal of sulfur dioxide by falling water droplets in the presence of inert solid particles  

NASA Astrophysics Data System (ADS)

An experimental analysis of the absorption removal of sulfur dioxide by the free falling water droplets containing the inert solid particles is presented. The wheat flour powder is introduced as the inert solid particles. Tests with and without the flour powder in the water droplets are examined. The mass fluxes and mass transfer coefficients of SO 2 for the cases with and without the flour powder are compared to elucidate the effects of the inert solid particles contained in the water droplets on the gas absorption. The results indicate aignificant difference between the two cases for the concentrations of the flour powder in the absorbent droplets ( Cs) within the ranges of the experimental conditions, namely 0.1 to 10 wt% flour powder in the absorbent droplets. In general, the inert solid particles of the flour powder as the impurities in the water droplets tend to decrease the SO 2 absorption rate for the experimental absorption system under investigation. Various values of Cs cause various levels of the interfacial resistance and affect the gas absorption rate. The interfacial resistance is recognized by introducing an interfacial mass transfer coefficient ks with its reciprocal being proportional to the magnitude of the interfacial resistance. The values of 1/ ks may be computed by the use of the equation 1/ ks=(1/ KOLs-1/ KOL), where KOLs and KOL are the overall liquid-phase mass transfer coefficients with and without the inert solid particles, respectively. The values of ks with Cs of 0.1 to 10 wt% are about 0.295-0.032 cms -1 for absorbing 1000-3000 ppmv SO 2 with the water droplets. This kind of information is useful for the SO 2 removal and the information of acid rain that the impurities of the inert solid particles contaminate the water droplets.

Liu, I.-Hung; Chang, Ching-Yuan; Liu, Su-Chin; Chang, I.-Cheng; Shih, Shin-Min

281

Dilution air dispensing apparatus  

SciTech Connect

This patent describes a dilution air dispensing apparatus for a double dome combustor. It comprises: a first dome combustor having an inlet opening and an exhaust opening, a first fuel nozzle operatively arranged in the inlet opening to dispense fuel to the first dome combustor, a second dome combustor having an inlet opening and an exhaust opening, a second fuel nozzle operatively arranged in the inlet opening to dispense fuel to the second dome combustor. The first and second dome combustor being joined towards their inlet ends to form a dilution air dispensing cavity therebetween. The dilution air dispensing cavity being formed by the inner adjacent walls of the first and second dome combustors. The dilution air dispensing cavity having a rearward portion which is located approximately one-third of the dome length from the inlets to the first and second dome combustors.

King, R.C.

1990-02-27

282

Muco-inert nanoparticle probes and drug carriers  

NASA Astrophysics Data System (ADS)

Mucus coats the exposed surfaces of the eyes and respiratory, gastrointestinal (GI) and cervicovaginal (CV) tracts, and protects mucosal tissues against pathogens and other foreign particulates. Most foreign particles are effectively trapped in mucus through steric and adhesive interactions, and are rapidly eliminated by different mucus clearance mechanisms. Nevertheless, mucus also immobilizes conventional drug and gene carriers, thereby precluding sustained and targeted drug delivery to mucosal sites. Synthetic particles engineered with muco-inert surfaces, and some viruses, can readily penetrate mucus gel, and may serve as useful probes to understand the biophysical barrier properties of mucus. Improved understanding of the mucus barrier could provide insights into methods to enhance drug and gene delivery at mucosal surfaces, as well as understanding the occasional failure of mucus to protect against infection or injury. Recently, muco-inert nanoparticles were developed by conjugating a dense layer of low MW polyethylene glycol to particle surfaces. Since they are slowed only by steric obstruction from the mucus mesh, various sized muco-inert nanoparticles can be used to probe the microstructure and microrheology of mucus. I applied this technique to determine whether the mucus barrier may be altered by exogenous factors, including the presence of detergent, pH changes and synthetic nanoparticles. I first studied the microrheology of native human cervicovaginal mucus (CVM), and found that CVM behaves as a viscoelastic solid at length scales ? 1 microm (preventing large particles from diffusing through) but as a viscoelastic liquid at length scales up to at least 500 nm (allowing smaller particles to diffuse through low viscosity fluid-filled pores). Treating CVM with a nonionic detergent, N9, shifted the viscoelastic liquid-solid transition point to < 200 nm, suggesting hydrophobic interactions between mucin fibers play an important role in regulating the mucus microstructure and consequently the microrheology. Indeed, N9 caused the average mucus pore size to decrease from ˜340 nm to 130 nm. I then looked at the effect of pH on mucus and found that the microstructure of CVM is essentially pH-independent over a broad range of physiological pH. Between pH 4 (the native pH of CVM) and 6--7, the average pore size in the mucus mesh remained unchanged, and between pH 1--2 and 8--9, there was at most a 2-fold drop in the average pore size (likely due to changes in electrostatic vs. hydrophobic interactions between mucin fibers). Finally, I found that mucoadhesive synthetic nanoparticles, at sufficiently high concentrations, can bundle mucin fibers and create large openings in the mucus microstructure. Disruption of the mucus barrier in this manner allowed a greater fraction of large (1 microm) muco-inert particles to diffuse through the mucus mesh. Muco-inert nanoparticles---also referred to as "mucus-penetrating particles" (MPP)---offer the potential for sustained and targeted drug delivery to mucosal surfaces. By penetrating luminal mucus layers, MPP may be able to reach the slowly cleared adherent mucus layer or deep folds of the epithelium and thereby achieve prolonged retention. I first measured the long range penetration of MPP compared to conventional mucoadhesive particles (CP) into CVM. With minimal dilution of CVM, MPP could penetrate up to 200 microm over 1 hr with ˜530 particles/mm2 penetrating 100 microm or more, while CP remained immobilized (note that physiological mucus layer thicknesses are no more than ˜200 microm). Furthermore, with 30% v/v dilution, MPP could penetrate up to 1.5 mm over 1 hr with ˜74,000 particles/mm2 penetrating 100 microm or more, while CP continued to remain stuck. I then studied the distribution and retention of MPP vs. CP in the mouse vagina to determine whether improved mucus penetration leads to more uniform distribution and prolonged retention. I found that MPP were not only more uniformly distributed in the vaginal lumen, but also penetrated deep into epithel

Wang, Ying-Ying

283

Determination of tellurium in urine by isotope dilution gas chromatography/mass spectrometry using (4-fluorophenyl)magnesium bromide as a derivatizing agent and a comparison with electrothermal atomic absorption spectrometry.  

PubMed

The antitumor drug AS-101 [ammoniumtrichloro (dioxoethylene-O,O')tellurate(IV)] is the first tellurium-containing compound that has been identified as possessing immunomodulating properties and minimal toxicity. We have developed a stable isotope dilution gas chromatography/mass spectrometry method using 120Te as an internal standard and (4-fluorophenyl)magnesium bromide as a derivatizing agent for Te determination in urine. The urine samples were digested using HNO3 + H2O2 prior to derivatization with lithium bis(trifluoroethyl)dithiocarbamate at a pH of 3. The trifluorodiethyldithiocarbamate of tellurium was reacted with the Grignard reagent in anhydrous diethyl ether to obtain Te-(FC6H4)2 for GC/MS analysis. All isotope ratio measurements were made by selected ion monitoring with a Finnigan MAT 8230 organic mass spectrometer using a 10-m fused silica capillary column. Overall percision values for the five major Te isotopes relative to 130Te were 0.6-3.1% when 10-ng samples of chelated Te were analyzed. No appreciable memory or carry-over effect was observed when two synthetic mixtures differing in 120Te:130Te ratios by a factor of 50 were sequentially analyzed. The isotope dilution GC/MS method was validated by determining Te in urine samples and comparing the values with electrothermal atomic absorption spectrometry. Te concentrations were determined in the 100-500 micrograms/L range with CVs of 1-4%. PMID:8210046

Aggarwal, S K; Kinter, M; Nicholson, J; Herold, D A

1994-04-15

284

Automated high-speed analysis of selected organic compounds in urban air by on-line isotopic dilution cryofocusing gas chromatography/mass spectrometry.  

PubMed

An automated environmental air monitor has been developed to measure selected organic compounds in urban air. The instrument is based on a cryofocusing-thermal desorption gas chromatographic mass spectrometry technique where the mass spectrometer is a slightly modified residual gas analyzer (RGA). The RGA was chosen as a detector because the whole system must be robust for long periods, with 24-h continuous air monitoring. RCA are extremely simple and seemed the most reliable mass spectrometers for this purpose. Moreover, because they have no physically limited ion source, contamination is considerably reduced, so maintenance intervals are longer.The gas chromatograph is equipped with a computer-controlled six-way sampling valve, with a 100-mL sampling loop and thermal desorption cold trap injector. Environmental air is enriched with an isotopically labeled internal standard in the sampling line. This internal standard is added with a validated, custom-made, permeation tube device. The "on-line" internal standard provides for high quality quantitative data because all variations in instrument sensitivity in cryofocusing or in thermal desorption efficiency are taken into account. High repetition rates (down to 5 min for a full analytical cycle) are obtained with the use of an isothermal gas chromatography program, microbore capillary column, and environmental air sampling during the gas chromatography run. PMID:24226389

Davoli, E; Cappellini, L; Maggi, M; Fanelli, R

1994-11-01

285

Inert anodes and advanced smelting of aluminum  

SciTech Connect

This report provides a broad assessment of open literature and patents that exist in the area of inert anodes and their related cathode systems and cell designs, technologies that are relevant for the advanced smelting of aluminum. The report also discusses the opportunities, barriers, and issued associated with these technologies from a technical, environmental, and economic viewpoint. It discusses the outlook for the direct retrofit of advanced reduction technologies to existing aluminum smelters, and compares retrofits to ''brown field'' usage and ''green field'' adoption of the technologies. A number of observations and recommendations are offered for consideration concerning further research and development efforts that may be directed toward these advanced technologies. The opportunities are discussed in the context of incremental progress that is being made in conventional Hall-Heroult cell systems.

ASME Technical Working Group on Inert Anode Technologies

1999-07-01

286

Mucosal vaccination against tuberculosis using inert bioparticles.  

PubMed

Needle-free, mucosal immunization is a highly desirable strategy for vaccination against many pathogens, especially those entering through the respiratory mucosa, such as Mycobacterium tuberculosis. Unfortunately, mucosal vaccination against tuberculosis (TB) is impeded by a lack of suitable adjuvants and/or delivery platforms that could induce a protective immune response in humans. Here, we report on a novel biotechnological approach for mucosal vaccination against TB that overcomes some of the current limitations. This is achieved by coating protective TB antigens onto the surface of inert bacterial spores, which are then delivered to the respiratory tract. Our data showed that mice immunized nasally with coated spores developed humoral and cellular immune responses and multifunctional T cells and, most importantly, presented significantly reduced bacterial loads in their lungs and spleens following pathogenic challenge. We conclude that this new vaccine delivery platform merits further development as a mucosal vaccine for TB and possibly also other respiratory pathogens. PMID:23959722

Reljic, Rajko; Sibley, Laura; Huang, Jen-Min; Pepponi, Ilaria; Hoppe, Andreas; Hong, Huynh A; Cutting, Simon M

2013-11-01

287

Mucosal Vaccination against Tuberculosis Using Inert Bioparticles  

PubMed Central

Needle-free, mucosal immunization is a highly desirable strategy for vaccination against many pathogens, especially those entering through the respiratory mucosa, such as Mycobacterium tuberculosis. Unfortunately, mucosal vaccination against tuberculosis (TB) is impeded by a lack of suitable adjuvants and/or delivery platforms that could induce a protective immune response in humans. Here, we report on a novel biotechnological approach for mucosal vaccination against TB that overcomes some of the current limitations. This is achieved by coating protective TB antigens onto the surface of inert bacterial spores, which are then delivered to the respiratory tract. Our data showed that mice immunized nasally with coated spores developed humoral and cellular immune responses and multifunctional T cells and, most importantly, presented significantly reduced bacterial loads in their lungs and spleens following pathogenic challenge. We conclude that this new vaccine delivery platform merits further development as a mucosal vaccine for TB and possibly also other respiratory pathogens.

Reljic, Rajko; Sibley, Laura; Huang, Jen-Min; Pepponi, Ilaria; Hoppe, Andreas; Hong, Huynh A.

2013-01-01

288

Helium dilution refrigeration system  

DOEpatents

A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

Roach, P.R.; Gray, K.E.

1988-09-13

289

Dilution, Concentration, and Flotation  

ERIC Educational Resources Information Center

As both classroom teaching practice and literature show, many students have difficulties learning science concepts such as density. Here are some investigations that identify the relationship between density and floating through experimenting with successive dilution of a liquid, or the systematic change of concentration of a saltwater solution.…

Liang, Ling; Schmuckler, Joseph S.

2004-01-01

290

Helium dilution refrigeration system  

DOEpatents

A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains .sup.3 He and .sup.4 He liquids which are precooled by a coupled container containing .sup.3 He liquid, enabling the phase separation of a .sup.3 He rich liquid phase from a dilute .sup.3 He-.sup.4 He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the .sup.3 He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute .sup.3 He-.sup.4 He liquid phase.

Roach, Patrick R. (Darien, IL) [Darien, IL; Gray, Kenneth E. (Naperville, IL) [Naperville, IL

1988-01-01

291

The performance of two purification media in their removal of impurities from inert gases  

Microsoft Academic Search

Ultra-high-purity (UHP) inert gases such as N2 and Ar are utilized in the semiconductor industry as purge and carrier gases for IC manufacturing processes. High quality product production is extremely dependent on process gas purity at the point-of-use (POU). Removal of impurities such as moisture, O2, CO2, and CO is highly critical at the POU due to the detrimental effects

Jian Wei; Dmitry Kondrashov; Kareem Vakhshoori; Armando Colorado

1999-01-01

292

Modelling of CO Oxidation in Dilution Jet Flows.  

National Technical Information Service (NTIS)

Existing equilibrium chemistry and laminar flamelet computer codes are inadequate for calculation of post-flame carbon monoxide burn-up in gas turbine combustion chamber dilution zones. The amount of reaction occurring in such zones is small, but signific...

P. V. Chleboun K. P. Hubbert C. G. W. Sheppard

1988-01-01

293

USING ISOTOPE DILUTION MASS SPECTROMETRY TO DETERMINE AQUEOUS TRICHLOROACETIC ACID  

EPA Science Inventory

The development, verification, and application of a method based on isotope dilution gas chromatography-mass spectrometry to determine aqueous trichloroacetic acid (TCAA) at the micrograms per litre level are described. The simultaneous determination of aqueous chloroform is also...

294

Nitrogen Gas Flow Driven Unintentional Incorporation of Al during the Growth of Dilute Nitride Semiconductor by Plasma-Assisted Molecular Beam Epitaxy  

NASA Astrophysics Data System (ADS)

We report the unintentional incorporation of Al during the growth of molecular beam epitaxy using RF plasma source, driven by N2 gas flow. The concentrations of N, Al, O, and C within GaNAs/GaAs/AlAs structure are investigated by secondary ion mass spectrometry. In spite of the closed shutter of Al cell, we observe Al incorporation with a concentration up to 1×1018 cm-3 in GaNAs layer and characteristically in the bottom side GaAs. Its concentration is solely dependent on N2 gas flow rate. Remarkably, the operation of the RF plasma has no impact on that. C and O show their concentrations corresponding to the extrinsic Al. The complex interactions between those elements predict a possible origin of material deteriorations and difficulty for the precise doping control.

Wu, Shudong; Kato, Masakazu; Uchiyama, Masayuki; Higashi, Kotaro; Ishikawa, Fumitaro; Kondow, Masahiko

2008-03-01

295

Nitrogen Gas Flow Driven Unintentional Incorporation of Al during the Growth of Dilute Nitride Semiconductor by Plasma-Assisted Molecular Beam Epitaxy  

Microsoft Academic Search

We report the unintentional incorporation of Al during the growth of molecular beam epitaxy using RF plasma source, driven by N2 gas flow. The concentrations of N, Al, O, and C within GaNAs\\/GaAs\\/AlAs structure are investigated by secondary ion mass spectrometry. In spite of the closed shutter of Al cell, we observe Al incorporation with a concentration up to 1×1018

Shudong Wu; Masakazu Kato; Masayuki Uchiyama; Kotaro Higashi; Fumitaro Ishikawa; Masahiko Kondow

2008-01-01

296

Praxair's dilute oxygen combustion technology for pyrometallurgical applications  

Microsoft Academic Search

Dilute oxygen combustion (DOC) technology uses separate high-velocity fuel and oxygen jets to generate strong in-furnace gas recirculation, producing combustion between the fuel and a highly diluted oxygen and furnace-gas mixture. These very low NOx oxy-fuel burners have been developed and commercially demonstrated in steel reheating furnaces. The burner design meets industry needs for increased productivity and lower operating costs

M. F. Riley; H. Kobayashi; A. C. Deneys

2001-01-01

297

Praxair’s dilute oxygen combustion technology for pyrometallurgical applications  

Microsoft Academic Search

Dilute oxygen combustion (DOC) technology uses separate high-velocity fuel and oxygen jets to generate strong in-furnace gas\\u000a recirculation, producing combustion between the fuel and a highly diluted oxygen and furnace-gas mixture. These very low NOx\\u000a oxy-fuel burners have been developed and commercially demonstrated in steel reheating furnaces. The burner design meets industry\\u000a needs for increased productivity and lower operating costs

M. F. Riley; H. Kobayashi; A. C. Deneys

2001-01-01

298

Electrolytic production of high purity aluminum using ceramic inert anodes  

DOEpatents

A method of producing commercial purity aluminum in an electrolytic reduction cell comprising ceramic inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The ceramic inert anodes used in the process may comprise oxides containing Fe and Ni, as well as other oxides, metals and/or dopants.

Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA); Weirauch, Douglas A. (Murrysville, PA); DiMilia, Robert A. (Baton Rouge, LA); Dynys, Joseph M. (New Kensington, PA); Phelps, Frankie E. (Apollo, PA); LaCamera, Alfred F. (Trafford, PA)

2002-01-01

299

Electrolytic production of high purity aluminum using inert anodes  

DOEpatents

A method of producing commercial purity aluminum in an electrolytic reduction cell comprising inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The inert anodes used in the process preferably comprise a cermet material comprising ceramic oxide phase portions and metal phase portions.

Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA); Weirauch, Jr., Douglas A. (Murrysville, PA)

2001-01-01

300

Drying of Slurries in Fluidized Bed of Inert Particles  

Microsoft Academic Search

A fluid bed dryer with inert particles was used for drying of slurries. Experiments were performed in a cylindrical column 215 mm in diameter and 1200 mm in height with glass spheres as inert particles. Slurries of Zineb fungicide, copper hydroxide, calcium carbonate, and pure water were used as the feed material. The effects of operating conditions on dryer throughput and product

Zeljko B. Grbavcic; Zorana Lj Arsenijevic; Radmila V. Garic-Grulovic

2004-01-01

301

SWELLING AND INERT GAS DIFFUSION IN IRRADIATED URANIUM  

Microsoft Academic Search

The increases in volume which occur when uranium is irradiated are of ; considerable importance in nuclear engineering since they impose a ceiling to ; irradiation levels and efficiency. These limitations may be overcome to some ; extent by principles of design or by the development of improved materials based ; on an understanding of the fundamental processes involved in

R. S. Barnes; A. T. Churchman; A. J. E. Foreman; O. S. Plail; S. F. Pugh; G. N. Walton; G. C. Curtis; V. W. Eldred; J. A. Enderby; L. M. Wyatt

1959-01-01

302

Inert Welding/Brazing Gas Filters and Dryers  

NASA Technical Reports Server (NTRS)

The use of hybridized carbon/silicon carbide (C/SiC) fabric to reinforce ceramic matrix composite face sheets and the integration of such face sheets with a foam core creates a sandwich structure capable of withstanding high-heat-flux environments (150 W/sq cm) in which the core provides a temperature drop of 1,000 C between the surface and the back face without cracking or delamination of the structure. The composite face sheet exhibits a bilinear response, which results from the SiC matrix not being cracked on fabrication. In addition, the structure exhibits damage tolerance under impact with projectiles, showing no penetration to the back face sheet. These attributes make the composite ideal for leading-edge structures and control surfaces in aerospace vehicles, as well as for acreage thermal protection systems and in high-temperature, lightweight stiffened structures. By tailoring the coefficient of thermal expansion (CTE) of a carbon fiber containing ceramic matrix composite (CMC) face sheet to match that of a ceramic foam core, the face sheet and the core can be integrally fabricated without any delamination. Carbon and SiC are woven together in the reinforcing fabric. Integral densification of the CMC and the foam core is accomplished with chemical vapor deposition, eliminating the need for bond-line adhesive. This means there is no need to separately fabricate the core and the face sheet, or to bond the two elements together, risking edge delamination during use. Fibers of two or more types are woven together on a loom. The carbon and ceramic fibers are pulled into the same "pick" location during the weaving process. Tow spacing may be varied to accommodate the increased volume of the combined fiber tows while maintaining a target fiber volume fraction in the composite. Foam pore size, strut thickness, and ratio of face sheet to core thickness can be used to tailor thermal and mechanical properties. The anticipated CTE for the hybridized composite is managed by the choice of constituents, varying fiber tow sizes and constituent part ratios. This structural concept provides high strength and stiffness at low density 1.06 g/cu cm in panels tested. Varieties of face sheet constructions are possible, including variations in fiber type and weave geometry. The integrated structures possible with this composite could eliminate the need for non-load-bearing thermal protection systems on top of a structural component. The back sheet can readily be integrated to substructures through the incorporation of ribs. This would eliminate weight and cost for aerospace missions.

Goudy, Jerry

2009-01-01

303

Role of Carbon Dioxide in Inert Gas Narcosis.  

National Technical Information Service (NTIS)

The role of carbon dioxide and oxygen in high pressure narcosis was studied by exposing animals to hyperbaric conditions while maintaining them normoxic and normocapnic. Chickens were the experimental animal used. The unanaesthetized restrained birds were...

H. S. Weiss L. W. Torley

1975-01-01

304

Durable cathodes for high-power inert-gas arcs  

NASA Technical Reports Server (NTRS)

Cathode design minimizes evaporation of electrode material which may deposit on associated optical surfaces. It also results in stable operation and precise positioning of arc relative to optical collector. Innovation applies to high power light sources and to arcs used in industrial furnaces.

Decker, A. J.; Gettleman, C. C.; Goldman, G. C.; Hall, J. H.; Pollack, J. L.

1971-01-01

305

A compact rotating dilution refrigerator  

NASA Astrophysics Data System (ADS)

We describe the design and performance of a new rotating dilution refrigerator that will primarily be used for investigating the dynamics of quantized vortices in superfluid 4He. All equipment required to operate the refrigerator and perform experimental measurements is mounted on two synchronously driven, but mechanically decoupled, rotating carousels. The design allows for relative simplicity of operation and maintenance and occupies a minimal amount of space in the laboratory. Only two connections between the laboratory and rotating frames are required for the transmission of electrical power and helium gas recovery. Measurements on the stability of rotation show that rotation is smooth to around 10-3 rad s-1 up to angular velocities in excess of 2.5 rad s-1. The behavior of a high-Q mechanical resonator during rapid changes in rotation has also been investigated.

Fear, M. J.; Walmsley, P. M.; Chorlton, D. A.; Zmeev, D. E.; Gillott, S. J.; Sellers, M. C.; Richardson, P. P.; Agrawal, H.; Batey, G.; Golov, A. I.

2013-10-01

306

Inert Higgs doublet extension of the NMSSM  

NASA Astrophysics Data System (ADS)

We introduce one pair of inert Higgs doublets {Hd,Hu} and singlets {Nc,N}, and consider their couplings with the Higgs doublets of the minimal supersymmetric standard model (MSSM), W ?yNNchuHd+yN'NhdHu. We assign extra U(1)Z' gauge charges only to the extra vectorlike superfields, and so all the MSSM superfields remain neutral under the new U(1)Z'. They can be an extension of the "? term," W ??Shuhd in the next-to MSSM (NMSSM). Because of the U(1)Z', the maximally allowed low energy value of yN can be lifted up to 0.85, avoiding a Landau pole (LP) below the grand unification scale. Such colorless vectorlike superfields remarkably enhance the radiative MSSM Higgs mass particularly for large tan? through the yN term and the corresponding holomorphic soft term. As a result, the lower bound of ? and the upper bound of tan? can be relaxed to disappear from the restricted parameter space of the original NMSSM, 0.6?? ?0.7 and 1m˜t?700 GeV. Thus, the valid parameter space significantly expands up to 0?? ?0.75, 0?yN?0.88, and 2?tan??50, evading the LP problem and also explaining the 126 GeV Higgs mass naturally.

Kyae, Bumseok

2014-04-01

307

Neutrinos from Inert Doublet dark matter  

SciTech Connect

We investigate the signatures of neutrinos produced in the annihilation of WIMP dark matter in the Earth, the Sun and at the Galactic centre within the framework of the Inert Doublet Model and extensions. We consider a dark matter candidate, that we take to be one of the neutral components of an extra Higgs doublet, in three distinct mass ranges, which have all been shown previously to be consistent with both WMAP abundance and direct detection experiments exclusion limits. Specifically, we consider a light WIMP with mass between 4 and 8 GeV (low), a WIMP with mass around 60-70 GeV (middle) and a heavy WIMP with mass above 500 GeV (high). In the first case, we show that capture in the Sun may be constrained using Super-Kamiokande data. In the last two cases, we argue that indirect detection through neutrinos is challenging but not altogether excluded. For middle masses, we try to make the most benefit of the proximity of the so-called 'iron resonance' that might enhance the capture of the dark matter candidate by the Earth. The signal from the Earth is further enhanced if light right-handed Majorana neutrinos are introduced, in which case the scalar dark matter candidate may annihilate into pairs of mono-energetic neutrinos. In the case of high masses, detection of neutrinos from the Galactic centre might be possible, provided the dark matter abundance is substantially boosted.

Andreas, Sarah; Tytgat, Michel H.G.; Swillens, Quentin, E-mail: Sarah.Andreas@rwth-aachen.de, E-mail: mtytgat@ulb.ac.be, E-mail: qswillen@ulb.ac.be [Service de Physique Theorique, Universite Libre de Bruxelles, CP225, Bld du Triomphe, B-1050 Brussels (Belgium)] [Service de Physique Theorique, Universite Libre de Bruxelles, CP225, Bld du Triomphe, B-1050 Brussels (Belgium)

2009-04-15

308

Weak-localization-like temperature-dependent conductivity of a dilute two-dimensional hole gas in a parallel magnetic field.  

PubMed

We have studied the magnetotransport properties of a high mobility two-dimensional hole gas (2DHG) in a 10 nm GaAs quantum well with densities in the range of (0.7-1.6) x 10(10) cm(-2) on the metallic side of the zero-field "metal-insulator transition." In a parallel field well above B(c) that suppresses the metallic conductivity, the 2DHG exhibits a conductivity Delta(g)(T) approximately (1/pi) (e(2)/h)lnT reminiscent of weak localization for Fermi liquids. The experiments are consistent with the coexistence of two phases in our system: a metallic phase and a weakly insulating Fermi liquid phase. PMID:12097059

Gao, Xuan P A; Mills, Allen P; Ramirez, Arthur P; Pfeiffer, Loren N; West, Kenneth W

2002-07-01

309

An analysis of the effect of inert gases on ozone generation using dielectric barrier discharge in oxygen  

NASA Astrophysics Data System (ADS)

This paper studies the influence of inert gases He, Ar, Kr and Xe on ozone generation in a dielectric barrier reactor fed by oxygen feed gas. Results show that inert gas additions would lead to lower applied voltage, discharge power and reduced field. The electron energy distribution function shifts to the right though inert gas addition would lead to a lower reduced field with He, Ar and Kr addition, but it shifts to the left with Xe addition. The effective electron density decreases with inert gas content. With respect to Ar/O2, Kr/O2 and Xe/O2 mixture, conversion ratio of oxygen into ozone and ozone yield would increase with increasing Ar, Kr or Xe content, the growth rates follow the order of Xe > Kr > Ar. Such behaviors can be ascribed to the fact that Ar*, Kr* and Xe* could provide another effective pathway to produce oxygen atom through penning dissociation of O2 and metastable species due to their relatively low excitation threshold and considerable rate coefficients.

Wei, Linsheng; Yuan, Dingkun; Zhang, Yafang; Hu, Zhaoji; Tan, Zhihong; Dong, Guopan; Tao, Siqi

2014-01-01

310

Conversion of methane to hydrogen in a reversible flow superadiabatic inert porous medium reactor  

NASA Astrophysics Data System (ADS)

Using the analysis of the experimental data on partial oxidation of methane as an example, we have shown that the chemical processes in the inert medium of a reciprocating flow reactor can be modeled with good accuracy by the standard kinetic scheme for homogeneous processes due to the fact that the gas flow in the region of combustion is described by two temperatures — the gas and framework temperatures. Such a modification of the chemical model requires neither changing the recognized mechanism of homogeneous chemistry nor correcting the volume heat transfer coefficient.

Alabbadi, N. M.; Al-Musa, A. S.; Dmitrenko, Yu. M.; Martynenko, V. V.; Shabunya, S. I.; Al-Maiman, S. I.; Al-Enazi, K. B.; Al-Zhuhani, M. S.

2011-11-01

311

Growth and development in inert non-aqueous liquids. [of higher plants  

NASA Technical Reports Server (NTRS)

A preview is presented of the survival and growth capabilities of higher plants in non-aqueous, inert liquids. The two media which were used are mineral (white) oil and fluorochemical inert liquid FC-75. Both liquids dissolve oxygen and carbon dioxide readily, but are insoluble in water. Consequently, plants submerged in these liquids are capable of gas exchange with the atmosphere, but possess a water impermeable coating the dimensions of which are determined by the size of the liquid holding container. In a sense, growing plants in a tank of mineral oil imparts on them a cuticle. Plants plus prescribed volumes of water were innoculated into mineral oil. Organisms with minimal water supplied could then be observed. Also, submersed plants covered with an oil slick were shown to be capable of growth in dessicating atmospheres.

Siegel, S. M.

1974-01-01

312

The Physics and Technology of Dilute Nitrides  

Microsoft Academic Search

Dilute nitrides have emerged from conventional III–V semiconductors such as GaAs or InP by the insertion of nitrogen into the group V sub-lattice, which has a profound influence on the electronic properties of these materials and allows widely extended band structure engineering. This is expected to lead to novel devices, e.g. for optical data transmission, solar cells, biophotonics or gas

N Balkan

2004-01-01

313

Nonthermal plasma processing for dilute VOCs decomposition  

Microsoft Academic Search

The performance of nonthermal plasma processing for dilute (100 or 1000 ppm) trichloroethylene (TCE) decomposition in air was investigated in combination with titania (TiO2) catalysts. One type of catalyst consisted of 2-3-mm-diameter spherical titania pellets coated with vanadium oxide, V2O5. Homemade various-sized titania pellets sintered at 400°C and 1000°C were also tested. Gas chromatograph mass spectrometer analysis of the plasma-processed

Tetsuji Oda; Tadashi Takahahshi; Kei Yamaji

2002-01-01

314

Fuel-dilution effect on differential molecular diffusion in laminar hydrogen diffusion flames  

NASA Astrophysics Data System (ADS)

Laminar flame calculations have been made for a Tsuji counterflow geometry to investigate salient features caused by the differential diffusion effect in nitrogen-diluted hydrogen diffusion flames. A strong dependence of the differential diffusion parameter zHdilution is found, where zHinert gas dilution. This feature causes the differential diffusion parameter to increase with the amount of fuel dilution. The zH

Chen, Yung-cheng; Chen, Jyh-Yuan

1998-12-01

315

Results from electrolysis test of a prototype inert anode: Inert Electrode Program  

SciTech Connect

Nonconsumable or inert anodes are being developed at the Pacific Northwest Laboratory (PNL)({sup a}) for use in the electrolytic production of aluminum. A series of laboratory test on the laboratory scale (Hart et al. 1987; Strachan et al. 1989; Marschman 1989) has shown the technology to be potentially feasible. A series of larger-scale experiments are now being run to determine the viability of the technology on a commercial scale. The results reported here are from a test performed at the Reynolds Metals Company, Manufacturing Technology Laboratory, Sheffield, Alabama, using a prototype anode. The prototype anode was approximately 15 cm in diameter and 20 cm high (Figure 1.1). The objectives of the test were to determine if an anode, produced by a commercial vendor, could survive in a test under conditions approximating those found in a commercial electrolysis cell; to familiarize the Reynolds staff with the operation of such an anode in a subsequent pilot cell test of the inert anode technology; and to familiarize the PNL staff with the operations at the Reynolds Metals Company facility. 8 refs., 39 figs., 9 tabs.

Strachan, D.M.; Windisch, C.F. Jr.; Koski, O.H.; Morgan, L.G. (Pacific Northwest Lab., Richland, WA (USA)); Peterson, R.D.; Richards, N.E.; Tabereaux, A.T. (Reynolds Metals Co., Sheffield, AL (USA). Mfg. Technology Lab.)

1990-05-01

316

40 CFR 174.705 - Inert ingredients from sexually compatible plant.  

Code of Federal Regulations, 2013 CFR

...Inert ingredients from sexually compatible plant. 174.705 Section 174.705 Protection...PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS List of Approved...Inert ingredients from sexually compatible plant. An inert ingredient, and...

2013-07-01

317

Technical basis for storage of Zircaloy-clad spent fuel in inert gases  

SciTech Connect

This report summarizes the technical bases to establish safe conditions for dry storage of Zircaloy-clad fuel. Dry storage of fuel with zirconium alloy cladding has been licensed in Canada, the Federal Republic of Germany, and Switzerland. In addition, dry storage demonstrations, hot cell tests, and modeling have been conducted using Zircaloy-clad fuel. The demonstrations have included irradiated boiling water reactor, pressurized heavy-water reactor, and pressurized water reactor (PWR) fuel assemblies. Irradiated fuel has been emplaced in and retrieved from metal casks, dry wells, silos, and a vault. Dry storage tests and demonstrations have involved {similar_to}5,000 fuel rods, and {similar_to}600 rods have been monitored during dry storage in inert gases with maximum cladding temperatures ranging from 50 to 570{sup 0}C. Although some tests and demonstrations are still in progress, there is currently no evidence that any rods exposed to inert gases have failed (one PWR rod exposed to an air cover gas failed at {similar_to}70{sup 0}C). Based on this favorable experience, it is concluded that there is sufficient information on fuel rod behavior, storage conditions, and potential cladding failure mechanisms to support licensing of dry storage in the United States. This licensing position includes a requirement for inert cover gases and a maximum cladding temperature guideline of 380{sup 0}C for Zircaloy-clad fuel. Using an inert cover gas assures that even if fuel with cladding defects were placed in dry storage, or if defects develop during storage, the defects would not propagate. Tests and demonstrations involving Zircaloy-clad rods and assemblies with maximum cladding temperatures above 400{sup 0}C are in progress. When the results from these tests have been evaluated, the viability of higher temperature limits should be examined. Acceptable conditions for storage in air and dry storage of consolidated fuel are issues yet to be resolved.

Johnson, A.B. Jr.; Gilbert, E.R.

1983-09-01

318

Operator's Manual for Computerized Gas Metering System (Flammable Gas).  

National Technical Information Service (NTIS)

The computerized metering system for flammable gas prevents an explosive mixture from occurring when testing a vessel. Because the original metering system for inert gas lacked this safety precaution, additional hardware and software features were made to...

D. Bell K. Blaedel M. Brooks J. Cervelli G. Koide

1984-01-01

319

Fast and solvent-free quantitation of boar taint odorants in pig fat by stable isotope dilution analysis-dynamic headspace-thermal desorption-gas chromatography/time-of-flight mass spectrometry.  

PubMed

Boar taint is a specific off-odour of boar meat products, known to be caused by at least three unpleasant odorants, with very low odour thresholds. Androstenone is a boar pheromone produced in the testes, whereas skatole and indole originate from the microbial breakdown of tryptophan in the intestinal tract. A new procedure, applying stable isotope dilution analysis (SIDA) and dynamic headspace-thermal desorption-gas chromatography/time-of-flight mass spectrometry (dynHS-TD-GC/TOFMS) for the simultaneous quantitation of these boar taint compounds in pig fat was elaborated and validated in this paper. The new method is characterised by a simple and solvent-free dynamic headspace sampling. The deuterated compounds d3-androstenone, d3-skatole and d6-indole were used as internal standards to eliminate matrix effects. The method validation performed revealed low limits of detection (LOD) and quantitation (LOQ) with high accuracy and precision, thus confirming the feasibility of the new dynHS-TD-GC/TOFMS approach for routine analysis. PMID:24731353

Fischer, Jochen; Haas, Torsten; Leppert, Jan; Lammers, Peter Schulze; Horner, Gerhard; Wüst, Matthias; Boeker, Peter

2014-09-01

320

Nitrogen-related effects on low-temperature electronic properties of two-dimensional electron gas in very dilute nitride GaNxAs1-x/AlGaAs (x = 0 and 0.08%) modulation-doped heterostructures  

NASA Astrophysics Data System (ADS)

The low-temperature (4 K) two-dimensional (2D) electron gas mobility data versus carrier concentration in the modulation-doped dilute nitride GaAs1-xNx/Al0.3Ga0.7As (x = 0 and 0.08%) heterostructures are analyzed. Theoretical analysis is based on Fermi-Dirac statistics for the occupation of the quantum confined electronic states in the triangular quantum wells and the width of the quantum well versus 2D concentration. In addition, the mobility analysis is based on Matthiessen's rule for various scattering mechanisms. We found that the N-related neutral cluster alloy scattering together with crystal dislocations created at the interface strongly affects the electrons' mobility in the N-contained channel sample. We also found that as the electron concentration in the well increases from ˜1 × 1011 to 3.5 × 1011 cm-2 the carriers mainly occupy the first subband, tending to remain closer and closer to the hetero-interface.

Mootabian, Mahnaz; Eshghi, Hosein

2013-07-01

321

Stable-isotope dilution gas chromatography-mass spectrometric measurement of 3-hydroxyglutaric acid, glutaric acid and related metabolites in body fluids of patients with glutaric aciduria type 1 found in newborn screening.  

PubMed

We developed a simple and sensitive stable-isotope dilution method for the quantification of 3-hydroxyglutaric acid (3HGA) and glutaric acid (GA) in body fluids. In our method, tert-butyldimethylsilyl (tBDMS) derivatives of 3HGA and GA were measured with a conventional electron-impact ionization (EI) mode in gas chromatography-mass spectrometry (GC-MS). The control values for 3HGA in nmol/ml were 0.15+/-0.08 (serum; n=10) and 0.07+/-0.03 (CSF; n=10). In addition, glutarylcarnitine and free carnitine were quantified by electrospray tandem mass spectrometry. Using these methods, we monitored 3HGA, GA, and glutarylcarnitine in the body fluids of three patients with glutaric aciduria type 1 found during newborn screening. None of the patients had experienced neurological strokes, which are possibly caused by the accumulation of 3HGA, at 15-24 months of age under a disease-specific treatment, including carnitine supplementation. Our data showed that 3HGA levels were relatively high in some serum samples with lower glutarylcarnitine and carnitine levels, suggesting that carnitine supplementation may play a role in preventing the accumulation of 3HGA in patients with this disease. PMID:16055049

Shigematsu, Yosuke; Hata, Ikue; Tanaka, Yukie; Tajima, Go; Sakura, Nobuo; Naito, Etsuo; Yorifuji, Toru

2005-08-25

322

Diluted magnetic semiconductors  

Microsoft Academic Search

Diluted magnetic semiconductors (DMSs), i.e. semiconducting crystals whose lattice is made up in part of substitutional magnetic ions (e.g. Cd1-xMnxTe, Hg1-xFex Se, Zn1-xCoxS), are reviewed. The focus is on materials of the type A1-xII MnxB VI, which are the most thoroughly understood. However, the similarities and differences between these materials and the A1-x IIFexBVI and A1-IICoxBVI systems are discussed wherever

Nitin Samarth; J. K. Furdyna

1990-01-01

323

On-line monitoring of benzene air concentrations while driving in traffic by means of isotopic dilution gas chromatography/mass spectrometry.  

PubMed

There is no shortage of information about the average benzene concentrations in urban air, but there is very little about microenvironmental exposure, such as in-vehicle concentrations while driving in various traffic conditions, while refuelling, or while in a parking garage. The main reason for this lack of data is that no analytical instrumentation has been available to measure on-line trace amounts of benzene in such situations. We have recently proposed a highly accurate, high-speed cryofocusing gas chromatography/mass spectrometry (GC/MS) system for monitoring benzene concentrations in air. Accuracy of the analytical data is achieved by enrichment of the air sample before trapping, with a stable isotope permeation tube system. The same principles have been applied to a new instrument, specifically designed for operation on an electric vehicle (Ducato Elettra, Fiat). The zero emission vehicle and the fully transportable, battery-operated GC/MS system provide a unique possibility of monitoring benzene exposure in real everyday situations such as while driving, refuelling, or repairing a car. All power consumptions have been reduced so as to achieve a battery-operated GC/MS system. Liquid nitrogen cryofocusing has been replaced by a packed, inductively heated, graphitized charcoal microtrap. The instrument has been mounted on shock absorbers and installed in the van. The whole system has been tested in both fixed and mobile conditions. The maximum monitoring period without external power supply is 6 h. The full analytical cycle is 4 min, allowing close to real-time monitoring, and the minimum detectable level is 1 microgram/m3 for benzene. In-vehicle monitoring showed that, when recirculation was off and ventilation on, i.e., air from outside the vehicle was blown inside, concentrations varied widely in different driving conditions: moving from a parking lot into normal traffic on an urban traffic condition roadway yielded an increase in benzene concentration from 17 to 62.3 micrograms/m3 even if the actual distance was small. A larger increase was observed when a car was left with the engine running at a distance 2 m from the zero emission vehicle: We measured an increment of benzene concentrations from 15.2 to 174.4 micrograms/m3 with a car equipped with a catalytic converter, and from 19.1 to 386.3 micrograms/m3 with a car without such a converter. PMID:8738357

Davoli, E; Cappellini, L; Moggi, M; Ferrari, S; Fanelli, R

1996-01-01

324

Inertance Tube Modeling and the Effects of Temperature  

NASA Astrophysics Data System (ADS)

Pulse tube refrigerators (PTRs) have made dramatic improvements in reliability, efficiency and usage. Inertance tube PTRs have been one of the keys to these improvements. The inertance tube is the component in the PTR that most easily affects the control of the PTR fluid dynamics. In one application in multistage cryocoolers, the performance of inertance tubes at the cryogenic temperatures is of interest. One purpose of this paper is to understand how temperature and the size of the reservoir influence the phase shift between mass flow rate and pressure at the inlet of the inertance tube. Various models including a two dimensional Computational Fluid Dynamics (CFD) will be compared to understand how these models can predict the phase shift and the acoustic power.

Dodson, C.; Razani, A.; Roberts, T.

2010-04-01

325

Inert electrodes program: Fiscal Year 1987 Annual Report  

SciTech Connect

The Inert Electrodes Program is being conducted at the Pacific Northwest Laboratory (PNL) for the US Department of Energy (DOE), Office of Industrial Programs (OIP). The purpose of the program is to develop long-lasting, energy-efficient anodes, cathodes, and ancillary equipment for Hall-Heroult cells used by aluminum industry. The program is divided into three tasks with the following objectives: Inert Anode Development - to improve the energy efficiency of Hall-Heroult cells by development of inert anodes; Stable Cathode Studies - to develop methods for retrofitting Hall-Heroult cells with TiB/sub 2/-based cathode materials; and Sensor Development - to devise sensors to control the chemistry of Hall-Heroult Cells using stable anodes and cathodes. This Inert Electrodes Program annual report highlights the major technical accomplishment of FY 1987. The accomplishments are presented in the following sections: Management, Materials Development and Testing, Materials Evaluation, Stable Cathode Studies, and Sensor Development. 50 refs., 47 figs.

Koski, O.H.; Marschman, S.C.; Schilling, C.H.; Windisch, C.F.

1988-12-01

326

114. SMALL ARMS (BUILDINGS 9798) AND INERT STOREHOUSE (BLDGS. 1031040) ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

114. SMALL ARMS (BUILDINGS 97-98) AND INERT STOREHOUSE (BLDGS. 103-1040) PLAN AND ELEVATIONS, FULLER/SCOTT, MARCH 15, 1941. QP ACC 1791. - Quonset Point Naval Air Station, Roger Williams Way, North Kingstown, Washington County, RI

327

Cermet sphere-pac concept for inert matrix fuel  

Microsoft Academic Search

In the inert matrix fuel concept, plutonium reprocessed from spent fuel is burned in an inert matrix, e.g. yttria-stabilized zirconia. Coming from wet reprocessing, the internal gelation can perform an easy micro-spheres production. Utilization of these particles in a sphere-pac realizes a direct fuel production. Besides being economical, this direct usage offers an almost dustless fabrication. One disadvantage of yttria-stabilized

M. A. Pouchon; M. Nakamura; Ch. Hellwig; F. Ingold; C. Degueldre

2003-01-01

328

Inertization of pyrite cinders and co-inertization with electric arc furnace flue dusts by pyroconsolidation at solid state  

Microsoft Academic Search

The viability of a pyroconsolidation process to render pyrite cinders inert and to co-inert pyrite cinders with a hazardous polymetallic residue such as electric arc furnace flue dusts (EAF) containing Pb, Cu, Zn, As, Cr, Ni and Mo were investigated. The effects of pyroconsolidation temperature (800–1200 °C), milling pyrite cinders and additions of both CaO and EAF on the resulting microstructure

J Viñals; M. J Balart; A Roca

2002-01-01

329

Process and apparatus for igniting a burner in an inert atmosphere  

DOEpatents

According to this invention there is provided a process and apparatus for the ignition of a pilot burner in an inert atmosphere without substantially contaminating the inert atmosphere. The process includes the steps of providing a controlled amount of combustion air for a predetermined interval of time to the combustor then substantially simultaneously providing a controlled mixture of fuel and air to the pilot burner and to a flame generator. The controlled mixture of fuel and air to the flame generator is then periodically energized to produce a secondary flame. With the secondary flame the controlled mixture of fuel and air to the pilot burner and the combustion air is ignited to produce a pilot burner flame. The pilot burner flame is then used to ignited a mixture of main fuel and combustion air to produce a main burner flame. The main burner flame then is used to ignite a mixture of process derived fuel and combustion air to produce products of combustion for use as an inert gas in a heat treatment process.

Coolidge, Dennis W. (Katy, TX) [Katy, TX; Rinker, Franklin G. (Perrysburg, OH) [Perrysburg, OH

1994-01-01

330

Dilution jet mixing program  

NASA Technical Reports Server (NTRS)

Parametric tests were conducted to quantify the mixing of opposed rows of jets (two-sided injection) in a confined cross flow. Results show that jet penetrations for two sided injections are less than that for single-sided injections, but the jet spreading rates are faster for a given momentum ratio and orifice plate. Flow area convergence generally enhances mixing. Mixing characteristics with asymmetric and symmetric convergence are similar. For constant momentum ratio, the optimum S/H(0) with in-line injections is one half the optimum value for single sided injections. For staggered injections, the optimum S/H(0) is twice the optimum value for single-sided injection. The correlations developed predicted the temperature distributions within first order accuracy and provide a useful tool for predicting jet trajectory and temperature profiles in the dilution zone with two-sided injections.

Srinivasan, R.; Coleman, E.; Johnson, K.

1984-01-01

331

Characterization and modeling for dilute and dense sprays  

NASA Technical Reports Server (NTRS)

The present numerical modeling of dilute and dense spray combustion solves the governing gas-phase equations in Eulerian coordinates by means of a time-marching multiple pressure correction procedure that is based on the operator-splitting technique. A sequence of validating cases involving (1) nonevaporating, (2) evaporating, (3) burning, (4) dilute, and (5) dense spray cases is undertaken; it is found that in the combusting dilute spray case, the present procedure correctly predicts the general features of flows and yields qualitative agreement with experimental data. In the other cases, reasonably good agreement with experimental results is obtained.

Chen, C. P.; Kim, Y. M.; Shang, H. M.

1992-01-01

332

Stress in dilute suspensions  

NASA Technical Reports Server (NTRS)

Generally, two types of theory are used to describe the field equations for suspensions. The so-called postulated equations are based on the kinetic theory of mixtures, which logically should give reasonable equations for solutions. The basis for the use of such theory for suspensions is tenuous, though it at least gives a logical path for mathematical arguments. It has the disadvantage that it leads to a system of equations which is underdetermined, in a sense that can be made precise. On the other hand, the so-called averaging theory starts with a determined system, but the very process of averaging renders the resulting system underdetermined. A third type of theory is proposed in which the kinetic theory of gases is used to motivate continuum equations for the suspended particles. This entails an interpretation of the stress in the particles that is different from the usual one. Classical theory is used to describe the motion of the suspending medium. The result is a determined system for a dilute suspension. Extension of the theory to more concentrated systems is discussed.

Passman, Stephen L.

1989-01-01

333

A pure Eulerian model for simulating dilute spray combustion  

Microsoft Academic Search

A pure Eulerian model is developed to simulate steady-state dilute spray combustion. This model is based on a fundamental description of various interacting processes which occur during spray combustion including gas-phase and spray droplet-phase turbulent flow, gas-phase turbulent combustion, radiation heat transfer and spray droplet evaporation. Both gas-phase and spray droplet-phase conservation equations are described using Eulerian coordinates. A comprehensive

Y. C. Guo; C. K. Chan; K. S. Lau

2002-01-01

334

Extinction of diffusion flames burning diluted methane and diluted propane in diluted air  

Microsoft Academic Search

A theoretical and experimental investigation of the extinction limits of counterflow diffusion flames burning methane and propane is outlined. A diffusion flame is stabilized between counterflowing streams of a fuel diluted with nitrogen and air diluted with nitrogen. Extinction limits for such flames were measured over a wide parametric range. Results for methane and propane were found to be in

I.K. Puri; K. Seshadri

1986-01-01

335

Post irradiation examination of uranium inclusions in inert matrices  

Microsoft Academic Search

The inert matrix materials CeO2, MgO, Y2O3, MgAl2O4 and Y3Al5O12 were selected as candidates for inert matrices for the EFTTRA22Experimental Feasibility of Targets for TRAnsmutation, a European project in which CEA, NRG, EdF, FzK, JRC-ITU and JRC-IAM cooperate.-T3 neutron irradiation experiment. Most targets contain 20% enriched 235U fissile inclusions with an average size of roughly 150 ?m. The volume fraction

E. A. C. Neeft; K. Bakker; H. A. Buurveld; J. Minkema; A. Paardekooper; R. P. C. Schram; C. Sciolla; O. Zwaagstra; B. Beemsterboer; J. R. W. Woittiez; P. van Vlaanderen; W. J. Tams; H. Hein; R. Conrad; A. van Veen

2001-01-01

336

Gas shielding apparatus  

DOEpatents

An apparatus for preventing oxidation by uniformly distributing inert shielding gas over the weld area of workpieces such as pipes being welded together. The apparatus comprises a chamber and a gas introduction element. The chamber has an annular top wall, an annular bottom wall, an inner side wall and an outer side wall connecting the top and bottom walls. One side wall is a screen and the other has a portion defining an orifice. The gas introduction element has a portion which encloses the orifice and can be one or more pipes. The gas introduction element is in fluid communication with the chamber and introduces inert shielding gas into the chamber. The inert gas leaves the chamber through the screen side wall and is dispersed evenly over the weld area.

Brandt, Daniel (Los Alamos, NM)

1985-01-01

337

Dilution refrigeration for space applications  

NASA Technical Reports Server (NTRS)

Dilution refrigerators are presently used routinely in ground based applications where temperatures below 0.3 K are required. The operation of a conventional dilution refrigerator depends critically on the presence of gravity. To operate a dilution refrigerator in space many technical difficulties must be overcome. Some of the anticipated difficulties are identified in this paper and possible solutions are described. A single cycle refrigerator is described conceptually that uses forces other than gravity to function and the stringent constraints imposed on the design by requiring the refrigerator to function on the earth without using gravity are elaborated upon.

Israelsson, U. E.; Petrac, D.

1990-01-01

338

Determination of Ethane-1,2-diamine in Inert Complexes.  

ERIC Educational Resources Information Center

Describes a procedure for determining ethane-1,2-diamine (EN) which is generally applicable for inert or labile complexes or for EN in its salts, although it cannot be used directly with ammonium or coordinated ammonia. It gives results with five percent accuracy or better and requires less than one hour laboratory time. (JN)

Searle, Graeme H.

1985-01-01

339

The inert doublet model: an archetype for dark matter  

Microsoft Academic Search

The inert doublet model (IDM), a two Higgs extension of the standard model with an unbroken Z2 symmetry, is a simple and yet rich model of dark matter. We present a systematic analysis of the dark matter abundance and investigate the potentialities for direct and gamma indirect detection. We show that the model should be within the range of future

Laura Lopez Honorez; Emmanuel Nezri; Josep F. Oliver; Michel H. G. Tytgat

2007-01-01

340

Preliminary Design Report, Shippingport Spent Fuel Drying and Inerting System.  

National Technical Information Service (NTIS)

A process description and system flow sheets have been prepared to support the design/build package for the Shippingport Spent Fuel Canister (SSFC) drying and inerting process skid. A process flow diagram was prepared to show the general steps to dry and ...

2002-01-01

341

Inert Electrodes Program fiscal year 1988 annual report  

SciTech Connect

The Inert Electrodes Program, being conducted by Pacific Northwest Laboratory (PNL), involves improving the Hall-Heroult cells used by the Aluminum Industry for the electrochemical production of aluminum. The PNL research centers on developing more energy efficient, longer-lasting anodes and cathodes and ancillary equipment. Major accomplishments for Fiscal Year 1988 are summarized below. 14 refs., 56 figs., 9 tabs.

Strachan, D.M.; Marschman, S.C.; Davis, N.C.; Friley, J.R.; Schilling, C.H.

1989-10-01

342

Optical Third-Harmonic Coefficients for the Inert Gases.  

National Technical Information Service (NTIS)

Optical third-harmonic coefficients are calculated for the inert gases and are compared with recent experimental values. They were found to range from 0.9 x 10 to the 39th power esu/atom for He to 222 x 10 to the 39th power esu/atom for Xe. The calculated...

E. L. Dawes

1967-01-01

343

Combustion of hydrocarbon fuels within porous inert media  

Microsoft Academic Search

There has been a recent surge of interest in the combustion of hydrocarbon fuels within porous inert media. The interest has been directed by the needs of industry to develop high performance radiant heaters while complying with increasingly stringent emissions regulations. This paper reviews the processes associated with non-catalytic combustion within porous media, and describes related experimental and modeling research.

J. R. Howell; M. J. Hall; J. L. Ellzey

1996-01-01

344

Direct conversion of natural gas to methanol by controlled oxidation  

Microsoft Academic Search

A process is described for converting natural gas containing methane to methanol, comprising: thoroughly and intimately mixing natural gas with gaseous air or oxygen to achieve substantially complete homogeneity of these gases; feeding the resulting gas mixture to an inert reactor under elevated pressure, the inert reactor having an internal surface surrounding a zone in which the gases react. The

H. D. Gesser; N. R. Hunter; L. Morton

1986-01-01

345

Sea Urchin Embryology: Sperm Dilution  

NSDL National Science Digital Library

Lab directions for up to two 50 min periods and the last of the dilution labs. Includes set up information, materials, procedure, experimental design, things to observe, math possibilities, thought-provoking questions and an assessment.

PhD David Epel (Stanford U. Hopkins Marine Station)

2007-04-20

346

Sea Urchin Embryology: Simple Dilutions  

NSDL National Science Digital Library

Starting from a known concentration students learn to use dilutions to determine the concentration of an unknown. The following skills are used in this lesson: 1. making dilutions 2. reading the meter on a simple homemade spectrophotometer 3. keeping careful laboratory records 4. graphing on linear graph paper 5. determining an unknown concentration from known 6. using a colored filter to enhance contrast and sensitivity

PhD David Epel (Stanford U. Hopkins Marine Station)

2006-12-20

347

Dilute acid hydrolysis of softwoods  

Microsoft Academic Search

Whole tree chips obtained from softwood forest thinnings were converted to ethanol via a two-stage dilute acid hydrolysis\\u000a followed by yeast fermentation. The chips were first impregnated with dilute sulfuric acid, then pretreated in a steam explosion\\u000a reactor to hydrolyze, more than 90% of the hemicellulose and approx 10% of the cellulose. The hydrolysate was filtered and\\u000a washed with water

Quang A. Nguyen; Melvin P. Tucker; Fred A. Keller; Delicia A. Beaty; Kevin M. Connors; Fannie P. Eddy

1999-01-01

348

The Influence of Charge Dilution and Injection Timing on Low Temperature Diesel Combustion and Emissions  

Microsoft Academic Search

The effects of charge dilution on low-temperature diesel combustion and emissions were investigated in a small- bore single-cylinder diesel engine over a wide range of injection timing. The fresh air was diluted with additional N2 and CO2, simulating 0 to 65% exhaust gas recirculation in an engine. Diluting the intake charge lowers the flame temperature T due to the reactant

Sanghoon Kook; Choongsik Bae

349

Free-Fall Dilute-Phase Hydrogasification of Coal.  

National Technical Information Service (NTIS)

Raw, high-volatile bituminous coal and lignite have been gasified using pure hydrogen gas in a continuous free-fall, dilute-phase (FDP) reactor. Long duration operability and reliability of the FDP concept were demonstrated in tests of 5.5 to 8 hr duratio...

H. F. Chambers J. A. Mima P. M. Yavorsky

1976-01-01

350

FIELD AND LABORATORY EVALUATION OF A WOODSTOVE DILUTION SAMPLING SYSTEM  

EPA Science Inventory

The paper discusses field and laboratory evaluation of a woodstove dilution sampling system. Two sampling methods have been developed and used by EPA to test emissions from woodstoves: both remove flue gas directly from the appliance chimney. The two methods have been developed t...

351

Inert-sterile neutrino: Cold or warm dark matter candidate  

SciTech Connect

In usual particle models, sterile neutrinos can account for the dark matter of the Universe only if they have masses in the keV range and are warm dark matter. Stringent cosmological and astrophysical bounds, in particular, imposed by x-ray observations, apply to them. We point out that in a particular variation of the inert doublet model, sterile neutrinos can account for the dark matter in the Universe and may be either cold or warm dark matter candidates, even for masses much above the keV range. These inert-sterile neutrinos, produced nonthermally in the early Universe, would be stable and have very small couplings to standard model particles, rendering very difficult their detection in either direct or indirect dark matter searches. Their existence could be revealed only by discovering other particles of the model in collider experiments.

Gelmini, Graciela B.; Osoba, Efunwande [Department of Physics and Astronomy, UCLA, 475 Portola Plaza, Los Angeles, California 90095 (United States); Palomares-Ruiz, Sergio [Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico, P-1049-001, Lisboa (Portugal)

2010-03-15

352

Evolution of weak disturbances in inert binary mixtures  

NASA Technical Reports Server (NTRS)

The evolution of weak disturbances in inert binary mixtures is determined for the one-dimensional piston problem. The interaction of the dissipative and nonlinear mechanisms is described by Burgers' equation. The binary mixture diffusion mechanisms enter as an additive term in an effective diffusivity. Results for the impulsive motion of a piston moving into an ambient medium and the sinusoidally oscillating piston are used to illustrate the results and elucidate the incorrect behavior pertaining to the associated linear theory.

Rasmussen, M. L.

1977-01-01

353

Biodiesel Impact on Engine Lubricant Dilution During Active Regeneration of Aftertreatment Systems  

Microsoft Academic Search

Experiments were conducted with ultra low sulfur diesel (ULSD) and 20% biodiesel blends (B20) to compare lube oil dilution levels and lubricant properties for systems using late in-cylinder fuel injection for aftertreatment regeneration. Lube oil dilution was measured by gas chromatography (GC) following ASTM method D3524 to measure diesel content, by Fourier transform infrared (FTIR) spectrometry following a modified ASTM

X. He; A. Williams; E. Christensen; J. Burton; R. McCormick

2011-01-01

354

Yttrium stabilised zirconia inert matrix fuel irradiation at an international research reactor  

NASA Astrophysics Data System (ADS)

Different concepts have been developed during the last decade to transmute transuranium elements (TRU) using uranium-free inert matrix fuels (IMF) in a once-through-cycle to reduce the amount of TRU in the nuclear waste. For today's LWRs yttrium stabilised zirconia (YSZ) and other oxides like alumina, spinel or ceria have been proposed as inert matrix materials. By employing IMF, a larger fraction of plutonium can potentially be consumed in comparison with MOX fuels without breeding new plutonium. The aim of the presented study is to measure the general thermal behaviour of YSZ-based IMF under irradiation conditions similar to those in current LWRs in direct comparison to standard MOX fuel. Of particular interest are the fuel thermal conductivity (and its degradation with burnup), fission gas release (FGR), fuel densification and fuel swelling. A secondary aim is the direct comparison of the fuel performance between YSZ-based IMF and MOX fuel. The irradiation is performed under HBWR conditions and has reached an average assembly burnup of ˜300 kW d cm -3 until the end of 2004, which is equivalent to ˜29 MW d kg -1 for the MOX fuel.

Streit, M.; Wiesenack, W.; Tverberg, T.; Hellwig, Ch.; Oberländer, B. C.

2006-06-01

355

Study of Thermo-Acoustic Instabilities in a Rijke Tube Without and With Porous Inert Medium  

NASA Astrophysics Data System (ADS)

Porous inert medium has been used in the past to reduce combustion noise in atmospheric pressure systems. It is envisioned that this same approach could be used to mitigate combustion instabilities encountered in gas turbines using lean premixed combustion concept. In this study, a simple Rijke tube is used to investigate the effect of porous inert media on thermo-acoustic instabilities. The Rijke tube set up utilizes a simple tube with a localized heat source. Sound pressure level measurements are taken at the tube exit to determine the sound power spectra in decibels. Such measurements were taken without and with porous medium inserted within the Rijke tube. The porous media is a 2.54 cm thick ceramic disk with 10 to 20 pores per inch. Results show that the Rijke tube behavior without the porous media follows the trends observed by previous investigators. The porous media was effective in reducing the sound pressure level, and thus, it offers the potential to mitigate thermo-acoustic instabilities through proper geometric design.

Osmer, Cody; Agrawal, Ajay

2010-11-01

356

The Optimum Plutonium Inert Matrix Fuel Form for Reactor-Based Plutonium Disposition  

SciTech Connect

The University of Florida has underway an ongoing research program to validate the economic, operational and performance benefits of developing an inert matrix fuel (IMF) for the disposition of the U.S. weapons plutonium (Pu) and for the recycle of reprocessed Pu. The current fuel form of choice for Pu disposition for the Department of Energy is as a mixed oxide (MOX) (PuO2/UO2). We will show analyses that demonstrate that a Silicon Carbide (SiC) IMF offers improved performance capabilities as a fuel form for Pu recycle and disposition. The reason that UF is reviewing various materials to serve as an inert matrix fuel is that an IMF fuel form can offer greatly reduced Pu and transuranic isotope (TRU) production and also improved thermal performance characteristics. Our studies showed that the Pu content is reduced by an order of magnitude while centerline fuel temperatures are reduced approximately 380 degrees centigrade compared to MOX. These reduced temperatures result in reduced stored heat and thermal stresses in the pellet. The reduced stored heat reduces the consequences of the loss of coolant accident, while the reduced temperatures and thermal stresses yield greatly improved fuel performance. Silicon Carbide is not new to the nuclear industry, being a basic fuel material in gas cooled reactors.

Tulenko, J.S.; Wang, J.; Acosta, C.

2004-10-06

357

The Optimum Plutonium Inert Matrix Fuel Form for Reactor-Based Plutonium Disposition  

SciTech Connect

The University of Florida has underway an ongoing research program to validate the economic, operational and performance benefits of developing an inert matrix fuel (IMF) for the disposition of the U.S. weapons plutonium (Pu) and for the recycle of reprocessed Pu. The current fuel form of choice for Pu disposition for the Department of Energy is as a mixed oxide (MOX) (PuO2/UO2). We will show analyses that demonstrate that a Silicon Carbide (SiC) IMF offers improved performance capabilities as a fuel form for Pu recycle and disposition. The reason that UF is reviewing various materials to serve as an inert matrix fuel is that an IMF fuel form can offer greatly reduced Pu and transuranic isotope (TRU) production and also improved thermal performance characteristics. Our studies showed that the Pu content is reduced by an order of magnitude while centerline fuel temperatures are reduced approximately 380 degrees centigrade compared to MOX. These reduced temperatures result in reduced stored heat and thermal stresses in the pellet. The reduced stored heat reduces the consequences of the loss of coolant accident, while the reduced temperatures and thermal stresses yield greatly improved fuel performance. Silicon Carbide is not new to the nuclear industry, being a basic fuel material in gas cooled reactors.

Tulenko, J.S.; Wang, J.; Acosta, C.

2004-10-03

358

Kinetics of switch grass pellet thermal decomposition under inert and oxidizing atmospheres.  

PubMed

Grass pellets are a renewable resource that have energy content similar to that of wood. However, the higher ash and chlorine content affects combustion. Thermal degradation analysis of a fuel is useful in developing effective combustion. Thermogravimetric analysis (TGA) of the thermal degradation of grass pellets under inert (nitrogen) and oxidizing (air) atmospheres was conducted. Non-isothermal conditions were employed with 4 different heating rates. Kinetic parameters (activation energy and pre-exponential factors) were estimated using the iso-conversional method. Both pyrolysis and oxidative atmospheric thermal degradation exhibited two major loss process: volatilization of cellulose, hemicelluloses and lignin and burning or slow oxidation of the residual char. The activation energy and pre-exponential factors were high for the oxidizing environment. During pyrolysis, major decomposition occurred with 40% to 75% conversion of the mass to gas with an activation energy of 314 kJ/mol. In air the decomposition occurred with 30% to 55% conversion with an activation energy of 556 kJ/mol. There was a substantial effect of heating rate on mass loss and mass loss rate. The TG shifted to higher temperature ranges on increasing the heating rate. In both pyrolyzing and oxidizing conditions, average combustion and devolatilization rates increased. Enhanced combustion takes place with higher activation energy in oxidizing atmosphere compared to the inert atmosphere due to presence of air. PMID:23026316

Chandrasekaran, Sriraam R; Hopke, Philip K

2012-12-01

359

Superparamagnetism in Magnetically Dilute Systems  

Microsoft Academic Search

Superparamagnetic behavior observed in magnetically dilute systems is discussed. The clusters that behave like superparamagnetic fine particles are ferromagnetic or ferrimagnetic regions separated magnetically from the matrix, because these regions are surrounded by nonmagnetic atoms. The magnetic properties of dilute oxide systems such as: 0.9 ZnFe2O4-0.1 NiFe2O4; 0.9 FeTiO3-0.1 Fe2O3; and Y1.5Ca1.5Fe4.5Sn1.5O12 are better understood if we take into account

Yoshikazu Ishikawa

1964-01-01

360

Reduced temperature aluminum production in an electrolytic cell having an inert anode  

DOEpatents

Aluminum is produced by electrolytic reduction of alumina in a cell having a cathode, an inert anode and a molten salt bath containing metal fluorides and alumina. The inert anode preferably contains copper, silver and oxides of iron and nickel. Reducing the molten salt bath temperature to about 900-950.degree. C. lowers corrosion on the inert anode constituents.

Dawless, Robert K. (Monroeville, PA); Ray, Siba P. (Murrysville, PA); Hosler, Robert B. (Sarver, PA); Kozarek, Robert L. (Apollo, PA); LaCamera, Alfred F. (Trafford, PA)

2000-01-01

361

The performance improvements of train suspension systems with mechanical networks employing inerters  

Microsoft Academic Search

This paper investigates the performance benefits of train suspension systems employing a new mechanical network element called an inerter. An inerter is a true mechanical two-terminal element with the applied force proportional to the relative acceleration across the terminals. Until now, ideal inerters have been applied to car and motorcycle suspension systems, for which a significant performance improvement was reported.

Fu-Cheng Wang; Min-Kai Liao; Bo-Huai Liao; Wei-Jiun Su; Hsiang-An Chan

2009-01-01

362

Unidentified Inert Ingredients in Pesticides: Implications for Human and Environmental Health  

Microsoft Academic Search

BACKGROUND: By statute or regulation in the United States and elsewhere, pesticide ingredients are divided into two categories: active and inert (sometimes referred to as other ingredients, adjuvants, or coformulants). Despite their name, inert ingredients may be biologically or chemically active and are labeled inert only because of their function in the formulated product. Most of the tests required to

Caroline Cox; Michael Surgan

2006-01-01

363

Motorcycle Tailpipe Dilution CVS Study.  

National Technical Information Service (NTIS)

A new exhaust dilution system has recently been designed and built for use in motorcycle testing at EPA. Prior to being put into use, it was necessary to determine if the new system was capable of meeting the requirements as described in section 86.509(b)...

1976-01-01

364

Heavy-Duty Waste Hauler with Chemically Correct Natural Gas Engine Diluted with EGR and Using a Three-Way Catalyst: Final Report, 24 February 2004 -- 23 February 2006  

SciTech Connect

This report discusses the development of a E7G 12-liter, lean-burn natural gas engine--using stoichiometric combustion, cooled exhaust gas recirculation, and three-way catalyst technologies--for refuse haulers.

Reppert, T.; Chiu, J.

2005-09-01

365

Quantitative Analysis by Isotopic Dilution Using Mass Spectroscopy: The Determination of Caffeine by GC-MS.  

ERIC Educational Resources Information Center

Describes a laboratory technique for quantitative analysis of caffeine by an isotopic dilution method for coupled gas chromatography-mass spectroscopy. Discusses caffeine analysis and experimental methodology. Lists sample caffeine concentrations found in common products. (MVL)

Hill, Devon W.; And Others

1988-01-01

366

DEVELOPMENT OF SAMPLING METHODOLOGY FOR DILUTION AIR SAMPLING OF CONDENSIBLE EMISSIONS FROM STATIONARY SOURCES  

EPA Science Inventory

This report describes the initial development of a technique using dilution of stack gas with conditioned ambient air for measurement of the particulate mass of condensible emissions from stationary sources. he methodology developed is designed for widespread application to measu...

367

40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.  

Code of Federal Regulations, 2010 CFR

...that you use a diluted exhaust flow meter that meets the specifications...for measuring diluted exhaust flow must meet the linearity verification...meters: (1) For constant-volume sampling (CVS) of the total flow of diluted exhaust, you...

2010-07-01

368

Immobilization of inert TRISO-coated fuel in glass for geological disposal  

NASA Astrophysics Data System (ADS)

Vitrification of TRISO-coated gas reactor fuel particles was achieved via two methods: glass melting and sintering. Inert TRISO-coated fuel particles and a borosilicate glass were used. With glass melting at 1200-1300 °C floatation and decomposition of carbon and silicon carbide occurred. Thermal pre-treatment of the particles for oxidation of pyrocarbon did not improve the coating properties of the glass. During cooling most of the particles floated and sorbed on the crucible or mold walls. The sintered glass at 700 °C showed better coating properties of the TRISO-coated fuel particles despite higher porosity compared to glass made by melting. Aqueous leaching properties of glass with particles are similar regardless the mode of fabrication, indicating the good chemical durability of the sintered glass. Sintered glasses may constitute a good technique for TRISO-coated fuel particles immobilization for an eventual deep geological disposal.

Abdelouas, Abdesselam; Noirault, Samuel; Grambow, Bernd

2006-11-01

369

Effects of dilution on fine particle mass and partitioning of semivolatile organics in diesel exhaust and wood smoke.  

PubMed

Experiments were conducted to examine the effects of dilution on fine particle mass emissions from a diesel engine and wood stove. Filter measurements were made simultaneously using three dilution sampling systems operating at dilution ratios ranging from 20:1 to 510:1. Denuders and backup filters were used to quantify organic sampling artifacts. For the diesel engine operating at low load and wood combustion, large decreases in fine particle mass emissions were observed with increases in dilution. For example, the PM2.5 mass emission rate from a diesel engine operating at low load decreased by 50% when the dilution ratio was increased from 20:1 to 350:1. Measurements of organic and elemental carbon indicate that the changes in fine particle mass with dilution are caused by changes in partitioning of semivolatile organic compounds. At low levels of dilution semivolatile species largely occur in the particle phase, but increasing dilution reduces the concentration of semivolatile species, shifting this material to the gas phase in order to maintain phase equilibrium. Emissions of elemental carbon do not vary with dilution. Organic sampling artifacts are shown to vary with dilution because of the combination of changes in partitioning coupled with adsorption of gas-phase organics by quartz filters. The fine particle mass emissions from the diesel engine operating at medium load did not vary with dilution because of the lower emissions of semivolatile material and higher emissions of elemental carbon. To measure partitioning of semivolatile materials under atmospheric conditions, partitioning theory indicates that dilution samplers need to be operated such that the diluted exhaust achieves atmospheric levels of dilution. Too little dilution can potentially overestimate the fine particle mass emissions, and too much dilution (with clean air) can underestimate them. PMID:16433346

Lipsky, Eric M; Robinson, Allen L

2006-01-01

370

Detailed Studies on Flame Extinction by Inert Particles in Normal- and Micro-gravity  

NASA Technical Reports Server (NTRS)

The combustion of dusty flows has been studied to lesser extent than pure gas phase flows and sprays. Particles can have a strong effect by modifying the dynamic response and detailed structure of flames through the dynamic, thermal, and chemical couplings between the two phases. A rigorous understanding of the dynamics and structure of two-phase flows can be attained in stagnation flow configurations, which have been used by others to study spray combustion as well as reacting dusty flows. In earlier studies on reacting dusty flows, the thermal coupling between the two phases as well as the effect of gravity on the flame response were not considered. However, in Ref. 6, the thermal coupling between chemically inert particles and the gas was addressed in premixed flames. The effects of gravity was also studied showing that it can substantially affect the profiles of the particle velocity, number density, mass flux, and temperature. The results showed a strong dynamic and thermal dependence of reacting dusty flows to particle number density. However, the work was only numerical and limited to twin-flames, stagnation, premixed flames. In Ref. 7 the effects of chemically inert particle clouds on the extinction of strained premixed and non-premixed flames were studied both experimentally and numerically at 1-g. It was shown and explained that large particles can cause more effective flame cooling compared to smaller particles. The effects of flame configuration and particle injection orientation were also addressed. The complexity of the coupling between the various parameters in such flows was demonstrated and it was shown that it was impossible to obtain a simple and still meaningful scaling that captured all the pertinent physics.

Andac, M. G.; Egolfopoulos, F. N.; Campbell, C. S.

2001-01-01

371

Vapor-liquid equilibrium constants at infinite dilution determined by a gas stripping method: ethane, propane, n-butane, n-pentane in the methane-n-decane system  

SciTech Connect

A new apparatus to measure partition coefficients Kinfinity /SUB s/ at infinite dilution up to 200 10/sup 5/ Pa and 423 K is described. Measurements of the systems: (1) methane-ethane-n-decane and methane-propane-n-decane at 294.25 K; and (2) methane-n-butane-n-decane at 344.25 K illustrate the reproducibility and good agreement with literature data. In addition, new data were obtained for the system methane-npentane-n-decane at 344.25 K up to 101 10/sup 5/ Pa.

Legret, D.; Desteve, J.; Renon, H.; Richon, D.

1983-01-01

372

Angiographic results in intracranial aneurysms treated with inert platinum coils.  

PubMed

This study was designed in an attempt to identify the risk factors that could be significantly associated with angiographic recurrences after selective endovascular treatment of aneurysms with inert platinum coils. A retrospective analysis of all patients with selective endovascular coil occlusion of intracranial aneurysms was prospectively collected from 1999 to 2003. There were 455 aneurysms treated with inert platinum coils and followed by digital subtraction angiography. Angiographic results were classified according Roy and Raymond's classification. Recurrences were subjectively divided into minor and major. The most significant predictors for angiographic recurrences were determined by ANOVAs logistic regression, Cochran-Mantel-Haenszel test, Fisher exact probability. Short-term (4.3 ± 1.4 months) follow-up angiograms were available in 377 aneurysms, middle-term (14.1 ± 4.0 months) in 327 and long-term (37.4 ± 11.5 months) in 180. Recurrences were found in 26.8% of treated aneurysms with a mean of 21 ± 15.7 months of follow-up. Major recurrences needing retreatment were present in 8.8% during a mean period follow-up of 17.9 ± 12.29 months after the initial endovascular treatment. One patient (0.2%) experienced a bleed during the follow-up period. Recurrences after endovascular treatment of aneurysms with inert platinum coils are frequent, but hemorrhages are unusual. Single aneurysm, ruptured aneurysm, neck greater than 4 mm and time of follow-up were risk factors for recurrence after endovascular treatment. The retreatment of recurrent aneurysm decreases the risk of major recurrences 9.8 times. Long-term angiogram monitoring is necessary for the population with significant recurrence predictors. PMID:23217634

Vanzin, J R; Mounayer, C; Abud, D G; D'agostini Annes, R; Moret, J

2012-12-01

373

Inert Electrodes Program: Fiscal year 1990 annual report  

SciTech Connect

The Inert Electrodes Program, conducted by Pacific Northwest Laboratory (PNL), involves improving the Hall-Heroult Cells used by the aluminum industry for the electrochemical production of aluminum. The PNL research centers on developing more energy-efficient, longer-lasting anodes, cathodes, and ancillary equipment. During the FY 1989 and FY 1990, preparations for the pilot cell test continued. Numerous unanticipated problems were encountered that delayed the test schedule. The delays resulted primarily from three factors: (1) modifications for anode design based on the results obtained from the prototype test (documented here); (2) difficulties in procuring a manufacturer for the cermet inert anodes to be used in the pilot cell; and (3) problems in the actual scale-up activities, both in the production of the ferrite powder and in the fabrication of the anodes themselves. Issues related to scaling up the fabrication of the anodes are still being addressed in FY 1991. Important accomplishments in FY 1989 and FY 1990 include the completion of laboratory cell tests in which the effects of current density, pre-corrosion, and silica content on anode performance were confirmed; the performance of tests that resulted in the identification of the reaction layer on cermet anodes; the initiation of electrochemical tests to determine the source of the anode impedance; the completion of studies to identify and summarize optimal fabrication conditions for the cermet inert anodes, including advanced compositions; the testing of anodes with advanced composition; the refinement of the electrical connection for the anode; and modeling the dynamics of the anode array to be used in the pilot cell. 15 refs., 23 figs.

Windisch, C.F. Jr; Strachan, D.M.

1991-08-01

374

Angiographic Results in Intracranial Aneurysms Treated with Inert Platinum Coils  

PubMed Central

Summary This study was designed in an attempt to identify the risk factors that could be significantly associated with angiographic recurrences after selective endovascular treatment of aneurysms with inert platinum coils. A retrospective analysis of all patients with selective endovascular coil occlusion of intracranial aneurysms was prospectively collected from 1999 to 2003. There were 455 aneurysms treated with inert platinum coils and followed by digital subtraction angiography. Angiographic results were classified according Roy and Raymond's classification. Recurrences were subjectively divided into minor and major. The most significant predictors for angiographic recurrences were determined by ANOVAs logistic regression, Cochran-Mantel-Haenszel test, Fisher exact probability. Short-term (4.3±1.4 months) follow-up angiograms were available in 377 aneurysms, middle-term (14.1±4.0 months) in 327 and long-term (37.4±11.5 months) in 180. Recurrences were found in 26.8% of treated aneurysms with a mean of 21±15.7 months of follow-up. Major recurrences needing retreatment were present in 8.8% during a mean period follow-up of 17.9±12.29 months after the initial endovascular treatment. One patient (0.2%) experienced a bleed during the follow-up period. Recurrences after endovascular treatment of aneurysms with inert platinum coils are frequent, but hemorrhages are unusual. Single aneurysm, ruptured aneurysm, neck greater than 4 mm and time of follow-up were risk factors for recurrence after endovascular treatment. The retreatment of recurrent aneurysm decreases the risk of major recurrences 9.8 times. Long-term angiogram monitoring is necessary for the population with significant recurrence predictors.

Vanzin, J.R.; Mounayer, C.; Abud, D.G.; D'agostini Annes, R.; Moret, J.

2012-01-01

375

Method to make accurate concentration and isotopic measurements for small gas samples  

NASA Astrophysics Data System (ADS)

Carbon isotopic ratio measurements of CO2 and CH4 provide valuable insight into carbon cycle processes. However, many of these studies, like soil gas, soil flux, and water head space experiments, provide very small gas sample volumes, too small for direct measurement by current constant-flow Cavity Ring-Down (CRDS) isotopic analyzers. Previously, we addressed this issue by developing a sample introduction module which enabled the isotopic ratio measurement of 40ml samples or smaller. However, the system, called the Small Sample Isotope Module (SSIM), does dilute the sample during the delivery with inert carrier gas which causes a ~5% reduction in concentration. The isotopic ratio measurements are not affected by this small dilution, but researchers are naturally interested accurate concentration measurements. We present the accuracy and precision of a new method of using this delivery module which we call 'double injection.' Two portions of the 40ml of the sample (20ml each) are introduced to the analyzer, the first injection of which flushes out the diluting gas and the second injection is measured. The accuracy of this new method is demonstrated by comparing the concentration and isotopic ratio measurements for a gas sampled directly and that same gas measured through the SSIM. The data show that the CO2 concentration measurements were the same within instrument precision. The isotopic ratio precision (1?) of repeated measurements was 0.16 permil for CO2 and 1.15 permil for CH4 at ambient concentrations. This new method provides a significant enhancement in the information provided by small samples.

Palmer, M. R.; Wahl, E.; Cunningham, K. L.

2013-12-01

376

Testing New Inert Matrix and Thoria Fuels for Plutonium Incineration  

SciTech Connect

One major issue for nuclear power continues to be the public concern about rad-waste and proliferation risk induced by large plutonium stockpiles accumulated worldwide. In this context, nuclear fuels which exhibit no-plutonium production, and possibly allow for an efficient utilization of the plutonium to get rid of, are of great interest. This is the basic reason for the efforts that many international institutions are devoting to R and D on such new U-free fuel concepts as Inert Matrix (IMF) and Thorium fuels. At the moment the major merit of such innovative fuels is primarily related to the safe closure of the nuclear fuel cycle as especially expected from those new concepts like ADS (Accelerated Driven System) for the transmutation of plutonium, minor actinides and LLFP. Both ceramic inert matrix (IM) and thoria (T) fuels have been identified as suitable to the scope of burning weapon and civilian plutonium and to act also as possible carrier for transmutation of minor actinides. For testing the irradiation behaviour of these new materials, three kinds of fuels have been selected: inert matrix (IM) fuel, inert matrix thoria-doped (IMT) fuel, and thoria (T) fuel. A first experiment, IFA-652, 40 MWD/kg burnup target, including high enriched uranium (HEU) as fissile phase, instead of plutonium, is currently underway in the Halden HWBR. The reason for this choice was that manufacturing of Pu containing fuels is more complex and there was no fabrication facility available at the needed time for the Pu fuel. It is expected, however, that the relative behaviour of the different kind of matrices would be only slightly dependent on the adopted fissile material. So, the comparison of the in-pile performance of the three fuels will constitute a significant common database also for plutonium bearing fuels. The primary aim for the IFA-652 experiment is the measurement of basic characteristics under LWR irradiation conditions over a period of 4-5 years. The design of a second experiment, truly based on plutonium bearing fuel with 80 MWd/kg target burnup, is under preparation. Beyond exploitation in the future transmuters (ADS), the selected fuels are also considered promising candidates for a more effective burning of all kind of plutonium in the present commercial LWRs, what may represent their near term application especially for the weapon Pu stockpile reduction. Most likely this latter aspect is of interest for a wider number of countries which do exploit the benefits of nuclear energy. (authors)

Vettraino, F. [ENEA, Via Martiri di Monte Sole, 4, Bologna 40129 (Italy); Padovan, E. [Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milano (Italy); Tverberg, T. [OECD Halden Reactor Project, Institut for Energiteknikk, 1751 Halden (Norway)

2002-07-01

377

Coating crystalline nuclear waste forms to improve inertness  

SciTech Connect

Crystalline waste forms of high simulated waste loading were successfully coated with layers of pyrolytic carbon and silicon carbide. Sol-gel technology was used to produce microspheres that contained simulated waste. A separate process for cesium immobilization was developed, which loads 5 wt % Cs onto zeolite particles for subsequent coating. The chemical vapor deposition process was developed for depositing thin layers of carbon and silicon carbide onto particles in a fluidized-bed coater. Pyrolytic carbon-coated particles were extremely inert in numerous leach tests. Aqueous leach test results of coated waste forms were below detection limits of such sensitive analytical techniques as atomic absorption and inductively coupled plasma atomic emission.

Stinton, D.P.; Angelini, P.; Caputo, A.J.; Lackey, W.J.

1981-01-01

378

Numerical modeling for dilute and dense sprays  

NASA Technical Reports Server (NTRS)

We have successfully implemented a numerical model for spray-combustion calculations. In this model, the governing gas-phase equations in Eulerian coordinate are solved by a time-marching multiple pressure correction procedure based on the operator-splitting technique. The droplet-phase equations in Lagrangian coordinate are solved by a stochastic discrete particle technique. In order to simplify the calculation procedure for the circulating droplets, the effective conductivity model is utilized. The k-epsilon models are utilized to characterize the time and length scales of the gas phase in conjunction with turbulent modulation by droplets and droplet dispersion by turbulence. This method entails random sampling of instantaneous gas flow properties and the stochastic process requires a large number of computational parcels to produce the satisfactory dispersion distributions even for rather dilute sprays. Two major improvements in spray combustion modelings were made. Firstly, we have developed a probability density function approach in multidimensional space to represent a specific computational particle. Secondly, we incorporate the Taylor Analogy Breakup (TAB) model for handling the dense spray effects. This breakup model is based on the reasonable assumption that atomization and drop breakup are indistinguishable processes within a dense spray near the nozzle exit. Accordingly, atomization is prescribed by injecting drops which have a characteristic size equal to the nozzle exit diameter. Example problems include the nearly homogeneous and inhomogeneous turbulent particle dispersion, and the non-evaporating, evaporating, and burning dense sprays. Comparison with experimental data will be discussed in detail.

Chen, C. P.; Kim, Y. M.; Shang, H. M.; Ziebarth, J. P.; Wang, T. S.

1992-01-01

379

RF stacking without emittance dilution  

SciTech Connect

A long-established technique for accumulating high current in a storage ring is to inject additional beam off-momentum and move it into the main beam stack by rf acceleration. This procedure necessarily dilutes the longitudinal phase space density, because the rf perturbs the stack as the new beam approaches closely in momentum. For accumulators that use beam cooling to obtain a high phase space density, this perturbation may result in an unacceptable performance limitation. Using broadband rf to establish and manipulate azimuthal barriers to the motion of the stack and injected beam permits practically dilution-free longitudinal phase space stacking. The concept is described and illustrated with a detailed example which pertains to the Fermilab Recycler ring.

J. A. MacLachlan

2000-06-23

380

Sea Urchin Embryology: Simple Dilutions 2  

NSDL National Science Digital Library

SUMMARY: Building on what was learned in SIMPLE DILUTION, students will determine the best dilution strategy to solve a dilution problem. 1. Students are given an unknown dye solution and asked to determine its concentration by comparing it with standards they create. 2. Repeated "serial" dilutions will be necessary to determine accurate concentration readings. 3. Varying the color of the filters and the path length will aid in seeing lower concentrations.

PhD David Epel (Stanford U. Hopkins Marine Station)

2006-12-20

381

Dynamics and Structure of Dusty Reacting Flows: Inert Particles in Strained, Laminar, Premixed Flames  

NASA Technical Reports Server (NTRS)

A detailed numerical study was conducted on the dynamics and thermal response of inert, spherical particles in strained, laminar, premixed hydrogen/air flames. The modeling included the solution of the steady conservation equations for both the gas and particle phases along and around the stagnation streamline of an opposed-jet configuration, and the use of detailed descriptions of chemical kinetics and molecular transport, For the gas phase, the equations of mass, momentum, energy, and species are considered, while for the particle phase, the model is based on conservation equations of the particle momentum balance in the axial and radial direction, the particle number density, and the particle thermal energy equation. The particle momentum equation includes the forces as induced by drag, thermophoresis, and gravity. The particle thermal energy equation includes the convective/conductive heat exchange between the two phases, as well as radiation emission and absorption by the particle. A one-point continuation method is also included in the code that allows for the description of turning points, typical of ignition and extinction behavior. As expected, results showed that the particle velocity can be substantially different than the gas phase velocity, especially in the presence of large temperature gradients and large strain rates. Large particles were also found to cross the gas stagnation plane, stagnate, and eventually reverse as a result of the opposing gas phase velocity. It was also shown that the particle number density varies substantially throughout the flowfield, as a result of the straining of the flow and the thermal expansion. Finally, for increased values of the particle number density, substantial flame cooling to extinction states and modification of the gas phase fluid mechanics were observed. As also expected, the effect of gravity was shown to be important for low convective velocities and heavy particles. Under such conditions, simulations indicate that the magnitude and direction of the gravitational force can substantially affect the profiles of the particle velocity, number density, mass flux, and temperature.

Egolfopoulos, Fokion N.; Campbell, Charles S.

1999-01-01

382

Dynamics and Structure of Dusty Reacting Flows: Inert Particles in Strained, Laminar, Premixed Flames  

NASA Technical Reports Server (NTRS)

A detailed numerical study was conducted on the dynamics and thermal response of inert spherical particles in strained, laminar, premixed hydrogen/air flames. The modeling included the solution of the steady conservation equations for both the gas and particle phases along and around the stagnation streamline of an opposed-jet configuration, and the use of detailed descriptions of chemical kinetics and molecular transport. For the gas phase, the equations of mass, momentum, energy, and species are considered, while for the particle phase, the model is based on conservation equations of the particle momentum balance in the axial and radial direction, the particle number density, and the particle thermal energy equation. The particle momentum equation includes the forces as induced by drag, thermophoresis, and gravity. The particle thermal energy equation includes the convective/conductive heat exchange between the two phases, as well as radiation emission and absorption by the particle. A one-point continuation method is also included in the code that allows for the description of turning points, typical of ignition and extinction behavior. As expected, results showed that the particle velocity can be substantially different than the gas phase velocity, especially in the presence of large temperature gradients and large strain rates. Large particles were also found to cross the gas stagnation plane, stagnate, and eventually reverse as a result of the opposing gas phase velocity. It was also shown that the particle number density varies substantially throughout the flowfield, as a result of the straining of the flow and the thermal expansion. Finally, for increased values of the particle number density, substantial flame cooling to extinction states and modification of the gas phase fluid mechanics were observed. As also expected, the effect of gravity was shown to be important for low convective velocities and heavy particles. Under such conditions, simulations indicate that the magnitude and direction of the gravitational force can substantially affect the profiles of the particle velocity, number density, mass flux, and temperature.

Egolfopoulos, Fokion N.; Campbell, Charles S.; Wu, Ming-Shin (Technical Monitor)

1999-01-01

383

The gaseous explosive reaction : the effect of inert gases  

NASA Technical Reports Server (NTRS)

Attention is called in this report to previous investigations of gaseous explosive reactions carried out under constant volume conditions, where the effect of inert gases on the thermodynamic equilibrium was determined. The advantage of constant pressure methods over those of constant volume as applied to studies of the gaseous explosive reaction is pointed out and the possibility of realizing for this purpose a constant pressure bomb mentioned. The application of constant pressure methods to the study of gaseous explosive reactions, made possible by the use of a constant pressure bomb, led to the discovery of an important kinetic relation connecting the rate of propagation of the zone of explosive reaction within the active gases, with the initial concentrations of those gases: s = K(sub 1)(A)(sup n1)(B)(sup n2)(C)(sup n3)------. By a method analogous to that followed in determining the effect of inert gases on the equilibrium constant K, the present paper records an attempt to determine their kinetic effect upon the expression given above.

Stevens, F W

1928-01-01

384

Teflon films for chemically-inert microfluidic valves and pumps  

PubMed Central

We present a simple method for fabricating chemically-inert Teflon microfluidic valves and pumps in glass microfluidic devices. These structures are modeled after monolithic membrane valves and pumps that utilize a featureless polydimethylsiloxane (PDMS) membrane sandwiched between two etched glass wafers. The limited chemical compatibility of PDMS has necessitated research into alternative materials for microfluidic devices. Previous work has shown that spin-coated amorphous fluoropolymers and Teflon-fluoropolymer laminates can be fabricated and substituted for PDMS in monolithic membrane valves and pumps for space flight applications. However, the complex process for fabricating these spin-coated Teflon films and laminates may preclude their use in many research and manufacturing contexts. As an alternative, we show that commercially-available fluorinated ethylene-propylene (FEP) Teflon films can be used to fabricate chemically-inert monolithic membrane valves and pumps in glass microfluidic devices. The FEP Teflon valves and pumps presented here are simple to fabricate, function similarly to their PDMS counterparts, maintain their performance over extended use, and are resistant to virtually all chemicals. These structures should facilitate lab-on-a-chip research involving a vast array of chemistries that are incompatible with native PDMS microfluidic devices.

Grover, William H.; von Muhlen, Marcio G.; Manalis, Scott R.

2014-01-01

385

Asymptotic analysis of stationary adiabatic premixed flames in porous inert media  

SciTech Connect

The structure of adiabatic premixed flames within porous inert media is investigated using the asymptotic expansion method. For this, the flame structure is divided into three characteristic length scales. The two innermost length scales, the gas-phase diffusion length scale and the reaction length scale, are the same scales defined in the classical premixed flame structure analysis. The outermost length scale, the solid-phase diffusion length scale, is related to the heat conduction in the porous matrix. The differences among these three characteristic length-scales result in large temperature differences between the phases and justify the application of asymptotic expansions to determine an approximate (analytical) solution. Since the main focus of this work is the examination of the processes in the outer and the first inner regions, the simplest kinetic mechanism of one global step is adopted to represent the fuel and oxygen consumption. Then, the description of the reaction zone is obtained using the large activation energy asymptotic method. The description of the problem of the order of the gas-phase length scale is obtained using the boundary layer expansion. This work evaluates the influence of the equivalence ratio, the ratio of the solid to the gas thermal conductivities, the porosity of the medium and the fuel Lewis number on such flames. A parameter that universalizes the flame properties is then identified and discussed. (author)

Pereira, Fernando M.; Oliveira, Amir A.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Fachini, Fernando F. [Instituto Nacional de Pesquisas Espaciais, 12630-000 Cachoeira Paulista, SP (Brazil)

2008-11-15

386

Asymptotic analysis of stationary adiabatic premixed flames in porous inert media  

SciTech Connect

The structure of adiabatic premixed flames within porous inert media is investigated using the asymptotic expansion method. For this, the flame structure is divided into three characteristic length scales. The two innermost length scales, the gas-phase diffusion length scale and the reaction length scale, are the same scales defined in the classical premixed flame structure analysis. The outermost length scale, the solid-phase diffusion length scale, is related to the heat conduction in the porous matrix. The differences among these three characteristic length-scales result in large temperature differences between the phases and justify the application of asymptotic expansions to determine an approximate (analytical) solution. Since the main focus of this work is the examination of the processes in the outer and the first inner regions, the simplest kinetic mechanism of one global step is adopted to represent the fuel and oxygen consumption. Then, the description of the reaction zone is obtained using the large activation energy asymptotic method. The description of the problem of the order of the gas-phase length scale is obtained using the boundary layer expansion. This work evaluates the influence of the equivalence ratio, the ratio of the solid to the gas thermal conductivities, the porosity of the medium and the fuel Lewis number on such flames. A parameter that universalizes the flame properties is then identified and discussed. (author)

Pereira, Fernando M.; Oliveira, Amir A.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Fachini, Fernando F. [Instituto Nacional de Pesquisas Espaciais, 12630-000 Cachoeira Paulista, SP (Brazil)

2009-01-15

387

BASIC RESEARCH ON HIGH DILUTION EFFECTS  

Microsoft Academic Search

Basic research on high dilution effects started with homeopathic therapy. So many models have been tested that we have tried to classify them according to the general concept of regulation. Firstly, succussed dilutions must be separated from unsuccussed very low doses from a physical point of view. This leads us to discuss the validity of the controls in high dilution

MADELEINE BASTIDE

388

46 CFR 153.964 - Discharge by gas pressurization.  

Code of Federal Regulations, 2010 CFR

...transfer may not authorize cargo discharge by gas pressurization unless: (a) The tank to be offloaded has an SR or PV venting system; (b) The pressurization medium is either the cargo vapor or a nonflammable, nontoxic gas inert to the...

2009-10-01

389

46 CFR 153.964 - Discharge by gas pressurization.  

Code of Federal Regulations, 2010 CFR

...transfer may not authorize cargo discharge by gas pressurization unless: (a) The tank to be offloaded has an SR or PV venting system; (b) The pressurization medium is either the cargo vapor or a nonflammable, nontoxic gas inert to the...

2010-10-01

390

Numerical Investigation of Fuel Dilution Effects on the Performance of the Conventional and the Highly Preheated and Diluted Air Combustion Furnaces  

Microsoft Academic Search

This numerical study investigates the effects of using a diluted fuel (50% natural gas and 50% N2) in an industrial furnace under several cases of conventional combustion (air with 21% O2 at 300 and 1273 K) and the highly preheated and diluted air (1273 K with 10% O2 and 90% N2) combustion (HPDAC) conditions using an in-house computer program. It

Kiomars Abbasi Khazaei; Ali Asghar Hamidi; Masoud Rahimi

2009-01-01

391

ULTRA-DILUTE COMBUSTION OF PRIMARY REFERENCE FUELS  

Microsoft Academic Search

Using n-heptane and iso-octane as gasoline surrogate fuels, the laminar flame speeds, flame thicknesses, reaction zone thicknesses, and flammability limits of fuel\\/air\\/residual gas mixtures are computationally studied over ranges of pressures, temperatures, and dilution levels representative of unthrottled HCCI operation. These calculations are further used to characterize the combustion regime for spark-initiated HCCI combustion. In a turbulent premixed combustion regime

YIMIN HUANG; CHIH-JEN SUNG; KAMAL KUMAR

2007-01-01

392

Structure of the self-gravitating dilute-boson sphere  

NASA Astrophysics Data System (ADS)

The sensitivity of the Newtonian self-gravitating dilute-boson-gas solution obtained by Membrado et al. (1989) and Abad et al. (1989) is investigated analytically. Particular attention is given to the effects of (1) including the second leading term in the equation of state and (2) introducing a repulsive cosmological constant. The derivation is outlined; the general trends are shown in graphs; and the case of the axion is treated as an example.

Membrado, M.; Pacheco, A. F.; Sanudo, J.

1991-01-01

393

Development of a compact dilution refrigerator for zero gravity operation  

NASA Technical Reports Server (NTRS)

A compact dilution refrigerator design based on internal charcoal adsorption is being tested for operation in zero gravity. This refrigerator is self-contained with no external pumps or gas handling system and provides reliable operation since it has no moving parts. All operations are performed with heaters and are completely computer controlled. The refrigerator is capable of providing many hours of operation at very low temperature before the charcoal pumps must be recycled.

Roach, Pat R.; Helvensteijn, Ben

1990-01-01

394

Sonic black holes in dilute Bose-Einstein condensates  

Microsoft Academic Search

The sonic analog of a gravitational black hole in dilute-gas Bose-Einstein\\u000acondensates is investigated. It is shown that there exist both dynamically\\u000astable and unstable configurations which, in the hydrodynamic limit, exhibit a\\u000abehavior completely analogous to that of gravitational black holes. The\\u000adynamical instabilities involve creation of quasiparticle pairs in positive and\\u000anegative energy states. We illustrate these features

L. J. Garay; J. R. Anglin; J. I. Cirac; P. Zoller

2001-01-01

395

Gas stream purifier  

NASA Technical Reports Server (NTRS)

A gas stream purifier has been developed that is capable of removing corrosive acid, base, solvent, organic, inorganic, and water vapors as well as particulates from an inert mixed gas stream using only solid scrubbing agents. This small, lightweight purifier has demonstrated the ability to remove contaminants from an inert gas stream with a greater than 99 percent removal efficiency. The Gas Stream Purifier has outstanding market and sales potential in manufacturing, laboratory and science industries, medical, automotive, or any commercial industry where pollution, contamination, or gas stream purification is a concern. The purifier was developed under NASA contract NAS9-18200 Schedule A for use in the international Space Station. A patent application for the Gas Stream Purifier is currently on file with the United States Patent and Trademark Office.

Adam, Steven J.

1994-01-01

396

Gas mixtures for spark gap closing switches  

DOEpatents

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

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

1988-01-01

397

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

398

Drill Pipe Corrosion Control Using an Inert Drilling Fluid  

SciTech Connect

The results of a geothermal drill pipe corrosion field test are presented. When a low-density drilling fluid was required for drilling a geothermal well because of an underpressured, fractured formation, two drilling fluids were alternately used to compare drill pipe corrosion rates. The first fluid was an air-water mist with corrosion control chemicals. The other fluid was a nitrogen-water mist without added chemicals. The test was conducted during November 1980 at the Baca location in northern New Mexico. Data from corrosion rings, corrosion probes, fluid samples and flow line instrumentation are plotted for the ten day test period. it is shown that the inert drilling fluid, nitrogen, reduced corrosion rates by more than an order of magnitude. Test setup and procedures are also discussed.

Caskey, B. C.; Copass, K. S.

1981-01-01

399

Unidentified Inert Ingredients in Pesticides: Implications for Human and Environmental Health  

PubMed Central

Background By statute or regulation in the United States and elsewhere, pesticide ingredients are divided into two categories: active and inert (sometimes referred to as other ingredients, adjuvants, or coformulants). Despite their name, inert ingredients may be biologically or chemically active and are labeled inert only because of their function in the formulated product. Most of the tests required to register a pesticide are performed with the active ingredient alone, not the full pesticide formulation. Inert ingredients are generally not identified on product labels and are often claimed to be confidential business information. Objectives In this commentary, we describe the shortcomings of the current procedures for assessing the hazards of pesticide formulations and demonstrate that inert ingredients can increase the toxicity of and potential exposure to pesticide formulations. Discussion Inert ingredients can increase the ability of pesticide formulations to affect significant toxicologic end points, including developmental neurotoxicity, genotoxicity, and disruption of hormone function. They can also increase exposure by increasing dermal absorption, decreasing the efficacy of protective clothing, and increasing environmental mobility and persistence. Inert ingredients can increase the phytotoxicity of pesticide formulations as well as the toxicity to fish, amphibians, and microorganisms. Conclusions Pesticide registration should require full assessment of formulations. Evaluations of pesticides under the National Environmental Policy Act, the Endangered Species Act, and similar statutes should include impact assessment of formulations. Environmental monitoring for pesticides should include inert ingredients. To enable independent research and risk assessment, inert ingredients should be identified on product labels.

Cox, Caroline; Surgan, Michael

2006-01-01

400

Dilute Oxygen Combustion Phase 2 Final Report  

SciTech Connect

A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NOx through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NOx production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature (~1366 K) oxidant (7-27% O2 vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d+ scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d+ scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW (~0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric arrangement, firing rate, and fuel injection velocity. NOx emissions increased with increasing furnace nitrogen content and furnace temperature, but remained relatively insensitive to variations in fuel injection velocity and firing rate. NOx emissions below 5-10-3 g/MJ (10 ppm-air equivalent at 3% O2 dry) were obtained for furnace temperatures below 1533 K (2300?F) and furnace nitrogen levels between 1 and 40%. CO emissions were typically low (<35 ppm). Detailed in-furnace species measurements revealed the importance of the interior furnace circulation patterns, as influenced by fuel and oxidant injection schemes, on pollutant emissions. The combustion stability traits of several DOC burner arrangements were ascertained through furnace pressure measurements, wit6h increased stability occurring as furnace temperature increased and as the separation distance between fuel and oxidant inputs decreased. Based on current market conditions, oxy-fuel conversion of batch steel reheat furnaces with a DOC burner is justified on the basis of lower utility costs alone. However, conversion of continuous steel reheat furnaces, which are responsible for most steel production, required additional economic incentives, such as further fuel savings, increased furnace productivity, or emission credits.

Ryan, H.M.; Riley, M.F.; Kobayashi, H.

2005-09-30

401

Dilute oxygen combustion. Phase I report  

SciTech Connect

A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NO{sub x}) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NO{sub x} through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NO{sub x} production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature ({approximately}1366 K) oxidant (7-27% O{sub 2} vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d{sup +} scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d{sup +} scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW ({approximately}0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric arrangement, firing rate, and fuel injection velocity. NO{sub x} emissions increased with increasing furnace nitrogen content and furnace temperature, but remained relatively insensitive to variations in fuel injection velocity and firing rate. NO{sub x} emissions below 5{times}10{sup -3} g/MJ (10 ppm-air equivalent at 3% O{sub 2} dry) were obtained for furnace temperatures below 1533 K (2300{degree}F) and furnace nitrogen levels between 1 and 40%. CO emissions were typically low (<35 ppm). Detailed in- furnace species measurements revealed the importance of the interior furnace circulation patterns, as influenced by fuel and oxidant injection schemes, on pollutant emissions. The combustion stability traits of several DOC burner arrangements were ascertained through furnace pressure measurements, with increased stability occurring as furnace temperature increased and as the separation distance between fuel and oxidant inputs decreased. Based on current market conditions, oxy-fuel conversion of batch steel reheat furnaces with a DOC burner is justified on the basis of utility costs alone. However, conversion of continuous steel reheat furnaces, which are responsible for most steel production, requires additional economic incentives, such as further fuel savings, increased furnace productivity, or emission credits.

NONE

1997-10-01

402

Dilute Oxygen Combustion Phase I Final Report  

SciTech Connect

A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NOx through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NOx production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature (~1366 K) oxidant (7-27% O2 vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d+ scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d+ scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW (~0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric arrangement, firing rate, and fuel injection velocity. NOx emissions increased with increasing furnace nitrogen content and furnace temperature, but remained relatively insensitive to variations in fuel injection velocity and firing rate. NOx emissions below 5-10-3 g/MJ (10 ppm-air equivalent at 3% O2 dry) were obtained for furnace temperatures below 1533 K (2300°F) and furnace nitrogen levels between 1 and 40%. CO emissions were typically low (<35 ppm). Detailed in-furnace species measurements revealed the importance of the interior furnace circulation patterns, as influenced by fuel and oxidant injection schemes, on pollutant emissions. The combustion stability traits of several DOC burner arrangements were ascertained through furnace pressure measurements, wit6h increased stability occurring as furnace temperature increased and as the separation distance between fuel and oxidant inputs decreased. Based on current market conditions, oxy-fuel conversion of batch steel reheat furnaces with a DOC burner is justified on the basis of lower utility costs alone. However, conversion of continuous steel reheat furnaces, which are responsible for most steel production, required additional economic incentives, such as further fuel savings, increased furnace productivity, or emission credits.

Ryan, H.M.; Riley, M.F.; Kobayashi, H.

1997-10-31

403

Absorbing phase transitions in diluted conserved threshold transfer process  

NASA Astrophysics Data System (ADS)

Absorbing phase transitions in the conserved threshold transfer process (CTTP) on diluted lattices, i.e., on infinite percolation networks, were studied in two dimensions by Monte Carlo simulations. Lattice dilution was found to be irrelevant to the critical behavior for the concentration of diluted sites x far less than the critical concentration xc (=1-pc, with pc being the percolation threshold), whereas for x close to xc the critical exponents slightly deviated from those of the pure CTTP and new critical exponents were established at xc. The results for xgas (CLG) model, whereas the results for x=xc were different from those of the CLG model, for which nonuniversal power-law behavior was observed [Lee, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.84.041123 84, 041123 (2011)]. On the other hand, the critical exponents of the CTTP on a percolation backbone were similar to those on an infinite network and similar to those of the CLG model on a backbone network. The diluted CTTP in three and four dimensions was also investigated, and the critical exponents were similar to those in two dimensions; i.e., the critical exponents were independent of or weakly dependent on the dimensionality. A comment on the recent claim of the absence of a Manna class was also presented.

Lee, Sang Bub; Kim, Jong Soo

2013-03-01

404

Propagation of wave-like unstabilized combustion fronts in inert porous media  

NASA Astrophysics Data System (ADS)

This work has demonstrated a new kind of gas filtration combustion process called Wave-Like Unstabilized Gas Filtration Combustion. For the first time, the streamwise-propagation unstabilized homogeneous gas combustion fronts have been experimentally and analytically studied for very lean mixtures, phi?{0.15-0.27}, of methane/air occurring in densely packed beds, varepsilon? 0.4, of inert spherical alumina particles, dsb{p} = {5.56-12.70}mm. These gas combustion fronts are characterized by wave-like temperature profiles that propagate in the same direction as the combustible gas filtrating through the packed bed. Previously, only unstabilized combustion fronts characterized by "fully-developed" S-shaped temperature profiles have been reported in the literature. Those fronts are primarily stationary or propagate upstream, counter to the gas flow. The thermal mechanisms responsible for such unstabilized gas filtration combustion have been identified and quantified. This work shows that interphase heat transfer is the dominant heat transfer mechanism determining the diffusion of heat and the speed of the combustion front. It further establishes that the reflective/scattering properties of the alumina particles with their low emissivity and large back scattering cross sections (i.e. radiation trapping) bring about the front's high peak temperatures and wave-like structure at very low equivalence ratios. In addition, wave-like combustion fronts are characterized by "excess enthalpy burning" resulting in super-adiabatic peak combustion temperatures, increased lean flammability limits and increased "apparent" flame speeds for a given equivalence ratio. Through scaling analysis, this work has unambiguously identified the key non-dimensional parameters governing this process. This analysis has also demonstrated the primary mechanisms determining the speed and direction of gas filtration combustion fronts. A criterion for thermal equilibrium in a two-phase system has been developed. For the first time, analytical closed form solutions of the governing equations of this process have been obtained using two linear analytical models. The models have been developed from first principles to simulate the time dependent spatially varying temperatures of thermal fronts and wave-like combustion fronts. These models are a two-phase model and a pseudohomogeneous, one-temperature model. Comparison of model predictions with experimental results shows excellent qualitative and good quantitative agreement.

Koester, Garold Eugene

405

Flow characterization and dilution effects of N2 and CO2 on premixed CH4/air flames in a swirl-stabilized combustor  

NASA Astrophysics Data System (ADS)

Numerically-aided experimental studies are conducted on a swirl-stabilized combustor to investigate the dilution effects on flame stability, flame structure, and pollutant emissions of premixed CH4/air flames. Our goal is to provide a systematic assessment on combustion characteristics in diluted regimes for its application to environmentally-friendly approaches such as biogas combustion and exhaust-gas recirculation technology. Two main diluting species, N2 and CO2, are tested at various dilution rates. The results obtained by means of optical diagnostics show that five main flame regimes can be observed for N2-diluted flames by changing excess air and dilution rate. CO2-diluted flames follow the same pattern evolution except that all the domains are shifted to lower excess air. Both N2 and CO2 dilution affect the lean blowout (LBO) limits negatively. This behavior can be counter-balanced by reactant preheating which is able to broaden the flammability domain of the diluted flames. Flame reactivity is degraded by increasing dilution rate. Meanwhile, flames are thickened in the presence of both diluting species. NOx emissions are significantly reduced with dilution and proved to be relevant to flame stability diagrams: slight augmentation in NOx emission profiles is related to transitional flame states where instability occurs. Although dilution results in increase in CO emissions at certain levels, optimal dilution rates can still be proposed to achieve an ideal compromise.

Han, Yue; Cai, Guo-Biao; Wang, Hai-Xing; Renou, Bruno; Boukhalfa, Abdelkrim

2014-03-01

406

Band anticrossing in dilute nitrides  

SciTech Connect

Alloying III-V compounds with small amounts of nitrogen leads to dramatic reduction of the fundamental band-gap energy in the resulting dilute nitride alloys. The effect originates from an anti-crossing interaction between the extended conduction-band states and localized N states. The interaction splits the conduction band into two nonparabolic subbands. The downward shift of the lower conduction subband edge is responsible for the N-induced reduction of the fundamental band-gap energy. The changes in the conduction band structure result in significant increase in electron effective mass and decrease in the electron mobility, and lead to a large enhance of the maximum doping level in GaInNAs doped with group VI donors. In addition, a striking asymmetry in the electrical activation of group IV and group VI donors can be attributed to mutual passivation process through formation of the nearest neighbor group-IV donor nitrogen pairs.

Shan, W.; Yu, K.M.; Walukiewicz, W.; Wu, J.; Ager III, J.W.; Haller, E.E.

2003-12-23

407

Residual Resistivity of Dilute Alloys  

NASA Astrophysics Data System (ADS)

The residual resistivity for 156 dilute alloys of 19 hosts of different groups of the periodic table has been studied on the basis of the single parametric model potential formalism. Ashcroft's empty core model (EMC) potential is explored for the first time with five different local field correction functions, viz, Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F), and Sarkar et al. (S) to investigate the effect of the exchange and correlation on the aforesaid properties. The comparison of the presently computed outcomes with the available theoretical and experimental data is highly encouraging. The investigation of residual resistivity is found to be quite sensitive to the selection of local field correction function, showing a significant variation with the change in the function.

Vora, Aditya M.

408

Dilute-Acid Hydrolysis of Lignocellulosic Biomass  

Microsoft Academic Search

In recent years, treatment of lignocellulosic biomass with dilute sulfuric acid has been primarily used as a means of hemicellulose\\u000a hydrolysis and pretreatment for enzymatic hydrolysis of cellulose. A significant advancement has also been made in the area\\u000a of dilute acid hydrolysis of cellulose. An overview of reactor theory as it applies to the dilute acid hydrolysis and recent\\u000a developments

Y. Y. Lee; Prashant Iyer; R. W. Torget

409

Young Infants' Reasoning about Physical Events Involving Inert and Self-Propelled Objects  

ERIC Educational Resources Information Center

The present research examined whether 5- to 6.5-month-old infants would hold different expectations about various physical events involving a box after receiving evidence that it was either inert or self-propelled. Infants were surprised if the inert but not the self-propelled box: reversed direction spontaneously (Experiment 1); remained…

Luo, Yuyan; Kaufman, Lisa; Baillargeon, Renee

2009-01-01

410

SIMULATION OF DRYING SUSPENSIONS IN SPOUT-FLUID BEDS OF INERT PARTICLES  

Microsoft Academic Search

In spouted and spout fluid bed dryers, the suspension is spread into the bed of inert particles, covering these particles with a thin layer. As the inert particles circulate, this suspension layer is dried and must become brittle enough to break off by the particle attrition. The powder produced is then carried out by air. Problems with the spout stability,

E. F. Costa Jr; M. Cardoso; M. L. Passos

2001-01-01

411

Paste Residence Time in a Spouted Bed Dryer. IV: Effect of the Inert Particle Size Distribution  

Microsoft Academic Search

The residence time distribution and mean residence time of a 10% sodium bicarbonate solution that is dried in a conventional spouted bed with inert bodies were measured with the stimulus-response method. Methylene blue was used as a chemical tracer, and the effects of the paste feed mode, size distribution of the inert bodies, and mean particle size on the residence

Luciana A. Tacon; Luis A. P. Freitas

2011-01-01

412

Suppression of hard bubbles in LPE garnet films by inert atmosphere annealing  

Microsoft Academic Search

A new method for the suppression of hard bubbles in single-layer LPE garnet films has been developed. The method involves annealing the films in an inert atmosphere for a few hours at temperatures near 1100 °C. The proposed mechanism involves enhanced diffusion of Ga from the substrate into the film due to oxygen vacancies produced by annealing in the inert

R. C. LeCraw; E. M. Gyorgy; R. Wolfe

1974-01-01

413

Effects of inert additives on the divergence speed of plates driven by mixed explosives  

Microsoft Academic Search

Practical explosive charges frequently contain additives, which can be considered as inert during the conversion to detonation waves. While there is much experimental evidence concerning the effects of such additives on detonation parameters, little is known about their effects on the driving capacity of mixed explosives. Measurements on the effects of inert additives on the collision speeds between plates produced

I. M. Voskoboinikov; A. A. Kotomin; N. F. Voskoboinikova

1983-01-01

414

Fiscal year 1989 annual report for the Sensors Development Program: Inert Electrodes Program  

SciTech Connect

The Sensors Development Program is conducted at the Pacific Northwest Laboratory (PNL) for the US Department of Energy (DOE), Office of Industrial Programs (OIP). The work is being performed in conjunction with the Inert Electrodes Program at PNL. The objectives of the Sensors Development Program are to (1) investigate and develop methods of process monitoring/control for operating electrolytic cells and (2) determine safe operating conditions for the inert anodes. The majority of work in FY 1989 involved (1) evaluating Digital Signal Analysis (DSA) methods to monitor inert anode operation and to determine alumina concentration in both PNL bench-scale laboratory cells and the Prototype Inert Anode Test and (2) developing the reference anode against which inert anode voltage signals could be measured by the DSA-based or other methods. 3 refs., 14 figs., 2 tabs.

Windisch, C.F. Jr.; Koski, O.H.; Stice, N.D.; Morgan, L.G. (Pacific Northwest Lab., Richland, WA (USA)); Nikias, C.L. (Northeastern Univ., Boston, MA (USA))

1990-04-01

415

Pulse Tube Coolers with an Inertance Tube: Theory, Modeling and Practice  

NASA Technical Reports Server (NTRS)

We have studied the advantages to be gained by replacing the conventional orifice of a pulse tube cooler by an inertance tube - a long thin tube that introduces the possibility for additional phase shift between pressure and mass flow in the pulse tube section. The case for the use of an inertance tube is most clearly made with an electrical analogy where the 'inductance' added by the inertance tube allows for optimal power transfer at the cold heat exchanger. Detailed modeling of a pulse tube system with an inertance tube confirms these advantages. Comparison between a laboratory cooler with an orifice and with an inertance tube will be presented and reasons wily it is difficult to realize all the expected gain will be given.

Roach, Pat R.; Kashani, Ali; McCreight, Craig R. (Technical Monitor)

1997-01-01

416

Consequence of diluting modified ?-cyclodextrins in a side-chain crown ether polysiloxane and in a side-chain liquid-crystalline polysiloxane-containing crown ether as stationary phases in capillary gas chromatography  

Microsoft Academic Search

Summary  This paper investigates the possibility of using a sidechain crown ether polysiloxane (PDB-14-C4) and a side-chain liquid-crystalline polysiloxane-containing crown ether (PSC-3) as matrices for peralkylated -CD employed as stationary phases. Three columns, coated with PSC-3 + permethylated -CD, PDB-14-C4 + permethylated -CD and PDB-14-C4 + perethylated -CD were characterized by gas chromatography. The column efficiencies, phase transitions, and selectivities were

P. Jing; R.-N. Fu; R.-J. Dai; J.-L. Ge; J.-L. Gu; Z. Huang; Y. Chen

1996-01-01

417

DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS  

SciTech Connect

There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Laboratory imbibition tests show that imbibition rate is not very sensitive to the surfactant concentration (in the range of 0.05-0.2 wt%) and small amounts of trapped gas saturation. It is however very sensitive to oil permeability and water-oil-ratio. Less than 0.5 M Na2CO3 is needed for in situ soap generation and low adsorption; NaCl can be added to reach the necessary total salinity. The simulation result matches the laboratory imbibition experimental data. Small fracture spacing and high permeability would be needed for high rate of recovery.

Kishore K. Mohanty

2005-07-01

418

Determining inert content in coal dust/rock dust mixture  

DOEpatents

A method and apparatus for determining the inert content of a coal dust and rock dust mixture uses a transparent window pressed against the mixture. An infrared light beam is directed through the window such that a portion of the infrared light beam is reflected from the mixture. The concentration of the reflected light is detected and a signal indicative of the reflected light is generated. A normalized value for the generated signal is determined according to the relationship .phi.=(log i.sub.c `log i.sub.co) / (log i.sub.c100 -log i.sub.co) where i.sub.co =measured signal at 0% rock dust i.sub.c100 =measured signal at 100% rock dust i.sub.c =measured signal of the mixture. This normalized value is then correlated to a predetermined relationship of .phi. to rock dust percentage to determine the rock dust content of the mixture. The rock dust content is displayed where the percentage is between 30 and 100%, and an indication of out-of-range is displayed where the rock dust percent is less than 30%. Preferably, the rock dust percentage (RD%) is calculated from the predetermined relationship RD%=100+30 log .phi.. where the dust mixture initially includes moisture, the dust mixture is dried before measuring by use of 8 to 12 mesh molecular-sieves which are shaken with the dust mixture and subsequently screened from the dust mixture.

Sapko, Michael J. (Finleyville, PA); Ward, Jr., Jack A. (Oakmont, PA)

1989-01-01

419

Dry processing of power plant coal rich in inerts  

NASA Astrophysics Data System (ADS)

A system for pneumatic classifying was constructed in order to examine the effects of quality and composition of coal as well as the machine-related factors, such as the sieve shaking frequency, sieve hole size, air distribution, position of the separating weirs, and arrangement of the charging chute. It was determined that the Berry pneumatic table fulfills the requirements for product purity when the supply of material is held constant and the machine related factors are optimized. For a bituminous coal with a mean ash content between 40% and 50%, the best separation results were obtained. At a purity rate of inerts of over 97%, it was possible to reduce the ash content of the coal by 20%. Due to its compactness, the system can be put in operation at different sites. It is economic to operate, and can be adapted to any required capacity as a result of its modular design. During the tests a high degree of wear was noted on the fan and fan housing. The fan housing was protected to a great extent by synthetic plates.

Gross, J.; Ditzler, H.

1982-07-01

420

Investigation of materials for inert electrodes in aluminum electrodeposition cells  

SciTech Connect

Work was divided into major efforts. The first was the growth and characterization of specimens; the second was Hall cell performance testing. Cathode and anode materials were the subject of investigation. Preparation of specimens included growth of single crystals and synthesis of ultra high purity powders. Special attention was paid to ferrites as they were considered to be the most promising anode materials. Ferrite anode corrosion rates were studied and the electrical conductivities of a set of copper-manganese ferrites were measured. Float Zone, Pendant Drop Cryolite Experiments were undertaken because unsatisfactory choices of candidate materials were being made on the basis of a flawed set of selection criteria applied to an incomplete and sometimes inaccurate data base. This experiment was then constructed to determine whether the apparatus used for float zone crystal growth could be adapted to make a variety of important based melts and their interactions with candidate inert anode materials. The third major topic was Non Consumable Anode (Data Base, Candidate Compositions), driven by our perception that the basis for prior selection of candidate materials was inadequate. Results are presented. 162 refs., 39 figs., 18 tabs.

Haggerty, J. S.; Sadoway, D. R.

1987-09-14

421

Coating of crystalline nuclear waste forms to improve inertness  

SciTech Connect

Microspheres of a crystalline waste form prepared by sol-gel processing were successfully coated with layers of pyrolytic carbon and silicon carbide to isolate the radioactive wastes from the biosphere. A separate process for cesium immobilization was developed which loads 5 wt% Cs onto zeolite particles for subsequent coating. Pyrolytic carbon-coated particles showed leach rates approx. =2 to 4 orders of magnitude less than the candidate reference borosilicate glass waste form. Aqueous leach-test results of coated waste forms were below detection limits of such sensitive analytical techniques as atomic absorption and inductively coupled plasma atomic emission. Significant progress was made in applying sol-gel and fluidized bed coating technology to the solidification of high-level nuclear wastes. The authors successfully prepared microspheres containing simulated wastes of Synroc-B, Synroc-D, a modified Synroc-D where alumina was previously removed from the waste, and a very high waste-loading composition containing 90% waste and 10% ZrO/sub 2/. Each of these compositions was sintered at 1000/sup 0/C and coated with pyrocarbon at temperatures as low as 1000/sup 0/C. Silicon carbide can be applied to these pyrocarbon-coated particles at temperatures as low as 900/sup 0/C for additional inertness or for oxidation resistance. Cesium was isolated by pyrocarbon-coating cesium-loaded zeolite. Pyrocarbon and SiC coatings successfully reduced the leach rates to below detection limits.

Stinton, D.P.; Angelini, P.; Caputo, A.J.; Lackey, W.J.

1982-08-01

422

PHS with inert blocking groups for DUV negative resist  

NASA Astrophysics Data System (ADS)

The synthesis, characterization, and lithographic evaluation of a polyhydroxystyrene (PHS) modified with isopropyloxycarbonate groups is described. The inert blocking group is attached to the hydroxyl sites on PHS resin to slow the dissolution rate and make the resin useful in resists designed for 0.263 N TMAH developers. A negative tone resist (CGR-IP) that is formulated with the modified polymer is compatible with the industry standard 0.263 N TMAH developer and is capable of resolving 0.22 micrometer L/S features and 0.14 micrometer isolated lines on a 0.50 NA imaging system. Reaction with PHS resin occurs primarily at the phenolic sites as shown by carbon-13 NMR and 10% protection is sufficient to lower the dissolution rate to an acceptable level so that there is less than 50 angstrom film loss in exposed areas. The blocking group described here is not acid labile and reaming intact after the resist film is baked at 150 degrees Celsius.

Brunsvold, William R.; Conley, Will; Varanasi, Pushkara R.; Khojasteh, Mahmoud; Patel, Niranjan M.; Molless, Antoinette F.; Neisser, Mark O.; Breyta, Gregory

1997-07-01

423

Porous HMX initiation studies -- Sugar as an inert simulant  

SciTech Connect

For several years the authors have been using magnetic particle velocity gauges to study the shock loading of porous HMX (65 and 73% TMD) of different particle sizes to determine their compaction and initiation characteristics. Because it has been difficult to separate the effects of compaction and reaction, an inert simulant was needed with properties similar to HMX. Sugar was selected as the simulant for several reasons: (1) the particle size distribution of C and H granulated sugar is similar to the coarse HMX the authors have been using (120 {micro}m average size), (2) the particle size of C and H confectioners (powdered) sugar is similar to the fine HMX in the studies (10 {micro}m average size), (3) it is an organic material, and (4) sugar was readily available. Because the densities of HMX and sugar are somewhat different, the authors chose to do the experiments on sugar compacts at 65 and 73% TMD. As expected, no reaction was observed in the sugar experiments. Compaction wave profiles were similar to those measured earlier for the HMX, i.e., the compaction waves in the coarse sugar were quite disperse while those in the fine sugar were much sharper. This indicates that the compaction wave profiles are controlled by particle size and not reaction. Also, the coarse sugar gauge signals exhibited a great deal of noise, thought to the be result of fracto-emission.

Sheffield, S.A.; Gustavsen, R.L.; Alcon, R.R.

1997-11-01

424

Thermo-dynamical process simulation of dilution refrigerator  

NASA Astrophysics Data System (ADS)

The design, analysis and optimization of a dilution refrigerator are carried via simulation of the thermo dynamical processes. To this end we have developed a comprehensive numerical simulation model, SIDFO (Simulation of Integrated Dilution Refrigerator for Optimization) based on enthalpy - balance considerations taking into account for several important micro-effects which are normally ignored by existing methods. The simulation has produced several unique results of the underlying phenomena occurring at various stages of the very low temperature process presented in this paper. The corresponding simulation results are compared with published experimental data of operational machines and found to comply well. The presence of 4He in the circulating gas and its consequences for the generalized cooling power is also thoroughly examined here.

Pradhan, Jedidiah; Das, Nisith Kr.; Chakraborty, Alok

2013-10-01

425

Dry dilution refrigerator with He-4 precool loop  

NASA Astrophysics Data System (ADS)

He-3/He-4 dilution refrigerators (DR) are very common in sub-Kelvin temperature research. We describe a pulse tube precooled DR where a separate He-4 circuit condenses the He-3 of the dilution loop. Whereas in our previous work the dilution circuit and the He-4 circuit were separate, we show how the two circuits can be combined. Originally, the He-4 loop with a base temperature of ˜ 1 K was installed to make an additional cooling power of up to 100 mW available to cool cold amplifiers and electrical lines. In the new design, the dilution circuit is run through a heat exchanger in the vessel of the He-4 circuit so condensation of the He-3 stream of the DR is done by the He-4 stage. A much reduced condensation time (factor of 2) of the He-3/He-4 gas mixture at the beginning of an experiment is achieved. A compressor is no longer needed with the DR as the condensation pressure remains below atmospheric pressure at all times; thus the risk of losing expensive He-3 gas is small. The performance of the DR has been improved compared to previous work: The base temperature of the mixing chamber at a small He-3 flow rate is now 4.1 mK; at the highest He-3 flow rate of 1.2 mmol/s this temperature increases to 13 mK. Mixing chamber temperatures were measured with a cerium magnesium nitrate (CMN) thermometer which was calibrated with a superconducting fixed point device.

Uhlig, Kurt

2014-01-01

426

Dilute Oxygen Combustion. Phase 3 Report.  

National Technical Information Service (NTIS)

Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total o...

M. F. Riley

2000-01-01

427

Dilute Oxygen Combustion - Phase 3 Report  

Microsoft Academic Search

Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu\\/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from

Riley; Michael F

2000-01-01

428

Dilute Oxygen Combustion; Phase 3 Final Report  

Microsoft Academic Search

Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu\\/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from

M. F. Riley; H. M. Ryan

2000-01-01

429

EPS dilution after SEOs and earnings management  

Microsoft Academic Search

Purpose – Firms are concerned about earnings per share (EPS) dilution after equity issues. The purpose of this paper is to investigate whether firms manage upward their discretionary accruals around seasoned equity offerings (SEOs) to mitigate the impact of dilution on reported earnings. Design\\/methodology\\/approach – The authors employ adjusted discretionary accruals from cash flow statements, normalized by the average common

Hui Di; Dalia Marciukaityte; Eugenie A. Goodwin

2012-01-01

430

Atmospheric dilution of fume hood exhaust gases  

Microsoft Academic Search

Guidelines are proposed for the design of fume hood exhaust systems such that sufficient atmospheric dilution is obtained to prevent unacceptable contamination of fresh air intakes. An empirical design criterion, which has been employed successfully at a number of large pharmaceutical research laboratories, is presented. The literature on the calculation of atmospheric dilution near buildings is reviewed, and suggestions are

JAMES HALITSKY

1982-01-01

431

Development of Improved Technologies and Techniques for Reducing Base Gas Requirements in Underground Gas Storage Facilities: Simulation Study of Hanson Field Gas Storage Reservoir. Final Report May 1989-November 1989.  

National Technical Information Service (NTIS)

Base gas requirements in the U.S. amount to a few trillion cubic feet. The Gas Research Institute has proposed a gas storage operating plan whereby an inert gas or a low BTU gas could be injected to replace part of the hydrocarbon gas. A reservoir simulat...

A. D. Modine

1989-01-01

432

From inert to explosive, the hydrolytic reactivity of R-NSO compounds understood: a computational study.  

PubMed

We present a computational study on the concerted hydrolysis of several classes of N-sulfinylamines of generic formula R-N?S?O, such as the -amines themselves (R-NSO), -hydrazines (R-NH-NSO), -hydrazides (R-CO-NH-NSO) and -amides (R-CO-NSO), as these species are known to possess a wide range of hydrolytic reactivity. Two possible mechanisms of hydrolysis, with a water dimer across the S?O and N?S bonds, in the gas phase are investigated. The reactivity is discussed with respect to the electronic structures, established with the use of the quantum theory of Atoms in Molecules, Natural Bond Orbital and Natural Resonance Theory approaches. For the inert N-sulfinylhydrazines and the keto tautomers of N-sulfinylhydrazides, extended ?-conjugation adds a sulfide-like resonance structure that is responsible for their insensitivity toward moisture. Activation barriers for hydrolysis, where water acts as a nucleophilic reagent, decrease with increasing positive charge on the NSO sulfur atom, a finding that might prove useful as a predictive tool in the determination of the general reactivity of an N-sulfinyl compound by experimentalists. PMID:21428403

Ivanova, Elena V; Muchall, Heidi M

2011-04-14

433

A thermodynamic assessment of the potential synthesis of condensed hydrocarbons during cooling and dilution of volcanic gases  

Microsoft Academic Search

The possibility for abiotic synthesis of condensed hydrocarbons in cooling\\/diluting terrestrial volcanic gases has been evaluated on the basis of the consideration of metastable chemical equilibria involving gaseous CO, CO2, H2 and H2O. The stabilities of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) have been evaluated for several typical volcanic gas compositions under various conditions for cooling\\/diluting of quenched volcanic gas.

Mikhail Y. Zolotov; Everett L. Shock

2000-01-01

434

Trace gas disequilibria during deep-water formation  

Microsoft Academic Search

We present high-precision measurements by a new isotope dilution technique of a suite of inert gases in the North Pacific. Remarkably smooth gradients in Ar, Kr and Xe from near equilibrium in intermediate waters to several percent undersaturated in deep waters were observed. The general pattern in the deepest waters was that Ar, Kr and Xe were undersaturated (Ar least

Roberta C. Hamme; Jeffrey P. Severinghaus

435

Trace gas disequilibria during deep-water formation  

Microsoft Academic Search

We present high-precision measurements by a new isotope dilution technique of a suite of inert gases in the North Pacific. Remarkably smooth gradients in Ar, Kr and Xe from near equilibrium in intermediate waters to several percent undersaturated in deep waters were observed. The general pattern in the deepest waters was that Ar, Kr and Xe were undersaturated (Ar least

Roberta C. Hamme; Jeffrey P. Severinghaus

2007-01-01

436

Argon purge gas cooled by chill box  

NASA Technical Reports Server (NTRS)

Cooling argon purge gas by routing it through a shop-fabricated chill box reduces charring of tungsten inert gas torch head components. The argon gas is in a cooled state as it enters the torch and prevents buildup of char caused by the high concentrations of heat in the weld area during welding operations.

Spiro, L. W.

1966-01-01

437

Clamp and Gas Nozzle for TIG Welding  

NASA Technical Reports Server (NTRS)

Tool that combines clamp with gas nozzle is aid to tungsten/inert-gas (TIG) welding in hard-to-reach spots. Tool holds work to be welded while directing a stream of argon gas at weld joint, providing an oxygen-free environment for tungsten-arc welding.

Gue, G. B.; Goller, H. L.

1982-01-01

438

Analysis of several hazardous conditions for large transfer and back-dilution sequences in Tank 241-SY-101  

SciTech Connect

The first transfer of 89 kgal of waste and back-dilution of 61 kgal of water in Hanford Tank 241-SY-101 was accomplished December 18--20, 1999. Limits were placed on the transfer and back-dilution volumes because of concerns about potential gas release, crust sinking, and degradation of mixer pump performance. Additional transfers and back-dilutions are being planned that will bring the total to 500 kgal, which should dissolve a large fraction of the solids in the tank and dilute it well beyond the point where significant gas retention can occur. This report provides the technical bases for removing the limits on transfer and back-dilution volume by evaluating the potential consequences of several postulated hazardous conditions in view of the results of the first campaign and results of additional analyses of waste behavior.

CW Stewart; LA Mahoney; WB Barton

2000-01-28

439

Sodium conversion experiments in the Inert Carrier Process demonstration plant  

SciTech Connect

The purpose of the sodium treatment studies reported here was to evaluate the use of the Inert Carrier Process (ICP) for converting sodium metal to a stable disposal form. The ICP demonstration plant consists of a closed loop of silicone oil that is circulated through a reservoir called a disperser. Solid sodium particles were fed to the disperser and kept suspended in the silicone oil carrier by turbulence. The sodium did not react with the silicone oil carrier. The dispersion of sodium in silicone oil was fed to an in-line mixer (''jet'' mixer) where it was mixed with a reactant. Water was used as the reactant in most of the tests, generating sodium hydroxide and hydrogen as the initial products. Analysis of the final solid product from the reaction indicated that the sodium hydroxide initial product interacted with the silicone oil. Complete reaction of the sodium in the demonstration plant required at least a 6/1 molar ratio of water to sodium. Good separation of the product solution was difficult because of the small difference in density between the aqueous product phase and the organic carrier phase. Emulsification of the silicone oil-aqueous solution was minimized by applying heat to the separator. Foaming of the silicone oil in the separator occurred, aggravated by the evolution of hydrogen from the sodium conversion reaction. Bench-scale tests were conducted to analyze and resolve several problems encountered in the plant experiments, such as incomplete reaction in the jet mixer, poor separation of the product from the silicone oil, formation of an oil aqueous solution emulsion in the separator, and oil foaming in the separator. Solidification tests were carried out to immobilize the sodium conversion product by mixing it with various binders. The most satisfactory binder was EPON 828, an epoxy resin.

Keneshea, F.J.; Hobart, S.A.; Kelly, M.T.; Pohl, C.S.; Riley, D.

1983-01-01

440

Reduction Kinetics of Iron Ore-Graphite Composite Pellets in a Packed-Bed Reactor under Inert and Reactive Atmospheres  

NASA Astrophysics Data System (ADS)

The rate of reduction of iron ore-graphite composite pellets in a packed-bed reactor under controlled atmosphere (inert and reducing) has been studied through experiments and modeling exercises. A customized high-mass, high-temperature thermogravimetric setup was constructed to carry out reduction experiments in a packed-bed reactor. A very low overall apparent activation energy estimated from experimental data indicates that the packed-bed reduction is unlikely to be chemical kinetics controlled. A kinetic model has been developed to calculate the temporal evolution of various phases of iron oxides and metallic iron. The rate-dependent parameters of the kinetic model are estimated from experimental data by applying an optimization tool. The predicted phases at various degrees of reduction were verified by X-ray diffraction and metallographic investigation, and a reasonable agreement between the results has been observed. It is observed that both the rate and the extent of metallic-iron production increase under reactive atmosphere. In addition, a simplified thermal model has been developed to ascertain the role of heat transfer on the kinetics of the reduction process under inert atmosphere. The reduction kinetics of the packed bed under reactive atmosphere, on the other hand, is not controlled by heat transfer and might possibly be controlled by CO-gas mass transfer through the pellets.

Chowdhury, G. M.; Roy, G. G.; Roy, S. K.

2008-04-01

441

Composition suitable for use as inert electrode having good electrical conductivity and mechanical properties  

DOEpatents

An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. 8 figs.

Ray, S.P.; Rapp, R.A.

1984-06-12

442

Composition suitable for use as inert electrode having good electrical conductivity and mechanical properties  

DOEpatents

An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily.

Ray, Siba P. (Plum Boro, PA); Rapp, Robert A. (Columbus, OH)

1984-01-01

443

Inert anode containing base metal and noble metal useful for the electrolytic production of aluminum  

DOEpatents

An inert anode for production of metals such as aluminum is disclosed. The inert anode comprises a base metal selected from Cu and Ag, and at least one noble metal selected from Ag, Pd, Pt, Au, Rh, Ru, Ir and Os. The inert anode may optionally be formed of sintered particles having interior portions containing more base metal than noble metal and exterior portions containing more noble metal than base metal. In a preferred embodiment, the base metal comprises Cu, and the noble metal comprises Ag, Pd or a combination thereof.

Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA)

2000-01-01

444

Effects of External EGR Loop on Cycle-to-Cycle Dynamics of Dilute SI Combustion  

SciTech Connect

Operation of spark-ignition (SI) engines with high levels of charge dilution through exhaust gas recirculation (EGR) achieves significant efficiency gains while maintaining stoichiometric operation for compatibility with three-way catalysts. Dilution levels, however, are limited by cyclic variability including significant numbers of misfires that becomes significant with increasing dilution. This variability has been shown to have both stochastic and deterministic components. Stochastic effects include turbulence, mixing variations, and the like, while the deterministic effect is primarily due to the nonlinear dependence of flame propagation rates and ignition characteristics on the charge composition, which is influenced by the composition of residual gases from prior cycles. The dynamics of operation with an external EGR loop differ substantially from those of dilute operation without external recirculation, both in time-scale and cylinder synchronization effects, especially when misfires are encountered. This paper examines these differences and the implications for prior-cycle-based control strategies.

Kaul, Brian C [ORNL] [ORNL; Finney, Charles [ORNL] [ORNL; Wagner, Robert [ORNL] [ORNL; Edwards, Michelle L [ORNL] [ORNL

2014-01-01

445

Inert anode containing oxides of nickel, iron and zinc useful for the electrolytic production of metals  

DOEpatents

An inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode includes a ceramic oxide material preferably made from NiO, Fe.sub.2 O.sub.3 and ZnO. The inert anode composition may comprise the following mole fractions of NiO, Fe.sub.2 O.sub.3 and ZnO: 0.2 to 0.99 NiO; 0.0001 to 0.8 Fe.sub.2 O.sub.3 ; and 0.0001 to 0.3 ZnO. The inert anode may optionally include other oxides and/or at least one metal phase, such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. The Ni--Fe--Co--O ceramic material exhibits very low solubility in Hall cell baths used to produce aluminum.

Ray, Siba P. (Murrysville, PA); Weirauch, Jr., Douglas A. (Murrysville, PA); Liu, Xinghua (Monroeville, PA)

2002-01-01

446

Inert anode containing oxides of nickel iron and cobalt useful for the electrolytic production of metals  

DOEpatents

An inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode includes a ceramic oxide material preferably made from NiO, Fe.sub.2 O.sub.3 and CoO. The inert anode composition may comprise the following mole fractions of NiO, Fe.sub.2 O.sub.3 and CoO: 0.15 to 0.99 NiO; 0.0001 to 0.85 Fe.sub.2 O.sub.3 ; and 0.0001 to 0.45 CoO. The inert anode may optionally include other oxides and/or at least one metal phase, such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. The Ni--Fe--Co--O ceramic material exhibits very low solubility in Hall cell baths used to produce aluminum.

Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA); Weirauch, Jr., Douglas A. (Murrysville, PA)

2002-01-01

447

46 CFR 194.15-17 - Compressed gases other than inert gases.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS HANDLING, USE, AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-17 Compressed gases other than inert gases. (a)...

2013-10-01

448

Energy levels of the electrons localized over the surface of an inert film with address electrodes  

SciTech Connect

The problem of searching for the potential energy and the energy spectrum of the electrons localized over the surface of a thin liquid or solid inert film due to address electrodes placed under the film is considered.

Petrin, A. B., E-mail: a_petrin@mail.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2013-03-15

449

77 FR 15101 - Results From Inert Ingredient Test Orders Issued Under EPA's Endocrine Disruptor Screening...  

Federal Register 2010, 2011, 2012, 2013

...inert ingredients in pesticide products: Acetone, isophorone, di-sec-octyl phthalate, toluene, methyl ethyl ketone, butyl benzyl phthalate, dibutyl phthalate, diethyl phthalate, and dimethyl phthalate. The test orders required...

2012-03-14

450

For cermet inert anode containing oxide and metal phases useful for the electrolytic production of metals  

DOEpatents

A cermet inert anode for the electrolytic production of metals such as aluminum is disclosed. The inert anode comprises a ceramic phase including an oxide of Ni, Fe and M, where M is at least one metal selected from Zn, Co, Al, Li, Cu, Ti, V, Cr, Zr, Nb, Ta, W, Mo, Hf and rare earths, preferably Zn and/or Co. Preferred ceramic compositions comprise Fe.sub.2 O.sub.3, NiO and ZnO or CoO. The cermet inert anode also comprises a metal phase such as Cu, Ag, Pd, Pt, Au, Rh, Ru, Ir and/or Os. A preferred metal phase comprises Cu and Ag. The cermet inert anodes may be used in electrolytic reduction cells for the production of commercial purity aluminum as well as other metals.

Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA); Weirauch, Douglas A. (Murrysville, PA)

2002-01-01

451

Results of Waste Transfer and Back-Dilution in Tanks 241-SY-101 and 241-SY-102  

SciTech Connect

This report chronicles the process of remediation of the flammable gas hazard in Tank 241-SY-101 (SY-101) by waste transfer and back-dilution from December 18, 1999 through April 2, 2000. A brief history is given of the development of the flammable gas retention and release hazard in this tank, and the transfer and dilution systems are outlined. A detailed narrative of each of the three transfer and dilution campaigns is given to provide structure for the balance of the report. Details of the behavior of specific data are then described, including the effect of transfer and dilution on the waste levels in Tanks SY-101 and SY-102, data from strain gauges on equipment suspended from the tank dome, changes in waste configuration as inferred from neutron and gamma logs, headspace gas concentrations, waste temperatures, and the mixerpump operating performance. Operating data and performance of the transfer pump in SY-101 are also discussed.

LA Mahoney; ZI Antoniak; WB Barton; JM Conner; NW Kirch; CW Stewart; BE Wells

2000-07-26

452

Determination of acrylamide in Chinese traditional carbohydrate-rich foods using gas chromatography with micro-electron capture detector and isotope dilution liquid chromatography combined with electrospray ionization tandem mass spectrometry.  

PubMed

The present study developed two analytical methods for quantification of acrylamide in complex food matrixes, such as Chinese traditional carbohydrate-rich foods. One is based on derivatization with potassium bromate and potassium bromide without clean-up prior to gas chromatography with micro-electron capture detector (GC-MECD). Alternatively, the underivatized acrylamide was detected by high-performance liquid chromatography coupled to quadrupole tandem mass spectrometry (HPLC-MS/MS) in the positive electrospray ionization mode. For both methods, the Chinese carbohydrate-rich samples were homogenized, defatted with petroleum ether and extracted with aqueous solution of sodium chloride. Recovery rates for acrylamide from spiked Chinese style foods with the spiking level of 50, 500 and 1000 microg kg(-1) were in the range of 79-93% for the GC-MECD including derivatization and 84-97% for the HPLC-MS/MS method. Typical quantification limits of the HPLC-MSMS method were 4 microg kg(-1) for acrylamide. The GC-MECD method achieved quantification limits of 10 microg kg(-1) in Chinese style foods. Thirty-eight Chinese traditional foods purchased from different manufacturers were analyzed and compared with four Western style foods. Acrylamide contaminant was found in all of samples at the concentration up to 771.1 and 734.5 microg kg(-1) detected by the GC and HPLC method, respectively. The concentrations determined with the two different quantitative methods corresponded well with each other. A convenient and fast pretreatment procedure will be optimized in order to satisfy further investigation of hundreds of samples. PMID:17386622

Zhang, Yu; Ren, Yiping; Zhao, Hangmei; Zhang, Ying

2007-02-19

453

Sample Diluter for Detecting Hypergolic Propellants and other Toxic or Hazardous Gases  

NASA Technical Reports Server (NTRS)

Hardware was developed to dilute vapor samples of purged hypergolic propellants (with air) into the range of existing instruments for detection of such toxic vapors. Since these detectors are normally used to monitor at the threshold limit value (TLV), most do not have quantitative capability at percent levels which relate to lower explosion limit (LEL) and fire hazards. For example, the upper limits of Energetic Sciences (ESI) 6000 series detectors used at KSC are 200 parts per million (ppm) for monomethyl hydrazine (MMH) and 500 ppm for nitrogen dioxide (NO2) arising from decomposition of nitrogen tetroxide (N2O4). Orbiter Processing Facility (OPF) personnel servicing Shuttle thrusters need to measure up to 250 ppm MMH and 7,500 ppm NO2 with portable, intrinsically safe instruments. Our objective was to quickly fabricate a sample diluter out of existing materials as a temporary measure while other parallel efforts were conducted to provide a commercial or in-house-developed instrument to detect high propellant levels. A 3 to 1 diluter would bring 500 ppm MMH into the range of the existing fuel ESI, and a 30 to 1 diluter would do the same for NO2. In this way, familiar equipment already available would be used, resulting in minimal paperwork, safety, and training impacts and low cost. An MMH vapor sample-diluter was constructed from a 1/4-inch Kynar tee, along with specially designed lengths of sample and dilution tubing. The sample line was 3 feet of Bev-A-Line 4, 1/4-inch tube leading to the straight run of the tee. The side run of the tee had a 17-inch length of Bev-A-Line 4, 1/4-inch tube, for nominal 3 to 1 dilution. A gas sample bag was prepared and assayed at 113 ppm ppm MMH, and diluted vapor samples were assayed at 39.5 ppm, or a measured dilution of 2.9 to 1. For NO2, a 316 stainless steel (SS) 1/8-inch tee with 49.5 inches of coiled, 1/8-inch outside diameter (OD) 316 SS tubing was used as the sampling end of the dilution system. The side run of the tee was open. The measured dilution ratio, based on the input value of 6,480 ppm NO2, and the average output value of 233 ppm, was 28 to 1. Thus, sample-diluters were successful in diluting concentrated hypergolic propellant vapors, both MMH and N2O4 into the ranges of existing TLV detectors.

Barile, R. G.; Hodge, T. R.; Meneghelli, B. J.; Gursky, R.; Lueck, D. E.