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1

DETERMINATION OF ACRYLAMIDE IN RAT SERUM AND SCIATIC NERVE BY GAS CHROMATOGRAPHY-ELECTRON-CAPTURE DETECTION  

EPA Science Inventory

A modified method for the derivatization and analysis of acrylamide as 2-bromopropenamide by gas chromatography/electron capture detection was validated in serum and sciatic nerve from rats. he method was accurate and precise over the concentration range of 2240 to 74700 ppm (w/v...

2

Identification and quantification of lignans in wheat bran by gas chromatography-electron capture detection.  

PubMed

Whole grain cereals are an important source of bioavailable lignans, the group of compounds with potential anti-cancerogenic, antioxidant, anti-proliferative, pro-apoptotic, and antiangiogenic properties. The aim of this work was to develop a sensitive method for determination of wheat bran lignans. The analysis of lignans secoisolariciresinol, hydroxymatairesinol, lariciresinol, matairesinol, pinoresinol, syringaresinol is based on derivatization with pentafluoropropionic anhydride (PFPA) and gas chromatography-electron capture detection (GC-ECD), using styrene glycol as internal standard. To our knowledge, this is the first time that EC detection has been used for lignan analysis. The results show that the technique is reproducible and sensitive enough for detecting lignans in wheat at parts-per-billion (ppb) levels, except for hydroxymatairesinol. The method developed showed good recovery (85-105%) and precision (4-20%) for five types of lignans and thus represents a simpler and more affordable alternative to state-of-the-art wheat lignan liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. PMID:21315909

Cukelj, Nikolina; Jakasa, Ivone; Sarajlija, Hrvoje; Novotni, Dubravka; Curi?, Duška

2010-12-25

3

Application of pentafluorophenyldimethylsilyl derivatization for gas chromatography–electron-capture detection of supercritically extracted sterols  

Microsoft Academic Search

We report a convenient method of extracting and detecting sterols in environmental water samples. Particle-associated sterols were extracted onto glass-fibre filters then the filters were supercritical fluid extracted (at 33 MPa, 80°C for 30 min) followed by pentafluorophenyldimethylsilyl (flophemesyl) derivatization for gas chromatographic–electron-capture detection (GC–ECD). Optimal derivatization of epicoprostanol, coprostanol, cholesterol, dihydrocholesterol, stigmasterol, ?-sitosterol and stigmastanol with neat flophemesyl chloride

Leonard Y Jayasinghe; Philip J Marriott; Peter D Carpenter; Peter D Nichols

1998-01-01

4

Identification and quantification of lignans in wheat bran by gas chromatography-electron capture detection  

Microsoft Academic Search

Whole grain cereals are an important source of bioavailable lignans, the group of compounds with potential anti-cancerogenic, antioxidant, anti-proliferative, pro-apoptotic, and antiangiogenic properties. The aim of this work was to develop a sensitive method for determination of wheat bran lignans. The analysis of lignans secoisolariciresinol, hydroxymatairesinol, lariciresinol, matairesinol, pinoresinol, syringaresinol is based on derivatization with pentafluoropropionic anhydride (PFPA) and gas

Nikolina ?ukelj; Ivone Jakasa; Hrvoje Sarajlija; Dubravka Novotni; Duška ?uri?

2011-01-01

5

Part-per-trillion determination of chlorobenzenes in water using dispersive liquid–liquid microextraction combined gas chromatography–electron capture detection  

Microsoft Academic Search

In this study, a simple, rapid and efficient method, dispersive liquid–liquid microextraction (DLLME) combined gas chromatography–electron capture detection (GC–ECD), for the determination of chlorobenzenes (CBs) in water samples, has been described. This method involves the use of an appropriate mixture of extraction solvent (9.5?l chlorobenzene) and disperser solvent (0.50ml acetone) for the formation of cloudy solution in 5.00ml aqueous sample

Reyhaneh Rahnama Kozani; Yaghoub Assadi; Farzaneh Shemirani; Mohammad-Reza Milani Hosseini; Mohammad Reza Jamali

2007-01-01

6

Determination of chlorophenols in water samples using simultaneous dispersive liquid–liquid microextraction and derivatization followed by gas chromatography-electron-capture detection  

Microsoft Academic Search

Simultaneous dispersive liquid–liquid microextraction (DLLME) and derivatization combined with gas chromatography-electron-capture detection (GC-ECD) was used to determine chlorophenols (CPs) in water sample. In this derivatization\\/extraction method, 500?L acetone (disperser solvent) containing 10.0?L chlorobenzene (extraction solvent) and 50?L acetic anhydride (derivatization reagent) was rapidly injected by syringe in 5.00mL aqueous sample containing CPs (analytes) and K2CO3 (0.5%, w\\/v). Within a few

Nazir Fattahi; Yaghoub Assadi; Mohammad Reza Milani Hosseini; Elham Zeini Jahromi

2007-01-01

7

Analysis of corky off-flavour compounds at ultra trace level with multidimensional gas chromatography-electron capture detection.  

PubMed

A robust method for routine quality control of corky off-flavour compounds in wine and cork soak matrices has been established. Based on an automated headspace solid phase microextraction (HS-SPME), the method needs only marginal sample preparation and achieves low (sub-ng L(-1)) trace level detection limits (LODs) for the most relevant off-flavour compounds, such as 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA) and 2,4,6-tribromoanisole (TBA). Particularly for wine matrix, reliable trace level quantification had only been achieved after applying heart-cutting multidimensional gas chromatography (MDGC). Using a halogen-sensitive electron capture detector (ECD) and quantification with a stable isotope dilution assay (SIDA), LODs of 0.1ng L(-1) for TCA, TeCA and TBA could be obtained. Since a SIDA based quantification method is used with a non-mass spectrometric detector, the necessary chromatographic resolution of internal standard and target analyte peaks resulted from the use of highly deuterated [(2)H(5)]-isotopologues. PMID:23219330

Slabizki, Petra; Schmarr, Hans-Georg

2012-11-19

8

Direct and simultaneous determination of trace-level carbon tetrachloride, peroxyacetyl nitrate, and peroxypropionyl nitrate using gas chromatography-electron capture detection.  

PubMed

Gas chromatography equipped with electron capture detector (GC-ECD) has been widely used for detecting atmospheric peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN). However, to the best of our knowledge, only a few capillary columns have been adopted for separation to achieve the direct and simultaneous analysis of the two atmospheric pollutants. This paper demonstrates a novel method for directly and simultaneously measuring atmospheric carbon tetrachloride (CCl(4)), PAN, and PPN using GC-ECD with a DB-1 separation column. The responses of the GC-ECD to PAN, PPN, and CCl(4) were individually calibrated by using gas mixtures prepared via volatilization of synthesized solutions of PAN and PPN or high-purity CCl(4) reagent in a Teflon Bag. The concentrations of PAN and PPN in the synthesized solutions were quantified by ion chromatography (IC). Further calibration of the GC-ECD for PAN was conducted by in situ photochemical formation of gaseous PAN which was quantified by a NO(x) analyzer. The two calibration methods agreed well with each other, and the overall uncertainties for measuring atmospheric PAN were estimated to be ± 13% and ± 15% based on the calibrations of IC and NO(x), respectively. The detection limits (three times the signal to noise ratio) for PAN, PPN, and CCl(4) were estimated to be 22, 36, and 5 pptv (parts per trillion by volume), respectively. The atmospheric concentrations of these compounds were measured for several days in August in Beijing, and the values obtained in this study were found to be in good agreement with the data reported in the literature for Beijing using other GC-ECD methods. PMID:23107119

Zhang, Gen; Mu, Yujing; Liu, Junfeng; Mellouki, Abdelwahid

2012-10-02

9

Copper clean-up procedure for ultrasonic extraction and analysis of pyrethroid and phenylpyrazole pesticides in sediments by gas chromatography-electron capture detection.  

PubMed

A rapid ultrasonic extraction method coupled with a heated-copper clean-up procedure for removing interfering constituents was developed for analyzing pyrethroid and phenylpyrazole pesticides in sediments. Incubation of the 60 mL extract with 12 g copper granules at 60 °C for 2h was determined to be the optimal conditions for removing the interfering constituents. Eleven pyrethroid and phenylpyrazole pesticides were spiked into sediment samples to determine the effectiveness of the ultrasonic extraction method. The average recoveries of pyrethroids and phenylpyrazoles in sediment at 4 °C storage on day 0, 1, 7, 14, and 21 ranged from 98.6 to 120.0%, 79.2 to 116.0%, 85.0 to 119.7%, 93.6 to 118.7%, and 92.1 to 118.2%, respectively, with all percent relative standard deviations less than 10% (most <6%). This illustrated the stability of pyrethroids and phenylpyrazoles in sediment during sediment aging at 4 °C. Recoveries of the pesticides ranged from 98.6% to 120.0% for lowest fortification level (2-16 ?g kg?¹), from 97.8% to 117.9% for middle fortification level (10-80 ?g kg?¹), and from 94.3% to 118.1% for highest fortification level (20-160 ?g kg?¹). Relative standard deviations of pesticide recoveries were usually less than 7%. Method detection limits of target pesticides ranged from 0.22 ?g kg?¹ to 3.72 ?g kg?¹. Furthermore, field sediment samples collected from four residential lakes during a three-month monitoring period were analyzed to evaluate the effectiveness of this method. Bifenthrin was detected in all of sediment samples (highest concentration 260.33±41.71 ?g kg?¹, lowest concentration 5.68±0.38 ?g kg?¹, and fipronil sulfone was detected at least once in sediment samples collected from three sites with concentrations ranging from 1.73±0.53 to 7.53±0.01 ?g kg?¹. PMID:21684581

Wu, Jun; Lin, Youjian; Lu, Jian; Wilson, Chris

2011-08-15

10

Validated semiquantitative/quantitative screening of 51 drugs in whole blood as silylated derivatives by gas chromatography-selected ion monitoring mass spectrometry and gas chromatography electron capture detection.  

PubMed

A comprehensively validated procedure is presented for simultaneous semiquantitative/quantitative screening of 51 drugs of abuse or drugs potentially hazardous for traffic safety in serum, plasma or whole blood. Benzodiazepines (12), cannabinoids (3), opioids (8), cocaine, antidepressants (13), antipsychotics (5) and antiepileptics (2) as well as zolpidem, zaleplon, zopiclone, meprobamate, carisoprodol, tizanidine and orphenadrine and internal standard flurazepam, were isolated by high-yield liquid-liquid extraction (LLE). The dried extracts were derivatized by two-step silylation and analyzed by the combination of two different gas chromatographic (GC) separations with both electron capture detection (ECD) and mass spectrometry (MS) operating in a selected ion-monitoring (SIM) mode. Quantitative or semiquantitative results were obtained for each substance based on four-point calibration. In the validation tests, accuracy, reproducibility, linearity, limit of detection (LOD) and limit of quantitation (LOQ), selectivity, as well as extraction efficiency and stability of standard stock solutions were tested, and derivatization was optimized in detail. Intra- and inter-day precisions were within 2.5-21.8 and 6.0-22.5%, and square of correlation coefficients of linearity ranged from 0.9896 to 0.9999. The limit of quantitation (LOQ) varied from 2 to 2000 ng/ml due to a variety of the relevant concentrations of the analyzed substances in blood. The method is feasible for highly sensitive, reliable and possibly routinely performed clinical and forensic toxicological analyses. PMID:15171931

Gunnar, Teemu; Mykkänen, Sirpa; Ariniemi, Kari; Lillsunde, Pirjo

2004-07-01

11

Extraction and Gas Chromatography\\/Electron Capture Analysis of Polychlorinated Biphenyls in Railcar Paint Scrapings  

Microsoft Academic Search

Polychlorinated biphenyls (PCBs) in dried paints may present an occupational exposure hazard to maintenance workers and welders who are unaware of their past use in specialized metal coatings. Prior to their restriction to closed systems in 1970, PCBs were routinely added to these paints to impart properties of heat resistance, plasticity, and antifouling. Gas chromatography with electron capture detection was

Michael S. Welsh

1995-01-01

12

Determination of indicator polychlorinated biphenyls (PCBs) by gas chromatography-electron capture detector.  

PubMed

An effective method for determination of indicator polychlorinated biphenyls (PCBs) has been validated using gas chromatography (GC) equipped with electron capture detector (ECD). The GC-ECD method was validated by determining the linear range (working range) for determination of the compounds, minimum detectable quantities (MDQ), the precision and accuracy of the method for the analysis of the compounds. MDQ obtained for the compounds ranges from 0.0005 to 0.002ng. Indeed the method was found to be more sensitive as the number of chlorine atoms attached to the biphenyl increases. The precision and accuracy of the GC method validated ranges from 2.4% to 14.5% and -7.0% to 14.6% respectively. Coefficient of variation associated with the repeatability of the retention times and corresponding peak areas was found to be 0.0001-0.0007 for the retention times and 0.0014-0.059 for the peak areas. Percentage recoveries for the compounds were in the range of 95.7-101.0%. The validated method was then applied to determine levels of indicator PCBs in sediments sampled from eleven sampling points along the Lake Bosuntwi in Ghana and the highest PCB load of 19.17ngg(-1) was recorded at Pipie No. 2. PCB 52 and PCB 101 were found to be the most ubiquitous indicator PCBs in the study area, both with 90.91% occurrence. PMID:24016628

Afful, Samuel; Awudza, Johannes A M; Twumasi, Stevester K; Osae, Shiloh

2013-09-06

13

An Examination of Pentafluorobenzoyl Derivatization Strategies for the Analysis of Fatty Alcohols using Gas Chromatography/Electron Capture Negative Ion Chemical Ionization-Mass Spectrometry  

PubMed Central

Gas chromatography/electron capture negative ion chemical ionization-mass spectrometry (GC/ECNICI-MS) combined with pentafluorobenzoyl derivatization (PFBoyl) is frequently used for the sensitive detection of fatty alcohols (FOH). However, this derivatization technique suffers from a lack of established reaction protocols, time-consuming reactions, and the presence of reagent artifacts or unwanted derivatization byproducts which can hinder analyte detection. Here, strategies are presented to reduce the problems associated with PFBoyl-derivatization, including 1) the optimization of reaction conditions (derivatization time and temperature) for a variety of PFBoyl-derivatized FOH, 2) an investigation of microwave-accelerated derivatization (MAD) as a rapid alternative heating mechanism for the PFBoyl-derivatization of FOH, and 3) an analysis of an alternative strategy employing a solvent extraction procedure post-derivatization to reduce the detrimental effects commonly associated with PFBoyl derivatization reagents. The optimal reaction conditions for the PFBoyl-derivatization of FOH was determined to be 60 °C for 45 min. The investigation in MAD demonstrated the potential of obtaining comparable PFBoyl-derivatizations to those obtained using traditional heating methods, albeit in a reaction time of 3 min. An examination of several solvents for post-derivatization extraction revealed improved relative response factors in comparison to those obtained without solvent extraction. The best solvents for the PFBoyl-FOH extraction, dichloromethane and tert-butyl methyl ether, were also compared to the no solvent extraction samples with standard response curves and PFBoyl-derivatized FOH in Bligh-Dyer extracted rat plasma.

Bowden, John A.; Ford, David A.

2010-01-01

14

Analysis of 5-methoxytryptamine at the femtomole level in the rat and quail brain by gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry.  

PubMed

A sensitive method for the measurement of endogenous 5-methoxytryptamine in brain tissue has been developed using capillary column gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry. 5-Methoxytryptamine was first converted to N-[2H3]acetyl-5-methoxytryptamine by reaction with hexa-deuterated acetic anhydride, followed by reaction with pentafluoropropionic anhydride to yield the highly electron-capturing 3,3'-spirocyclic pentafluoro-propionyl indolenine derivative. Quantitative analysis was carried out by selected-ion monitoring of the [M-HF].- and [M-HF-DF].- ion intensity of the 3.3'-spirocyclic pentafluoropropionyl indolenine derivative, using 5-methoxy-[alpha, alpha, beta, beta-2H4]tryptamine as the internal standard. The presence of 5-methoxytryptamine in the brain tissue was demonstrated. In the absence of a monoamine oxidase inhibitor, the mean +/- S.D. levels of 5-methoxytryptamine in the rat and quail whole brain were found to be 30 +/- 6 and 347 +/- 52 pg/g, respectively. The possible physiological functions of 5-methoxytryptamine as a neuromodulator and/or neurotransmitter have to be considered. PMID:8844409

Tsang, C W; Chan, C L; Li, P; Pang, S F

1996-07-12

15

Optimized cleanup method for the determination of short chain polychlorinated n-alkanes in sediments by high resolution gas chromatography/electron capture negative ion-low resolution mass spectrometry.  

PubMed

The performances of three adsorbents, i.e. silica gel, neutral and basic alumina, in the separation of short chain polychlorinated n-alkanes (sPCAs) from potential interfering substances such as polychlorinated biphenyls (PCBs) and organochlorine pesticides were evaluated. To increase the cleanup efficiency, a two-step cleanup method using silica gel column and subsequent basic alumina column was developed. All the PCB and organochlorine pesticides could be removed by this cleanup method. The very satisfying cleanup efficiency of sPCAs has been achieved and the recovery in the cleanup method reached 92.7%. The method detection limit (MDL) for sPCAs in sediments was determined to be 14 ng g(-1). Relative standard deviation (R.S.D.) of 5.3% was obtained for the mass fraction of sPCAs by analyzing four replicates of a spiked sediment sample. High resolution gas chromatography/electron capture negative ion-low resolution mass spectrometry (HRGC/ECNI-LRMS) was used for sPCAs quantification by monitoring [M-HCl](-) ions. When applied to the sediment samples from the mouth of the Daliao River, the optimized cleanup method in conjunction with HRGC/ECNI-LRMS allowed for highly selective identifications for sPCAs. The sPCAs levels in sediment samples are reported to range from 53.6 ng g(-1) to 289.3 ng g(-1). C(10)- and C(11)-PCAs are the dominant residue in most of investigated sediment samples. PMID:21889633

Gao, Yuan; Zhang, Haijun; Chen, Jiping; Zhang, Qing; Tian, Yuzeng; Qi, Peipei; Yu, Zhengkun

2011-08-03

16

Simultaneous determination of amitraz and its metabolite residue in food animal tissues by gas chromatography-electron capture detector and gas chromatography-mass spectrometry with accelerated solvent extraction.  

PubMed

A new method has been developed for determination and confirmation of amitraz and its main metabolite, 2,4-dimethylaniline, in food animal tissues using gas chromatography-electron capture detector (GC-ECD) and gas chromatography-mass spectrometry detector (GC-MS). This method is based on a new extraction procedure using accelerated solvent extraction (ASE). It consists of an n-hexane/methanol extraction step, a cleaning-up step by BakerBond octadecyl C(18) silica bonded cartridge, hydrolysis and derivatization to 2,4-dimethyl-7-F-butyramide for GC-ECD analysis. For confirmation using GC-MS, hydrolysis and derivatization were not needed. Parameters for extraction pressure, temperature and cycle of ASE, clean-up, derivatization and analysis procedure have been optimized. Spike recoveries from 50 to 300 microg/kg levels were found to be between 72.4 and 101.3% with relative standard deviation less than 11.5% in GC-ECD, from 5 to 20 microg/kg levels were found to be between 77.4 and 107.1% with relative standard deviation less than 11.6% in GC-MS. The LOD and LOQ are 5 and 10 microg/kg, respectively, for these two analytes using GC-ECD. For GC-MS, LOD and LOQ were 2 and 5 microg/kg, respectively. The rapid and reliable method can be used for characterization and quantification of residues of amitraz and its main metabolite, 2,4-dimethylaniline, in liver and kidney samples of swine, sheep and bovine. PMID:20554255

Yu, Huan; Tao, Yanfei; Le, Tao; Chen, Dongmei; Ishsan, Awais; Liu, Yu; Wang, Yulian; Yuan, Zonghui

2010-04-29

17

Homogeneous liquid–liquid extraction combined with gas chromatography–electron capture detector for the determination of three pesticide residues in soils  

Microsoft Academic Search

In this study, a new method was developed for analyzing malathion, cypermethrin and lambda-cyhalothrin from soil samples by using homogeneous liquid–liquid extraction (HLLE) and gas chromatography with electron capture detector (GC–ECD). Acetone was used as extraction solvent for the extraction of target pesticides from soil samples. When the extraction process was finished, the target analytes in the extraction solvent were

Xuedong Wang; Xinna Zhao; Xiujuan Liu; Yanyan Li; Lingyan Fu; Jia Hu; Changjiang Huang

2008-01-01

18

Sample pretreatment optimization for the analysis of short chain chlorinated paraffins in soil with gas chromatography-electron capture negative ion-mass spectrometry.  

PubMed

Accurately quantifying short chain chlorinated paraffins (SCCPs) in soil samples with gas chromatograph coupled with electron capture negative ionization mass spectrometry (GC-ECNI-MS) is difficult because many other polychlorinated pollutants are present in the sample matrices. These pollutants (e.g., polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and toxaphene) can cause serious interferences during SCCPs analysis with GC-MS. Four main columns packed with different adsorbents, including silica gel, Florisil and alumina, were investigated in this study to determine their performance for separating interfering pollutants from SCCPs. These experimental results suggest that the optimum cleanup procedure uses a silica gel column and a multilayer silica gel-Florisil composite column. This procedure completely separated 22 PCB congeners, 23 OCPs and three toxaphene congeners from SCCPs. However, p,p'-DDD, cis-nonachlor and o,p'-DDD were not completely removed and only 53% of the total toxaphene was removed. This optimized method was successfully and effectively applied for removing interfering pollutants from real soil samples. SCCPs in 17 soil samples from different land use areas within a suburban region were analyzed with the established method. The concentrations of SCCPs in these samples were between 7 and 541 ng g(-1) (mean: 84 ng g(-1)). Similar homologue SCCPs patterns were observed between the soil samples collected from different land use areas. In addition, lower chlorinated (Cl(6/7)) C(10)- and C(11)- SCCPs were the dominant congeners. PMID:23287694

Chen, Laiguo; Huang, Yumei; Han, Shuang; Feng, Yongbin; Jiang, Guo; Tang, Caiming; Ye, Zhixiang; Zhan, Wei; Liu, Ming; Zhang, Sukun

2012-12-13

19

Determination of PCBs in Rocky Flats Type IV waste sludge by gas chromatography/electron capture detection  

SciTech Connect

Type IV Rocky Flats Plant (RFP) radioactive sludge samples must be evaluated for polychlorinated biphenyl (PCB) content before disposal. The Type IV sludge consists of organic solvents, degreasers, cutting oils, and transuranic (TRU) waste mixed with calcium silicate (MicroCel E{reg_sign}) and Oil Dri{reg_sign} to form a grease or paste-like material. For laboratory studies a nonradioactive simulated Type IV RFP sludge was prepared having a composition similar to that expected from field samples. A simplified method was developed for extraction, purification and analysis of PCBs using samples of simulated sludge spiked with Aroclors 1254 and 1260 (reports provided to Argonne indicated Aroclors 1254 and 1260 as the most likely PCB contaminants in RFP sludge samples). The developed method was compared to the Environmental Protection Agency (EPA) accepted SW-846 method for analysis of PCBs (Method 8081). The accuracy and precision data were found to be similar for the two methods. The developed method was also tested with samples of simulated sludge spiked with Pu (in solid and solution forms). Reduction of radioactivity in final extract versus in the spike sample ranged from a factor of 10{sup 5} to 10{sup 7}.

Parish, K.J.; Applegate, D.V.; Boparai, A.S.; Reedy, G.T.

1993-12-01

20

Determination of pyrethroid metabolites in human urine using liquid phase microextraction coupled in-syringe derivatization followed by gas chromatography\\/electron capture detection  

Microsoft Academic Search

Metabolites of synthetic pyrethroids such as cis-3-(2,2-dibromovinyl)-2,2-di-methylcyclo-propane-1-carboxylic acid, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid), 3-phenoxybenzoic acid (3-PBA), and 4-fluoro-3-PBA are\\u000a biomarkers for exposure to phenothrin, tetramethrin, cyfluthrin, cypermethrin, deltamethrin, and permethrin. In this study,\\u000a the pyrethroid metabolites in workers’ urine samples were monitored for the first time with a novel sample pretreatment process\\u000a combining hollow fiber liquid phase microextraction (HF-LPME) and in-syringe

Chiu-Hwa Lin; Cheing-Tong Yan; Ponnusamy Vinoth Kumar; Hong-Ping Li; Jen-Fon Jen

21

Determination of organochlorine pesticides in propolis by gas chromatography–electron capture detection using double column series solid-phase extraction  

Microsoft Academic Search

A rapid and reliable method was developed and applied for the simultaneous determination of 17 organochlorine pesticides (OCPs)\\u000a in propolis. After extraction with hexane and acetone (1:1, v\\/v), four sorbents (florisil, silica, graphitized carbon, and\\u000a tandem graphitized carbon plus florisil) were assayed for the clean-up step. The elution solvents hexane and ethyl acetate\\u000a (1:1, v\\/v), hexane and dichloromethane (3:7, v\\/v),

Fang Chen; Lanzhen Chen; Qiang Wang; Jinhui Zhou; Xiaofeng Xue; Jing Zhao

2009-01-01

22

Validated semiquantitative\\/quantitative screening of 51 drugs in whole blood as silylated derivatives by gas chromatography-selected ion monitoring mass spectrometry and gas chromatography electron capture detection  

Microsoft Academic Search

A comprehensively validated procedure is presented for simultaneous semiquantitative\\/quantitative screening of 51 drugs of abuse or drugs potentially hazardous for traffic safety in serum, plasma or whole blood. Benzodiazepines (12), cannabinoids (3), opioids (8), cocaine, antidepressants (13), antipsychotics (5) and antiepileptics (2) as well as zolpidem, zaleplon, zopiclone, meprobamate, carisoprodol, tizanidine and orphenadrine and internal standard flurazepam, were isolated by

Teemu Gunnar; Sirpa Mykkänen; Kari Ariniemi; Pirjo Lillsunde

2004-01-01

23

Liquid-liquid extraction followed by solid-phase extraction for the determination of lipophilic pesticides in beeswax by gas chromatography-electron-capture detection and matrix-matched calibration.  

PubMed

Analytical methods for the simultaneous analysis of lindane, chlorpyriphos, z-chlorfenvinphos, endosulfan A and B, 4,4'-DDE, 4,4'-TDE, acrinathrine, bromopropylate, tetradifon, coumaphos and fluvalinate in pure beeswax samples are studied. For the analysis of bleached beeswaxes, a liquid-liquid extraction with acetonitrile followed by a clean-up on polymeric cartridges is the best option in terms of recovery and precision. However, some interferences that hinder the identification and quantification of important varroacides are found when non-bleached beeswaxes are analyzed. The analysis of all compounds in the latter samples require a clean-up by coupling an ODS cartridge before the polymeric cartridge. Considerations about the influence of the matrix in the quantitative analysis by a classical external standard calibration are also made and the use of a matrix-matched calibration is advised. Recoveries resulted to be about 100% with coefficients of variation between 10% and 20% (n = 5) for concentrations of 0.5 and 5 mg/kg. PMID:15453423

Jiménez, J J; Bernal, J L; del Nozal, Ma J; Alonso, C

2004-09-01

24

Photolytic clean-up of biological samples for gas chromatographic analysis of chlorinated paraffins  

Microsoft Academic Search

A method based on gas chromatography electron capture detection (GC-ECD) for the analysis of chlorinated paraffins (CPs) in biological samples has been investigated. The method includes photolytic destruction of halogenated aromatic compounds, such as PCBs, to eliminate some of the interferences in the analysis of CPs in environmental samples. Gel permeation chromatography was used to isolate CPs from the interfering

Ulrika Fridén; Bo Jansson; Harun Parlar

2004-01-01

25

Rapid determination of dichlorodiphenyltrichloroethane and its main metabolites in aqueous samples by one-step microwave-assisted headspace controlled-temperature liquid-phase microextraction and gas chromatography with electron capture detection  

Microsoft Academic Search

A rapid and sensitive analytical method for the determination of dichlorodiphenyltrichloroethane (DDT) and its main metabolites in environmental aqueous samples has been developed using one-step microwave-assisted headspace controlled-temperature liquid-phase micro-extraction (MA-HS-CT-LPME) technique coupled with gas chromatography–electron-capture detection (GC–ECD). In this study, the one-step extraction of DDT and its main metabolites was achieved by using microwave heating to accelerate the evaporation

Ponnusamy Vinoth Kumar; Jen-Fon Jen

2011-01-01

26

Photolytic clean-up of biological samples for gas chromatographic analysis of chlorinated paraffins.  

PubMed

A method based on gas chromatography electron capture detection (GC-ECD) for the analysis of chlorinated paraffins (CPs) in biological samples has been investigated. The method includes photolytic destruction of halogenated aromatic compounds, such as PCBs, to eliminate some of the interferences in the analysis of CPs in environmental samples. Gel permeation chromatography was used to isolate CPs from the interfering components of Toxaphene and chlordane after the photolysis. GC-ECD gave a detection limit of 20 ng CPs/g fresh muscle tissue. The recovery of CPs from a spiked moose liver sample was estimated to 94%. PMID:14664836

Fridén, Ulrika; Jansson, Bo; Parlar, Harun

2004-02-01

27

Identification and determination of chlorinated paraffins using multivariate evaluation of gas chromatographic data.  

PubMed

Chlorinated paraffins (CPs) were found in the biodegradable fraction of source separated waste from Uppsala, Sweden. We identified and quantified the CPs by multivariate evaluation of gas chromatography-electron capture detection chromatograms. Using principal component analyses (PCA) we identified different types of CP-formulations and also obtain quantitative data. PCA yielded better identifications of individual CP-formulations than visual comparison of chromatograms. Partial least squares regression gave good calibration curves of the standards, but did not work for the waste samples. No source of CPs could be identified in the waste collection chain, and as the waste samples seemed to contain at least two different CP-formulations the source was probably to be found in the waste material itself. The method was used to determine CPs in additional environmental samples, demonstrating that multivariate methods may be developed into a powerful tool for identification and quantification of complex mixture. PMID:22325442

Nilsson, Marie-Louise; Bengtsson, Staffan; Kylin, Henrik

2012-01-11

28

Detection of gas leakage  

DOEpatents

A method of detecting leaks and measuring volumes as well as an apparatus, the Power-free Pump Module (PPM), that is a self-contained leak test and volume measurement apparatus that requires no external sources of electrical power during leak testing or volume measurement, where the invention is a portable, pneumatically-controlled instrument capable of generating a vacuum, calibrating volumes, and performing quantitative leak tests on a closed test system or device, all without the use of alternating current (AC) power. Capabilities include the ability is to provide a modest vacuum (less than 10 Torr), perform a pressure rise leak test, measure the gas's absolute pressure, and perform volume measurements. All operations are performed through a simple rotary control valve which controls pneumatically-operated manifold valves.

Thornberg, Steven (Peralta, NM); Brown, Jason (Albuquerque, NM)

2012-06-19

29

33 CFR 127.1203 - Gas detection.  

Code of Federal Regulations, 2013 CFR

... 2 2013-07-01 2013-07-01 false Gas detection. 127.1203 Section 127.1203 ...FACILITIES WATERFRONT FACILITIES HANDLING LIQUEFIED NATURAL GAS AND LIQUEFIED HAZARDOUS GAS Waterfront Facilities Handling Liquefied...

2013-07-01

30

A comparison of three solvent-free techniques coupled with gas chromatography for determining trihalomethanes in urine samples.  

PubMed

The analysis of volatile organic compounds in samples of biological fluids characterized by complex matrices is highly challenging. This paper presents a comparison of the results obtained in this field using three solvent-free techniques: thin-layer headspace with autogenous generation of liquid sorbent (TLHS) and membrane separation of the trace substances (pervaporation, PV), both of which are coupled to direct aqueous injection gas chromatography-electron capture detection (TLHS-DAI-GC-ECD and PV-DAI-GC-ECD), as well as conventional static headspace analysis followed by GC analysis with ECD detection (HS-GC-ECD). Basic validation parameters of the HS-GC-ECD, TLHS-DAI-GC-ECD and PV-DAI-GC-ECD procedures were calculated for water and urine samples. The calibration curves for all procedures were linear within the concentration range examined. The intermediate precisions of the procedures were good and reached about 10% (for all analytes) for HS-GC-ECD and TLHS-DAI-GC-ECD. The poorest results were obtained for PV-DAI-GC-ECD: about 20% for all analytes. The lowest method detection limits were obtained for the TLHS-DAI-GC-ECD procedure: below 0.0022 microg/L for all analytes. The enrichment factors did not differ significantly between water and urine samples, indicating little or no matrix effect in all procedures. PMID:17437090

Jakubowska, Natalia; Polkowska, Zaneta; Kujawski, Wojciech; Konieczka, Piotr; Namie?nik, Jacek

2007-04-17

31

An alternative gas-phase in vitro exposure system for toxicity testing: the interaction between nitrous oxide and A549 cells.  

PubMed

An original in vitro approach was adopted to expose cells to volatile agents. The anaesthetic nitrous oxide (N(2)O) was chosen as the model agent, and type II pneumocyte-like cells (A549 cells) were used as the target to represent the lungs. A time-lapse microscopy station was equipped with a manual gas mixer that allowed the generation of a mixture of N(2)O/air/CO(2) in the gas phase, to provide a uniform distribution of the volatile agent. The dissolution of N(2)O in the culture medium was monitored by gas chromatography-electron capture detection. Biochemical alterations, in terms of homocysteine accumulation, demonstrated that intracellular methionine synthase had been inactivated by N(2)O absorbed by the cells, a process that also occurs in vivo. Toll-like receptors, which are key molecules in inflammatory lung diseases, were also investigated at the molecular level. Our experiments indicated that biochemical and molecular alterations occurred in the cells, even under conditions where neither morphologic changes nor consistent alterations in cell proliferation were evident. This in vitro exposure system can be efficiently adopted for looking at the repeat-dose effects of volatile agents on respiratory tissues. Moreover, it could be of further benefit for identifying the wide range of specific cell targets, and for monitoring relevant endpoints in the cellular and molecular processes that occur during exposure to volatile compounds. PMID:22103938

Stellavato, Antonietta; Cammarota, Marcella; Miraglia, Nadia; Simonelli, Angela; Giuliano, Mariateresa

2011-10-01

32

Detection of bacterial growth by gas absorption.  

PubMed Central

When 24 different aerobic organisms were grown in a shaken culture, all were found to first absorb gas from the headspace. In a rudimentary medium, such as tryptic soy broth, 16 of the 24 organisms did not produce gas following the initial gas absorption. We have developed a simple, noninvasive method for detecting both gas absorption and production in multiple culture vials. The time to positivity was compared with that obtained by the BACTEC 460 blood culture system. For nearly all of these organisms, there was no difference. For some of those organisms that did not produce gas, e.g. Staphylococcus epidermidis, Moraxella osloensis, and Neisseria meningitidis, detection by gas absorption was a few hours faster. Gas absorption appears to be a promising technique for a new automated blood culture system because of its simplicity and because medium without special additives can be used to detect organisms that do not produce gas.

Waters, J R

1992-01-01

33

Rapid determination of dichlorodiphenyltrichloroethane and its main metabolites in aqueous samples by one-step microwave-assisted headspace controlled-temperature liquid-phase microextraction and gas chromatography with electron capture detection.  

PubMed

A rapid and sensitive analytical method for the determination of dichlorodiphenyltrichloroethane (DDT) and its main metabolites in environmental aqueous samples has been developed using one-step microwave-assisted headspace controlled-temperature liquid-phase micro-extraction (MA-HS-CT-LPME) technique coupled with gas chromatography-electron-capture detection (GC-ECD). In this study, the one-step extraction of DDT and its main metabolites was achieved by using microwave heating to accelerate the evaporation of analytes into the controlled-temperature headspace to form a cloudy mist vapor zone for LPME sampling. Parameters influencing extraction efficiency were thoroughly optimized, and the best extraction for DDT and its main metabolites from 10-mL aqueous sample at pH 6.0 was achieved by using 1-octanol (4-?L) as the LPME solvent, sampling at 34°C for 6.5 min under 249W of microwave irradiation. Under optimum conditions, excellent linear relationship was obtained in the range of 0.05-1.0 ?g/L for 1-dichloro-2,2-bis-(p'-chlorophenyl)ethylene (p,p'-DDE), 0.1-2.0 ?g/L for o,p'-DDT, 0.15-3.0 ?g/L for 1,1-dichloro-2,2-bis-(p'-chlorophenyl)ethane (p,p'-DDD) and p,p'-DDT, with detection limits of 20 ng/L for p,p'-DDE, and 30 ng/L for o,p'-DDT, p,p'-DDD and p,p'-DDT. Precision was in the range of 3.2-11.3% RSD. The proposed method was validated with environmental water samples. The spiked recovery was between 95.5% and 101.3% for agricultural-field water, between 94% and 99.7% for sea water and between 93.5% and 98% for river water. Thus the established method has been proved to be a simple, rapid, sensitive, inexpensive and eco-friendly procedure for the determination of DDT and its main metabolites in environmental water samples. PMID:21251695

Vinoth Kumar, Ponnusamy; Jen, Jen-Fon

2011-01-19

34

Microwave radar detection of gas pipeline leaks  

Microsoft Academic Search

We are developing a microwave radar sensing and imaging system to detect and locate gas leaks in natural gas pipelines. The underlying detection principle is radar backscattering from the index-of-refraction inhomogeneities introduced by the dispersion of methane in air. An essential first step in the development effort is modeling to estimate the radar cross section. This paper describes the modeling

N. Gopalsami; D. B. Kanareykin; V. D Asanov; S. Bakhtiari; A. C. Raptis

2002-01-01

35

Microwave Radar Detection of Gas Pipeline Leaks  

Microsoft Academic Search

We are developing a microwave radar sensing and imaging system to detect and locate gas leaks in natural gas pipelines. The underlying detection principle is radar backscattering from the index-of-refraction inhomogeneities introduced by the dispersion of methane in air. An essential first step in the development effort is modeling to estimate the radar cross section. This paper describes the modeling

N. Gopalsami; D. B. Kanareykin; V. Asanov; S. Bakhtiari; A. C. Raptis

2003-01-01

36

System and method for detecting gas  

DOEpatents

A system to detect a presence of a specific gas in a mixture of gaseous byproducts comprising moisture vapor is disclosed. The system includes an electrochemical cell, a transport to deliver the mixture of gaseous byproducts from the electrochemical cell, a gas sensor in fluid communication with the transport, the sensor responsive to a presence of the specific gas to generate a signal corresponding to a concentration of the specific gas, and a membrane to prevent transmission of liquid moisture, the membrane disposed between the transport and the gas sensor.

Chow, Oscar Ken (Simsbury, CT); Moulthrop, Lawrence Clinton (Windsor, CT); Dreier, Ken Wayne (Madison, CT); Miller, Jacob Andrew (Dexter, MI)

2010-03-16

37

Method for detecting gas turbine engine flashback  

SciTech Connect

A method for monitoring and controlling a gas turbine, comprises predicting frequencies of combustion dynamics in a combustor using operating conditions of a gas turbine, receiving a signal from a sensor that is indicative of combustion dynamics in the combustor, and detecting a flashback if a frequency of the received signal does not correspond to the predicted frequencies.

Singh, Kapil Kumar; Varatharajan, Balachandar; Kraemer, Gilbert Otto; Yilmaz, Ertan; Lacy, Benjamin Paul

2012-09-04

38

Microwave radar detection of gas pipeline leaks.  

SciTech Connect

We are developing a microwave radar sensing and imaging system to detect and locate gas leaks in natural gas pipelines. The underlying detection principle is radar backscattering from the index-of-refraction inhomogeneities introduced by the dispersion of methane in air. An essential first step in the development effort is modeling to estimate the radar cross section. This paper describes the modeling results and the experimental efforts underway to validate the model. For the case of leaks from small holes in a pressurized gas pipeline, we modeled the gas dynamics of the leak jet to determine the plume geometry and the variation of methane concentration in air as a function of distance from the leak source. From the static and dynamic changes in the index of refraction in the turbulent plume, the radar backscatter cross sections were calculated. The results show that the radar cross sections of the leak plumes should be detectable by special-purpose radars.

Gopalsami, N.; Kanareykin, D. B.; Asanov, V. D; Bakhtiari, S.; Raptis, A. C.

2002-10-02

39

Detection of gas atoms with carbon nanotubes  

PubMed Central

Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

Arash, B.; Wang, Q.

2013-01-01

40

Detectivity of gas leakage based on electromagnetic radiation transfer  

Microsoft Academic Search

Standoff detection of gas leakage is a fundamental need in petrochemical and power industries. The passive gas imaging system using thermal imager has been proven to be efficient to visualize leaking gas which is not visible to the naked eye. The detection probability of gas leakage is the basis for designing a gas imaging system. Supposing the performance parameters of

Yunting Long; Lingxue Wang; Jiakun Li; Changxing Zhang; Bei Zhang

2011-01-01

41

46 CFR 154.1350 - Flammable gas detection system.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Flammable gas detection system. 154.1350 Section...SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Instrumentation § 154.1350 Flammable gas detection system. (a) The...

2009-10-01

42

46 CFR 154.1350 - Flammable gas detection system.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Flammable gas detection system. 154.1350 Section...SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Instrumentation § 154.1350 Flammable gas detection system. (a) The...

2010-10-01

43

A photoacoustic spectrometer for trace gas detection  

NASA Astrophysics Data System (ADS)

A high-resolution external laser photoacoustic spectrometer has been developed for trace gas detection with absorption transitions in coincidence with CO2 laser emission lines (9,2-10,9 ?m: 920-1086 cm-1). The CO2 laser operates in 90 CW lines with power of up to 15 W. A PC-controlled step motor can tune the laser lines. The resonance frequency of first longitudinal mode of the photoacoustic cell is at 1600 Hz. The cell Q-factor and cell constant are measured close to 50 and 28 mVcmW-1, respectively. The spectrometer has been tested in preliminary studies to analyze the absorption transitions of ozone (O_3). The ethylene (C_2H_4) from papaya fruit is also investigated using N2 as carrier gas at a constant flow rate.

Telles, E. M.; Bezerra, E.; Scalabrin, A.

2005-06-01

44

Sensor array for toxic gas detection  

DOEpatents

A portable instrument for use in the field in detecting and identifying a hazardous component in air or other gas including an array of small sensors which upon exposure to the gas from a pattern of electrical responses, a source of standard response patterns characteristic of various components, and microprocessor means for comparing the sensor-formed response pattern with one or more standard patterns to thereby identify the component on a display. The number of responses may be increased beyond the number of sensors by changing the operating voltage, temperature or other condition associated with one or more sensors to provide a plurality of responses from each of one or more of the sensors. In one embodiment, the instrument is capable of identifying anyone of over 50-100 hazardous components.

Stetter, Joseph R. (Naperville, IL); Zaromb, Solomon (Hinsdale, IL); Penrose, William R. (Naperville, IL)

1987-01-01

45

Development of a sample preparation method for the analysis of current-use pesticides in sediment using gas chromatography.  

PubMed

Pyrethroid insecticides have been implicated as the cause of sediment toxicity to Hyalella azteca in both agricultural and urban areas of California; however, for a subset of these toxic sediments (approximately 30%), the cause of toxicity remains unidentified. This article describes the analytical method development for seven additional pesticides that are being examined to determine if they might play a role in the unexplained toxicity. A pressurized liquid extraction method was optimized to simultaneously extract diazinon, methyl parathion, oxyfluorfen, dicofol, fenpropathrin, pyraclostrobin, and indoxacarb from sediment, and the extracts were cleaned using a two-step solid-phase extraction procedure. The final extract was analyzed for the target pesticides by gas chromatography/nitrogen-phosphorus detector (GC/NPD), and gas chromatography/electron capture detector (GC/ECD), after sulfur was removed by shaking with copper and cold crystallization. Three sediments were used as reference matrices to assess method accuracy and precision. Method detection limits were 0.23-1.8 ng/g dry sediment using seven replicates of sediment spiked at 1.0 ng/g dry sediment. Recoveries ranged from 61.6 to 118% with relative standard deviations of 2.1-17% when spiked at 5.0 and 50 ng/g dry sediment. The three reference sediments, spiked with 50 ng/g dry weight of the pesticide mixture, were aged for 0.25, 1, 4, 7, and 14 days. Recoveries of the pesticides in the sediments generally decreased with increased aging time, but the magnitude of the decline was pesticide and sediment dependent. The developed method was applied to field-collected sediments from the Central Valley of California. PMID:19798461

Wang, Dongli; Weston, Donald P; Ding, Yuping; Lydy, Michael J

2009-10-02

46

IMPLEMENTATION OF OPTICAL TECHNOLOGIES FOR PORTABLE GAS LEAK DETECTION  

Microsoft Academic Search

Collaboration has been the key to the successful development of an optically based instrument, that provides an unconventional approach to remote gas leak detection. The VOGUE project (Visualisation Of Gas for Utilities and the Environment) was a EC co- funded development that involved representatives of four gas utilities, two universities and four technology providers. To improve our understanding of gas

Russ Pride; Jane Hodgkinson; Stuart Murray

47

Leak Detection Using A Nitrogen-Helium Gas System  

Microsoft Academic Search

A combined nitrogen purge and helium leak-detection system has been developed to safely pressure test and commission oil and gas process equipment. The system is able to detect leaks of a much lower magnitude than conventional leak detection systems and it offers several advantages over conventional hydrostatic testing. Inert nitrogen gas (used as the pressurizing medium) also safely purges the

R. E. Cooper

1988-01-01

48

46 CFR 154.1350 - Flammable gas detection system.  

Code of Federal Regulations, 2011 CFR

...flammable gas detection system must have enough flame arrestors for all gas sampling lines to prevent flame propagation to the spaces served by the system...known concentration. (r) The calibration test procedure and type and concentration of...

2011-10-01

49

Naturally fractured tight gas reservoir detection optimization. Final report.  

National Technical Information Service (NTIS)

This DOE-funded research into seismic detection of natural fractures is one of six projects within the DOE's Detection and Analysis of Naturally Fractured Gas Reservoirs Program, a multidisciplinary research initiative to develop technology for prediction...

1997-01-01

50

ENVIRONMENTAL APPLICATION OF GAS CHROMATOGRAPHY/ATOMIC EMISSION DETECTION  

EPA Science Inventory

A gas chromatography/atomic emission detector (GC/AED) system has been evaluated for its applicability to environmental analysis. Detection limits, elemental response factors, and regression analysis data were determined for 58 semivolatile environmental contaminants. Detection l...

51

Detectivity of gas leakage based on electromagnetic radiation transfer  

NASA Astrophysics Data System (ADS)

Standoff detection of gas leakage is a fundamental need in petrochemical and power industries. The passive gas imaging system using thermal imager has been proven to be efficient to visualize leaking gas which is not visible to the naked eye. The detection probability of gas leakage is the basis for designing a gas imaging system. Supposing the performance parameters of the thermal imager are known, the detectivity based on electromagnetic radiation transfer model to image gas leakage is analyzed. This model takes into consideration a physical analysis of the gas plume spread in the atmosphere-the interaction processes between the gas and its surrounding environment, the temperature of the gas and the background, the background surface emissivity, and also gas concentration, etc. Under a certain environmental conditions, through calculating the radiation reaching to the detector from the camera's optical field of view, we obtain an entity "Gas Equivalent Blackbody Temperature Difference (GEBTD)" which is the radiation difference between the on-plume and off-plume regions. Comparing the GEBTD with the Noise Equivalent Temperature Difference (NETD) of the thermal imager, we can know whether the system can image the gas leakage. At last, an example of detecting CO2 gas by JADE MWIR thermal imager with a narrow band-pass filter is presented.

Long, Yunting; Wang, Lingxue; Li, Jiakun; Zhang, Changxing; Zhang, Bei

2011-05-01

52

Determination of polyethylene glycols of different molecular weight in the stratum corneum  

Microsoft Academic Search

We developed a sensitive method for determination of polyethylene glycols (PEGs) of different molecular weight (MW) in the human stratum corneum (SC) obtained by tape stripping. The analysis is based on derivatization with pentafluoropropionic anhydride (PFPA) and gas chromatography–electron capture detection (GC–ECD). The identification and quantification of PEGs was done using individual oligomers. The method showed to be suitable for

I. Jakasa; F. Calkoen; S. Kezic

2004-01-01

53

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR ANALYSIS OF PESTICIDE SAMPLES BY GC/ECD (BCO-L-24.0)  

EPA Science Inventory

The purpose of this SOP is to describe the methods used for detection and quantification by gas chromatography electron capture detector (GC/ECD) of pesticides in a variety of matrices, including air, house dust, soil, handwipes, and surface wipes. Other SOP's detail the extract...

54

Validation of proton transfer reaction-mass spectrometry (PTR-MS) measurements of gas-phase organic compounds in the atmosphere during the New England Air Quality Study (NEAQS) in 2002  

NASA Astrophysics Data System (ADS)

Organic compounds were measured by proton transfer reaction-mass spectrometry (PTR-MS) on board the National Oceanic and Atmospheric Administration's research ship Ronald H. Brown during the New England Air Quality Study (NEAQS) in July and August of 2002. PTR-MS has the potential to measure many important organic species with a fast time response, but its validity has not been proven sufficiently. The results obtained by PTR-MS during NEAQS were compared with those from (oxygenated) hydrocarbon measurements by gas chromatography/mass spectrometry (GC-MS), peroxyacyl nitrate measurements by gas chromatography/electron capture detection, and carboxylic acid measurements by mist chamber/ion chromatography. The PTR-MS and GC-MS data for methanol, acetonitrile, acetone, isoprene, benzene, and toluene agreed within the measurement uncertainties. The comparison for C8 aromatics and acetaldehyde was less quantitative due to calibration inaccuracies. In addition, PTR-MS measured the sum of methyl vinyl ketone and methacrolein at 71 amu, the sum of C9 aromatics at 121 amu, and the sum of monoterpenes at 81 and 137 amu. The PTR-MS signal at 61 amu was found to correlate well with data for acetic acid. The signal at 73 amu correlated reasonably well with methyl ethyl ketone data, but the quantitative disagreement suggested interference from other species, possibly methyl glyoxal. The signal at 77 amu correlated well with data for peroxyacetyl nitrate, and the sensitivity inferred from the field data agreed within 30% with the results from laboratory calibrations. Finally, the signal at 105 amu was attributed to styrene and peroxy isobutyryl nitrate. These results prove that many important organic species can be measured accurately and with a fast response time by PTR-MS.

de Gouw, J. A.; Goldan, P. D.; Warneke, C.; Kuster, W. C.; Roberts, J. M.; Marchewka, M.; Bertman, S. B.; Pszenny, A. A. P.; Keene, W. C.

2003-11-01

55

Gas pipeline leak detection system using the online simulation method  

Microsoft Academic Search

Management of natural gas pipeline is an important task for economical and safety operation, loss prevention and environmental protection from methane emission. A leak detection of gas pipeline, therefore, plays a key role in the overall integrity management for a pipeline system. Especially for a long pipeline operated alongside of densely populated areas, a leak detection system is an indispensable

Reiko Maeshima; Akira Kinoshita; Hitoshi Shiraishi; Ichiro Koshijima

2000-01-01

56

Detection of a simulated gas leak in a wind tunnel  

NASA Astrophysics Data System (ADS)

This paper brings together considerations of gas leak behaviour and leak detector design and use, with a view to improving the detection of low-pressure natural gas leaks. An atmospheric boundary layer wind tunnel has been used to study ground-based releases of methane at full scale over distances of up to 3 m, under controlled conditions. These scales are relevant to the detection of natural gas leaks from mains and services using hand-portable gas detectors. The mean spatial distribution of the leaking gas plume was determined and used to test and fit a Gaussian dispersion model. This was used for subsequent analysis with respect to the ability of gas leak detectors to confirm and locate a leak. For ground-based leaks, gas concentrations drop rapidly with height such that instruments should ideally sample the air from within 100 mm of ground level. The rapid dilution of gas with distance from the source means that instruments with lower limits of detection, ideally of a few parts per million, have much improved ability to detect a leak from greater distances downwind. Finally, observations showed the variable temporal nature of the gas and the potential for confusion when sampling gas at a single point in time and space.

Hodgkinson, J.; Shan, Q.; Pride, R. D.

2006-06-01

57

Comparison of the limulus amebocyte lysate test and gas chromatography-mass spectrometry for measuring lipopolysaccharides (endotoxins) in airborne dust from poultry-processing industries.  

PubMed Central

The lipopolysaccharide (endotoxin) content in airborne dust samples from three different poultry slaughterhouses was determined with both the chromogenic Limulus amebocyte lysate assay and gas chromatography-mass spectrometry analysis of lipopolysaccharide-derived 3-hydroxy fatty acids. Gram-negative cell walls were also measured by using two-dimensional gas chromatography/electron-capture analysis of diaminopimelic acid originating from the peptidoglycan. The correlation between the results of the Limulus assay and those of gas chromatography-mass spectrometry for determination of the lipopolysaccharide content in the dust samples was poor, whereas a good correlation was obtained between lipopolysaccharide and diaminopimelic acid concentrations with the gas chromatographic methods. The results suggest that it is predominantly cell-wall-dissociated lipopolysaccharides that are measured with the Limulus assay, whereas the gas chromatographic methods allow determination of total concentrations of lipopolysaccharide, including Limulus-inactive lipopolysaccharide, gram-negative cells, and cellular debris.

Sonesson, A; Larsson, L; Schutz, A; Hagmar, L; Hallberg, T

1990-01-01

58

Comparison of the limulus amebocyte lysate test and gas chromatography-mass spectrometry for measuring lipopolysaccharides (endotoxins) in airborne dust from poultry-processing industries.  

PubMed

The lipopolysaccharide (endotoxin) content in airborne dust samples from three different poultry slaughterhouses was determined with both the chromogenic Limulus amebocyte lysate assay and gas chromatography-mass spectrometry analysis of lipopolysaccharide-derived 3-hydroxy fatty acids. Gram-negative cell walls were also measured by using two-dimensional gas chromatography/electron-capture analysis of diaminopimelic acid originating from the peptidoglycan. The correlation between the results of the Limulus assay and those of gas chromatography-mass spectrometry for determination of the lipopolysaccharide content in the dust samples was poor, whereas a good correlation was obtained between lipopolysaccharide and diaminopimelic acid concentrations with the gas chromatographic methods. The results suggest that it is predominantly cell-wall-dissociated lipopolysaccharides that are measured with the Limulus assay, whereas the gas chromatographic methods allow determination of total concentrations of lipopolysaccharide, including Limulus-inactive lipopolysaccharide, gram-negative cells, and cellular debris. PMID:2187411

Sonesson, A; Larsson, L; Schütz, A; Hagmar, L; Hallberg, T

1990-05-01

59

Dynamic photoacoustic spectroscopy for trace gas detection  

NASA Astrophysics Data System (ADS)

We present a method of photoacoustic spectroscopy in which a laser beam tuned to an absorption feature of a gas is swept through its plume at the speed of sound. The resulting coherent addition of acoustic waves leads to an amplification of the signal without the need for a resonant chamber, thus enhancing the ability to remotely sense the gas. We demonstrate the concept using a tunable CO2 laser and SF6 gas in conjunction with a microphone. Sound pressure levels of 83 dB (relative to 20 ?Pa) are generated from a 15-ppm plume.

Wynn, C. M.; Palmacci, S.; Clark, M. L.; Kunz, R. R.

2012-10-01

60

Brief: Acoustic gas-kick detection with wellhead sonar  

SciTech Connect

The capability to detect gas kicks (gas influxes into a borehole) quickly as the borehole is being drilled is of the utmost importance for drilling safety and efficiency. In this paper a novel kick-detection system based on an acoustic pulse-echo technique is described. Computer simulations and full-scale experimental results show that this system can detect small gas influxes (typically < 1 bbl) at depths as great as 16,400 ft. The system, which has surface-based equipment, functions irrespective of mud circulation.

Bang, J.; Mjaaland, S. [IKU Petroleum Research, Trondheim (Norway); Hendriks, P. [Shell Research, Rijswijk (Netherlands); Jensen, L.K.

1995-02-01

61

Detection of Greenhouse-Gas-Induced Climatic Change.  

National Technical Information Service (NTIS)

The objective of this report is to assemble and analyze instrumental climate data and to develop and apply climate models as a basis for (1) detecting greenhouse-gas-induced climatic change, and (2) validation of General Circulation Models.

P. D. Jones T. M. L. Wigley

1998-01-01

62

Leak Detection and Location in Gas Pipelines. Appendix 2, .  

National Technical Information Service (NTIS)

Describes a new theoretical method for detecting and locating leaks in long pipelines, based on an extended Kalman filter for the nonlinear Distributed Parameter (DP) system representing gas flow in pipes. Artificial leak states at predefined positions al...

A. Benkherouf A. Y. Allidina

1985-01-01

63

Naturally fractured tight gas reservoir detection optimization  

SciTech Connect

Building upon the partitioning of the Greater Green River Basin (GGRB) that was conducted last quarter, the goal of the work this quarter has been to conclude evaluation of the Stratos well and the prototypical Green River Deep partition, and perform the fill resource evaluation of the Upper Cretaceous tight gas play, with the goal of defining target areas of enhanced natural fracturing. The work plan for the quarter of November 1-December 31, 1998 comprised four tasks: (1) Evaluation of the Green River Deep partition and the Stratos well and examination of potential opportunity for expanding the use of E and P technology to low permeability, naturally fractured gas reservoirs, (2) Gas field studies, and (3) Resource analysis of the balance of the partitions.

NONE

1999-06-01

64

Semiconductor laser source for natural gas leak detection  

Microsoft Academic Search

The feasibility of using semiconductor lasers as infrared sources for handheld natural gas leak detectors was assessed. The detection system was assumed to be based on the differential absorption (DIAL) technique and to operate at ambient temperatures. The absorption spectra of the major components of natural gas, methane and ethane, were measured in the spectral range from 1.2 to 2.0

R. A. Elliott

1985-01-01

65

46 CFR 154.1345 - Gas detection.  

Code of Federal Regulations, 2010 CFR

...c) A vessel that carries methyl bromide or sulfur dioxide must have a fixed...d) A vessel that carries sulfur dioxide must have a fixed gas...on a vessel that carries methyl bromide or sulfur dioxide must be set at...

2010-10-01

66

46 CFR 154.1345 - Gas detection.  

Code of Federal Regulations, 2010 CFR

...c) A vessel that carries methyl bromide or sulfur dioxide must have a fixed...d) A vessel that carries sulfur dioxide must have a fixed gas...on a vessel that carries methyl bromide or sulfur dioxide must be set at...

2009-10-01

67

Development of Trace Gas Detection Instrumentation.  

National Technical Information Service (NTIS)

Breadboard hardware was constructed to demonstrate detection of a gaseous species by the heterodyne principle. The characteristics of the component parts were investigated and preliminay measurements were made to establish the sensitivity and selectivity ...

1973-01-01

68

Ultrasonic gas accumulation detection and evaluation in nuclear cooling pipes  

NASA Astrophysics Data System (ADS)

This paper presents a novel ultrasonic guided wave based inspection methodology for detecting and evaluating gas accumulation in nuclear cooling pipe system. The sensing is in-situ by means of low-profile permanently installed piezoelectric wafer sensors to excite interrogating guided waves and to receive the propagating waves in the pipe structure. Detection and evaluation is established through advanced cross time-frequency analysis to extract the phase change in the sensed signal when the gas is accumulating. A correlation between the phase change and the gas amount has been established to provide regulatory prediction capability based on measured sensory data.

Yu, Lingyu; Lin, Bin; Shin, Yong-June; Wang, Jingjiang; Tian, Zhenhua

2012-03-01

69

Detection system for a gas chromatograph  

DOEpatents

A method and apparatus are described for the quantitative analysis of vaporizable compounds, and in particular of polycyclic aromatic hydrocarbons which may be induced to fluoresce. The sample to be analyzed is injected into a gas chromatography column and is eluted through a narrow orifice into a vacuum chamber. The free expansion of the eluted sample into the vacuum chamber creates a supersonic molecular beam in which the sample molecules are cooled to the extent that the excited vibrational and rotational levels are substantially depopulated. The cooled molecules, when induced to fluoresce by laser excitation, give greatly simplified spectra suitable for analytical purposes. The laser induced fluorimetry provides great selectivity, and the gas chromatograph provides quantitative transfer of the sample to the molecular beam.

Hayes, John M. (Ames, IA); Small, Gerald J. (Ames, IA)

1984-01-01

70

Naturally fractured tight gas reservoir detection optimization  

SciTech Connect

During this quarter, work began on the regional structural and geologic analysis of the greater Green River basin (GGRB) in southwestern Wyoming, northwestern Colorado and northeastern Utah. The ultimate objective of the regional analysis is to apply the techniques developed and demonstrated during earlier phases of the project to sweet-spot delineation in a relatively new and underexplored play: tight gas from continuous-type Upper Cretaceous reservoirs of the GGRB. The primary goal of this work is to partition and high-grade the greater Green River basin for exploration efforts in the Cretaceous tight gas play. The work plan for the quarter of January 1, 1998--March 31, 1998 consisted of three tasks: (1) Acquire necessary data and develop base map of study area; (2) Process data for analysis; and (3) Initiate structural study. The first task and second tasks were completed during this reporting period. The third task was initiated and work continues.

NONE

1998-09-30

71

Gas imaging detectivity model combining leakage spot size and range  

NASA Astrophysics Data System (ADS)

As to visualize the leaking gas cloud which is not visible to the naked eyes, three categories of techniques have emerged, Backscatter Absorption Gas Imaging, Passive Thermal Imaging, and Imaging Spectrometer. Among these systems, Signal to Noise Ratio (SNR) is generally used to deduce gas leakage detection limit and leads to several performance evaluation parameters, such as Noise-Equivalent Spectral Radiance and Noise-Equivalent Concentration-Path Length. However, in most cases, measuring the SNR accurately is not accessible and usually needs auxiliary instruments. Therefore, we focus on researching a gas leakage detection model according to the general parameter of a thermal imager, Noise Equivalent Temperature Difference (NETD). Firstly, the Gas Equivalent Blackbody Temperature Difference (GEBTD) is obtained by calculating the attenuated radiation of the On-plume path and that of the Off-plume path respectively. A simplified form of GEBTD was derived by our previous paper, assuming that the work range was short and the affection of atmospheric transmission was omitted. But in this paper, more factors are considered to establish a more realistic and accurate detectivity model. The radiation of the gas cloud and the attenuation of the atmosphere are taken into account as well as the size of the leakage spot which inevitably affects the concentration path length. Secondly, the NETD and the GEBTD are compared to determine the detection capability. At last, an experiment is designed to verify the accuracy and reliability of this model on the basis of the gas cloud concentration cone distribution model.

Li, Jiakun; Wang, Lingxue; Wang, Meirong; Gao, Yue; Jin, Weiqi

2012-05-01

72

Naturally fractured tight gas reservoir detection optimization  

SciTech Connect

In March, work continued on characterizing probabilities for determining natural fracturing associated with the GGRB for the Upper Cretaceous tight gas plays. Structural complexity, based on potential field data and remote sensing data was completed. A resource estimate for the Frontier and Mesa Verde play was also completed. Further, work was also conducted to determine threshold economics for the play based on limited current production in the plays in the Wamsutter Ridge area. These analyses culminated in a presentation at FETC on 24 March 1999 where quantified natural fracture domains, mapped on a partition basis, which establish ''sweet spot'' probability for natural fracturing, were reviewed. That presentation is reproduced here as Appendix 1. The work plan for the quarter of January 1, 1999--March 31, 1999 comprised five tasks: (1) Evaluation of the GGRB partitions for structural complexity that can be associated with natural fractures, (2) Continued resource analysis of the balance of the partitions to determine areas with higher relative gas richness, (3) Gas field studies, (4) Threshold resource economics to determine which partitions would be the most prospective, and (5) Examination of the area around the Table Rock 4H well.

NONE

1999-04-30

73

Detection of individual gas molecules adsorbed on graphene  

Microsoft Academic Search

The ultimate aim of any detection method is to achieve such a level of sensitivity that individual quanta of a measured entity can be resolved. In the case of chemical sensors, the quantum is one atom or molecule. Such resolution has so far been beyond the reach of any detection technique, including solid-state gas sensors hailed for their exceptional sensitivity.

F. Schedin; A. K. Geim; S. V. Morozov; E. W. Hill; P. Blake; M. I. Katsnelson; K. S. Novoselov

2007-01-01

74

Detection of Individual Gas Molecules Absorbed on Graphene  

Microsoft Academic Search

The ultimate aspiration of any detection method is to achieve such a level of sensitivity that individual quanta of a measured value can be resolved. In the case of chemical sensors, the quantum is one atom or molecule. Such resolution has so far been beyond the reach of any detection technique, including solid-state gas sensors hailed for their exceptional sensitivity.

F. Schedin; A. K. Geim; S. V. Morozov; D. Jiang; E. H. Hill; P. Blake; K. S. Novoselov

2006-01-01

75

Portable chemical gas sensor prototype for nitroaromatic compounds detection  

Microsoft Academic Search

This paper presents the conception and the development of portable gas sensor prototypes for nitroaromatic compounds detection. It is based on quartz crystal microbalance (QCM) principle and a data processing. The sensitive material is a polymer which was chosen for its good sensibility and robustness. This prototype is able to detect 3 ppm of nitroaromatic compound with a high selectivity.

F. Thery-Merland; P. Montmeat; E. Pasquinet; L. Hairault

2004-01-01

76

Fire detection in coal mines based on semiconductor gas sensors  

Microsoft Academic Search

Purpose – Due to the environmental conditions, the detection and identification of hazardous situations in coal mines is a challenge. The purpose of this research is to focus on the underground fire detection, especially of smoldering fires, which are characterized by the outgassing of CO and C2H4. Design\\/methodology\\/approach – The study developed a system based on a single semiconductor gas

Peter Reimann; Andreas Schütze

2012-01-01

77

Detection of gas leaks in the subsurface environment  

NASA Astrophysics Data System (ADS)

Leaking valves, connections and distribution pipelines are significant sources of fugitive gas and volatile chemical emissions in chemical manufacturing, gas production, transmission, and oil refineries. A gas leak detection method has been developed based on continuous monitoring of the oxygen concentration surrounding a natural gas pipeline. The method utilizes optical fibers coated with an oxygen permeable polymeric film containing a luminescent sensor molecule. When the specialty fiber is illuminated by a light source that excites the luminophor, the functional cladding compound has the ability to detect and quantify leaks by measuring small changes in oxygen concentrations in the surrounding environment. Key features of the technology include long-term performance based on well understood platinum porphyrin chemistry, in addition to the capability of distributed sensing using fiber optic evanescent field spectroscopy. Results of leak detection in various environments namely atmospheric conditions, dry sand as well as saturated sand is reported, along with test results on long term system performance.

Ghandehari, Masoud; Khalil, Gamal; Kimura, Fletcher

2005-05-01

78

Research on airborne infrared leakage detection of natural gas pipeline  

NASA Astrophysics Data System (ADS)

An airborne laser remote sensing technology is proposed to detect natural gas pipeline leakage in helicopter which carrying a detector, and the detector can detect a high spatial resolution of trace of methane on the ground. The principle of the airborne laser remote sensing system is based on tunable diode laser absorption spectroscopy (TDLAS). The system consists of an optical unit containing the laser, camera, helicopter mount, electronic unit with DGPS antenna, a notebook computer and a pilot monitor. And the system is mounted on a helicopter. The principle and the architecture of the airborne laser remote sensing system are presented. Field test experiments are carried out on West-East Natural Gas Pipeline of China, and the results show that airborne detection method is suitable for detecting gas leak of pipeline on plain, desert, hills but unfit for the area with large altitude diversification.

Tan, Dongjie; Xu, Bin; Xu, Xu; Wang, Hongchao; Yu, Dongliang; Tian, Shengjie

2011-11-01

79

Detect, troubleshoot gas-turbine blade failures  

SciTech Connect

Approximately 40% of all gas-turbine failures stem from blading problems. This article describes state-of-the-art condition monitoring technologies that can help avoid or minimize the damage, and troubleshoot failures when they occur. In today`s gas-turbine (GT) fleet, predominant blade-failure mechanism and commonly affected components include: low-cycle fatigue--compressor and turbine disks; high-cycle fatigue--compressor and turbine blades and disks, compressor stator vanes; thermal fatigue--nozzles, combustors; environmental attack, such as oxidation, sulfidation, hot corrosion, and standby corrosion--hot-section blades and stators, transition pieces, and combustors; creep damage--hot-section nozzles and blades; erosion and wear; impact overload damage; thermal aging; combined failure mechanisms, such as creep/fatigue corrosion/fatigue, oxidation/erosion, and so on. Avoiding GT blade problems requires that two conditions be met: first, and most important, the basic design has to be sound, with adequate safety factors incorporates. Second, the proper operating regime must be maintained. Properly applied, condition monitoring can help maintain the operating regime and minimize blade distress. Should blade failures occur, data captured in a monitoring program may provide valuable clues to help identify the root causes. Reviewed here are the latest GT condition monitoring techniques, as well as several case histories that illustrate their importance.

Meher-Homji, C.B. [Boyce Engineering International Inc., Houston, TX (United States)

1995-12-01

80

Metal oxide nanostructures for gas detection  

NASA Astrophysics Data System (ADS)

Currently, most of gas sensors on the market are produced in thin or thick film technologies with the use of ceramic substrates. It is expected that the miniature sensors needed in portable applications will be based on one-dimensional structures due to their low power consumption, fast and stable time response, small dimensions and possibility of embedding in integrated circuit together with signal conditioning electronics. The authors manufactured resistance type gas sensors based on ZnO and WO3 nanostructures. ZnO:Al nanorods with good cristallinity were obtained with electrodeposition method, while ZnO:Al nanofibres with varying diameters were obtained by electrospinning method. The sensors were built as a nanowire network. WO3 films with nanocrystalline surface were manufactured by deposition of a three layer WO3/W/WO3 structure by RF sputtering and successive annealing of the structure in appropriate temperature range. In effect a uniform nanostructurized metal oxide layer was formed. Investigation of sensors characteristics revealed good sensitivity to nitrogen dioxide at temperatures lower than these for conventional conductometric type sensors.

Maziarz, Wojciech; Pisarkiewicz, Tadeusz; Rydosz, Artur; Wysocka, Kinga; Czyrnek, Grzegorz

2013-07-01

81

Temperature detection in a gas turbine  

SciTech Connect

A temperature detector includes a first metal and a second metal different from the first metal. The first metal includes a plurality of wires and the second metal includes a wire. The plurality of wires of the first metal are connected to the wire of the second metal in parallel junctions. Another temperature detector includes a plurality of resistance temperature detectors. The plurality of resistance temperature detectors are connected at a plurality of junctions. A method of detecting a temperature change of a component of a turbine includes providing a temperature detector include ing a first metal and a second metal different from the first metal connected to each other at a plurality of junctions in contact with the component; and detecting any voltage change at any junction.

Lacy, Benjamin; Kraemer, Gilbert; Stevenson, Christian

2012-12-18

82

Gas Transport and Detection Following Underground Nuclear Explosions  

NASA Astrophysics Data System (ADS)

Some extremely rare radioactive noble gases are by-products of underground nuclear explosions, and the detection of significant levels of these gases (e.g., Xe-133 and Ar-37) at the surface is a very strong indicator of the occurrence of an underground nuclear event. Because of their uniqueness, such noble gas signatures can be confirmatory of the nuclear nature of an event while signatures from other important detection methods, such as anomalous seismicity, are generally not. As a result, noble gas detection at a suspected underground nuclear test site is considered to be the most important technique available to inspectors operating under the On-Site-Inspection protocol of the Comprehensive Nuclear Test Ban Treaty. A one-kiloton chemical underground explosion, the Non-Proliferation Experiment (NPE), was carried out at the Nevada Test Site in 1993 and represented the first On-Site-Inspection oriented test of subsurface gas transport with subsequent detection at the surface using soil gas sampling methods. A major conclusion of the experiment was that noble gases from underground nuclear tests have a good possibility of being detected even if the test is well contained. From this experiment and from computer simulations, we have also learned significant lessons about the modes of gas transport to the surface and the importance of careful subsurface sampling to optimize the detected noble gas signature. Understanding transport and sampling processes for a very wide range of geologic and testing scenarios presents significant challenges that we are currently addressing using sensitivity studies, which we attempt to verify using experiments such as the NPE and a new subsurface gas migration experiment that is now being undertaken at the National Center for Nuclear Security. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Carrigan, C. R.; Sun, Y.; Wagoner, J. L.; Zucca, J. J.

2011-12-01

83

Naturally fractured tight gas reservoir detection optimization  

SciTech Connect

The work plan for October 1, 1997 to September 30, 1998 consisted of investigation of a number of topical areas. These topical areas were reported in four quarterly status reports, which were submitted to DOE earlier. These topical areas are reviewed in this volume. The topical areas covered during the year were: (1) Development of preliminary tests of a production method for determining areas of natural fracturing. Advanced Resources has demonstrated that such a relationship exists in the southern Piceance basin tight gas play. Natural fracture clusters are genetically related to stress concentrations (also called stress perturbations) associated with local deformation such a faulting. The mechanical explanation of this phenomenon is that deformation generally initiates at regions where the local stress field is elevated beyond the regional. (2) Regional structural and geologic analysis of the Greater Green River Basin (GGRB). Application of techniques developed and demonstrated during earlier phases of the project for sweet-spot delineation were demonstrated in a relatively new and underexplored play: tight gas from continuous-typeUpper Cretaceous reservoirs of the Greater Green River Basin (GGRB). The effort included data acquisition/processing, base map generation, geophysical and remote sensing analysis and the integration of these data and analyses. (3) Examination of the Table Rock field area in the northern Washakie Basin of the Greater Green River Basin. This effort was performed in support of Union Pacific Resources- and DOE-planned horizontal drilling efforts. The effort comprised acquisition of necessary seismic data and depth-conversion, mapping of major fault geometry, and analysis of displacement vectors, and the development of the natural fracture prediction. (4) Greater Green River Basin Partitioning. Building on fundamental fracture characterization work and prior work performed under this contract, namely structural analysis using satellite and potential field data, the GGRB was divided into partitions that will be used to analyze the resource potential of the Frontier and Mesaverde Upper Cretaceous tight gas play. A total of 20 partitions were developed, which will be instrumental for examining the Upper Cretaceous play potential. (5) Partition Analysis. Resource assessment associated with individual partitions was initiated starting with the Vermilion Sub-basin and the Green River Deep (which include the Stratos well) partitions (see Chapter 5). (6) Technology Transfer. Tech transfer was achieved by documenting our research and presenting it at various conferences.

NONE

1998-11-30

84

Methods for gas detection using stationary hyperspectral imaging sensors  

SciTech Connect

According to one embodiment, a method comprises producing a first hyperspectral imaging (HSI) data cube of a location at a first time using data from a HSI sensor; producing a second HSI data cube of the same location at a second time using data from the HSI sensor; subtracting on a pixel-by-pixel basis the second HSI data cube from the first HSI data cube to produce a raw difference cube; calibrating the raw difference cube to produce a calibrated raw difference cube; selecting at least one desired spectral band based on a gas of interest; producing a detection image based on the at least one selected spectral band and the calibrated raw difference cube; examining the detection image to determine presence of the gas of interest; and outputting a result of the examination. Other methods, systems, and computer program products for detecting the presence of a gas are also described.

Conger, James L. (San Ramon, CA); Henderson, John R. (Castro Valley, CA)

2012-04-24

85

[A mobile sensor for remote detection of natural gas leakage].  

PubMed

The detection of natural gas pipeline leak becomes a significant issue for body security, environmental protection and security of state property. However, the leak detection is difficult, because of the pipeline's covering many areas, operating conditions and complicated environment. A mobile sensor for remote detection of natural gas leakage based on scanning wavelength differential absorption spectroscopy (SWDAS) is introduced. The improved soft threshold wavelet denoising was proposed by analyzing the characteristics of reflection spectrum. And the results showed that the signal to noise ratio (SNR) was increased three times. When light intensity is 530 nA, the minimum remote sensitivity will be 80 ppm x m. A widely used SWDAS can make quantitative remote sensing of natural gas leak and locate the leak source precisely in a faster, safer and more intelligent way. PMID:22512213

Zhang, Shuai; Liu, Wen-qing; Zhang, Yu-jun; Kan, Rui-feng; Ruan, Jun; Wang, Li-ming; Yu, Dian-qiang; Dong, Jin-ting; Han, Xiao-lei; Cui, Yi-ben; Liu, Jian-guo

2012-02-01

86

Speciation analysis by gas chromatography with plasma source spectrometric detection  

Microsoft Academic Search

State-of-the-art species-selective analysis by gas chromatography (GC) with plasma source spectrometric detection is discussed for organometal and organometalloid compounds. Various plasmas, inductively coupled plasma, microwave induced plasma, capacitatively coupled plasma, direct current plasma and alternating current plasma, are characterized and critically compared as sources of radiation for atomic emission spectrometry and sources of ions for mass spectrometry. Interfaces between gas

Ryszard ?obi?ski; Freddy C. Adams

1997-01-01

87

Gas detection with vertical InAs nanowire arrays.  

PubMed

Nanowire-based devices show great promise for next generation (bio)chemical sensors as evidenced by the large volume of high-quality publications. Here, a nanoscale gas sensing device is presented, based on gold-free grown vertical InAs nanowire arrays. The nanowires are contacted Ohmically in their as-grown locations using an air bridge construction, leaving the nanowire surface free for gas adsorption. Noise measurements were performed to determine the measurement resolution for gas detection. These devices are sensitive to NO(2) concentrations well below 100 ppb at room temperature. NO(2) exposure leads to both a reduction in carrier density and electron mobility. PMID:20503976

Offermans, Peter; Crego-Calama, Mercedes; Brongersma, Sywert H

2010-07-14

88

Surface Ionization Gas Detection at SnO2 Surfaces  

NASA Astrophysics Data System (ADS)

In surface ionization (SI) gas detection adsorbed analyte molecules are converted into ionic species at a heated solid surface and extracted into free space by an oppositely biased counter electrode. In the present work we consider the formation of positive and negative analyte gas ions at SnO2 surfaces. We find that SI leads to positive ion formation only, with the SI efficiency scaling with the ionization energy of the analyte gas molecules. Aromatic and aliphatic hydrocarbons with amine functional groups exhibit particularly high SI efficiencies.

Krenkow, A.; Oberhüttinger, C.; Habauzit, A.; Kessler, M.; Göbel, J.; Müller, G.

2009-05-01

89

A case of portomesenteric venous gas detected on computed tomography.  

PubMed

Abstract Portomesenteric vein gas is a rare condition, which patogenesis is not completly understood. One of causes is e.g. mesenteric ischemia. Patogenesis of this condition are: intraabdominal sepsis, interventional procedures, liver transplantation, Crohn disease and trauma. In 15% of causes its idiopatic. Hepatic portal venous gas predict high risk of mortality (>50%). An advanced radiology techniques such as computed tomography can be helpfull in recognizing of this pathology stage. We want to report a case of 83-year-old man with acute abdominal pain after cardiovascular procedure, with portomesenteric vein gas and bowel pneumatosis detected on computed tomography. PMID:24133110

Sierocka, Anita; Kalbarczyk, Katarzyna; Pawlus, Jan; Sulikowski, Tadeusz; Ostrowski, Marek

2013-09-01

90

Backscatter Absorption Gas Imaging of VOC's and its use in Petrochemical Leak Detection.  

National Technical Information Service (NTIS)

This paper reports on progress made in the development of backscatter absorption gas imaging (BAGI) instrumentation suitable for hydrocarbon leak detection. While prototypes of the gas imager have been demonstrated to detect natural gas leaks in the past,...

U. B. Goers T. J. Kulp T. G. McRae

2000-01-01

91

Photonic-bandgap-fiber sensors for gas detection  

SciTech Connect

Currently, the technology available for rapid detection and characterization of different gaseous species is limited. Existing methods are either too slow or too error-prone to allow the real-time analysis of similar gasses in a mixture. Although marginal success has been reported using other techniques, we believe that Raman spectroscopy possesses the clearest capabilities to serve as a gas sensing tool. Because spontaneous Raman spectroscopy produces signals which vary linearly with gas concentration, and Raman spectra are unique to individual molecules, this technique provides both concentration and definitive identification information. Unfortunately, Raman crosssections for most gasses of interest are extremely small and detected powers are usually tiny.

M.P. Buric; K.P. Chen; J. Falk; S.D. Woodruff1

2010-01-01

92

ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT  

SciTech Connect

The extensive network of high-pressure natural gas transmission pipelines covering the United States provides an important infrastructure for our energy independence. Early detection of pipeline leaks and infringements by construction equipment, resulting in corrosion fractures, presents an important aspect of our national security policy. The National Energy Technology Laboratory Strategic Center for Natural Gas (SCVG) is and has been funding research on various applicable techniques. The WVU research team has focused on monitoring pipeline background acoustic signals generated and transmitted by gas flowing through the gas inside the pipeline. In case of a pipeline infringement, any mechanical impact on the pipe wall, or escape of high-pressure gas, generates acoustic signals traveling both up and down stream through the gas. Sudden changes in flow noise are detectable with a Portable Acoustic Monitoring Package (PAMP), developed under this contract. It incorporates a pressure compensating microphone and a signal- recording device. Direct access to the gas inside the line is obtained by mounting such a PAMP, with a 1/2 inch NPT connection, to a pipeline pressure port found near most shut-off valves. An FFT of the recorded signal subtracted by that of the background noise recorded one-second earlier appears to sufficiently isolate the infringement signal to allow source interpretation. Using cell phones for data downloading might allow a network of such 1000-psi rated PAMP's to acoustically monitor a pipeline system and be trained by neural network software to positively identify and locate any pipeline infringement.

John L. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Patrick Browning

2004-10-31

93

ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT  

SciTech Connect

The extensive network of high-pressure natural gas transmission pipelines covering the United States provides an important infrastructure for our energy independence. Early detection of pipeline leaks and infringements by construction equipment, resulting in corrosion fractures, presents an important aspect of our national security policy. The National Energy Technology Laboratory Strategic Center for Natural Gas (SCVG) is and has been funding research on various applicable techniques. The WVU research team has focused on monitoring pipeline background acoustic signals generated and transmitted by gas flowing through the gas inside the pipeline. In case of a pipeline infringement, any mechanical impact on the pipe wall, or escape of high-pressure gas, generates acoustic signals traveling both up and down stream through the gas. Sudden changes in flow noise are detectable with a Portable Acoustic Monitoring Package (PAMP), developed under this contract. It incorporates a pressure compensating microphone and a signal- recording device. Direct access to the gas inside the line is obtained by mounting such a PAMP, with a 1/2 inch NPT connection, to a pipeline pressure port found near most shut-off valves. An FFT of the recorded signal subtracted by that of the background noise recorded one-second earlier appears to sufficiently isolate the infringement signal to allow source interpretation. Using cell phones for data downloading might allow a network of such 1000-psi rated PAMP's to acoustically monitor a pipeline system and be trained by neural network software to positively identify and locate any pipeline infringement.

John L. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Patrick Browning

2004-12-01

94

Remote laser detection of natural gas leakages from pipelines  

Microsoft Academic Search

A differential absorption lidar based on a tunable TEA CO2 laser emitting at 42 lines of the 'hot' 0111 — 1110 band in the range from 10.9 to 11.4 ?m is developed for detecting natural gas leakages from oil pipelines by measuring the ethane content in the atmosphere. The ethane detection sensitivity is 0.9 ppm km. The presence of methane

V O Petukhov; V A Gorobets; Yu M Andreev; G V Lanskii

2010-01-01

95

Remote laser detection of natural gas leakages from pipelines  

Microsoft Academic Search

A differential absorption lidar based on a tunable TEA CO laser emitting at 42 lines of the 'hot' 01¹1 - 11¹0 band in the range from 10.9 to 11.4 m is developed for detecting natural gas leakages from oil pipelines by measuring the ethane content in the atmosphere. The ethane detection sensitivity is 0.9 ppm km. The presence of methane

V O Petukhov; V A Gorobets; Yu M Andreev; G V Lanskii

2010-01-01

96

Non-selective NDIR array for gas detection  

Microsoft Academic Search

A micro component for a non-selective NDIR (non dispersive infrared) gas detection system is presented in this work. This device consist of an IR detection module composed of a thermopile and a thin film filter array. The thermopile arrays (up to 4x4) are built on a silicon substrate by bulk micro-machining processes. The whole matrix is built on a thin

R. Rubio; J. Santander; S. Marco; L. Fonseca; J. Fonollosa; M. Moreno

2005-01-01

97

Surface Ionization Gas Detection on Platinum and Metal Oxide Surfaces  

Microsoft Academic Search

Surface ionization (SI) gas detection experiments have been performed on platinum (Pt) and metal oxide (MOX) films. The probability of surface ion emission varies with temperature in an Arrhenius-type manner. Among all hydrocarbons studied so far those with amine functional groups exhibited the lowest activation energies allowing detection in the ppm concentration range at emitter operation temperatures of about 400degC.

A. Hackner; A. Habauzit; G. Muller; E. Comini; G. Faglia; G. Sberveglieri

2009-01-01

98

Gas pipelines LPV modelling and identification for leakage detection  

Microsoft Academic Search

A new approach to gas leakage detection in high pressure distribution networks is proposed, where the pipeline is modelled as a Linear Parameter Varying (LPV) System driven by the source node mass flow with the pressure as the scheduling parameter, and the system output as the mass flow at the offtake. Using a recently proposed successive approximations LPV system subspace

P. Lopes dos Santos; T.-P. Azevedo-Perdicou?lis; J. A. Ramos; G. Jank; J. L. Martins de Carvalho; J. Milhinhos

2010-01-01

99

Ultrasonic Detection of Surface Flaws in Gas Turbine Ceramics.  

National Technical Information Service (NTIS)

A 45 MHz ultrasonic surface wave technique was developed and evaluated for detection of small surface flaws of < 100 microns (0.004 inches) in gas turbine quality ceramics. The surface wave technique, which employs conventional immersion C-scan recording,...

T. Derkacs I. M. Matay

1979-01-01

100

Gas sensor array for blueberry fruit disease detection and classification  

Microsoft Academic Search

A conducting polymer gas sensor array (electronic nose) was evaluated for detecting and classifying three common postharvest diseases of blueberry fruit: gray mold caused by Botrytis cinerea, anthracnose caused by Colletotrichum gloeosporioides, and Alternaria rot caused by Alternaria sp. Samples of ripe rabbiteye blueberries (Vaccinium virgatum cv. Brightwell) were inoculated individually with one of the three pathogens or left non-inoculated,

Changying Li; Gerard W. Krewer; Pingsheng Ji; Harald Scherm; Stanley J. Kays

2010-01-01

101

Wavelet denoising for infrared laser spectroscopy and gas detection.  

PubMed

After a brief introduction to wavelet theory, this paper discusses the critical parameters to be considered in wavelet denoising for infrared laser spectroscopy. In particular, it is shown that measurement dispersion as well as sensibility can be dramatically improved when using wavelet denoising for gas detection by infrared laser absorption spectroscopy. PMID:22732543

Mappe-Fogaing, Irène; Joly, Lilian; Durry, Georges; Dumelié, Nicolas; Decarpenterie, Thomas; Cousin, Julien; Parvitte, Bertrand; Zéninari, Virginie

2012-06-01

102

Position sensitive radioactivity detection for gas and liquid chromatography  

DOEpatents

A method and apparatus are provided for the position sensitive detection of radioactivity in a fluid stream, particularly in the effluent fluid stream from a gas or liquid chromatographic instrument. The invention represents a significant advance in efficiency and cost reduction compared with current efforts.

Cochran, Joseph L. (Knoxville, TN); McCarthy, John F. (Loudon, TN); Palumbo, Anthony V. (Oak Ridge, TN); Phelps, Tommy J. (Knoxville, TN)

2001-01-01

103

Anomaly detection for health management of aircraft gas turbine engines  

Microsoft Academic Search

This paper presents a comparison of different pattern recognition algorithms to identify slow time scale anomalies for health management of aircraft gas turbine engines. A new tool of anomaly detection, based on symbolic dynamics and information theory, is compared with traditional pattern recognition tools of principal component analysis (PCA) and artificial neural network (ANN). Time series data of the observed

Devendra Tolani; Murat Yasar; Shin Chin; Asok Ray

2005-01-01

104

Pattern Recognition for Selective Odor Detection with Gas Sensor Arrays  

PubMed Central

This paper presents a new pattern recognition approach for enhancing the selectivity of gas sensor arrays for clustering intelligent odor detection. The aim of this approach was to accurately classify an odor using pattern recognition in order to enhance the selectivity of gas sensor arrays. This was achieved using an odor monitoring system with a newly developed neural-genetic classification algorithm (NGCA). The system shows the enhancement in the sensitivity of the detected gas. Experiments showed that the proposed NGCA delivered better performance than the previous genetic algorithm (GA) and artificial neural networks (ANN) methods. We also used PCA for data visualization. Our proposed system can enhance the reproducibility, reliability, and selectivity of odor sensor output, so it is expected to be applicable to diverse environmental problems including air pollution, and monitor the air quality of clean-air required buildings such as a kindergartens and hospitals.

Kim, Eungyeong; Lee, Seok; Kim, Jae Hun; Kim, Chulki; Byun, Young Tae; Kim, Hyung Seok; Lee, Taikjin

2012-01-01

105

Semiconductor laser source for natural gas leak detection  

NASA Astrophysics Data System (ADS)

The feasibility of using semiconductor lasers as infrared sources for handheld natural gas leak detectors was assessed. The detection system was assumed to be based on the differential absorption (DIAL) technique and to operate at ambient temperatures. The absorption spectra of the major components of natural gas, methane and ethane, were measured in the spectral range from 1.2 to 2.0 micrometers where cryogenic cooling of detectors is not required. Both spectra exhibited absorption features due to overtones of the fundamental C-H stretching modes strong enough to be suitable for DIAL measurements. It is found that lasers made from InGaAs emitting near 1.65 micrometers are suitable for methane detection however, considerable materials development would be needed to develop a laser for ethane detection.

Elliott, R. A.

1985-06-01

106

On-chip gas detection in silicon optical microcavities.  

PubMed

We demonstrate a chip-scale photonic system for the room-temperature detection of gas composition and pressure using a slotted silicon microring resonator. We measure shifts in the resonance wavelength due to the presence and pressure of acetylene gas and resolve differences in the refractive index as small as 10(-4) in the near-IR. The observed sensitivity of this device (enhanced due to the slot-waveguide geometry) agrees with the expected value of 490 nm/refractive index unit. PMID:18542525

Robinson, Jacob T; Chen, Long; Lipson, Michal

2008-03-17

107

Fuel leak detection apparatus for gas cooled nuclear reactors  

DOEpatents

Apparatus is disclosed for detecting nuclear fuel leaks within nuclear power system reactors, such as high temperature gas cooled reactors. The apparatus includes a probe assembly that is inserted into the high temperature reactor coolant gaseous stream. The probe has an aperture adapted to communicate gaseous fluid between its inside and outside surfaces and also contains an inner tube for sampling gaseous fluid present near the aperture. A high pressure supply of noncontaminated gas is provided to selectively balance the pressure of the stream being sampled to prevent gas from entering the probe through the aperture. The apparatus includes valves that are operable to cause various directional flows and pressures, which valves are located outside of the reactor walls to permit maintenance work and the like to be performed without shutting down the reactor.

Burnette, Richard D. (San Diego, CA)

1977-01-01

108

Detection of adulteration of cottonseed oil by gas chromatography  

Microsoft Academic Search

To detect adulterant vegetable oils in cottonseed oil, soybean, rapeseed, and ricebran oils were mixed into cottonseed oil\\u000a extracted experimentally from seeds. These adulterated oils and the component oils were analyzed for sterols, fatty acids,\\u000a and triglycerides by gas chromatography. In sterol analysis, stigmasterol was determined for adulteration with soybean and\\u000a ricebran oils. Brassicasterol content seemed to be reliable as

Chromatography C. IMAI; H. Watanabe; N. Haga; T. Ii

1974-01-01

109

Capacitive micromachined ultrasonic resonator for ultra sensitive trace gas detection  

NASA Astrophysics Data System (ADS)

The ultra-sensitive trace gas detection has become increasingly important due to the demand for environment and sci-tech progress. In recent years a capacitive micromachined ultrasonic transducer (CMUT) with circular diaphragms used for imaging has been successfully used to detect chemical gases, and shows promising results. However, its behavior is the same as that of CMUTs for ranging, imaging and therapy applications, where the acoustic radiation with a certain power, produced by the vibration of circular diaphragms operating at the first bending mode, is required but is undesirable for gas sensing since it disturbs inevitably the environment to be measured. This paper, therefore, presents to optimize its behavior after an ideal capacitive micromachined ultrasonic resonator (CMUR) and then to utilize second-order and high-order bending modes of the circular diaphragm to minimize its acoustic radiation and obtain higher resonance frequency also. Since the resonance frequencies of high-order modes much higher than the fundamental frequency, an ultra-high operating frequency of GHz can be reached so that raising greatly the sensitivity of the CMUR and being able to realize the ultra-sensitive trace gas detections.

Ge, Li-Feng

2013-01-01

110

Exposure to Pesticides at Sublethal Level and Their Distribution Within a Honey Bee ( Apis mellifera ) Colony  

Microsoft Academic Search

Honey bee colonies were exposed to pesticides used in agriculture or within bee hives by beekeepers: coumaphos; diazinon;\\u000a amitraz or fluvalinate. Samples of bee workers, larvae and royal jelly were analysed using Gas Chromatography-Electron Capture\\u000a Detection (GC-ECD). Amitraz was quantified using High Performance Liquid Chromatography (HPLC), and Gas Chromatography-Tandem\\u000a Mass Spectrometry (GC\\/MS\\/MS) was used for quantification of diazinon. Sixth day

Maja Ivana Smodiš Škerl; Veronika Kmecl; Aleš Gregorc

2010-01-01

111

Liquid metal-to-gas leak-detection instruments. [LMFBR  

SciTech Connect

It is desirable for liquid-metal-cooled reactors that small liquid metal-to-gas leaks be reliably detected. Testing has been performed on a number of detection systems to evaluate their sensitivity, response time, and performance characteristics. This testing has been scheduled in three phases. The first phase was aimed at screening out the least suitable detectors and optimizing the performance of the most promising. In the second phase, candidates were tested in a 1500 ft/sup 3/ walk-in type enclosure in which leaks were simulated on 24-in. and 3-in. piping. In the third phase of testing, selected type detectors were tested in the 1500-ft/sup 3/ enclosure with Clinch River Breeder Reactor Plant (CRBRP) pipe insulation configurations and detector tubing configuration with cell gas recirculation simulated. Endurance testing of detection equipment was also performed as part of this effort. Test results have been shown that aerosol-type detectors will reliably detect leaks as small as a few grams per hour when sampling pipe insulation annuli.

Matlin, E.; Witherspoon, J.E.; Johnson, J.L.

1982-01-01

112

Sulfur gas geochemical detection of hydrothermal systems. Final report  

SciTech Connect

The purpose of this investigation was to determine whether a system of exploration using sulfur gases was capable of detecting convecting hydrothermal systems. Three surveying techniques were used at the Roosevelt Hot Springs KGRA in Utah. These were (a) a sniffing technique, capable of instantaneous determinations of sulfur gas concentration, (b) an accumulator technique, capable of integrating the sulfur gas emanations over a 30 day interval, and (c) a method of analyzing the soils for vaporous sulfur compounds. Because of limitations in the sniffer technique, only a limited amount of surveying was done with this method. The accumulator and soil sampling techniques were conducted on a 1000 foot grid at Roosevelt Hot Springs, and each sample site was visited three times during the spring of 1980. Thus, three soil samples and two accumulator samples were collected at each site. The results are shown as averages of three soil and two accumulator determinations of sulfur gas concentrations at each site. Soil surveys and accumulator surveys were conducted at two additional KGRA's which were chosen based on the state of knowledge of these hydrothermal systems and upon their differences from Roosevelt Hot Springs in an effort to show that the exploration methods would be effective in detecting geothermal reservoirs in general. The results at Roosevelt Hot Springs, Utah show that each of the three surveying methods was capable of detecting sulfur gas anomalies which can be interpreted to be related to the source at depth, based on resistivity mapping of that source, and also correlatable with major structural features of the area which are thought to be controlling the geometry of the geothermal reservoir. The results of the surveys at Roosevelt did not indicate that either the soil sampling technique or the accumulator technique was superior to the other.

Rouse, G.E.

1984-01-01

113

The Design and Implementation of Vehicle Tail Gas Detection System Based on Virtual Instrument  

Microsoft Academic Search

The design of the multifunctional portable vehicle tail gas detection system adopts virtual instrument technology based on computer. It utilizes portable computer and USB data collecting card to control the detection. So it can detect and record the vehicle tail gas in wide range accurately, and can count and analyze the component and content of the harmful gas. This system

Wenlian Li; Yang Li; Fang Xiao

2008-01-01

114

Intermediate Velocity Gas Detected Towards the NGC 6752 Globular Cluster  

NASA Astrophysics Data System (ADS)

We present medium resolution ultraviolet absorption measurements recorded with the HST-COS and FUSE spectrographs towards two post-AGB stars (UIT-1 and B1754) associated with the NGC 6752 globular cluster. We have detected intermediate velocity (IV) gas with Vlsr ˜ +38 km s-1 along the 3.9 kpc sight-line to the cluster in the absorption profiles of the CII, CII*, CIV, NI, OI, OVI, AlII, SiII, SiIV, SII, FeII and FeIII ions. The distance to this ""multi-phase"" IV gas lies in the 0.56--3.9 kpc range. We have fit the IV absorption profiles with models to determine column density values for the various ions. For the case of the highly ionized IV components the column density ratios of the SiIV, CIV, NV and OVI lines are most compatible with the predictions of ionization by turbulent mixing layers, shocks or halo SNRs. A gas-phase abundance analysis of the IV gas indicates that C, N, O, Al, Si and Fe appear to possess sub-solar metallicity values relative to that of sulfur. However, when the effects of element depletion onto interstellar dust in the halo is accounted for, the IVC gas probably has a value near to (or slightly less than) solar metallicity. The IV gas that is streaming away from the Galaxy is located within 3.9 kpc and its origin may well be linked to a galactic fountain in the disk. The IVC may be part of the trailing edge of the WE HVC complex, whose many constituent small clouds also possess positive velocities in this galactic direction.

Welsh, Barry Y.; Lallement, Rosine

2012-12-01

115

Low-cost gas correlation detection of methane  

NASA Astrophysics Data System (ADS)

Two instruments have been designed for airborne remote sensing of landfill methane emissions using the infrared absorption of reflected sunlight. A gas correlation filter wheel and a length modulated cell have been produced to discriminate between methane and other interfering species and the performance of the two systems discussed. The two systems have been interfaced with an Indium Gallium Arsenide (InGaAs) 2D detector array and an Indium Antimonide (InSb) point detector. The InGaAs array detector response rate was found to be too slow so experiments were done using the InSb detector. The gas correlation filter wheel has been shown to detect levels of methane equivalent to 200ppmv with a 30m pathlength at the 3.3?m methane band with the InSb point detector. It has been predicted that it should be possible to detect levels equivalent to 20ppmv over a 30m pathlength at the 1.65?m band with the gas correlation filter wheel and a fast response InGaAs detector. The length modulated device was found to have far less sensitivity in comparison to the filter wheel system, but could have enhanced performance with improved design.

Chapman, O. M.; Hilton, M.

2006-03-01

116

Naturally fractured tight gas - gas reservoir detection optimization. Quarterly report, June 1, 1996--September 30, 1996  

SciTech Connect

This document contains the status report for the Naturally Fractured Tight Gas-Gas Reservoir Detection Optimization project for the contract period 9/30/93 to 3/31/97. Data from seismic surveys are analyzed for structural imaging of reflector units. The data were stacked using the new, improved statics and normal moveout velocities. The 3-D basin modeling effort is continuing with code development. The main activities of this quarter were analysis of fluid pressure data, improved sedimentary history, lithologic unit geometry reconstruction algorithm and computer module, and further improvement, verification, and debugging of the basin stress and multi-phase reaction transport module.

Maxwell, J.M.; Ortoleva, P.; Payne, D.; Sibo, W.

1996-11-15

117

Sensitive gas chromatographic detection of acetaldehyde and acetone using a reduction gas detector  

NASA Astrophysics Data System (ADS)

The response of a newly available mercuric oxide Reduction Gas Detector (RGD-2) to subpicomole and larger quantities of acetaldehyde and acetone is tested. The RGD-2 is found to be capable of subpicomole detection for these carbonyls and is more sensitive than an FID (Flame Ionization Detector) by an order of magnitude. Operating parameters can be further optimized to make the RGD-2 some 20-40 times more sensitive than an FID. The detector is linear over a wide range and is easily adapted to a conventional gas chromatograph (GC). Such a GC-RGD-2 system should be suitable for atmospheric carbonyl measurements in clean as well as polluted environments.

O'Hara, Dean; Singh, Hanwant B.

118

ULTRASENSITIVE HIGH-TEMPERATURE SELECTIVE GAS DETECTION USING PIEZOELECTRIC MICROCANTILEVERS  

SciTech Connect

We have obtained very promising results in the Phase I study. Specifically, for temperature effects, we have established that piezoelectric cantilever sensors could retain their resonance peak strength at high temperatures, i.e., the Q values of the resonance peaks remained above 10 even when the temperature was very close to the Curie temperature. This confirms that a piezoelectric cantilever sensor can be used as a sensor up to its Curie temperature. Furthermore, we have shown that the mass detection sensitivity remained unchanged at different temperatures. For selective gas detection, we have demonstrated selective NH{sub 3} detection using piezoelectric cantilever sensors coated with mesoporous SiO{sub 2}. For high-temperature sensor materials development, we have achieved highly oriented Sr-doped lead titanate thin films that possessed superior dielectric and ferroelectric properties. Such highly oriented films can be microfabricated into high-performance piezoelectric microcantilever sensors that can be used up to 490 C. We have accomplished the goal of Phase I study in exploring the various aspects of a high-temperature gas sensor. We propose to continue the study in Phase II to develop a sensor that is suitable for high-temperature applications using piezoelectrics with a high Curie temperature and by controlling the effects of temperature. The lead titanate based thin film developed in Phase I is good for applications up to 490 C. In phase II, we will develop lithium niobate thin film based cantilevers for applications up to 1000 C.

Wan Y. Shih; Tejas Patil; Qiang Zhao; Yi-Shi Chiu; Wei-Heng Shih

2004-03-05

119

ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT  

SciTech Connect

The West Virginia University natural gas transmission line leak detection research is only considering using readily available 1/2 inch pipeline access ports for the detection of leak generated signals. The main problem with leak signals is the low signal to noise ratio. One of the acoustic signals associated with gas escaping through a leak is only temporary and is in the form of a rarefaction wave originating when the leak is formed. Due to pipeline friction, over distance such a step function transitions to a ramp function. The ability to identify a leak by pipeline monitoring and signal processing depends a great deal on the quality and signal to noise ratio of the characteristics of the detectors used. Combinations of sensing devices are being used for the WVU sensor package and are contained in a removable sensor housing. The four sensors currently installed are a 1/2 inch 3 Hz-40 Khz microphone, an audible range moving coil sensor, a piezo-electric pressure transducer, and the WVU designed floating 3 inch diameter diaphragm to detect flow transient induced pressure ramp type signals. The WVU diaphragm sensor, which is currently under development, uses the same diaphragm principle as a high quality capacitance type microphone, but utilizes aerodynamic signal amplification. This type of amplification only amplifies the ramp-signal itself, not the random pipeline noise.

John L Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Deepak Mehra

2003-04-01

120

Liquid chromatographic arsenic speciation with gas-phase chemiluminescence detection.  

PubMed

We present a newly developed gas-phase chemiluminescence (CL) detection method for the separation and quantification of inorganic and organic arsenic species. Arsenite, arsenate, dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) were separated by anion exchange using carbonate-bicarbonate and NaOH eluents with step-gradient elution. The separated species were passed through a UV photooxidation reactor which decomposed the organic species and converted them to inorganic As(V). Subsequent on-line hydride generation with acid and sodium borohydride produces AsH3 and H2, which are separated from the liquid in a gas-liquid separator. The produced AsH3, driven by H2, reacts with ozone in a small reflective cell located atop a photomultiplier tube, resulting in intense CL. In the present form, the limits of detection (LODs, signal-to-noise = 3), based on peak height, for arsenite, arsenate, MMA, and DMA are 0.4, 0.2, 0.5, and 0.3 microg/L, respectively, for a 100 microL injected sample. This analyzer demonstrates the robustness of the CL detection system for arsenic and provides an affordable alternative to atomic spectrometry for use as a detector after chromatographic speciation. We found no significant practical interferences. PMID:17949013

Idowu, Ademola D; Dasgupta, Purnendu K

2007-10-19

121

Hydrocarbon gas detection with microelectromechanical Fabry-Perot interferometer  

NASA Astrophysics Data System (ADS)

VTT Technical Research Centre of Finland has developed microelectromechanical (MEMS) Fabry-Perot interferometer (FPI) for hydrocarbon measurements. Fabry-Perot interferometer is a structure where is two highly reflective surfaces separated by a tunable air gap. The MEMS FPI is a monolithic device, i.e. it is made entirely on one substrate in a batch process, without assembling separate pieces together. The gap is adjusted by moving the upper mirror with electrostatic force, so there are no actual moving parts. The manufactured MEMS FPIs have been characterized. The tuning wavelength range of the MEMS FPI is 2.8-3.5 ?m and its spectral resolution is 50-60 nm. VTT has designed and manufactured a handheld size demonstrator device based on the technology presented in this abstract. This device demonstrates gas detecting by measuring cigarette lighter gas and various plastic materials transmission spectra. The demonstrator contains light source, gas cell, MEMS FPI, detector and control electronics. It is connected to a laptop by USB connection, additional power supply or connection is not needed.

Mannila, Rami; Tuohiniemi, Mikko; Mäkynen, Jussi; Näkki, Ismo; Antila, Jarkko

2013-05-01

122

Microfluidic gas flow profiling using remote detection NMR  

SciTech Connect

Miniaturized fluid handling devices have recently attracted considerable interest in many areas of science1. Such microfluidic chips perform a variety of functions, ranging from analysis of biological macromolecules2,3 to catalysis of reactions and sensing in the gas phase4,5. To enable precise fluid handling, accurate knowledge of the flow properties within these devices is important. Due to low Reynolds numbers, laminar flow is usually assumed. However, either by design or unintentionally, the flow characteristic in small channels is often altered, for example by surface interactions, viscous and diffusional effects, or electrical potentials. Therefore, its prediction is not always straight-forward6-8. Currently, most microfluidic flow measurements rely on optical detection of markers9,10, requiring the injection of tracers and transparent devices. Here, we show profiles of microfluidic gas flow in capillaries and chip devices obtained by NMR in the remote detection modality11,12. Through the transient measurement of dispersion13, NMR is well adaptable for non-invasive, yet sensitive determination of the flow field and provides a novel and potentially more powerful tool to profile flow in capillaries and miniaturized flow devices.

Hilty, Christian; McDonnell, Erin; Granwehr, Josef; Pierce,Kimberly; Han, Song-I Han; Pines, Alexander

2005-05-06

123

Flashback Detection Sensor for Hydrogen Augmented Natural Gas Combustion  

SciTech Connect

The use of hydrogen augmented fuel is being investigated by various researchers as a method to extend the lean operating limit, and potentially reduce thermal NOx formation in natural gas fired lean premixed (LPM) combustion systems. The resulting increase in flame speed during hydrogen augmentation, however, increases the propensity for flashback in LPM systems. Real-time in-situ monitoring of flashback is important for the development of control strategies for use of hydrogen augmented fuel in state-of-the-art combustion systems, and for the development of advanced hydrogen combustion systems. The National Energy Technology Laboratory (NETL) and Woodward Industrial Controls are developing a combustion control and diagnostics sensor (CCADS), which has already been demonstrated as a useful sensor for in-situ monitoring of natural gas combustion, including detection of important combustion events such as flashback and lean blowoff. Since CCADS is a flame ionization sensor technique, the low ion concentration produced in pure hydrogen combustion raises concerns of whether CCADS can be used to monitor flashback in hydrogen augmented combustion. This paper discusses CCADS tests conducted at 0.2-0.6 MPa (2-6 atm), demonstrating flashback detection with fuel compositions up to 80% hydrogen (by volume) mixed with natural gas. NETL’s Simulation Validation (SimVal) combustor offers full optical access to pressurized combustion during these tests. The CCADS data and high-speed video show the reaction zone moves upstream into the nozzle as the hydrogen fuel concentration increases, as is expected with the increased flame speed of the mixture. The CCADS data and video also demonstrate the opportunity for using CCADS to provide the necessary in-situ monitor to control flashback and lean blowoff in hydrogen augmented combustion applications.

Thornton, J.D.; Chorpening, B.T.; Sidwell, T.; Strakey, P.A.; Huckaby, E.D.; Benson, K.J. (Woodward)

2007-05-01

124

Polychlorinated biphenyl congeners and organochlorine insecticides in the water column and sediments of Daya Bay, China  

Microsoft Academic Search

Samples of sub-surface water, suspended particulate matter (SPM) and surface sediments collected from Daya Bay, China have been analysed for 12 polychlorinated biphenyl (PCB) congeners and 18 organochlorine insecticides, using gas chromatography electron capture detection. Total PCB levels varied from 91.1 to 1355.3 ng l?1 in water and from 0.85 to 27.37 ng g?1 dry weight in sediments. The levels

J. L. Zhou; K. Maskaoui; Y. W. Qiu; H. S. Hong; Z. D. Wang

2001-01-01

125

Quantum-cascade laser photoacoustic detection of methane emitted from natural gas powered engines  

NASA Astrophysics Data System (ADS)

In this work we present a laser photoacoustic arrangement for the detection of the important greenhouse gas methane. A quantum-cascade laser and a differential photoacoustic cell were employed. A detection limit of 45 ppbv in nitrogen was achieved as well as a great selectivity. The same methodology was also tested in the detection of methane issued from natural gas powered vehicles (VNG) in Brazil, which demonstrates the excellent potential of this arrangement for greenhouse gas detection emitted from real sources.

Rocha, M. V.; Sthel, M. S.; Silva, M. G.; Paiva, L. B.; Pinheiro, F. W.; Miklòs, A.; Vargas, H.

2012-03-01

126

The development of a pulsed laser imaging system for natural gas leak detection  

Microsoft Academic Search

The detection of gas leaks represents a critical operation performed regularly by the gas industry to maintain the integrity and safety of its vast network of piping, both above and below the ground. We are developing a technology that allows the real-time imaging of gas plumes in a television format. Termed backscatter absorption gas imaging (BAGI), the technique operates by

Thomas J. Kulp

1995-01-01

127

The Use of Microwave Radar for Remote Detection of Gas Pipeline Leaks  

Microsoft Academic Search

This report describes the development of a microwave (MW) radar sensing and imaging system to remotely detect and locate gas leaks in natural gas pipelines. It contains theoretical and experimental results to show feasibility of the radar technique. The gas dynamics of the leak jet are modeled first to determine the plume geometry and the variation of gas concentration in

N. Gopalsami; A. Dron; T. Elmer; A. C. Raptis

128

Liquefied Noble Gas (LNG) detectors for detection of nuclear materials  

NASA Astrophysics Data System (ADS)

Liquefied-noble-gas (LNG) detectors offer, in principle, very good energy resolution for both neutrons and gamma rays, fast response time (hence high-count-rate capabilities), excellent discrimination between neutrons and gamma rays, and scalability to large volumes. They do, however, need cryogenics. LNG detectors in sizes of interest for fissionable material detection in cargo are reaching a certain level of maturity because of the ongoing extensive R&}D effort in high-energy physics regarding their use in the search for dark matter and neutrinoless double beta decay. The unique properties of LNG detectors, especially those using Liquid Argon (LAr) and Liquid Xenon (LXe), call for a study to determine their suitability for Non-Intrusive Inspection (NII) for Special Nuclear Materials (SNM) and possibly for other threats in cargo. Rapiscan Systems Laboratory, Yale University Physics Department, and Adelphi Technology are collaborating in the investigation of the suitability of LAr as a scintillation material for large size inspection systems for air and maritime containers and trucks. This program studies their suitability for NII, determines their potential uses, determines what improvements in performance they offer and recommends changes to their design to further enhance their suitability. An existing 3.1 liter LAr detector (microCLEAN) at Yale University, developed for R&}D on the detection of weakly interacting massive particles (WIMPs) was employed for testing. A larger version of this detector (15 liters), more suitable for the detection of higher energy gamma rays and neutrons is being built for experimental evaluation. Results of measurements and simulations of gamma ray and neutron detection in microCLEAN and a larger detector (326 liter CL38) are presented.

Nikkel, J. A.; Gozani, T.; Brown, C.; Kwong, J.; McKinsey, D. N.; Shin, Y.; Kane, S.; Gary, C.; Firestone, M.

2012-03-01

129

Silicon carbide-based hydrogen and hydrocarbon gas detection  

NASA Astrophysics Data System (ADS)

Hydrogen and hydrocarbon detection in aeronautical applications is important for reasons of safety and emissions control. The use of silicon carbide as a semiconductor in a metal-semiconductor or metal-insulator-semiconductor structure opens opportunities to measure hydrogen and hydrocarbons in high temperature environments beyond the capabilities of silicon-based devices. The purpose of this paper is to explore the response and stability of Pd-SiC Schottky diodes as gas sensors in the temperature range from 100 to 400 C. The effect of heat treating on the diode properties as measured at 100 C is explored. Subsequent operation at 400 C demonstrates the diodes' sensitivity to hydrogen and hydrocarbons. It is concluded that the Pd-SiC Schottky diode has potential as a hydrogen and hydrocarbon sensor over a wide range of temperatures but further studies are necessary to determine the diodes' long term stability.

Hunter, Gary W.; Neudeck, Philip G.; Chen, Liang-Yu; Knight, D.; Liu, C. C.; Wu, Q. H. R.

1995-10-01

130

Derivatizations for improved detection of alcohols by gas chromatography and photoionization detection (GC-PID)  

SciTech Connect

Pentafluorophenyldimethylsilyl chloride (flophemesyl chloride, Fl) is a well known derivatization reagent for improved electron capture detection (ECD) in gas chromatography (GC)(GC-ECD), but it has never been utilized for improved detectability and sensitivity in GC-photoionization detection (GC-PID). A wide variety of flophemesyl alcohol derivatives have been used in order to show a new approach for realizing greatly reduced minimum detection limits (MDL) of virtually all alcohol derivatives in GC-PID analysis. This particular derivatization approach is inexpensive and easy to apply, leading to quantitative or near 100% conversion of the starting alcohols to the expected flophemesyl ethers (silyl ethers). Detection limits can be lowered by 2-3 orders of magnitude for such derivatives when compared with the starting alcohols, along with calibration plots that are linear over 5-7 orders of magnitude. Specific GC conditions have been developed for many flophemesyl derivatives, in all cases using packed columns. Both ECD and PID relative response factors (RRFs) and normalized RRFs have been determined, and such ratios can now be used for improved analytic identification from complex sample matrices, where appropriate. 28 references, 2 figures, 5 tables.

Krull, I.S.; Swartz, M.; Driscoll, J.N.

1984-01-01

131

A piezoelectric-sound-resonance cavity for hydrogen gas detection.  

PubMed

A new concept for hydrogen gas (H2) detection has been developed. This concept is based on a piezoelectric-sound-resonance cavity (PSRC). Detection uses sound resonance and the acoustic property differences of gases as a sensing mechanism in which there is a significant difference in the sound velocity and acoustic impedance between H2 and air. The PSRC sensor consists of two thin piezoelectric discs, separated by a small cavity. One disc excites a weak acoustic standing wave in the cavity, and the second senses the wave by monitoring the acoustic impedance characteristics of the cavity. Changes in H2 concentration result in a shift of the sound resonance state. Investigations of a PSRC prototype have demonstrated a sensitivity limit of <10 ppm, a fast response time approximately 1 second, and a signal (phase and voltage) in proportion to the change in H2 concentration (n) over the range of 10(-5) < n < 0.2. These performance characteristics are far superior to those of other methods. PMID:14561027

Dong, Shuxiang; Bai, Feiming; Li, Jie-Fang; Viehland, Dwight

2003-09-01

132

Detection and Identification of Bacteria by Gas Chromatography1  

PubMed Central

Ether extracts of cultures of 29 strains representing 6 species of Bacillus, and of individual strains of Escherichia coli, Aerobacter aerogenes, and Pseudomonas aeruginosa were examined in a gas chromatograph by use of flame ionization and electron capture detectors. Among the products detected were compounds with the chromatographic characteristics of acetic, propionic, and butyric acids, ethyl alcohol, diacetyl, acetoin, and 2,3-butanediol. The differences in peak areas of the various products formed by the bacteria were determined statistically for the chromatograms obtained with the two detectors, and the peaks were arranged in order of decreasing areas to yield a signature for each bacterial strain. Different signatures were obtained for the various genera and species and for strains of the same species. B. licheniformis, B. subtilis, and A. aerogenes formed significant quantities of a number of volatile compounds, and qualitative and quantitative differences between strains were noted. The electron capture detector was particularly sensitive to diacetyl and acetoin as well as to unknown compounds. By use of this detector, the presence of 5 pg of diacetyl and 20 pg of acetoin could be demonstrated. The quantity of acetoin detected in B. subtilis and B. licheniformis cultures was present in as little as 6.3 × 10-3 ?liters of medium. Images Fig. 1 Fig. 2 Fig. 3

Henis, Y.; Gould, J. R.; Alexander, M.

1966-01-01

133

Synergy between liquid chromatographic-pulsed amperometric detection and capillary-gas chromatographic methods for the detection of juice adulteration.  

PubMed

The use of liquid chromatography linked with pulsed amperometric detection, and capillary-gas chromatography to detect the adulteration of fruit juices is discussed. These are 2 complementary approaches which can be used to detect the addition of sugar syrups to juices at low levels. PMID:11417660

Hammond, D A

134

Single Carbon Nanotube Based Ion Sensor for Gas Detection  

Microsoft Academic Search

This paper presents a new method for carbon nanotube based gas sensing. Instead of sensing the gas directly, the gas molecules are first ionized and then the ionized molecules are sensed by the single carbon nanotube based ion sensor. The adsorption of ionized gas molecule on the carbon nanotube surface introduces electrons into the material and consequently changes the current

Jiangbo Zhang; Ning Xi; Hoyin Chan; Guangyong Li

2006-01-01

135

Improved low concentration gas detection system based on intracavity fiber laser  

NASA Astrophysics Data System (ADS)

The improvement of a low concentration gas detection system based on the intracavity fiber laser is proposed in this paper. The sensitivity of the system is deduced based on Lambert-Beer law. The optimized system was established with the gas cell made elaborately. In order to apply the wavelength sweeping technique, the fiber Bragg grating reflector was substituted by the wavelength independent Faraday rotation reflector. The sensitivity of the system for acetylene detection is reduced to less than 100 ppm by using the average of three absorption spectra. The acetylene detection coefficients of variation with different concentrations are measured. The gas measurement system is validated to detect low concentration gas effectively.

Zhang, Hongxia; Liu, Kun; Jia, Dagong; Xu, Tianhua; Liu, Tiegen; Peng, Gangding; Jing, Wencai; Zhang, Yimo

2011-02-01

136

Indikeringsprov med Senapsgas/Klorbensen (Detection of Mustard Gas Mixed with Chloro Benzene using Different Detection Material).  

National Technical Information Service (NTIS)

The report shows the results from detection with a mixture of mustard gas (HD) and chloro benzene. The purpose of the investigation was to see if the result is different when chloro benzene is mixed with mustard gas compared to when its not. We have found...

G. Olofsson G. Lindberg

1999-01-01

137

DETERMINATION OF DIMETHYLSELENIDE AND DIMETHYLDISELENIDE BY GAS CHROMOTOGRAPHY- PHOTOIONIZATION DETECTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

A simple method for the determination of volatile selenium compounds employing a gas chromatograph equipped with a photoionization detector is described. The method involves the direct injection of dimethylselenide (DMS) or dimethyldiselenide (DMDS) into the gas chromatograph; no derivatization of ...

138

Recent Developments in Modulation Spectroscopy for Trace Gas Detection Using Tunable Diode Lasers  

Microsoft Academic Search

The need for higher sensitive detection technology for trace gas samples, either in the laboratory setup or in the atmospheric remote sensing has been a goal for several decades. The development of the tunable diode laser has propelled the progress of trace detection technology, and modulation technology enables the improvement of the detection sensitivity. As a result, the detection of

Kyuseok Song; Euo Chang Jung

2003-01-01

139

46 CFR 154.709 - Cargo boil-off as fuel: Gas detection equipment.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Cargo boil-off as fuel: Gas detection equipment. 154...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and...Pressure and Temperature Control § 154.709 Cargo boil-off as fuel: Gas detection equipment....

2010-10-01

140

46 CFR 154.709 - Cargo boil-off as fuel: Gas detection equipment.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 false Cargo boil-off as fuel: Gas detection equipment. 154...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and...Pressure and Temperature Control § 154.709 Cargo boil-off as fuel: Gas detection equipment....

2009-10-01

141

Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997  

SciTech Connect

Economically viable natural gas production from the low permeability Mesaverde Formation in the Piceance Basin, Colorado requires the presence of an intense set of open natural fractures. Establishing the regional presence and specific location of such natural fractures is the highest priority exploration goal in the Piceance and other western US tight, gas-centered basins. Recently, Advanced Resources International, Inc. (ARI) completed a field program at Rulison Field, Piceance Basin, to test and demonstrate the use of advanced seismic methods to locate and characterize natural fractures. This project began with a comprehensive review of the tectonic history, state of stress and fracture genesis of the basin. A high resolution aeromagnetic survey, interpreted satellite and SLAR imagery, and 400 line miles of 2-D seismic provided the foundation for the structural interpretation. The central feature of the program was the 4.5 square mile multi-azimuth 3-D seismic P-wave survey to locate natural fracture anomalies. The interpreted seismic attributes are being tested against a control data set of 27 wells. Additional wells are currently being drilled at Rulison, on close 40 acre spacings, to establish the productivity from the seismically observed fracture anomalies. A similar regional prospecting and seismic program is being considered for another part of the basin. The preliminary results indicate that detailed mapping of fault geometries and use of azimuthally defined seismic attributes exhibit close correlation with high productivity gas wells. The performance of the ten new wells, being drilled in the seismic grid in late 1996 and early 1997, will help demonstrate the reliability of this natural fracture detection and mapping technology.

NONE

1997-12-31

142

Field tests of probes for detecting internal corrosion of natural gas transmission pipelines  

SciTech Connect

A field study was conducted to evaluate the use of electrochemical corrosion rate (ECR) probes for detecting corrosion in environments similar to those found in natural gas transmission pipelines. Results and interpretation will be reported from four different field tests. Flange and flush-mount probes were used in four different environments at a gas-gathering site and one environment but two different orientations at a natural gas plant. These sites were selected to represent normal and upset conditions in a gas transmission pipeline. The environments consisted of 2 different levels of humidified natural gas/organic/water mixtures removed from natural gas, and the environments at the 6 and 12 o'clock positions of a natural gas pipeline carrying 2-phase gas/liquid flow. Data are also presented comparing the ECR probe data to that for coupons used to determine corrosion rate and to detect the presence of microbiologically influenced corrosion (MIC).

Covino, Bernard S., Jr.; Bullard, Sophie J.; Cramer, Stephen D.; Holcomb, Gordon R.; Ziomek-Moroz, M.; Cayard, Michael S. (Intercorr International Inc.); Kane, Russell D. (Intercorr International Inc.); Meidinger, Brian (RMOTC-DOE)

2005-01-01

143

Thermally modulated nano-trampoline material as smart skin for gas molecular mass detection  

NASA Astrophysics Data System (ADS)

Conventional multi-component gas analysis is based either on laser spectroscopy, laser and photoacoustic absorption at specific wavelengths, or on gas chromatography by separating the components of a gas mixture primarily due to boiling point (or vapor pressure) differences. This paper will present a new gas molecular mass detection method based on thermally modulated nano-trampoline material as smart skin for gas molecular mass detection by fiber Bragg grating-based gas sensors. Such a nanomaterial and fiber Bragg grating integrated sensing device has been designed to be operated either at high-energy level (highly thermal strained status) or at low-energy level (low thermal strained status). Thermal energy absorption of gas molecular trigs the sensing device transition from high-thermal-energy status to low-thermal- energy status. Experiment has shown that thermal energy variation due to gas molecular thermal energy absorption is dependent upon the gas molecular mass, and can be detected by fiber Bragg resonant wavelength shift with a linear function from 17 kg/kmol to 32 kg/kmol and a sensitivity of 0.025 kg/kmol for a 5 micron-thick nano-trampoline structure and fiber Bragg grating integrated gas sensing device. The laboratory and field validation data have further demonstrated its fast response characteristics and reliability to be online gas analysis instrument for measuring effective gas molecular mass from single-component gas, binary-component gas mixture, and multi-gas mixture. The potential industrial applications include fouling and surge control for gas charge centrifugal compressor ethylene production, gas purity for hydrogen-cooled generator, gasification for syngas production, gasoline/diesel and natural gas fuel quality monitoring for consumer market.

Xia, Hua

2012-05-01

144

Laboratorietest och Utvaerdering av Gasindikeringsinstrument. Multi Gas Analyzer (MUGAS), Version II (Laboratory Test and Evaluation of a Gas Detection Instrument. Multi Gas Analyzer (MUGAS), Version II).  

National Technical Information Service (NTIS)

MUGAS (Multi Gas Analyzer) is a gas detection instrument developed by Telaire Europe AB, supported from the Swedish Rescue Services Agency. The instrument can be used to measure inflammable and toxic gases. The principle of measuring is based on an IR-tec...

L. Haegglund

1997-01-01

145

Single-Walled Carbon Nanotube Thin-Film Sensor for Ultrasensitive Gas Detection  

NASA Astrophysics Data System (ADS)

We demonstrated a gas sensor fabricated by growing a single-walled carbon nanotube (SWNT) thin film directly on a conventional sensor substrate. NO2 and Cl2 were detected down to the ppb level under room-temperature operation with a fast response. Using an electrical breakdown technique, gas response sensitivity was improved by an order of magnitude. The relationship between gas concentration and sensor response was derived based on the Langmuir adsorption isotherm, predicting a detection limit of 8 ppb for NO2. The SWNT thin-film gas sensor exhibits merits over other types of sensors by virtue of its simplicity in fabrication and feasible application.

Wongwiriyapan, Winadda; Honda, Shin-ichi; Konishi, Hirofumi; Mizuta, Tomoaki; Ikuno, Takashi; Ito, Tatsuya; Maekawa, Toru; Suzuki, Kengo; Ishikawa, Hiroshi; Oura, Kenjiro; Katayama, Mitsuhiro

2005-04-01

146

Comparison of various detection limit estimates for volatile sulphur compounds by gas chromatography with pulsed flame photometric detection.  

PubMed

This paper addresses the variations that presently exist regarding the definition, determination, and reporting of detection limits for volatile sulphur compounds by gas chromatography with pulsed flame photometric detection (GC-PFPD). Gas standards containing hydrogen sulphide (H(2)S), carbonyl sulphide (COS), sulphur dioxide (SO(2)), methyl mercaptan (CH(3)SH), dimethyl sulphide (DMS), carbon disulphide (CS(2)), and dimethyl disulphide (DMDS) in concentrations varying from 0.36ppb (v/v) up to 1.5ppm (v/v) in nitrogen were prepared with permeation tubes and introduced in the gas chromatograph using a 0.25-ml gas sampling loop. After measuring the PFPD response versus concentration, the method detection limit (MDL), the Hubaux-Vos detection limit (x(D)), the absolute instrument sensitivity (AIS), and the sulphur detectivity (D(s)) were determined for each sulphur compound. The results show that the MDL determined by the US Environmental Protection Agency procedure consistently underestimates the minimum concentrations of volatile sulphur compounds that can be practically distinguished from the background noise with the PFPD. The Hubaux-Vos detection limits and the AIS values are several times higher than the MDL, and provide more conservative estimates of the lowest concentrations that can be reliably detected. Sulphur detectivities are well correlated with AIS values but only poorly correlated with MDL values. The AIS is recommended as a reliable and cost-effective measure of detection limit for volatile sulphur compounds by GC-PFPD, since the AIS is easier and faster to determine than the MDL and the Hubaux-Vos detection limit. In addition, this study confirmed that the PFPD response is nearly quadratic with respect to concentration for all volatile sulphur compounds. PMID:17069822

Catalan, Lionel J J; Liang, Victor; Jia, Charles Q

2006-10-27

147

Gas hydrate detection and mapping on the US east coast  

SciTech Connect

Project objectives are to identify and map gas hydrate accumulations on the US eastern continental margin using remote sensing (seismic profiling) techniques and to relate these concentrations to the geological factors that-control them. In order to test the remote sensing methods, gas hydrate-cemented sediments will be tested in the laboratory and an effort will be made to perform similar physical tests on natural hydrate-cemented sediments from the study area. Gas hydrate potentially may represent a future major resource of energy. Furthermore, it may influence climate change because it forms a large reservoir for methane, which is a very effective greenhouse gas; its breakdown probably is a controlling factor for sea-floor landslides; and its presence has significant effect on the acoustic velocity of sea-floor sediments.

Ahlbrandt, T.S.; Dillon, W.P.

1993-12-31

148

Detection and Identification of Bacteria by Gas Chromatography.  

National Technical Information Service (NTIS)

Ether extracts of cultures of 29 strains representing 6 species of Bacillus, and of individual strains of Escherichia coli, Aerobacter aerogenes, and Pseudomonas aeruginosa were examined in a gas chromatograph by use of flame ionization and electron captu...

Y. Henis J. R. Gould M. Alexander

1966-01-01

149

Gas phase chemical detection with an integrated chemical analysis system  

SciTech Connect

Microfabrication technology has been applied to the development of a miniature, multi-channel gas phase chemical laboratory that provides fast response, small size, and enhanced versatility and chemical discrimination. Each analysis channel includes a sample preconcentrator followed by a gas chromatographic separator and a chemically selective surface acoustic wave detector array to achieve high sensitivity and selectivity. The performance of the components, individually and collectively, is described.

CASALNUOVO,STEPHEN A.; FRYE-MASON,GREGORY CHARLES; KOTTENSTETTE,RICHARD; HELLER,EDWIN J.; MATZKE,CAROLYN M.; LEWIS,PATRICK R.; MANGINELL,RONALD P.; BACA,ALBERT G.; HIETALA,VINCENT M.

2000-04-12

150

Fibre optic systems for gas detection principals, progress and prospects  

NASA Astrophysics Data System (ADS)

Gas sensing is evolving into an important application contributing particularly to environmental and safety monitoring. Fibre optic sensing will have an important role to play as the need for gas measurements increase. This paper seeks to overview of the optical techniques which are compatible with fibre optic technology and present a limited snapshot of the applications. Fibre optic techniques offer intrinsic safety, reliability and very long interrogation distances over the fibre link together with prospects for highly multiplexed and distributed systems. There are two basic approaches for fibre sensing targeted at gas measurements. The first involves some intermediate compound in contact with the end of the fibre (or deposited along the fibre) whose optical properties change with the presence of the gas of interest, usually measured spectroscopically. The second involves direct absorption spectroscopy typically in the near infrared. Former techniques are invariably responsive to a number of gas species and are usually difficult to calibrate accurately. The latter techniques are highly gas specific and can be accurately calibrated. However both approaches have their application sectors depending upon particular measurement requirements. The paper presents a brief overview of the principles of both these techniques and analyses some of their applications.

Culshaw, Brian

2010-11-01

151

A systems level characterization and tradespace evaluation of a simulated airborne Fourier transform infrared spectrometer for gas detection  

Microsoft Academic Search

The remote sensing gas detection problem is one with no straightforward solution. While success has been achieved in detecting and identifying gases released from industrial stacks and other large plumes, the fugitive gas detection problem is far more complex. Fugitive gas represents a far smaller target and may be generated by leaking pipes, vents, or small scale chemical production. The

Aaron Weiner

2010-01-01

152

A gas chromatography-thermal conductivity detection method for helium detection in postmortem blood and tissue specimens.  

PubMed

In cases of death by inert gas asphyxiation, it can be difficult to obtain toxicological evidence supporting assignment of a cause of death. Because of its low mass and high diffusivity, and its common use as a carrier gas, helium presents a particular challenge in this respect. We describe a rapid and simple gas chromatography-thermal conductivity detection method to qualitatively screen a variety of postmortem biological specimens for the presence of helium. Application of this method is demonstrated with three case examples, encompassing an array of different biological matrices. PMID:22337780

Schaff, Jason E; Karas, Roman P; Marinetti, Laureen

2012-03-01

153

46 CFR 154.709 - Cargo boil-off as fuel: Gas detection equipment.  

Code of Federal Regulations, 2011 CFR

...CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.709 Cargo boil-off as fuel: Gas detection equipment. (a)...

2011-10-01

154

46 CFR 154.709 - Cargo boil-off as fuel: Gas detection equipment.  

Code of Federal Regulations, 2012 CFR

...CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.709 Cargo boil-off as fuel: Gas detection equipment. (a)...

2012-10-01

155

Semiconductor Laser Source for Natural Gas Leak Detection. Final Report September 1, 1984 - March 31, 1985.  

National Technical Information Service (NTIS)

The feasibility of using semiconductor lasers as infrared sources for handheld natural gas leak detectors was assessed. The detection system was assumed to be based on the differential absorption (DIAL) technique and to operate at ambient temperatures. Th...

R. A. Elliott

1985-01-01

156

Innovative High Pressure Gas MEMs Based Neutron Detector for ICF and Active SNM Detection.  

National Technical Information Service (NTIS)

An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making th...

G. A. Chandler M. Derzon R. F. Renzi S. B. Martin

2007-01-01

157

Leak detection in liquefied gas pipelines by artificial neural networks  

Microsoft Academic Search

A leak detection system for pipelines was developed by using artificial neural networks (ANN) for leak sizing and location and by processing the field data. This system can detect and locate leaks down to 1% of flow rates in pipelines carrying hazardous materials in about 100 s. A reference pipeline was considered for practical implementation of the package. The ability

Salvatore Belsito; Paolo Lombardi; Paolo Andreussi; Sanjoy Banerjee

1998-01-01

158

A biosensor for the detection of gas toxicity using a recombinant bioluminescent bacterium  

Microsoft Academic Search

A whole-cell biosensor was developed for the detection of gas toxicity using a recombinant bioluminescent Escherichia coli harboring a lac::luxCDABE fusion. Immobilization of the cells within LB agar has been done to maintain the activity of the microorganisms and to detect the toxicity of chemicals through the direct contact with gas. Benzene, known as a representative volatile organic compound, was

Geun Cheol Gil; Robert J. Mitchell; Suk Tai Chang; Man Bock Gu

2000-01-01

159

Development of a pulsed laser imaging system for natural gas leak detection.  

National Technical Information Service (NTIS)

The detection of gas leaks represents a critical operation performed regularly by the gas industry to maintain the integrity and safety of its vast network of piping, both above and below the ground. We are developing a technology that allows the real-tim...

T. J. Kulp

1995-01-01

160

Propane gas leak detection by infrared absorption using carbon infrared emitter and infrared camera  

Microsoft Academic Search

The present study investigated the ability of a system using a carbon infrared emitter (CIE) and an infrared (IR) camera to detect a combustible gas, propane. The CIE transmitted infrared at wavelengths ranging from 1 to 5?m, and the infrared absorption band of propane gas (3.37?m) was obtained using a bandpass filter to remove other infrared wavelengths. The intensity of

Naoya Kasai; Chihiro Tsuchiya; Takabumi Fukuda; Kazuyoshi Sekine; Takeru Sano; Tatsumi Takehana

2011-01-01

161

Leak detection of Hydrogen Gas Using Anti-Stokes Raman Scattering  

Microsoft Academic Search

An experimental study was performed to evaluate the applicability of anti-Stokes Raman scattering to leak detection of hydrogen gas. The laser beam of wavelength 355 nm and Stokes beam of wavelength 416 nm were aligned in a collinear configuration, and hydrogen gas was released into air through a nozzle of aperture 1 mm placed immediately below the beam path. The

Tetsuo Fukuchi; Hideki Ninomiya

2008-01-01

162

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

Microsoft Academic Search

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

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

2009-01-01

163

Semiconductor laser source for natural gas leak detection. Final report, September 1, 1984March 31, 1985  

Microsoft Academic Search

The feasibility of using semiconductor lasers as infrared sources for handheld natural gas leak detectors was assessed. The detection system was assumed to be based on the differential absorption (DIAL) technique and to operate at ambient temperatures. The absorption spectra of the major components of natural gas, methane and ethane, were measured in the spectral range from 1.2 to 2.0

1985-01-01

164

Detection of Gas Phase Free Radicals by Electron Spin Resonance Spin Trapping Techniques.  

National Technical Information Service (NTIS)

It was demonstrated that gas phase free radicals can be detected by spin trapping techniques i.e. free radicals present in a carrier gas react with solid phenyl t-butyl nitrone (spin trap) to give nitroxides which give esr spectra characteristic of the ga...

E. G. Janzen J. L. Gerlock

1969-01-01

165

Gas Phase Chemical Detection with an Integrated Chemical Analysis System  

SciTech Connect

Microfabrication technology has been applied to the development of a miniature, multi-channel gas phase chemical laboratory that provides fast response, small size, and enhanced versatility and chemical discrimination. Each analysis channel includes a sample concentrator followed by a gas chromatographic separator and a chemically selective surface acoustic wave detector array to achieve high sensitivity and selectivity. The performance of the components, individually and collectively, is described. The design and performance of novel micromachined acoustic wave devices, with the potential for improved chemical sensitivity, are also described.

Baca, Albert G.; Casalnuovo, Stephen A.; Frye-Mason, Gregory C.; Heller, Edwin J.; Hietala, Susan L.; Hietala, Vincent M.; Kottenstette, Richard J.; Lewis, Patrick R.; Manginell, Ronald P.; Matzke, Carloyn M.; Reno, John L.; Sasaki, Darryl Y.; Schubert, W. Kent

1999-07-08

166

A High Pressure Noble Gas Approach for WIMP Detection  

NASA Astrophysics Data System (ADS)

Initial measurements of the charge and light yield in pure xenon gas at 20 bar are discussed. Preliminary findings are that the yields are not greatly different from those reported in liquid xenon. Also, they are similar to yields observed in 50 bar Ar(Xe) and 100 bar Ne(Xe) in the same apparatus. In addition, good nuclear recoil discrimination is observed at low recoil energies relevant to WIMP interactions. The findings suggest that a room-temperature, high pressure gas approach may be an attractive alternative to liquid phase detectors for future large scale WIMP measurement experiments.

White, J. T.; Nygren, D.; Ooi, W.; Salinas, G.; Wang, H.

2009-09-01

167

ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT  

SciTech Connect

The power point presentation for the Natural Gas Technologies II Conference held on February 8-11, 2004 in Phoenix AZ, published the presentations made at the conference, therefore required all presenters to submit their presentation prior to November 2003. However in the remainder of year, significant new test data became available which were incorporated in the actual presentation made at the Natural Gas Technologies II Conference. The 6th progress report presents the updated actual slide show used during the paper presentation by Richard Guiler.

John L. LOTH; GARY J. MORRIS; GEORGE M. PALMER; RICHARD GUILER

2004-01-05

168

LOW COST IMAGER FOR POLLUTANT GAS LEAK DETECTION - PHASE II  

EPA Science Inventory

An inexpensive imaging Instrument to quickly locate leaks of methane and other greenhouse and VOC gases would reduce the cost and effort expended by industry to comply with EPA regulations. In Phase I, of this WBIR program, a new gas leak visualization camera was demonstrated...

169

Porous One-Dimensional Photonic Crystal Coatings for Gas Detection  

Microsoft Academic Search

Herein, we present an overview of recent progress on the development of different types of porous 1-D photonic crystal coatings which are optically responsive to gas pressure changes in the environment. Modification of the surrounding vapor pressure gives rise to adsorption and condensation phenomena within the porous networks of the photonic crystal building blocks, varying their refractive index and hence

Nuria Hidalgo; Mauricio Ernesto Calvo; Silvia Colodrero; Hernán Miguez

2010-01-01

170

Instrumental Analysis in Environmental Chemistry - Gas Phase Detection Systems  

ERIC Educational Resources Information Center

|Discusses advances made in chemical analysis instrumentation used in environmental monitoring. This first of two articles is concerned with analytical instrumentation in which detection and dispersion depend ultimately on the properties of gaseous molecules. (JR)|

Stedman, Donald H.; Meyers, Philip A.

1974-01-01

171

Limit of detection of 15{sub N} by gas-chromatography atomic emission detection: Optimization using an experimental design  

SciTech Connect

This paper deals with the optimal conditions for the detection of {sup 15}N determined using a four-factor experimental design from [2{sup 13}C,-1,3 {sup 15}N] caffeine measured with an atomic emission detector (AED) coupled to gas chromatography (GC). Owing to the capability of a photodiodes array, AED can simultaneously detect several elements using their specific emission lines within a wavelength range of 50 nm. So, the emissions of {sup 15}N and {sup 14}N are simultaneously detected at 420.17 nm and 421.46 nm respectively. Four independent experimental factors were tested (1) helium flow rate (plasma gas); (2) methane pressure (reactant gas); (3) oxygen pressure; (4) hydrogen pressure. It has been shown that these four gases had a significant influence on the analytical response of {sup 15}N. The linearity of the detection was determined using {sup 15}N amounts ranging from 1.52 pg to 19 ng under the optimal conditions obtained from the experimental design. The limit of detection was studied using different methods. The limits of detection of {sup 15}N was 1.9 pg/s according to the IUPAC method (International-Union of Pure and Applied Chemistry). The method proposed by Quimby and Sullivan gave a value of 2.3 pg/s and that of Oppenheimer gave a limit of 29 pg/s. For each determination, and internal standard: 1-isobutyl-3.7 dimethylxanthine was used. The results clearly demonstrate that GC AED is sensitive and selective enough to detect and measure {sup 15}N-labelled molecules after gas chromatographic separation.

Deruaz, D.; Bannier, A.; Pionchon, C.

1995-08-01

172

[Gas pipeline leak detection based on tunable diode laser absorption spectroscopy].  

PubMed

The principle of tunable diode laser absorption spectroscopy and harmonic detection technique was introduced. An experimental device was developed by point sampling through small multi-reflection gas cell. A specific line near 1 653. 7 nm was targeted for methane measurement using a distributed feedback diode laser as tunable light source. The linearity between the intensity of second harmonic signal and the concentration of methane was determined. The background content of methane in air was measured. The results show that gas sensors using tunable diode lasers provide a high sensitivity and high selectivity method for city gas pipeline leak detection. PMID:19839297

Zhang, Qi-Xing; Wang, Jin-Jun; Liu, Bing-Hai; Cai, Ting-Li; Qiao, Li-Feng; Zhang, Yong-Ming

2009-08-01

173

Automated Peak Detection and Matching Algorithm for Gas Chromatography-Differential Mobility Spectrometry  

PubMed Central

A gas chromatography–differential mobility spectrometer (GC-DMS) involves a portable and selective mass analyzer that may be applied to chemical detection in the field. Existing approaches examine whole profiles and do not attempt to resolve peaks. A new approach for peak detection in the 2D GC-DMS chromatograms is reported. This method is demonstrated on three case studies: a simulated case study; a case study of headspace gas analysis of Mycobacterium tuberculosis (MTb) cultures consisting of three matching GC-DMS and GC-MS chromatograms; a case study consisting of 41 GC-DMS chromatograms of headspace gas analysis of MTb culture and media.

Fong, Sim S.; Rearden, Preshious; Kanchagar, Chitra; Sassetti, Christopher; Trevejo, Jose; Brereton, Richard G.

2013-01-01

174

Development of carbon nanotube-based gas sensors for NOx gas detection working at low temperature  

NASA Astrophysics Data System (ADS)

Carbon nanotube (CNT)-based NOx gas sensors which can operate at room temperature were prepared on Al2O3 substrates with interdigitated Pt-electrodes using both dc sputtering method and chemical vapor deposition (CVD) method. In this method, Al buffer layer and Fe catalytic thin film were prepared on the substrate by dc sputtering method and then CNTs were grown by thermal CVD method using ethylene gas. The scanning electron microscope (SEM) images of the CNTs on the substrates indicated that the vertically aligned multi-walled CNT (MWCNT) and the randomly oriented MWCNT were grown selectively by insertion of Al buffer layer. Gas sensing property to NO and NO2 gases were measured. Resistance of the prepared CNT-based gas sensor decreased with increase of NO and NO2 gas concentration. UV light irradiation was examined to detach the adsorbed gas molecule at room temperature. In this paper, it is suggested that CNT-based gas sensors have a great possibility to apply innovative NOx gas sensor from the experimental result.

Ueda, T.; Bhuiyan, M. M. H.; Norimatsu, H.; Katsuki, S.; Ikegami, T.; Mitsugi, F.

2008-05-01

175

Optimizing automated gas turbine fault detection using statistical pattern recognition  

NASA Astrophysics Data System (ADS)

A method enabling the automated diagnosis of Gas Turbine Compressor blade faults, based on the principles of statistical pattern recognition is initially presented. The decision making is based on the derivation of spectral patterns from dynamic measurements data and then the calculation of discriminants with respect to reference spectral patterns of the faults while it takes into account their statistical properties. A method of optimizing the selection of discriminants using dynamic measurements data is also presented. A few scalar discriminants are derived, in such a way that the maximum available discrimination potential is exploited. In this way the success rate of automated decision making is further improved, while the need for intuitive discriminant selection is eliminated. The effectiveness of the proposed methods is demonstrated by application to data coming from an Industrial Gas Turbine while extension to other aspects of Fault Diagnosis is discussed.

Loukis, E.; Mathioudakis, K.; Papailiou, K.

1992-06-01

176

Detecting gas hydrate behavior in crude oil using NMR.  

PubMed

Because of the associated experimental difficulties, natural gas hydrate behavior in black oil is poorly understood despite its grave importance in deep-water flow assurance. Since the hydrate cannot be visually observed in black oil, traditional methods often rely on gas pressure changes to monitor hydrate formation and dissociation. Because gases have to diffuse through the liquid phase for hydrate behavior to create pressure responses, the complication of gas mass transfer is involved and hydrate behavior is only indirectly observed. This pressure monitoring technique encounters difficulties when the oil phase is too viscous, the amount of water is too small, or the gas phase is absent. In this work we employ proton nuclear magnetic resonance (NMR) spectroscopy to observe directly the liquid-to-solid conversion of the water component in black oil emulsions. The technique relies on two facts. The first, well-known, is that water becomes essentially invisible to liquid state NMR as it becomes immobile, as in hydrate or ice formation. The second, our recent finding, is that in high magnetic fields of sufficient homogeneity, it is possible to distinguish water from black oil spectrally by their chemical shifts. By following changes in the area of the water peak, the process of hydrate conversion can be measured, and, at lower temperatures, the formation of ice. Taking only seconds to accomplish, this measurement is nearly direct in contrast to conventional techniques that measure the pressure changes of the whole system and assume these changes represent formation or dissociation of hydrates - rather than simply changes in solubility. This new technique clearly can provide accurate hydrate thermodynamic data in black oils. Because the technique measures the total mobile water with rapidity, extensions should prove valuable in studying the dynamics of phase transitions in emulsions. PMID:16570953

Gao, Shuqiang; House, Waylon; Chapman, Walter G

2006-04-01

177

Alkene determination by bromination and gas chromatography with element-selective atomic plasma spectroscopic detection  

Microsoft Academic Search

A gas chromatography (GC) method for the determination of alkenes in complex hydrocarbon mixtures containing aromatic and saturated hydrocarbons is presented. The method enables selective and quantitative bromination of alkenes without affecting aromatic and saturated compounds. The dibromoalkanes formed are detected with minimal interference from coeluting hydrocarbons by bromine-selective atomic emission detection, with sub-nanogram bromine sensitivity. The method is applied

Nitin R. Hardas; Raymond Adam; Peter C. Uden

1999-01-01

178

Portable and RemoteElectrochemical Sensing System for Detection of Tricresyl-phosphate in Gas Phase  

Microsoft Academic Search

A portable electrochemical sensor has been developed for determination of tricresyl phosphate (TCP) in gas phase.An alkaline catalyst column was used in an automatic TCP sampling system where gasified TCP was hydrolysed to cresol, making it electrochemically detectable. Hydrolysates werethen detected in the flow injection analysis (FIA). Amperometric measurements were performed utilizing theunicell, which includes a glassy carbon working electrode,

Xiaoyun Yang; Alice Zitova; Jeffrey Kirsch; Jeffrey W. Fergus; Ruel A. Overfelt; Aleksandr L. Simonian

179

Remote field eddy current testing for detection of stress corrosion cracks in gas transmission pipelines  

Microsoft Academic Search

Magnetic flux leakage (MFL) pigs are traditionally used for the detection of gross corrosion on steel pipelines used for the transmission of natural gas. Alternative nondestructive evaluation (NDE) modalities are required for the detection of stress corrosion cracking (SCC), which tends to exist in colonies oriented axially along the length of the pipeline. This paper describes the use of multi-phase

D. Kim; L. Udpa; S. Udpa

2004-01-01

180

Dual sample injection for gas chromatographic determination of sulfur species with flame photometric detection  

SciTech Connect

A gas chromatograph using flame photometric detection is very good for sulfur detection. A major difficulty is the range of sulfur concentrations encountered in air samples. A dual sample loop instrument is presented that overcomes this difficulty. A small loop is provided for samples of high concentration and a large loop is provided for low concentration samples. 4 references, 3 figures.

Barbour, F.A.; Cummings, R.E.; Guffey, F.D.

1984-06-01

181

Sensors for Toxic Gas Detection PLATINUM METALS PERFORM AN IMPORTANT ROLE  

Microsoft Academic Search

The utilisatwn of advanced sensing techniques for detecting, indicating and mon- itoring toxic gases in industry and the environment is very important for health and safety. In this paper, the application of electrochemical, semiconductor, catalyticFeld efSect and catalytic gas sensors for the detection of toxic gases, and the role of platinum group metals in these deoices, is discussed. It is

Yuan-Jin Lei

182

High-gain microstrip gas counters for soft X-ray detection  

NASA Astrophysics Data System (ADS)

This study describes development work in which systematic changes in the pitch of the electrode pattern of a Microstrip Gas Counter (MSGC) are explored in the search for higher gas gains and enhanced stability. We investigated the gas gain, soft X-ray energy resolution and the detector noise with pitch values set between 300?m and 1200?m. With the cathode width set to half of the pitch and anode width at 5?m, gas gains exceeding 50,000 were comfortably achieved. We present the optimised MSGC geometry which permits radiation detection in the sub-keVX-ray region.

Bateman, J. E.; Barlow, R.; Derbyshire, G. E.; Mir, J. A.; Stephenson, R.

2003-11-01

183

Gas-chromatographic detection of urinary tract infections caused by Escherichia coli and Klebsiella sp.  

PubMed Central

A gas-chromatographic method for the diagnosis of urinary tract infections caused by Escherichia coli and Klebsiella sp. is described. A total of 96 urine samples from individuals with clinical symptoms of urinary tract infection or pyrexia of unknown origin were tested by conventional and gas-chromatographic methods for bacteriuria. The gas-chromatographic method showed complete agreement with the conventional method in diagnosing all of 16 cases of bacteriuria caused by E. coli and 4 cases caused by Klebsiella sp. The remaining two cases of bacteriuria, caused by other bacteria, were not detected by the gas-chromatographic method.

Manja, K S; Rao, K M

1983-01-01

184

Hepatic gas: widening spectrum of causes detected at CT and US in the interventional era.  

PubMed

The spectrum of causes of hepatic gas detected at computed tomography (CT) and ultrasonography (US) is widening. There are many iatrogenic and noniatrogenic causes of hepatic parenchymal, biliary, hepatic venous, and portal venous gas. Hepatic gas may be an indicator of serious acute disease (infarct, infection, abscess, bowel inflammation, or trauma). In other clinical scenarios, it may be an expected finding related to therapeutic interventions (such as surgery; hepatic artery embolization for a tumor or for active bleeding in acute trauma cases; percutaneous tumor ablation performed with radiofrequency, cryotherapy, laser photocoagulation, or ethanol). In some cases, hepatic gas is an incidental finding of no clinical significance. Familiarity with the expanding list of newer intervention-related causes of hepatic gas detected at CT and US, knowledge of the patient's clinical history, and a careful search for associated clues on images are all factors that may allow the radiologist to better determine the clinical relevance of this finding. PMID:21918051

Shah, Priti A; Cunningham, Steven C; Morgan, Tara A; Daly, Barry D

185

False-alarm characterization in hyperspectral gas-detection applications  

NASA Astrophysics Data System (ADS)

Chemical cloud detection using long-wave infrared (LWIR) hyperspectral-imaging sensors has many civilian and military applications, including chemical warfare threat mitigation, environmental monitoring, and emergency response. Current capabilities are limited by variation in background clutter as opposed to the physics of photon detection, and this makes the statistical characterization of clutter and clutter-induced false alarms essential to the design of practical systems. In this exploratory work, we use hyperspectral data collected both on the ground and in the air to spectrally and spatially characterize false alarms. Focusing on two widely-used detectors, the matched filter (MF) and the adaptive cosine estimator (ACE), we compare empirical false-alarm rates to their theoretical counterparts - detector output under Gaussian, t and t-mixture distributed data - and show that these models often underestimate false-alarm rates. Next, we threshold real detection maps and show that true detections and false alarms often exhibit very different spatial behavior. To exploit this difference and understand how spatial processing affects performance, the spatial behavior of false alarms must be understood. We take a first step in this direction by showing that, although the behavior may `look' quite random, it is not well captured by the complete-spatial-randomness model. Finally, we describe how our findings impact the design of real detection systems.

DiPietro, Robert S.; Truslow, Eric; Manolakis, Dimitris G.; Golowich, Steven E.; Lockwood, Ronald B.

2012-09-01

186

Trace detection of oxygen - ionic liquids in gas sensor design.  

PubMed

This paper presents a novel electrochemical membrane sensor on basis of ionic liquids for trace analysis of oxygen in gaseous atmospheres. The faradaic response currents for the reduction of oxygen which were obtained by multiple-potential-step-chronoamperometry could be used for real time detection of oxygen down to concentrations of 30ppm. The theoretical limit of detection was 5ppm. The simple, non-expensive sensors varied in electrolyte composition and demonstrated a high sensitivity, a rapid response time and an excellent reproducibility at room temperature. Some of them were continuously used for at least one week and first results promise good long term stability. Voltammetric, impedance and oxygen detection studies at temperatures up to 200°C (in the presence and absence of humidity and CO2) revealed also the limitations of certain ionic liquids for some electrochemical high temperature applications. Application areas of the developed sensors are control and analysis processes of non oxidative and oxygen free atmospheres. PMID:24148432

Baltes, N; Beyle, F; Freiner, S; Geier, F; Joos, M; Pinkwart, K; Rabenecker, P

2013-07-11

187

Study of gas detection based on integrated cavity output spectroscopy  

NASA Astrophysics Data System (ADS)

A trace gases detection system based on integrated cavity output spectroscopy (ICOS) was developed, where a NIR tunable diode laser (TDL) was used as light source, an optical cavity composed by two plan-concave mirrors with reflection near 99.7% was used as the absorption cell. Trace water vapour (H2O), carbon dioxide (CO2), methane (CH4), carbon monoxide (CO) and mixture of CO2 and CO were tested by ICOS based on the characteristics absorption. The wavelength calibration, cavity transmission characteristics, quantitative measurement ability and sensitivity of the TDL-ICOS were also studied, and a evaluated minimum detectable sensitivity of 1.15 × 10-7 cm-1 was obtained when the system was used to CH4 detection. The experiment results show that TDL-ICOS is expected to be a reliable and promising system for the detection of trace gases since it has some advantages such as real-time monitoring, simple device, easy operation, high sensitivity, good stability and quantitative ability.

Pei, Shixin; Cui, Fenping; Su, Jing; Xu, Linhua; Sun, Tingting

2013-08-01

188

Fault Detection in Multivariate Signals With Applications to Gas Turbines  

Microsoft Academic Search

This paper proposes a fault detection method for multivariate signals. The method assesses whether or not the multivariate autocovariance functions of two independently sampled system signals coincide. If the first signal is known to be sampled from a well-functioning system, then rejection of signal equality is tantamount to concluding that the second signal is sampled from a faulty system. The

Hany Bassily; Robert Lund; John Wagner

2009-01-01

189

Gas detection for alternate-fuel vehicle facilities.  

PubMed

Alternative fuel vehicles' safety is driven by local, state, and federal regulations in which fleet owners in key metropolitan [table: see text] areas convert much of their fleet to cleaner-burning fuels. Various alternative fuels are available to meet this requirement, each with its own advantages and requirements. This conversion to alternative fuels leads to special requirements for safety monitoring in the maintenance facilities and refueling stations. A comprehensive gas and flame monitoring system needs to meet the needs of both the user and the local fire marshal. PMID:12754860

Ferree, Steve

2003-05-01

190

Visual detection of gas shows from coal core and cuttings using liquid leak detector  

USGS Publications Warehouse

Portions of core or cutting samples that have active gas shows can be identified by applying a liquid leak detector to the core surface. Although these gas shows can be caused by manmade changes to the coals' internal structure and surface of the core during the coring process, in many cases, the marked gas shows overlie changes in maceral composition, subtle fractures or coal, coal structure and so forth that seemingly are places where natural primary permeability is higher and gas shows would be favored. Given the limited time available for core description before a core is closed in a canister, using the liquid leak detector method to mark gas shows enhances core description by providing a photographic record of places of apparently increased gas flow likely related to enhanced coal permeability that cannot be easily detected otherwise.

Barker, C. E.

2006-01-01

191

Fabrication and characterization of micro-gas sensor for nitrogen oxides gas detection  

Microsoft Academic Search

WO3-based thin film micro-gas sensor was fabricated and the NOx gas sensing as well as electrical properties have been investigated. To obtain the optimal heat distribution, the structure of micro-hot plate was designed from the result of finite element simulation and was prepared by backside etching with KOH solution.The micro-hot plate was made out of N\\/O\\/N diaphragm with the thickness

Dae-Sik Lee; Jun-Woo Lim; Sang-Mun Lee; Jeung-Soo Huh; Duk-Dong Lee

2000-01-01

192

Fabry-Pérot cavity sensors for multipoint on-column micro gas chromatography detection.  

PubMed

We developed and characterized a Fabry-Pérot (FP) sensor module based micro gas chromatography (microGC) detector for multipoint on-column detection. The FP sensor was fabricated by depositing a thin layer of metal and a layer of gas-sensitive polymer consecutively on the endface of an optical fiber, which formed the FP cavity. Light partially reflected from the metal layer and the polymer-air interface generated an interference spectrum, which shifted as the polymer layer absorbed the gas analyte. The FP sensor module was then assembled by inserting the FP sensor into a hole drilled in the wall of a fused-silica capillary, which can be easily connected to the conventional gas chromatography (GC) column through a universal quick seal column connector, thus enabling on-column real-time detection. We characterized the FP sensor module based microGC detector. Sensitive detection of various gas analytes was achieved with subnanogram detection limits. The rapid separation capability of the FP sensor module assembled with both single- and tandem-column systems was demonstrated, in which gas analytes having a wide range of polarities and volatilities were well-resolved. The tandem-column system obtained increased sensitivity and selectivity by employing two FP sensor modules coated with different polymers, showing great system versatility. PMID:20441156

Liu, Jing; Sun, Yuze; Howard, Daniel J; Frye-Mason, Greg; Thompson, Aaron K; Ja, Shiou-Jyh; Wang, Siao-Kwan; Bai, Mengjun; Taub, Haskell; Almasri, Mahmoud; Fan, Xudong

2010-06-01

193

Detection of irradiated fruits by gas-chromatographic methods  

Microsoft Academic Search

To detect those fruits which have been subjected to low-dose irradiation (0.5-3 kGy), two methods of chromatography (GC-MS and LC-LC-GC-FID) were used to determine the radiolytic compounds of lipids formed after irradiation, such as alkanes and alkenes. Extraction of volatile hydrocarbon compounds from some parts of irradiated fruits, e. g. the flesh (avocado), seeds (papaya) and kernels (mango and apricot)

Serag El-Dien Ahmed Farag

1996-01-01

194

Numerical evidence of gas hydrate detection by means of electroseismics  

NASA Astrophysics Data System (ADS)

This work presents numerical evidence that methane hydrate-bearing sediments located below permafrost can be detected using electroseismics as a prospecting tool. The numerically solved equations are the ones developed by Pride; we modified them by using an extended Biot formulation to appropriately deal with a composite (rock-ice/rock-methane hydrate) solid matrix. We modeled the subsurface as a two dimensional medium, and we used electromagnetic sources to give rise to the so called SHTE and PSVTM modes. The obtained results show that the seismic response is sensitive to the methane hydrate concentration.

Zyserman, Fabio I.; Gauzellino, Patricia M.; Santos, Juan E.

2012-11-01

195

Electrochemical noise sensors for detection of localized and general corrosion of natural gas transmission pipelines  

SciTech Connect

The U.S. Department of Energy, National Energy Technology Laboratory funded a Natural Gas Infrastructure Reliability program directed at increasing and enhancing research and development activities in topics such as remote leak detection, pipe inspection, and repair technologies and materials. The Albany Research Center (ARC), U.S. Department of Energy was funded to study the use of electrochemical noise sensors for detection of localized and general corrosion of natural gas transmission pipelines. As part of this, ARC entered into a collaborative effort with the corrosion sensor industry to demonstrate the capabilities of commercially available remote corrosion sensors for use with the Nation's Gas Transmission Pipeline Infrastructure needs. The goal of the research was to develop an emerging corrosion sensor technology into a monitor for the type and degree of corrosion occurring at key locations in gas transmission pipelines.

Holcomb, Gordon R.; Bullard, Sophie J.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Russell, James H.; Ziomek-Moroz, Margaret

2002-09-01

196

Electron capture gas chromatographic detection of acethylmethylcarbinol produced by neisseria gonorrhoeae.  

PubMed Central

Acetylmethylcarbinol (acetoin) production by Neisseria gonorrhoeae and other Neisseria species was established by gas-liquid chromatography and by mass spectrometric data. Sixty-nine isolates of Neisseria were tested by incubating them in a chemically defined fluid medium. The medium was extracted with organic solvents and derivatized with heptafluorobutryic anhydride for gas chromatography and mass spectrometry. Cultures of 58 of the same strains were tested with the conventional Voges-Proskauer reagents, and results were compared with those of gas-liquid chromatography. When glucose was used as an energy source, N. gonorrhoeae, some N. meningitidis, and N. lactamica produced enough acetoin in 16 h to be detectable by either method, whereas other Neisseria species produce amounts detectable only by gas chromatography. The conventional acetylmethylcarbinol test with the chemically defined medium and maltose as an energy source might be used to develop methods that would differentiate certain members of the genus, including the pathogenic species.

Morse, C D; Brooks, J B; Kellogg, D S

1976-01-01

197

3D-1 Absolute Transit Time Detection for Ultrasonic Gas Flowmeters Based on Time and Phase Domain Characteristics  

Microsoft Academic Search

We present an absolute transit time detection algorithm for ultrasonic gas flowmeters (UFMs). The major objective is a reliable and accurate detection, even when the received signals experience a change and degradation of their shape. This can be due to parasitic effects, such as high gas temperatures and pressure fluctuations. We employ a time and phase domain based detection algorithm

Mario Kupnik; Edwin Krasser; M. Groschl

2007-01-01

198

Laser application in the fabrication of gas-tagged capsules. A leak detection system  

SciTech Connect

Encapsulation of a unique isotopic blend of krypton and xenon gas employs a special application of laser technology. The encapsulated gas is then used as the primary medium for detection and identification of failed nuclear fuel rods. The use of gas tagging as a means of detecting and identifying failed nuclear fuel rods has been successfully demonstrated and used by the Argonne National Laboratory, Experimental Breeder Reactor (EBR-2) Project, and the Westinghouse Hanford Company (WHC), Fast Flux Test Facility (FFTF) Fast Breeder Reactor Program. The Power Reactor and Nuclear Fuel Development Corporation (PNC) of Japan has selected this leak detection system for use in their MONJU Prototype Reactor fuel assemblies. The MONJU reactor is almost identical in design to the highly successful FFTF reactor, which is currently in standby status.

McCord, R.B.; Lysher, W.M.

1993-12-01

199

Energy resolution in X-ray detecting micro-strip gas counters  

NASA Astrophysics Data System (ADS)

Systematic measurements of the energy resolution available from a Micro-Strip Gas Counter (MSGC) are presented. The effect of factors such as bias potential, gas filling and strip geometry on the energy resolution are examined in detail and related to a simple model. The geometry of the MSGC is adapted to permit ``wall-less'' detection of X-rays and this results in useful improvements in the pulse height spectra.

Bateman, J. E.; Connolly, J. F.; Derbyshire, G. E.; Duxbury, D. M.; Mir, J. A.; Spill, E. J.; Stephenson, R.

2002-05-01

200

Remote CO, COS, CO2, SO2, HCl detection and temperature estimation of volcanic gas  

Microsoft Academic Search

Volcanic gas from an inaccessible fumarole at Aso volcano, Japan, was recently measured with a Fourier Transform InfraRed (FT-IR) spectral radiometer. Absorption features of CO, COS, CO2, SO2, and HCl were identified in the volcanic plume spectra. This is the first time the five volcanic gas components are detected simultaneously by a remote technique. Based on the measured CO\\/CO2 ratio

Toshiya Mori; Kenji Notsu

1997-01-01

201

Gas sensor arrays for early detection of infection in mammalian cell culture.  

PubMed

The detection of bacterial infections in a mammalian cell culture process is realised using a gas sensor array. In production-scale and laboratory-scale cultivations of a perfused recombinant CHO-cell culture producing human blood coagulation Factor VIII, we show that the gas sensor array identifies bacterial contamination earlier than conventional methods. The sensitivity of the instrument is verified by inoculation of a blank cell culture medium with defined bacterial cell counts. PMID:11888730

Bachinger, Thomas; Riese, Ulrich; Eriksson, Rolf K; Mandenius, Carl Fredrik

2002-05-01

202

Miniaturized Optical System for Detection of Ammonia Nitrogen in Water Based on Gas-Phase Colorimetry  

Microsoft Academic Search

A small-size gastight optical measuring system for detection of ammonia nitrogen in water was prepared based on gas-phase ammonia induced color change of the sensing element that was made by loading bromothymol blue (BTB) in a transparent porous glass fiber membrane. The gastight optical measuring system consists of a gas-testing and a liquid-sample chamber connected with each other by means

Yan-qing YAO; Dan-feng LU; Zhi-mei QI; Shanhong XIA

2012-01-01

203

Hydroacoustic detection and quantification of free gas -methane bubbles- in the ocean  

NASA Astrophysics Data System (ADS)

Extensive methane release as a free gas phase from cold vents is well known from deep (>2000m) and shallow (10s of meters) water depths. Supposedly, much more methane is transported into the water column by free gas than by dissolved gas, which is oxidized by anaerobic and aerobic processes and partly precipitated as carbonate. Rising gas bubbles are not affected by this 'filter' mechanisms. Because of the strength of the backscattered signal from gas bubbles in the water column, bubbles can be detected by single-beam or multi-beam echosounder systems. Thus, hydroacoustic systems with different frequencies can be used to 1) detect free gas in the water column, 2) map the distribution of active vent sites which release free gas, 3) monitor a possible periodicity in the release of bubbles induced by e.g. tides or currents, 4) quantify the gas volume and gas flux that is released in a local area or larger region. In the German research project LOTUS we use ship- mounted single-beam echosounders to map gas plumes (flares) and investigate their periodicity (Flare Imaging). Using specialized single-beam echosounder systems makes it possible to measure the bubble sizes and their distribution. In combination with the volume of the backscattering strength these measurements can be used to estimate the gas volume in a defined part of the water body. Though gas bubbles rise in the water column, they are - particularly methane - rapidly dissolved and thus become smaller. Their rising speed as well as their diminishing size can be determined, which helps to understand the dissolution behaviour of methane bubbles; they form a hydrate skin at distinct pressure and temperature conditions. For a detailed, long-term observation of active bubble-expulsing areas we developed a lander based 180 kHz multi beam system that 'looks' horizontally (GasQuant). The system records backscatter data from a 75° swath that covers an area of about 5300m2. Via calibration we can quantify the methane flux of every single bubble-vent and calculate the methane flux of a bubble vent area. Both hydroacoustic techniques were used during several cruises in 2002 to investigate bubble vents at Hydrate Ridge (HR), offshore Oregon. Several bubble-vent areas were detected at the northern summit of HR. They are related to carbonate chemoherms and morphological heights but were also found in areas which do not show any of these features. The GasQuant system was successfully deployed at the northern and southern summit. The data processing is currently in progress.

Greinert, J.; Artemov, Y.; Gimpel, P.

2003-04-01

204

Development of fault section detecting system for gas insulated transmission lines  

SciTech Connect

A fault section detecting system using optical magnetic field sensors developed for gas insulated transmission lines (GIL) is reported. A bismuth silicon oxide (Bi/sub 12/SiO/sub 20/, or BSO) single crystal was adopted for the optical magnetic field sensor. A method of mounting the sensors to GIL which enables the sensors to detect the conductor current from outside the enclosure was developed. With the developed fault detector, faults occurring inside a section of GIL between sensors are detected by discriminating the phases of conductor currents detected by the sensors. The system was confirmed to have sufficient performance for application to commerical GILS.

Nakamura, E.; Uchida, K.; Koshilishi, M.; Mitsui, T.; Miyamoto, S.; Nakamura, K.; Itaka, K.; Hara, T.; Yoda, T.

1986-01-01

205

Field evaluation of the British Gas elastic-wave vehicle for detecting stress corrosion cracking in natural gas transmission pipelines. Final report, June 1995  

Microsoft Academic Search

The objective of this project was to provide the gas pipeline industry with a more comprehensive understanding of the capabilities of the elastic-wave, in-line inspection system developed by British Gas (BG) for detecting stress corrosion cracking (SCC) in natural gas transmission pipelines.

D. L. Culbertson; C. E. Whitney

1995-01-01

206

Sensor Array Devices Utilizing Nano-structured Metal-oxides for Hazardous Gas Detection  

NASA Astrophysics Data System (ADS)

Methane and carbon monoxide are two hazardous gases which require continuous monitoring by gas sensors in underground coal mines for explosion prevention and toxicity, respectively. This work explored implementing miniaturized gas sensors in this area to simultaneously detect both gases for benefits of increased portability and reduced power consumption of the chemiresistive gas sensor device. The focus of this research was to understand how the particle size, morphology, and microstructure of the metaloxide film affected the gas sensor performance to the two gases of interest on miniaturized gas sensor devices in the form of microhotplate platforms. This was done through three main research studies. The first was conducted by growing SnO2 nanowires from SnO 2 particles using an Au-catalyst. Growth conditions including temperature, time, and oxygen partial pressure were explored to determine the formation aspects of the SnO2 nanowires. Gas sensor studies were completed that provided evidence that the SnO2 nanowires increased detection to a fixed concentration of carbon monoxide compared to SnO2 particles without nano-structure formation. A second research study was performed to compare the gas sensor performance of SnO2 nanoparticles, hierarchical particles, and micron-size particles. The nanoparticles were developed into an ink and deposited via ink-jet printing on the microhotplate substrates to control the microstructure of the metal-oxide film. By preventing agglomeration of the nanoparticle film, the SnO2 nanoparticles displayed similar gas sensor performance to methane and carbon monoxide as the hierarchical particles. Both nano-structures had much higher gas sensor response than the micron-size particles which confirms the surface area of the metal-oxide film is critical for reaction of the analyte gas at the surface. The last research study presented in the dissertation describes an oxide nanoparticle array developed for detecting methane and carbon monoxide in the presence of one another. A design of experiments was constructed and principal component analysis was used for determining the optimum temperatures of the metal-oxide elements. A four element array was developed with the SnO 2 and TiO2 sensor elements able to detect methane concentrations of interest and the ZnO and NiO sensor elements able to detect the carbon monoxide concentrations. A linear based prediction model was developed and tested for accuracy and reproducibility of the model to a series of random gas concentrations.

Andio, Mark A.

207

Calculating the detection limits of chamber-based soil greenhouse gas flux measurements.  

PubMed

Renewed interest in quantifying greenhouse gas emissions from soil has led to an increase in the application of chamber-based flux measurement techniques. Despite the apparent conceptual simplicity of chamber-based methods, nuances in chamber design, deployment, and data analyses can have marked effects on the quality of the flux data derived. In many cases, fluxes are calculated from chamber headspace vs. time series consisting of three or four data points. Several mathematical techniques have been used to calculate a soil gas flux from time course data. This paper explores the influences of sampling and analytical variability associated with trace gas concentration quantification on the flux estimated by linear and nonlinear models. We used Monte Carlo simulation to calculate the minimum detectable fluxes (? = 0.05) of linear regression (LR), the Hutchinson/Mosier (H/M) method, the quadratic method (Quad), the revised H/M (HMR) model, and restricted versions of the Quad and H/M methods over a range of analytical precisions and chamber deployment times (DT) for data sets consisting of three or four time points. We found that LR had the smallest detection limit thresholds and was the least sensitive to analytical precision and chamber deployment time. The HMR model had the highest detection limits and was most sensitive to analytical precision and chamber deployment time. Equations were developed that enable the calculation of flux detection limits of any gas species if analytical precision, chamber deployment time, and ambient concentration of the gas species are known. PMID:22565252

Parkin, T B; Venterea, R T; Hargreaves, S K

208

Detection of irradiated fruits by gas-chromatographic methods.  

PubMed

To detect those fruits which have been subjected to low-dose irradiation (0.5-3 kGy), two methods of chromatography (GC-MS and LC-LC-GC-FID) were used to determine the radiolytic compounds of lipids formed after irradiation, such as alkanes and alkenes. Extraction of volatile hydrocarbon compounds from some parts of irradiated fruits, e.g. the flesh (avocado), seeds (papaya) and kernels (mango and apricot) was carried out. The analysis of hydrocarbons by GC-MS proved the suitability of using C17:1, C16:2, C15:0 and C14:1 as markers for avocados irradiated with a low dose (0.75 kGy). The same indicators appeared following the analysis of papayas and mangoes irradiated with 1.5, and 3.0 kGy. Also, C15:0, C14:1 and C16:3 can be used to identify apricots irradiated with a low dose (0.5 kGy). The detection of alkenes was only improved by a more selective isolation, e.g. of dienes or trienes by LC-LC-GC-FID. Within a few minutes, apricots and avocados irradiated at low doses (0.5 and 0.75 kGy) can be recognized by the indicators C16:2, C17:2 and C16:3, without interfering peaks. In all cases, C16:1, C16:2, C16:3 as well as significant amounts of C17:2 can be used as markers for fruit irradiation. PMID:8711951

el-Dien, S; Farag, A

1996-06-01

209

Remote CO, COS, CO2, SO2, HCl detection and temperature estimation of volcanic gas  

NASA Astrophysics Data System (ADS)

Volcanic gas from an inaccessible fumarole at Aso volcano, Japan, was recently measured with a Fourier Transform InfraRed (FT-IR) spectral radiometer. Absorption features of CO, COS, CO2, SO2, and HCl were identified in the volcanic plume spectra. This is the first time the five volcanic gas components are detected simultaneously by a remote technique. Based on the measured CO/CO2 ratio of 2.6 × 10-3, the equilibrium temperature of the volcanic gas is estimated to be 750° ± 120°C.

Mori, Toshiya; Notsu, Kenji

1997-08-01

210

Naturally fractured tight gas reservoir detection optimization. Quarterly report, January--March 1995  

SciTech Connect

This report describes progress in the following five projects: (1) Geologic assessment of the Piceance Basin; (2) Regional stratigraphic studies, Upper Cretaceous Mesaverde Group, southern Piceance Basin, Colorado; (3) Structurally controlled and aligned tight gas reservoir compartmentalization in the San Juan and Piceance Basins--Foundation for a new approach to exploration and resource assessments of continuous type deposits; (4) Delineation of Piceance Basin basement structures using multiple source data--Implications for fractured reservoir exploration; and (5) Gas and water-saturated conditions in the Piceance Basin, western Colorado--Implications for fractured reservoir detection in a gas-centered coal basin.

NONE

1995-05-01

211

Development of an intelligent hypertext manual for the space shuttle hazardous gas detection system  

NASA Astrophysics Data System (ADS)

A computer-based Integrated Knowledge System (IKS), the Intelligent Hypertext Manual (IHM), is being developed for the Space Shuttle Hazardous Gas Detection System (HGDS) at the Huntsville Operations Support Center (HOSC). The IHM stores all HGDS related knowledge and presents them in an interactive and intuitive manner. The IHM's purpose is to provide HGDS personnel with the capabilities of: enhancing the interpretation of real time data; recognizing and identifying possible faults in the Space Shuttle sub-system related to hazardous gas detections; locating applicable documentation related to procedures, constraints, and previous fault histories; and assisting in the training of personnel.

Lo, Ching F.; Shi, George Z.; Bangasser, Carl; Fensky, Connie

212

[The detection of ephedrine by solid-phase immunoenzyme analytical and gas chromatographic methods].  

PubMed

Comparative analysis of ephedrine derivative content in 96 urine specimen obtained from people suspected in abuse with these drugs. Physical and chemical methods of the analysis (gas and thin-layer chromatography) as well as ELISA were used. It was stated that the latter is specific for determination of compounds related to ephedrine by structure and it allows one to detect its analogues in 87 cases. Gas chromatography made it possible to detect ephedrine derivatives in 94 specimen tested and thin-layer chromatography--in 64 specimen tested. The given ELISA may be recommended for medicolegal expert purposes and narcology practice. PMID:1882405

Miagkova, M A; Lushnikova, M V; Polevaia, O Iu; Gorbatova, T I; Akalaev, A N

213

Electrochemical corrosion rate sensors for detecting internal corrosion of natural gas transmission pipelines  

SciTech Connect

This paper is a report on the evaluation of the use of electrochemical corrosion rate probes to detect internal corrosion in natural gas transmission pipeline environments. Flange and flush-mount probes were used in four different environments at three different sites that were selected to represent normal and upset conditions in a gas transmission pipeline. The environments consisted of humidified natural gas, organic/water mixtures removed from natural gas, and the environments at the 6 and 12 o'clock positions of a natural gas pipeline carrying multiphase gas/liquid flow. This paper will summarize and extend results presented previously and add additional data. A re-analysis of previously-reported data will be presented along with the results of physical examinations on the probes. New data on the measurement of corrosion in multiphase gas/liquid environments and for coupons used to determine corrosion rate and to detect the presence of microbiologically-influenced corrosion (MIC) will also be presented.

Covino, Bernard S., Jr.; Bullard, Sophie J.; Cramer, Stephen D.; Holcomb, Gordon R.; Ziomek-Moroz, M.; Kane, R.D. (Intercorr International Inc.); Eden, D.C. (Intercorr International Inc.)

2005-01-01

214

Gas detection by structural variations of fluorescent guest molecules in a flexible porous coordination polymer  

NASA Astrophysics Data System (ADS)

The development of a new methodology for visualizing and detecting gases is imperative for various applications. Here, we report a novel strategy in which gas molecules are detected by signals from a reporter guest that can read out a host structural transformation. A composite between a flexible porous coordination polymer and fluorescent reporter distyrylbenzene (DSB) selectively adsorbed CO2 over other atmospheric gases. This adsorption induced a host transformation, which was accompanied by conformational variations of the included DSB. This read-out process resulted in a critical change in DSB fluorescence at a specific threshold pressure. The composite shows different fluorescence responses to CO2 and acetylene, compounds that have similar physicochemical properties. Our system showed, for the first time, that fluorescent molecules can detect gases without any chemical interaction or energy transfer. The host-guest coupled transformations play a pivotal role in converting the gas adsorption events into detectable output signals.

Yanai, Nobuhiro; Kitayama, Koji; Hijikata, Yuh; Sato, Hiroshi; Matsuda, Ryotaro; Kubota, Yoshiki; Takata, Masaki; Mizuno, Motohiro; Uemura, Takashi; Kitagawa, Susumu

2011-10-01

215

Remarks on detecting high-energy deuterium tritium fusion gamma rays using a gas Cherenkov detector  

Microsoft Academic Search

As fusion ignition conditions are approached using the national ignition facility (NIF), independent high-bandwidth gamma-ray fusion burn measurements become essential complements to information obtained from neutron diagnostics. The 16.75-MeV gamma rays that accompany deuterium tritium (d+t) fusion can be detected using a high-bandwidth gaseous carbon dioxide Cherenkov threshold detector. The detection energy threshold was set by the CO2 gas pressure.

J. M. Mack; R. R. Berggren; S. E. Caldwell; C. R. Christensen; S. C. Evans; J. R. Faulkner Jr.; R. L. Griffith; G. M. Hale; R. S. King; D. K. Lash; R. A. Lerche; J. A. Oertel; D. M. Pacheco; C. S. Young

2006-01-01

216

Determination of daminozide residues in apples using gas chromatography with nitrogen-phosphorus detection  

Microsoft Academic Search

A method was developed for the determination of daminozide in apples using gas chromatography (GC) with nitrogen-phosphorus detection (NPD). Daminozide is hydrolysed to 1,1-dimethylhydrazine (UDMH) by alkaline digestion. The UDMH generated is distilled from the apple matrix, derivatized with 2-nitrobenzaldehyde and analysed by GC-NPD. The limit of detection (LOD) and the limit of quantitation (LOQ) for daminozide are 1.9 ?g\\/kg

Jan Henk W. Brinkman; Anton G. van Dijk; Rolf Wagenaar; Jan K. Quirijns

1996-01-01

217

Picosecond standoff multiphoton detection of gas phase species: initial results  

NASA Astrophysics Data System (ADS)

In the implementation of laser-induced fluorescence (LIF) for the detection of vapor-phase organic compounds that accompany hazardous materials, multiphoton excitation offers a significant advantage over single photon methods. In particular, if the absorption spectra of unwanted background molecules overlap that of the target molecule, single photon LIF is plagued by false positives. Multiphoton methods alleviate this difficulty by requiring that the target molecule be in resonance with multiple molecular transitions. A promising multiphoton method is stimulated Raman adiabatic passage (STIRAP). This method involves a counterintuitive sequence of laser pulses which is capable of transferring 100% of the target molecules to the desired excited state from which fluorescence is to be observed. As a precursor to more complex molecules, we demonstrate the STIRAP technique on sodium vapor using the 3p (2P1/2) <-- 3s (2S1/2) and 5s (2S1/2) <-- 3p (2P1/2) transitions. This is the first time STIRAP has been achieved on a vapor using picosecond lasers. We produced light to couple the states using two synchronously pumped OPG/OPAs (pumped by the 355 nm light from a picosecond YAG). We measured the fluorescence from the 5s state to both 3p states (2P1/2, 2P3/2) and from both 3p states to the 3s state with monochromator using a gated CCD to eliminate Rayleigh scattered light. Our results indicate a four to five-fold increase in the transfer efficiency to the 5s state when the laser pulse that couples the 3p and 5s states precedes the laser pulse tuned to the 3p <-- 3s transition.

Johnson, J. Bruce; Lyon, Kevin; Murry, William D.; Britton, Daniel R.; Johnson, Michael J.

2008-05-01

218

Mid-infrared virtually imaged phased array spectrometer for rapid and broadband trace gas detection.  

PubMed

We present and characterize a two-dimensional (2D) imaging spectrometer based on a virtually imaged phased array (VIPA) disperser for rapid, high-resolution molecular detection using mid-infrared (MIR) frequency combs at 3.1 and 3.8 ?m. We demonstrate detection of CH4 at 3.1 ?m with >3750 resolution elements spanning >80 nm with ~600 MHz resolution in a <10 ?s acquisition time. In addition to broadband detection, we also demonstrate rapid, time-resolved single-image detection by capturing dynamic concentration changes of CH4 at a rate of ~375 frames per second. Changes in absorption above the noise floor of 5×10(-4) are readily detected on the millisecond time scale, leading to important future applications such as real-time monitoring of trace gas concentrations and detection of reactive intermediates. PMID:22859160

Nugent-Glandorf, Lora; Neely, Tyler; Adler, Florian; Fleisher, Adam J; Cossel, Kevin C; Bjork, Bryce; Dinneen, Tim; Ye, Jun; Diddams, Scott A

2012-08-01

219

Capillary gas chromatographic analysis of nitrogen dioxide and pans with luminol chemiluminescent detection.  

SciTech Connect

Peroxyacyl nitrates (PANs) and nitrogen dioxide are important atmospheric air pollutants in the troposphere. These atmospheric nitrogen species are strongly coupled chemically by a clearly temperature-dependent equilibrium in the troposphere. A chemical method that can measure both nitrogen dioxide and PANs rapidly and with sub-part-per-billion detection is described that is based upon a modified luminol detection system coupled to a capillary gas chromatographic column by using helium as a carrier. The system can readily separate and detect nitrogen dioxide, peroxyacetyl nitrate, peroxyproprionyl nitrate, and peroxybutyrl nitrate with detection limits in the low tens of parts per trillion with total analysis time of less than 1 min. Calibration of PAN by thermal decomposition to nitrogen dioxide is demonstrated with PAN detection sensitivities approximately 75% of the sensitivities observed for NO2 luminol detection by using helium as a carrier gas. The advantages of this method for simultaneous measurement of nitrogen dioxide and PANs over ozone chemiluminescent detection and electron capture detection are discussed, as well as potential applications of this method for heterogeneous surface chemistry studies of PANs and nitrogen dioxide and for tropospheric measurements.

Gaffney, J. S.; Bornick, R. M.; Chen, Y.-H.; Marley, N. A.; Environmental Research

1998-01-01

220

Thin-film-bulk-acoustic-resonator gas sensor for the detection of organophosphate vapor detection  

Microsoft Academic Search

A novel design of an organophosphate vapor sensor based on a thin film bulk acoustic resonator (TFBAR) is presented. The TFBAR device is consisted of an AlN piezoelectric stack and a Mo\\/AlN Bragg reflector. Poly (vinylidene fluoride) (PVDF) is coated on the surface of the piezoelectric stack as the special sensitive layer. The concentration of the target gas can be

Jing-jing Wang; Da Chen; Lu-yin Zhang; Yan Xu

2011-01-01

221

Detection of gas leaks along pipelines by spectrally tuned infrared imaging  

Microsoft Academic Search

We present a novel method developed for the localization of leaks along natural gas pipelines. Methane distributions in the atmosphere around the leaky pipeline are detected and visualized by spectrally tuned IR imaging. In contrast to conventional techniques which utilize laser radiation sources or scanning, we irradiate the overall region under investigation by 1 kW halogen lamps. The scene background

Werner Gross; Thomas Hierl; H. Scheuerpflug; U. Schirl; Max J. Schulz

1998-01-01

222

Detection of Pristine Gas Two Billion Years After the Big Bang  

Microsoft Academic Search

In the current cosmological model, only the three lightest elements were created in the first few minutes after the Big Bang; all other elements were produced later in stars. To date, however, heavy elements have been observed in all astrophysical environments. We report the detection of two gas clouds with no discernible elements heavier than hydrogen. These systems exhibit the

Michele Fumagalli; John M. O'Meara; J. Xavier Prochaska

2011-01-01

223

Empirical formulae studies of chlorofluorocarbons using gas chromatography coupled to atomic emission detection  

Microsoft Academic Search

Empirical formulae determination on gas chromatographically resolved analytes, through specific element quantitation on eluted peaks, challenges experimental design and procedure in atomic emission spectral detection. Molecular structural dependence of elemental response factors is a factor which is element dependent, fluorine showing notable non-linear tendencies. This study of compound independent calibration for F, Cl, C, H for chlorofluorocarbon (CFC) molecules shows

Nitin R. Hardas; Peter C. Uden

1999-01-01

224

Development of high sensitivity tin oxide based sensors for gas\\/odour detection at room temperature  

Microsoft Academic Search

An effort has been made to develop thick film tin oxide gas sensors which could detect various gases\\/odours at room temperature. To achieve this, the fabricated sensors were annealed in oxygen plasma for various durations. It was then found that, the room temperature sensitivity of such sensors was increased to about ten times as compared to the sensitivity of the

Roopali Srivastava; R Dwivedi; S. K Srivastava

1998-01-01

225

Detection of small gas bubble using ultrasonic transmission-mode tomography system  

Microsoft Academic Search

This paper presents the development of an ultrasonic transmission-mode tomography system for the detection of small gas bubble using higher frequency ultrasonic sensors. The selection of the sensors is important and must be suitable to the application design. Consideration on the natural limitation of ultrasonic wave is also noted as the higher the frequency of the ultrasonic transducer, the better

N. M. N. Ayob; M. H. F. Rahiman; Z. Zakaria; S. Yaacob; R. A. Rahim

2010-01-01

226

Comparison of Tests for Detecting Leaks in the Low-Pressure System of Anesthesia Gas Machines  

Microsoft Academic Search

Small leaks in the low-pressure system (LPS) of the an- esthesia gas machine can cause hypoxia or patient awareness. We sought to determine the relative sensi- tivities of the various tests recommended for detecting LPS leaks before anesthesia. Special adapters were fash- ioned to create leaks of six different sizes in the LPS that were equivalent to the following: a

Jeffrey A. Myers; Michael L. Good; J. Jeffrey Andrews

1997-01-01

227

Naturally fractured tight gas reservoir detection optimization. Quarterly technical progress report, April 1995--June 1995  

SciTech Connect

Research continued on methods to detect naturally fractured tight gas reservoirs. This report contains a seismic survey map, and reports on efforts towards a source test to select the source parameters for a 37 square mile compressional wave 3-D seismic survey. Considerations of the source tests are discussed.

NONE

1995-08-01

228

Naturally fractured tight gas reservoir detection optimization. Quarterly report, January--March 1995  

SciTech Connect

The objective is to determine methods for detection and mapping of natural fracture systems for economic production of natural gas from fractured reservoirs. This progress report covers: 3D P-wave survey; additional processing of 3D P-wave survey; review of multicomponent recording feasibility tests; minivibrator studies; and modeling of 3D-3C acquisition parameters.

NONE

1995-05-01

229

Flight Testing of an Advanced Airborne Natural Gas Leak Detection System  

SciTech Connect

ITT Industries Space Systems Division (Space Systems) has developed an airborne natural gas leak detection system designed to detect, image, quantify, and precisely locate leaks from natural gas transmission pipelines. This system is called the Airborne Natural Gas Emission Lidar (ANGEL) system. The ANGEL system uses a highly sensitive differential absorption Lidar technology to remotely detect pipeline leaks. The ANGEL System is operated from a fixed wing aircraft and includes automatic scanning, pointing system, and pilot guidance systems. During a pipeline inspection, the ANGEL system aircraft flies at an elevation of 1000 feet above the ground at speeds of between 100 and 150 mph. Under this contract with DOE/NETL, Space Systems was funded to integrate the ANGEL sensor into a test aircraft and conduct a series of flight tests over a variety of test targets including simulated natural gas pipeline leaks. Following early tests in upstate New York in the summer of 2004, the ANGEL system was deployed to Casper, Wyoming to participate in a set of DOE-sponsored field tests at the Rocky Mountain Oilfield Testing Center (RMOTC). At RMOTC the Space Systems team completed integration of the system and flew an operational system for the first time. The ANGEL system flew 2 missions/day for the duration for the 5-day test. Over the course of the week the ANGEL System detected leaks ranging from 100 to 5,000 scfh.

Dawn Lenz; Raymond T. Lines; Darryl Murdock; Jeffrey Owen; Steven Stearns; Michael Stoogenke

2005-10-01

230

Small Sodium-to-Gas Leak Behavior in Relation to LMFBR Leak Detection System Design.  

National Technical Information Service (NTIS)

Various aspects of sodium-to-gas leaks which must be considered in the design of leak detection systems for LMFBR's are discussed. Attention is focused primarily on small, weeping type leaks. Corrosion rates of steels in fused sodium hydroxide and corrosi...

J. Hopenfeld G. R. Taylor L. A. James

1976-01-01

231

Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection  

Microsoft Academic Search

An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated

Shawn Bryan Martin; Mark Steven Derzon; Ronald F. Renzi; Gordon Andrew Chandler

2007-01-01

232

New miniaturized SAW-sensor array for organic gas detection driven by multiplexed oscillators  

Microsoft Academic Search

The use of sensor arrays with polymer-coated surface acoustic wave (SAW) devices as the key element for analytical sensor systems is a very promising technique for organic gas detection in process or quality control. In this work we present a new improved array of eight SAW sensors showing up reduced size, sampling volume and assembling costs. Moreover, its most important

M Rapp; J Reibel; A Voigt; M Balzer; O Bülow

2000-01-01

233

Zeolite-based Impedimetric Gas Sensor Device in Low-cost Technology for Hydrocarbon Gas Detection  

PubMed Central

Due to increasing environmental concerns the need for inexpensive selective gas sensors is increasing. This work deals with transferring a novel zeolite-based impedimetric hydrocarbon gas sensor principle, which has been originally manufactured in a costly combination of photolithography, thin-film processes, and thick-film processes to a low-cost technology comprising only thick-film processes and one electroplating step. The sensing effect is based on a thin chromium oxide layer between the interdigital electrodes and a Pt-loaded ZSM-5 zeolite film. When hydrocarbons are present in the sensor ambient, the electrical sensor impedance increases strongly and selectively. In the present work, the chromium oxide film is electroplated on Au screen-printed interdigital electrodes and then oxidized to Cr2O3. The electrode area is covered with the screen-printed zeolite. The sensor device is self-heated utilizing a planar platinum heater on the backside. The best sensor performance is obtained at a frequency of 3 Hz at around 350 °C. The good selectivity of the original sensor setup could be confirmed, but a strong cross-sensitivity to ammonia occurs, which might prohibit its original intention for use in automotive exhausts.

Reiss, Sebastian; Hagen, Gunter; Moos, Ralf

2008-01-01

234

Good odorant practices ensure safer operations. [Natural gas odorant detection methods  

SciTech Connect

Regulations in Canada and the US require that combustible gas used as a fuel be odorized at such a level that a concentration in air of one-fifth the lower explosive limit the gas can be readily detected and recognized by a person with a normal sense of smell. These regulations do not specify how the odorant level should be determined. However, since the requirement is related to smell, the level should be determined by an olfactory method. There are two odorant monitoring methods commonly used by gas companies, the olfactory (odorometer) and the instrumentation (gas chromatograph) methods. The instrument method provides only quantitative results, which somehow must be related to an olfactory response. This paper discusses these methods.

Oudman, P. (Canada Western Natural Gas Co. Ltd., Calgary, Alberta (Canada))

1993-12-01

235

Long-period grating in multimode fiber for ammonia gas detection  

NASA Astrophysics Data System (ADS)

This article describes the design, development and characterization of a fiber optic sensor based on evanescent wave absorption in Long Period Grating (LPG) on multimode optical fibers, for the detection of toxic ammonia gas. The sensing length of the sensing element is only 10mm, but the dynamic range is as good as that of the conventional evanescent wave sensors. Sol-gel technology is employed for immobilizing a reversible ammonia sensitive dye on the grating region of a multimode fiber. Ammonia gas permeating into the immobilized dye, the color of the dye changes reversibly from yellow to blue with increasing concentration of ammonia gas. The concentration of ammonia gas can be determined by measuring the absorption at a given wavelength. The dynamic range of the sensor is from 0.027 to 2.04 mM/Ltr.

Suresh Kumar, P.; Scaria, Abraham V.; Vallabhan, C. P. G.; Nampoori, V. P. N.; Radhakrishnan, P.

2004-04-01

236

Studies on thermionic ionisation detection in comprehensive two-dimensional gas chromatography.  

PubMed

This study explores the application of specific thermionic ionisation detection in comprehensive 2-D GC (GC x GC) and represents the first report of GC x GC with nitrogen phosphorus detection (GC x GC-NPD). Of particular interest is the performance of the NPD with respect to peak parameters of asymmetry and sensitivity. Since GC x GC produces much narrower peaks than obtained with fast GC (e.g. 100 ms vs. <1 s) the effect of detector response time and any lack of symmetry arising from the detection step is important if peak separation (resolution) is to be maintained. It was observed that detector gas flows had a significant impact on peak asymmetry and peak magnitude, and that optimisation of the detector was critical, particularly for complex sample analysis by GC x GC-NPD. Peak asymmetries ranging from As = 1.8 to 8.0 were observed under different conditions of detector gas flows. Comparison of GC x GC-NPD with GC x GC-flame ionisation detection (FID) showed the former to be approximately 20 times more sensitive for the detection of nitrogen-containing methoxypyrazines analytes, and GC x GC-NPD had a larger linear detection range compared to GC x GC-FID. Furthermore, comparison of GC x GC-NPD and GC x GC-TOFMS chromatograms for the analysis of coffee head-space demonstrated the benefits of selective detection, ultimately realised in a comparatively simplified contour plot. PMID:17120822

Ryan, Danielle; Marriott, Philip

2006-10-01

237

AIRBORNE, OPTICAL REMOTE SENSNG OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION  

SciTech Connect

Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The scope of the work involved designing and developing an airborne, optical remote sensor capable of sensing methane and, if possible, ethane for the detection of natural gas pipeline leaks. Flight testing using a custom dual wavelength, high power fiber amplifier was initiated in February 2005. Ophir successfully demonstrated the airborne system, showing that it was capable of discerning small amounts of methane from a simulated pipeline leak. Leak rates as low as 150 standard cubic feet per hour (scf/h) were detected by the airborne sensor.

Jerry Myers

2005-04-15

238

Detection of Clostridium difficile in faeces by direct gas liquid chromatography.  

PubMed Central

Stool specimens examined for the presence of Clostridium difficile and its cytotoxin were screened by gas liquid chromatography for the presence of volatile fatty acids and p-cresol. Twenty seven of 110 (25%) stools yielded C difficile or cytotoxin; iso-valeric acid was detected in 63/110 (57%) and iso-caproic acid in 18/110 (16%) stools. Para-cresol was found in 24/71 (34%) stools examined. Iso-valeric acid was detected in 85% of stools positive for C difficile, whereas iso-caproic acid (41%) and p-cresol (52%) were found in much lower numbers of C difficile-positive stools. It is concluded that gas chromatographic detection of volatile fatty acids or p-cresol in faeces are not satisfactory screening tests for the presence of C difficile.

Levett, P N

1984-01-01

239

Dispersion modeling approach for quantification of methane emission rates from natural gas fugitive leaks detected by infrared imaging technique  

Microsoft Academic Search

Recently, infrared optical imaging has been applied in the oil and gas industry as a method to detect potential leaks in pipelines, components and equipment. The EPA suggested that this impending technique is considered as a smart gas LDAR (leak detection, monitoring and repair) for its rapid recognition of leaks, accuracy and robustness. In addition, compared to the conventional method

Anisa Safitri; Xiaodan Gao; M. Sam Mannan

2011-01-01

240

The use of soil mercury and radon gas surveys to assist the detection of concealed faults in Fuzhou City, China  

Microsoft Academic Search

Soil gas approaches have been proven useful for detecting buried faults in field survey. How about their applicability in urban area? A trial soil gas survey has been conducted in an attempt to evaluate this in Fuzhou City, Southeastern China. The detection was performed by measuring the adsorbed mercury, free mercury and radon gases in soil in the sites such

Guangcai Wang; Chenglong Liu; Jihua Wang; Wuzhou Liu; Peiren Zhang

2006-01-01

241

Analysis of epoxyeicosatrienoic acids by chiral liquid chromatography/electron capture atmospheric pressure chemical ionization mass spectrometry using [13C]-analog internal standards  

PubMed Central

The metabolism of arachidonic acid (AA) to epoxyeicosatrienoic acids (EETs) is thought to be mediated primarily by the cytochromes P450 (P450s) from the 2 family (2C9, 2C19, 2D6, and 2J2). In contrast, P450s of the 4 family are primarily involved in omega oxidation of AA (4A11 and 4A22). The ability to determine enantioselective formation of the regioisomeric EETs is important in order to establish their potential biological activities and to asses which P450 isoforms are involved in their formation. It has been extremely difficult to analyze individual EET enantiomers in biological fluids because they are present in only trace amounts and they are extremely difficult to separate from each other. In addition, the deuterium-labeled internal standards that are commonly used for stable isotope dilution liquid chromatography/mass spectrometry (LC/MS) analyses have different LC retention times when compared with the corresponding protium forms. Therefore, quantification by LC/MS-based methodology can be compromised by differential suppression of ionization of the closely eluting isomers. We report the preparation of [13C20]-EET analog internal standards and the use of a validated high-sensitivity chiral LC/electron capture atmospheric pressure chemical ionization (ECAPCI)-MS method for the trace analysis of endogenous EETs as their pentafluorobenzyl (PFB) ester derivatives. The assay was then used to show the exquisite enantioselectivity of P4502C19-, P4502D6-, P4501A1-, and P4501B1-mediated conversion of AA into EETs and to quantify the enantioselective formation of EETs produced by AA metabolism in a mouse epithelial hepatoma (Hepa) cell line.

Mesaros, Clementina; Lee, Seon Hwa; Blair, Ian A.

2012-01-01

242

Data-dependent middle-down nano-liquid chromatography-electron capture dissociation-tandem mass spectrometry: an application for the analysis of unfractionated histones.  

PubMed

Middle-down mass spectrometry (MS) combined with electron capture dissociation (ECD) represents an attractive method for characterization of proteins and their post-translational modifications (PTMs). Coupling online chromatographic separation with tandem mass spectrometry enables a high-throughput analysis, while improving sensitivity of the electrosprayed peptides and reducing sample amount requirements. However, middle-down ECD has not been thus far coupled with online chromatographic separation. In this work, we examine the feasibility of coupling middle-down ECD with online nanoflow-liqiud chromatography (nano-LC) for the analysis of large, >3 kDa, and highly modified polypeptides in a data-dependent acquisition mode. We evaluate the effectiveness of the method by analyzing peptides derived from Asp-N and Glu-C digestions of unfractionated histones from calf thymus and acid-extracted histones from HeLa, MCF-7, and Jurkat cells. Our results demonstrate that middle-down ECD is compatible with online chromatographic separation, providing high peptide and protein sequence coverage while allowing precise mapping of PTM sites. The high mass accuracy, obtained by the ICR mass analyzer, for both the precursor and product ions greatly increases confidence in peptide identification, particularly for modified peptides. Overall, for all samples examined, several histone variants were identified and modification sites were successfully localized, including single, multiple, and positional isomeric PTM sites. The vast majority of the identified peptides were in the mass range from 3 to 9 kDa. The data presented here highlight the feasibility and utility of nano-LC-ECD-MS/MS for high-throughput middle-down analysis. PMID:23448339

Kalli, Anastasia; Sweredoski, Michael J; Hess, Sonja

2013-03-12

243

[A line-by-line trace gas absorption model and its application in NDIR gas detection technology].  

PubMed

An accurate line-by-line integral trace gas absorption model is presented in the present article. It is for mid-infrared band and can be used in the study on and application to detecting trace gas (or pollution gas). First of all, two algorithms of trace gas radioactive properties, line-by-line integral method and band model method, were introduced. The merits and demerits of each were compared. Several recent developed line-by-line integral calculation models were also introduced. Secondly, the basic principle of line-by-line integral trace gas absorption calculation model was described in detail. The absorption coefficient is a function of temperature, frequency (wave number), pressure, gas volume mixing ratio and constants associated with all contributing line transitions. The average monochromatic absorption coefficient at a given frequency of a given gas species can be written as the product of the number density of the molecular species to which the spectral line belongs, the line intensity and a line shape factor. Efficient calculation of the line shape factor may be required for different atmospheric conditions. In the lower atmosphere, the shape of spectral lines is dominated by pressure broadening and can be represented most simply by the Lorentz line shape factor. At high altitudes, the shape of spectral lines is governed by Doppler broadening At intermediate altitudes, they can be modeled using the Voigt line shape factor, a convolution of the Lorentz and Doppler line shape factors. Finally, in the section of experiment, the results calculated by model were compared with that measured by Fourier transform infrared spectrometer. As an instance, the model was applied to the detectors design of NDIR (non-dispersive infrared) technology and the relationship between signal intensity of detectors and concentration of CO2/CO was simulated by model. Available concentration range of detector was given by calculating the results of the model. It is based on HITRAN molecular spectroscopic database. Far wings, temperature correction and instruments function were all calculated for the absorption coefficient calculation. Infrared absorption characters of various gases in atmosphere can be simulated by the model. PMID:18800702

Fang, Jing; Liu, Wen-qing; Zhang, Tian-shu

2008-06-01

244

CO(1-0) detection of molecular gas in the massive Spiderweb Galaxy (z = 2)  

NASA Astrophysics Data System (ADS)

The high-redshift radio galaxy MRC 1138-262 (`Spiderweb Galaxy'; z = 2.16) is one of the most massive systems in the early Universe and surrounded by a dense `web' of proto-cluster galaxies. Using the Australia Telescope Compact Array, we detected CO(1-0) emission from cold molecular gas - the raw ingredient for star formation - across the Spiderweb Galaxy. We infer a molecular gas mass of MH2 = 6 × 1010 M? (for MH2/L'CO = 0.8). While the bulk of the molecular gas coincides with the central radio galaxy, there are indications that a substantial fraction of this gas is associated with satellite galaxies or spread across the intergalactic medium on scales of tens of kpc. In addition, we tentatively detect CO(1-0) in the star-forming proto-cluster galaxy HAE 229, 250 kpc to the West. Our observations are consistent with the fact that the Spiderweb Galaxy is building up its stellar mass through a massive burst of widespread star formation. At maximum star formation efficiency, the molecular gas will be able to sustain the current star formation rate (SFR ? 1400 M? yr-1, as traced by Seymour et al.) for about 40 Myr. This is similar to the estimated typical lifetime of a major starburst event in infrared luminous merger systems.

Emonts, B. H. C.; Feain, I.; Röttgering, H. J. A.; Miley, G.; Seymour, N.; Norris, R. P.; Carilli, C. L.; Villar-Martín, M.; Mao, M. Y.; Sadler, E. M.; Ekers, R. D.; van Moorsel, G. A.; Ivison, R. J.; Pentericci, L.; Tadhunter, C. N.; Saikia, D. J.

2013-04-01

245

Tunnel-field-effect-transistor based gas-sensor: Introducing gas detection with a quantum-mechanical transducer  

NASA Astrophysics Data System (ADS)

A gas-sensor based on tunnel-field-effect-transistor (TFET) is proposed that leverages the unique current injection mechanism in the form of quantum-mechanical band-to-band tunneling to achieve substantially improved performance compared to conventional metal-oxide-semiconductor field-effect-transistors (MOSFETs) for detection of gas species under ambient conditions. While nonlocal phonon-assisted tunneling model is used for detailed device simulations, in order to provide better physical insights, analytical formula for sensitivity is derived for both metal as well as organic conducting polymer based sensing elements. Analytical derivations are also presented for capturing the effects of temperature on sensor performance. Combining the developed analytical and numerical models, intricate properties of the sensor such as gate bias dependence of sensitivity, relationship between the required work-function modulation and subthreshold swing, counter-intuitive increase in threshold voltage for MOSFETs and reduction in tunneling probability for TFETs with temperature are explained. It is shown that TFET gas-sensors can not only lead to more than 10 000× increase in sensitivity but also provide design flexibility and immunity against screening of work-function modulation through non-specific gases as well as ensure stable operation under temperature variations.

Sarkar, Deblina; Gossner, Harald; Hansch, Walter; Banerjee, Kaustav

2013-01-01

246

Diamond Film Gas Sensors for Leak Detection of Semiconductor Doping Gases  

NASA Astrophysics Data System (ADS)

Gas sensors for leak detection of toxic semiconductor doping gases such as PH3, B2H6, and AsH3 were fabricated using diamond films. The sensors have a double-layered structure composed of undoped and B-doped polycrystalline diamond layers with Pt electrodes. The relative changes in the resistance of the sensors were typically 10-20% for 0.2 ppm PH3 in air, and the highest value was over 100%. It was concluded that the diamond film gas sensors fabricated in the present work would be practically applicable as compact solid-state sensors with an advantage over the conventional aqueous electrolyte sensors.

Hayashi, Kazushi; Yokota, Yoshihiro; Tachibana, Takeshi; Miyata, Koichi; Kobashi, Koji; Fukunaga, Tetsuya; Takada, Tadashi

2000-01-01

247

Electrically detected magnetic resonance of neutral donors interacting with a two-dimensional electron gas.  

PubMed

We have measured the electrically detected magnetic resonance of donor-doped silicon field-effect transistors in resonant X- (9.7 GHz) and W-band (94 GHz) microwave cavities. The two-dimensional electron gas resonance signal increases by 2 orders of magnitude from X to W band, while the donor resonance signals are enhanced by over 1 order of magnitude. Bolometric effects and spin-dependent scattering are inconsistent with the observations. We propose that polarization transfer from the donor to the two-dimensional electron gas is the main mechanism giving rise to the spin resonance signals. PMID:21668263

Lo, C C; Lang, V; George, R E; Morton, J J L; Tyryshkin, A M; Lyon, S A; Bokor, J; Schenkel, T

2011-05-20

248

[Determination of blood cyanide using head-space gas chromatography with electron capture detection].  

PubMed

Two head-space gas chromatographic methods for the determination of hydrogen cyanide (HCN) in blood were demonstrated using electron capture detector (ECD). One was the double head-space gas sampling technique and the other used the reaction pre-column packed with Chloramine-T for the conversion of HCN into cyanogen chloride (CNC1). In the former method, HCN in blood was firstly released by acidification, and then the HCN gas was replaced into the another vial in which Chloramine-T solution had been placed. The head-space gas in the second vial was analyzed by gas chromatograph (GC). In the latter, HCN gas released was directly injected into the GC pre-connected the reaction column. The conversion of HCN into CNC1 was easily achieved by both methods. The use of dichloromethane as an internal standard and PTFE-faced septum for the sealing of vial greatly improved the precision and reliability of these analytical methods. The calibration curves by these methods gave good linearity and the lower detection limit taken from these plots was ca. 0.05 micrograms/ml. In particular, the reaction pre-column method, by which blood cyanide can be analyzed rapidly and accurately with only simple alteration of apparatus, is superior in the routine analysis of blood cyanide. PMID:2169555

Maseda, C; Matsubara, K; Hasegawa, M; Akane, A; Shiono, H

1990-04-01

249

Detection of gas leaks along pipelines by spectrally tuned infrared imaging  

NASA Astrophysics Data System (ADS)

We present a novel method developed for the localization of leaks along natural gas pipelines. Methane distributions in the atmosphere around the leaky pipeline are detected and visualized by spectrally tuned IR imaging. In contrast to conventional techniques which utilize laser radiation sources or scanning, we irradiate the overall region under investigation by 1 kW halogen lamps. The scene background is subtracted by a real-time computer evaluation of the image. The methane gas emitted from the leak creates a flickering cloud in the image which is easily recognized. Methane concentrations as low as 0.03 percent by volume are visible. The method was successfully tested under realistic conditions on a buried pipeline by a natural gas provider.

Gross, Werner; Hierl, Thomas; Scheuerpflug, H.; Schirl, U.; Schulz, Max J.

1998-12-01

250

Trace gas detection in hyperspectral imagery using the wavelet packet subspace  

NASA Astrophysics Data System (ADS)

This dissertation describes research into a new remote sensing method to detect trace gases in hyperspectral and ultra-spectral data. This new method is based on the wavelet packet transform. It attempts to improve both the computational tractability and the detection of trace gases in airborne and spaceborne spectral imagery. Atmospheric trace gas research supports various Earth science disciplines to include climatology, vulcanology, pollution monitoring, natural disasters, and intelligence and military applications. Hyperspectral and ultra-spectral data significantly increases the data glut of existing Earth science data sets. Spaceborne spectral data in particular significantly increases spectral resolution while performing daily global collections of the earth. Application of the wavelet packet transform to the spectral space of hyperspectral and ultra-spectral imagery data potentially improves remote sensing detection algorithms. It also facilities the parallelization of these methods for high performance computing. This research seeks two science goals, (1) developing a new spectral imagery detection algorithm, and (2) facilitating the parallelization of trace gas detection in spectral imagery data.

Salvador, Mark A. Z.

251

Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.  

SciTech Connect

An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated on the fast pulsed power experiments performed here at Sandia. This same system may dramatically improve active WMD and contraband detection as well when employed with ultrafast (10-50 ns) pulsed neutron sources.

Martin, Shawn Bryan; Derzon, Mark Steven; Renzi, Ronald F.; Chandler, Gordon Andrew

2007-12-01

252

Ellipse evolving common reflection point velocity analysis and its application to oil and gas detection  

NASA Astrophysics Data System (ADS)

An ellipse evolving common reflection point (CRP) is an innovative stack method. Under some velocity distribution, we can obtain a real zero-offset section by projecting seismic signals to isochrones along an elliptic trajectory. This paper introduces this method and its velocity analysis. By theoretical model and real seismic data processing, the ellipse evolving CRP velocity analysis more accurately estimates the CRP stack velocity of a complex geology section. The method also more clearly detects an interval velocity anomaly. It is a valuable method of reservoir prediction and oil and gas detection.

Zhou, Qing-Chun; Liu, Huai-Shan; Kondrashkov, V. V.; Li, Guo-Du; Lin, Yi-Hua

2009-03-01

253

Rapid gas chromatographic method for determining ethyl carbamate in alcoholic beverages with thermal energy analyzer detection.  

PubMed

A rapid column elution method has been developed for the determination of ethyl carbamate (EC) in alcoholic beverages. The beverage is mixed with Celite and packed in a column containing deactivated alumina capped with a layer of sodium sulfate. EC is then eluted with methylene chloride. The method, using a gas chromatograph-thermal energy analyzer with a nitrogen converter for detection and quantitation of EC, has been applied to a variety of alcoholic beverages. Recoveries +/- standard deviations of EC in wine and whisky fortified at the 20 and 133 micrograms/kg (ppb) levels averaged 87.3 +/- 5.3 and 88.7 +/- 3.6%, respectively. The method has a limit of detection of 1.5 ppb. Gas chromatography/mass spectrometry/mass spectrometry was used to confirm the identity and quantitation of EC in selected beverage extracts. PMID:3391950

Canas, B J; Havery, D C; Joe, F L

254

Selective chlorine dioxide determination using gas-diffusion flow injection analysis with chemiluminescent detection  

SciTech Connect

An automated chemiluminescent technique has been developed utilizing the advantages of gas-diffusion flow injection analysis. A gas-diffusion membrane separates the donor (sampling) stream from the acceptor (detecting) stream and removes ionic interferences. A novel chemiluminescence flow-through detector cell is used to measure the concentration of chlorine dioxide as a function of the intensity of the chemiluminescence produced from its reaction with luminol. The chemiluminescent reagent merges with the analyte directly in front of the photomultiplier tube in order to maximize the sensitivity of the system. The detection limit for chlorine dioxide is approximately 5 ppb. The method is over 1500 times more selective for chlorine dioxide than for chlorine on a mole basis. This method eliminates interference from iron and manganese compounds, as well as other oxychlorinated compounds such as chlorite ion and chlorate ion.

Hollowell, D.A.; Gord, J.R.; Gordon, G.; Pacey, G.E.

1986-06-01

255

The development of a pulsed laser imaging system for natural gas leak detection  

NASA Astrophysics Data System (ADS)

The detection of gas leaks represents a critical operation performed regularly by the gas industry to maintain the integrity and safety of its vast network of piping, both above and below the ground. We are developing a technology that allows the real-time imaging of gas plumes in a television format. Termed backscatter absorption gas imaging (BAGI), the technique operates by illuminating a scene with infrared laser radiation having a wavelength that is absorbed by the gas to be detected (in this case, methane). Backscattered laser radiation is used to create a video image of the scene. If a leak of the target gas is present in the field-of-view of the camera, it attenuates a portion of the backscatter and creates a dark cloud in the video picture. The specific purpose of this project is to investigate a new method of accomplishing BAGI using a pulsed laser source. The pulsed laser imager under development in this project is expected to have a range (greater than or equal to 40 m) and sensitivity (less than 10 ppm-m) that will surpass the respective attributes of a scanned continuous wave laser imager. The pulsed system will operate by flooding (rather than scanning) the imaged scene with pulses of laser radiation. Imaging will be accomplished using a focal-plane array camera that operates in a snapshot format. The higher power of the pulsed laser source and the more effective collection optics of the focal-plane array-based receiver will allow the performance enhancements to be achieved.

Kulp, Thomas J.

256

Detection of gas pockets in pressurised wastewater mains using dynamic system response analysis.  

PubMed

In the Netherlands, wastewater is mostly collected in combined sewer system and transported to a WWTP through pressure mains. These pressure mains form an element of the system that did not receive much attention lately with respect to monitoring of performance and maintenance. For that reason, their state of functioning is often not known. Failure of operation is only noticed when during storm conditions the capacity of the system drops, resulting in undesirable discharge to the surface water. A recently made inventory showed that about half of the pressure mains show increased pressure loss for no obvious reason. Reduction of the systems nominal capacity can result from many causes, like increased wall roughness, scaling and the occurrence of free gas in the pipeline. The occurrence of gas-pockets may be caused by degassing of dissolved gas, but also by air entrapment at the pump inlet or at air valves. A research project is started that will be carried out from 2003 to 2005. This project focuses on three goals: the description of the gas-water transport phenomena in wastewater pressure mains, a method to detect and diagnose gas problems, and to overcome future problems by either applying remedial measures or by developing improved design methods for wastewater pressure systems. This paper describes the layout of the experimental set-up to detect and diagnose gas problems and the first results of the experiments are presented and discussed. The results are used to validate a model (Wanda) developed by Delft Hydraulics that describes the phenomena involved in surges in air/water transport. PMID:17425069

Lubbers, C; Clemens, F

2007-01-01

257

Fast gas chromotography with luminol detection for measurement of nitrogen dioxide and PANs  

Microsoft Academic Search

Fast capillary gas chromatography has been coupled to a luminol-based chemiluminescence detection system for the rapid monitoring of nitrogen dioxide and peroxyacyl nitrates. A first-generation instrument was described recently (Gaffney et al., 1998). This system is capable of monitoring nitrogen dioxide and peroxyacyl nitrates (PANs; to and including the C4 species) with 1-min time resolution. This is an improvement by

Jeffrey S. Gaffney; Nancy A. Marley; Paul J. Drayton

1999-01-01

258

Using gas chromatography with atomic emission detection for determining organic pollutants in water  

Microsoft Academic Search

The efficiency of gas chromatography with atomic emission detection (AED) for determining the composition of complex mixtures\\u000a of organic water pollutants was studied by the example of 13 compounds of different classes. It was found that the correlation\\u000a between the ratio of AED signals for single element atoms of the compound in the sample and their predetermined ratio in individual

M. Yu. Vozhdaeva; L. G. Tsypysheva; L. I. Kantor; E. A. Kantor

2007-01-01

259

Onion sour skin detection using a gas sensor array and support vector machine  

Microsoft Academic Search

Onion is a major vegetable crop in the world. However, various plant diseases, including sour skin caused by Burkholderia cepacia, pose a great threat to the onion industry by reducing shelf-life and are responsible for significant postharvest losses\\u000a in both conventional and controlled atmosphere (CA) storage. This study investigated a new sensing approach to detect sour\\u000a skin using a gas

Changying Li; Ron Gitaitis; Bill Tollner; Paul Sumner; Dan MacLean

2009-01-01

260

Dispersive liquid–liquid microextraction combined with gas chromatography-flame photometric detection  

Microsoft Academic Search

A new method was used for the extraction of organophosphorus pesticides (OPPs) from water samples: dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography-flame photometric detection (GC-FPD). In this extraction method, a mixture of 12.0?L chlorobenzene (extraction solvent) and 1.00mL acetone (disperser solvent) is rapidly injected into the 5.00mL water sample by syringe. Thereby, a cloudy solution is formed. In fact,

Sana Berijani; Yaghoub Assadi; Mansoor Anbia; Mohammad-Reza Milani Hosseini; Elham Aghaee

2006-01-01

261

Determination of iodide by detection of iodine using gas-diffusion flow injection and chemiluminescence  

Microsoft Academic Search

This work describes development of a flow injection (FI) system for determination of iodide, based on the chemiluminescence (CL) reaction between iodine and luminol. Iodide in the sample zone is oxidized to iodine. Employment of a gas-diffusion (GD) unit allows for selective detection of the generated CL (425nm). Preliminary results showed for concentrations of less than 2mgL?1, that signals were

N. Ratanawimarnwong; N. Amornthammarong; N. Choengchan; P. Chaisuwan; M. Amatatongchai; P. Wilairat; I. D. McKelvie; D. Nacapricha

2005-01-01

262

Strategies for Detecting Hidden Geothermal Systems by Near-Surface Gas Monitoring  

Microsoft Academic Search

''Hidden'' geothermal systems are those systems above which hydrothermal surface features (e.g., hot springs, fumaroles, elevated ground temperatures, hydrothermal alteration) are lacking. Emissions of moderate to low solubility gases (e.g., CO2, CH4, He) may be one of the primary near-surface signals from these systems. Detection of anomalous gas emissions related to hidden geothermal systems may therefore be an important tool

Jennifer L. Lewicki; Curtis M. Oldenburg

2004-01-01

263

Electric field induced silicon carbide nanotubes: a promising gas sensor for detecting SO2  

NASA Astrophysics Data System (ADS)

Finding an effective strategy for detecting SO2 gas is very important in order to solve the problem of pollution of SO2. Based on the first-principles density functional theory (DFT) calculations, we herein explore the possibility of using (5, 5) silicon carbide nanotubes (SiCNTs) with an external electric field (EF) as a potential gas sensor for SO2 detection. It is found that SO2 molecules can be chemisorbed to the Si-C bonds of SiCNTs and can generate a different charge distribution under the EF, resulting in the breaking of some S-C bonds. It is these broken S-C bonds that induce a decrease in the band gap. Furthermore, with the concentration of SO2 exceeding 20%, the band gap of SiCNT under an EF of 9.00 V nm-1 would be reduced from 1.75 eV for SiCNT to zero, indicating the transformation from a semiconductor to a conductor. Hence, with an appropriate EF, SiCNTs can effectively respond to SO2 and serve as sensors for detecting SO2 gas.

Jia, Y. B.; Zhuang, G. L.; Wang, J. G.

2012-02-01

264

Prospects of Optical Single Atom Detection in Noble Gas Solids for Measurements of Rare Nuclear Reactions  

NASA Astrophysics Data System (ADS)

Optical detection of single atoms captured in solid noble gas matrices provides an alternative technique to study rare nuclear reactions relevant to nuclear astrophysics. I will describe the prospects of applying this approach for cross section measurements of the ^22Ne,,),25Mg reaction, which is the crucial neutron source for the weak s process inside of massive stars. Noble gas solids are a promising medium for the capture, detection, and manipulation of atoms and nuclear spins. They provide stable and chemically inert confinement for a wide variety of guest species. Because noble gas solids are transparent at optical wavelengths, the guest atoms can be probed using lasers. We have observed that ytterbium in solid neon exhibits intersystem crossing (ISC) which results in a strong green fluorescence (546 nm) under excitation with blue light (389 nm). Several groups have observed ISC in many other guest-host pairs, notably magnesium in krypton. Because of the large wavelength separation of the excitation light and fluorescence light, optical detection of individual embedded guest atoms is feasible. This work is supported by DOE, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

Singh, Jaideep; Bailey, Kevin G.; Lu, Zheng-Tian; Mueller, Peter; O'Connor, Thomas P.; Xu, Chen-Yu; Tang, Xiaodong

2013-04-01

265

Determination of polyethylene glycols of different molecular weight in the stratum corneum.  

PubMed

We developed a sensitive method for determination of polyethylene glycols (PEGs) of different molecular weight (MW) in the human stratum corneum (SC) obtained by tape stripping. The analysis is based on derivatization with pentafluoropropionic anhydride (PFPA) and gas chromatography-electron capture detection (GC-ECD). The identification and quantification of PEGs was done using individual oligomers. The method showed to be suitable for studying permeability in normal and impaired skin with respect to MW in the range of 150-600 Da. PMID:15522718

Jakasa, I; Calkoen, F; Kezic, S

2004-11-25

266

Research and Development of Non-Spectroscopic MEMS-Based Sensor Arrays for Targeted Gas Detection  

SciTech Connect

The ability to monitor the integrity of gas volumes is of interest to the stockpile surveillance community. Specifically, the leak detection of noble gases, at relevant concentration ranges and distinguished from other chemical species that may be simultaneously present, is particularly challenging. Aside from the laboratory-based method of gas chromatography-mass spectrometry (GC-MS), where samples may be collected by solid-phase microextraction (SPME) or cryofocusing, the other major approaches for gas-phase detection employ lasers typically operating in the mid-infrared wavelength region. While mass spectrometry can readily detect noble gases - the helium leak detector is an obvious example - laser-based methods such as infrared (IR) or Raman spectroscopy are completely insensitive to them as their monatomic nature precludes a non-zero dipole moment or changes in polarizability upon excitation. Therefore, noble gases can only be detected by one of two methods: (1) atomic emission spectroscopies which require the generation of plasmas through laser-induced breakdown, electrical arcing, or similar means; (2) non-spectroscopic methods which measure one or more physical properties (e.g., mass, thermal conductivity, density). In this report, we present our progress during Fiscal Year 2011 (FY11) in the research and development of a non-spectroscopic method for noble gas detection. During Fiscal Year 2010 (FY10), we demonstrated via proof-of-concept experiments that the combination of thermal conductivity detection (TCD) and coating-free damped resonance detection (CFDRD) using micro-electromechanical systems (MEMS) could provide selective sensing of these inert species. Since the MEMS-based TCD technology was directly adapted from a brassboard prototype commissioned by a previous chemical sensing project, FY11 efforts focused on advancing the state of the newer CFDRD method. This work, guided by observations previously reported in the open literature, has not only resulted in a substantially measureable increase in selectivity but has also revealed a potential method for mitigating or eliminating thermal drift that does not require a secondary reference sensor. The design of an apparatus to test this drift compensation scheme will be described. We will conclude this report with a discussion of planned efforts in Fiscal Year 2012 (FY12).

Loui, A; McCall, S K

2011-10-24

267

An overview of micromachined platforms for thermal sensing and gas detection  

SciTech Connect

Micromachined hotplates, membranes, filaments, and cantilevers have all been used as platforms for thermal sensing and gas detection. Compared with conventional devices, micromachined sensors are characterized by low power consumption, high sensitivity, and fast response time. Much of these gains can be attributed to the size reductions achieved by micromachining. In addition, micromachining permits easy, yet precise tailoring of the heat transfer characteristics of these devices. By simple alterations in device geometry and materials used, the relative magnitudes of radiation, convection and conduction losses and Joule heat gains can be adjusted, and in this way device response can be optimized for specific applications. The free-standing design of micromachined platforms, for example, reduces heat conduction losses to the substrate, thereby making them attractive as low power, fast-response heaters suitable for a number of applications. However, while micromachining solves some of the heat transfer problems typical of conventionally produced devices, it introduces some of its own. These trade-offs will be discussed in the context of several micromachined thermal and gas sensors present in the literature. These include micromachined flow sensors, gas thermal conductivity sensors, pressure sensors, uncooled IR sensors, metal-oxide and catalytic/calorimetric gas sensors. Recent results obtained for a microbridge-based catalytic/calorimetric gas sensor will also be presented as a means of further illustrating the concepts of thermal design in micromachined sensors.

Manginell, R.P.; Smith, J.H.; Ricco, A.J.

1997-03-01

268

Quantitation of dissolved gas content in emulsions and in blood using mass spectrometric detection  

PubMed Central

Quantitation of dissolved gases in blood or in other biological media is essential for understanding the dynamics of metabolic processes. Current detection techniques, while enabling rapid and convenient assessment of dissolved gases, provide only direct information on the partial pressure of gases dissolved in the aqueous fraction of the fluid. The more relevant quantity known as gas content, which refers to the total amount of the gas in all fractions of the sample, can be inferred from those partial pressures, but only indirectly through mathematical modeling. Here we describe a simple mass spectrometric technique for rapid and direct quantitation of gas content for a wide range of gases. The technique is based on a mass spectrometer detector that continuously monitors gases that are rapidly extracted from samples injected into a purge vessel. The accuracy and sample processing speed of the system is demonstrated with experiments that reproduce within minutes literature values for the solubility of various gases in water. The capability of the technique is further demonstrated through accurate determination of O2 content in a lipid emulsion and in whole blood, using as little as 20 ?L of sample. The approach to gas content quantitation described here should greatly expand the range of animals and conditions that may be used in studies of metabolic gas exchange, and facilitate the development of artificial oxygen carriers and resuscitation fluids.

Grimley, Everett; Turner, Nicole; Newell, Clayton; Simpkins, Cuthbert; Rodriguez, Juan

2011-01-01

269

Subsurface detection of fossil fuel pollutants by photoionization and gas chromatography/mass spectrometry.  

PubMed

This paper describes analysis of environmental pollutants at depth without bringing sample to the surface. It is based on an improved 3-stage Peltier freeze trap, which efficiently pre-concentrates volatile coal tar and petroleum hydrocarbons, and an integrated system for detecting pollutants on-line, in real-time by photoionization detection and quantitation by gas chromatography/mass spectrometry (GC/MS) as the probe is advanced into the subsurface. Findings indicate measurement precision and accuracy for volatiles meet EPA criteria for hazardous waste site investigations. When a Teflon membrane inlet is used to detect contaminants in groundwater, its 140 degrees C temperature limit restricts analyte collection in soil to C(2)-phenanthrenes. Two case studies demonstrate the probe is well-suited to tracking petroleum and coal tar plumes from source to groundwater. PMID:20594575

Robbat, Albert; Considine, Thomas; Antle, Patrick M

2010-07-01

270

Tunable photonic cavities for in-situ spectroscopic trace gas detection  

SciTech Connect

Compact tunable optical cavities are provided for in-situ NIR spectroscopy. MEMS-tunable VCSEL platforms represents a solid foundation for a new class of compact, sensitive and fiber compatible sensors for fieldable, real-time, multiplexed gas detection systems. Detection limits for gases with NIR cross-sections such as O.sub.2, CH.sub.4, CO.sub.x and NO.sub.x have been predicted to approximately span from 10.sup.ths to 10s of parts per million. Exemplary oxygen detection design and a process for 760 nm continuously tunable VCSELS is provided. This technology enables in-situ self-calibrating platforms with adaptive monitoring by exploiting Photonic FPGAs.

Bond, Tiziana; Cole, Garrett; Goddard, Lynford

2012-11-13

271

First Detection of a Counterrotating Molecular Gas Disk in a Spiral Galaxy: NGC 3626  

NASA Astrophysics Data System (ADS)

In this paper we report the detection of a massive counterrotating molecular gas disk in the early-type spiral NGC 3626, observed in the 1-0 and 2-1 lines of 12CO, mapped with the 30 m telescope and Bure interferometer. 12CO emission is concentrated in a compact nuclear disk of average radius r ~ 12" (1.2 kpc). In the outer disk, from r = 20" to r = 100" (2-10 kpc), 12CO is not detected, and the neutral gas content is largely dominated by H I. The observed 12CO velocity field pattern corresponds to a gaseous disk with a sense of rotation opposite to that of the stars. Counterrotation is shared by molecular and ionized gas in the center. There is no strong evidence of 12CO emission from gas in direct rotation. The estimated molecular mass in the 12CO nuclear disk is M(H2) ~ 0.3 x 109 M?, 3 times lower than the mass of the H I disk. Within the nuclear disk, 12CO is distributed in a central source of ~1" (100 pc) radius, where the derived 12CO rotation curve reaches ~240 km s-1, surrounded by a pseudoring of average radius ~6" (600 pc) characterized by strong noncircular motions. The dynamics of molecular gas, characterized by a regular counterrotating pattern and streaming motions typical of a steady density-wave driven flow and normal 12CO line widths, preclude the occurrence of violent large-scale shocks or of a nonequilibrium dynamical state for the gas. The available optical (H alpha , N [II] and S [II]) and radio continuum data (at 12.6 cm and 21 cm) indicate that no violent burst of star formation is associated with the nuclear molecular gas. This is confirmed by the lack of IRAS flux record for the nucleus of NGC 3626. The present 12CO observations suggest that we are probably seeing a late stage of a merger happened in NGC 3626.

Garcia-Burillo, S.; Sempere, M. J.; Bettoni, D.

1998-07-01

272

Leak detection of Hydrogen Gas Using Anti-Stokes Raman Scattering  

NASA Astrophysics Data System (ADS)

An experimental study was performed to evaluate the applicability of anti-Stokes Raman scattering to leak detection of hydrogen gas. The laser beam of wavelength 355 nm and Stokes beam of wavelength 416 nm were aligned in a collinear configuration, and hydrogen gas was released into air through a nozzle of aperture 1 mm placed immediately below the beam path. The anti-Stokes beam of wavelength 309 nm was generated by coherent anti-Stokes Raman scattering. The three beams were incident on a diffusing plate, and the anti-Stokes beam was selectively imaged using an image intensifier and two interference filters. The interference filters provided sufficient rejection at 355 nm, 416 nm, and at fluorescence wavelengths to provide a clear image at 309 nm. The anti-Stokes beam could be imaged down to hydrogen gas release rates of 2 ml/min when the nozzle exit was 0.5 mm below the laser beam and Stokes beam. The anti-Stokes beam could be imaged for separation distance (between the laser and Stokes beams and the nozzle exit) of <3.5 mm, for a gas release rate of 10 ml/min.

Fukuchi, Tetsuo; Ninomiya, Hideki

273

Semiconductor laser source for natural gas leak detection. Final report, September 1, 1984-March 31, 1985  

SciTech Connect

The feasibility of using semiconductor lasers as infrared sources for handheld natural gas leak detectors was assessed. The detection system was assumed to be based on the differential absorption (DIAL) technique and to operate at ambient temperatures. The absorption spectra of the major components of natural gas, methane and ethane, were measured in the spectral range from 1.2 to 2.0 micrometers where cryogenic cooling of detectors is not required. Both spectra exhibited absorption features due to overtones of the fundamental C-H stretching modes strong enough to be suitable for DIAL measurements. The literature on semiconductor lasers was reviewed both to determine which types emit in spectral regions overlapping the absorption bands of methane and ethane and which allow the high power pulsed operation necessary for DIAL systems. Lasers made from InGaAs emitting near 1.65 micrometers are suitable for methane detection. However, considerable materials development would be needed to develop a laser for ethane detection. Cleaved-coupled-cavity (CT) laser structures appear to be the most promising means of tuning and narrowing the linewidth of the emitted light. An experiment with a ten-emitter phased array (CT) laser showed significant line narrowing.

Elliott, R.A.

1985-06-01

274

A Cost Effective Multi-Spectral Scanner for Natural Gas Detection  

SciTech Connect

The objective of this project is to design, fabricate and demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first year of the project, a laboratory version of the multi-spectral scanner was designed, fabricated, and tested at EnUrga Inc. The multi-spectral scanner was also evaluated using a blind Department of Energy study at the Rocky Mountain Oilfield Testing Center. The performance of the scanner was inconsistent during the blind study. However, most of the leaks were outside the view of the multi-spectral scanner that was developed during the first year of the project. Therefore, a definite evaluation of the capability of the scanner was not obtained. Despite the results, sufficient number of plumes was detected fully confirming the feasibility of the multi-spectral scanner. During the second year, the optical design of the scanner was changed to improve the sensitivity of the system. Laboratory tests show that the system can reliably detect small leaks (20 SCFH) at 30 to 50 feet. A prototype scanner was built and evaluated during the second year of the project. Only laboratory evaluations were completed during the second year. The laboratory evaluations show the feasibility of using the scanner to determine natural gas pipeline leaks. Further field evaluations and optimization of the scanner are required before commercialization of the scanner can be initiated.

Yudaya Sivathanu; Jongmook Lim; Vinoo Narayanan; Seonghyeon Park

2005-12-07

275

Nanofiber-net-binary structured membranes for highly sensitive detection of trace HCl gas  

NASA Astrophysics Data System (ADS)

This work describes the detection of trace hydrogen chloride (HCl) gas through analyses of the resonance frequency signal from quartz crystal microbalance (QCM) sensors coated with polyaniline (PANI) functionalized polyamide 6 (PA 6) (PANI-PA 6) nanofiber-net-binary (NNB) structured membranes. The PA 6 NNB substrate comprising nanofibers and spider-web-like nano-nets fabricated by a versatile electro-spinning/netting (ESN) process offered an ideal interface for the uniform PANI functionalization and enhanced sensing performance. Benefiting from the large specific surface area, high porosity, and strong adhesive force to the QCM electrode of the PANI-PA 6 NNB membranes, the developed HCl-selective sensors exhibited a rapid response, good reproducibility and stability, and low detection limit (7 ppb) at room temperature. Additionally, the PANI-PA 6 NNB sensing membranes presented visible color changes upon cycled exposure to HCl and ammonia, suggesting their potential application in the development of colorimetric sensors. The PANI-PA 6 NNB coated QCM sensors are considered to be a promising candidate for trace HCl gas detection in practical applications.

Wang, Xianfeng; Wang, Jialin; Si, Yang; Ding, Bin; Yu, Jianyong; Sun, Gang; Luo, Wenjing; Zheng, Gang

2012-11-01

276

Fast gas chromotography with luminol detection for measurement of nitrogen dioxide and PANs.  

SciTech Connect

Fast capillary gas chromatography has been coupled to a luminol-based chemiluminescence detection system for the rapid monitoring of nitrogen dioxide and peroxyacyl nitrates. A first-generation instrument was described recently (Gaffney et al., 1998). This system is capable of monitoring nitrogen dioxide and peroxyacyl nitrates (PANs; to and including the C4 species) with 1-min time resolution. This is an improvement by a factor of five over gas chromatography methods with electron capture detection. In addition, the luminol method is substantially less expensive than laser fluorescent detection or mass spectroscopic methods. Applications in aircraft-based research have been published electronically and will appear shortly in Environmental Science and Technology (Gaffney et al., 1999a). An improved version of the instrument that has been designed and built makes use of a Hammamatsu photon-counting system. Detection limits of this instrumentation are at the low tens of ppt. The range of the instrument can be adjusted by modifying sampling volumes and detection counting times. A review of past work and of recent application of the instrumentation to field measurements of nitrogen dioxide and PANs is presented. The data clearly indicate that the luminol approach can determine the target species with time resolution of less than 1 min. Examples of applications for estimation of peroxyacetyl radical concentrations and nitrate radical formation rates are also presented. This instrumentation can further be used for evaluation of surfaces for loss of nitrogen dioxide and PANs, phenomena of possible importance for sampling interfaces and chamber wall design. Our high-frequency field data clearly indicate that the ''real world'' is not well mixed and that turbulent mixing and plume-edge chemistries might play an important role in urban- and regional-scale interactions. Dynamic flow systems might be required to evaluate such effects in new-generation chamber studies.

Gaffney, J. S.; Marley, N. A.; Drayton, P. J.

1999-09-30

277

Low-cost multispectral vegetation imaging system for detecting leaking CO? gas.  

PubMed

As a component of a multisensor approach to monitoring carbon sequestration sites for possible leaks of the CO? gas from underground reservoirs, a low-cost multispectral imaging system has been developed for indirect detection of gas leaks through observations of the resulting stress in overlying vegetation. The imager employs front-end optics designed to provide a full 50° field of view with a small, low-cost CMOS detector, while still maintaining quasi-collimated light through the angle-dependent interference filters used to define the spectral bands. Red and near-infrared vegetation reflectances are used to compute the normalized difference vegetation index (NDVI) and spatial and temporal patterns are analyzed statistically to identify regions of anomalous stress, which are then flagged for closer inspection with in-situ CO? sensors. The system is entirely self-contained with an onboard compact computer and is housed in a weather-proof housing to enable extended outdoor deployment. PMID:22307130

Hogan, Justin A; Shaw, Joseph A; Lawrence, Rick L; Larimer, Randal M

2012-02-01

278

Determination of acenocoumarol in human plasma by capillary gas chromatography with mass-selective detection.  

PubMed

A method for the determination of acenocoumarol in human plasma by capillary gas chromatography-mass-selective detection is described. After addition of a structurally related analogue as the internal standard, the compounds are extracted from plasma at acidic pH into toluene, back-extracted with a basic solution and re-extracted from hydrochloric acid solution with toluene, which is then evaporated to dryness. The compounds are converted into their methyl derivatives, which are determined by gas chromatography using a mass-selective detector at m/z 324 for acenocoumarol and m/z 338 for the internal standard. The reproducibility and accuracy of the method were found to be suitable over the acenocoumarol concentrations range 2.2-74 nmol/l. The method could be considered as selective for acenocoumarol in the presence of its major metabolites in plasma. PMID:8004241

Pommier, F; Ackermann, R; Sioufi, A; Godbillon, J

1994-03-18

279

ROSAT detection of diffuse hot gas in the edge-on galaxy NGC 4631  

NASA Astrophysics Data System (ADS)

ROSAT observation is presented of the edge-on spiral galaxy NGC 4631, a nearby Sc/SBd galaxy best known for its extended radio halo. Because of the low foreground Galactic X-ray-absorbing gas column density, NH approximately 1.4 x 1020cm-2, this observation is sensitive to gas of temperature greater than or equal to a few times 105 K. A soft (approximately 0.25 keV) X-ray radiation out to more than 8 kpc above the midplane of the galaxy was detected. The strongest X-ray emission in the halo is above the central disk, a region of about 3 kpc radius which shows high star formation activity. The X-ray emission in the halo is bordered by two extended filaments of radio continuum emission. Diffuse X-ray emission from hot gas in the galaxy's disk was found. The spectrum of the radiation can be characterized by a thermal plasma with a temperature of 3 x 106 K and a radiative cooling rate of approximately 8 x 1039 ergs s-1. This rate is only a few percent of the estimated supernova energy release in the interstellar medium of the galaxy. Analysis of the X-ray spectrum shows evidence for the presence of a cooler (several times 105 K) halo gas component that could consume a much larger fraction of the supernova energy. Strong evidence was found for disk/halo interaction. Hot gas apparently blows out from supershells in the galaxy's disk at a rate of approximately 1 solar mass yr-1. This outflow of hot gas drags magnetic field lines up in the halo and forms a magnetized gaseous halo. If the magnetic field lines are still anchored to the disk gas at large disk radii, the outflowing gas may be confined high above the disk by magnetic pressure. A strong X-ray source which coincides spatially with an H I supershell has been identified. However, the source is likely an extremely luminous X-ray binary with Lchi(0.1 - 2 keV) approximately 5 x 1039 ergs s-1, which makes it a stellar mass black hole candidate.

Wang, Q. David; Walterbos, Rene A. M.; Steakley, Michael F.; Norman, Colin A.; Braun, Robert

280

ROSAT detection of diffuse hot gas in the edge-on galaxy NGC 4631  

NASA Astrophysics Data System (ADS)

We present our ROSAT observation of the edge-on spiral galaxy NGC 4631, a nearby Sc/SBd galaxy best known for its extended radio halo. Because of the low foreground Galactic X-ray-absorbing gas column density, NHI approximately = 1.4 x 1020/sq cm, this observation is sensitive to gas of temperature greater than or approximately = a few x 105 K. We detected soft (approximately 0.25 keV) X-ray radiation out to more than 8 kpc above the midplane of the galaxy. The stongest X-ray emission in the halo is above the central disk, a region of about 3 kpc radius which shows high star formation activity. The X-ray emission in the halo is bordered by two extended filaments of radio continuum emission. We also found diffuse X-ray emission from hot gas in the galaxy's disk. The spectrum of the radiation can be characterized by a thermal plasma with a temperature of 3 x 106 K and a radiative cooling rate of approximately 8 x 1039 ergs/sec. This rate is only a few percent of the estimated supernova energy release in the interstellar medium of the galaxy. Analysis of the X-ray spectrum shows evidence for the presence of a cooler (several times 105 K) halo gas component that could consume a much larger fraction of the supernova energy. We found strong evidence for disk/halo interaction. Hot gas apparently blows out from supershells in the galaxy's disk at a rate of approximately 1 solar mass/yr. This outflow of hot gas drags magnetic field lines up in the halo and forms a magnetized gaseous halo. If the magnetic field lines are still anchored to the disk gas at large disk radii, the outflowing gas may be confined high above the disk by magnetic pressure. We have identified a strong X-ray source which coincides spatially with an H I supershell. However, the source is likely an extremely luminous X-ray binary with Lx(0.1-2 keV) approximately = 5 x 1039 ergs/sec, which makes it a stellar mass black hole candidate.

Wang, Q. Daniel; Walterbos, Rene A. M.; Steakley, Michael F.; Norman, Colin A.; Braun, Robert

1995-01-01

281

Fire Detection Using tin Oxide Gas Sensors Installed in an Indoor Space  

NASA Astrophysics Data System (ADS)

Many lives and facilities were lost by fire. Especially, there are many damages to elderly, toddlers and babies. In Japan, number of deaths over 65 years old reached to 53% in 2004. Number of over 81 years olds went to 20%. It takes for the elderly person more time to sense fire and also to evacuate to safe places. Although it is important to prevent the fire, it also needs to inform the fire breaking as early as possible. Human sense decreases with age and it is difficult to perceive the fire at an early stage. It is desired to develop a higher sensitive element for fire and its system which can detect fire at an early stage. In this experiment, tin oxide gas sensors were adopted to detect a smoldering fire at the early stage. Most common case of fire is the smoldering fire. The reliability of the sensor is higher and it is adopted in a gas alarm detector. The sensor can also detect slight amount of odor molecule. In our previous experiment, it became obvious that it was better to install the sensor to the ceiling to detect odor components generating from smoldering fire. Therefore, five sensors were installed in the ceiling away from each other and the method to detect the fire was examined. As a result, a characteristic was newly derived by adding the sensor outputs for one minute. The sensor output was input every 0.1s. The characteristic is called as the integrated characteristic. After that, the differential characteristic was derived using the integrated characteristic. The fire was determined using the differential characteristics. The materials causing a smoldering fire were woodchip, wallpaper and carpet as subjects. The system could detect the fire in several minutes for whole materials. The sensor is effective to detect the smoldering fire at an early stage. It is necessary to detect a cigarette smoke to distinguish as non fire. In this study, the discrimination was also examined using a quadratic function (ax2+b). The coefficients a and b were effective to identify smoldering fire and cigarette smoke. Principal component analysis for the arrival speed S which meant a kind of odor-speed was also useful to distinguish fire from non fire.

Shibata, Shin-Ichi; Higashino, Tsubasa; Sawada, Ayako; Oyabu, Takashi; Takei, Yoshinori; Nanto, Hidehito; Toko, Kiyoshi

282

Post-dive ultrasound detection of gas in the liver of rats and scuba divers.  

PubMed

In a previous study, we obtained histologic documentation of liver gas embolism in the rat model of rapid decompression. The aim of the study was to assess in the same model occurrence and time course of liver embolism using 2-D ultrasound imaging, and to explore by this means putative liver gas embolism in recreational scuba divers. Following 42 min compression at 7 ATA breathing air and 12 min decompression, eight surviving female rats were anesthetized and the liver imaged by ultrasound at 20 min intervals up to 120 min. A significant enhancement of echo signal was recorded from 60 to 120 min as compared to earlier post-decompression times. Enzymatic markers of liver damage (AST, ALT, and GGT) increased significantly at 24 h upon decompression. Twelve healthy experienced divers were studied basally and at 15-min intervals up to 60 min following a 30-min scuba dive at 30 msw depth. At 30 min upon surfacing echo images showed significant signal enhancement that progressed and reached plateau at 45 and 60 min. Total bilirubin at 24 h increased significantly (p = 0.02) with respect to basal values although within the reference range. In conclusion, 2-D ultrasound liver imaging allowed detection of gas embolism in the rat and defined the time course of gas accumulation. Its application to scuba divers revealed liver gas accumulation in all subjects in the absence of clear-cut evidence of liver damage or of any symptom. The clinical significance of our findings remains to be investigated. PMID:21318312

L'abbate, Antonio; Marabotti, Claudio; Kusmic, Claudia; Pagliazzo, Antonino; Navari, Alessandro; Positano, Vincenzo; Palermo, Mario; Benassi, Antonio; Bedini, Remo

2011-02-12

283

Potential application of microsensor technology in radioactive waste management with emphasis on headspace gas detection.  

SciTech Connect

Waste characterization is probably the most costly part of radioactive waste management. An important part of this characterization is the measurements of headspace gas in waste containers in order to demonstrate the compliance with Resource Conservation and Recovery Act (RCRA) or transportation requirements. The traditional chemical analysis methods, which include all steps of gas sampling, sample shipment and laboratory analysis, are expensive and time-consuming as well as increasing worker's exposure to hazardous environments. Therefore, an alternative technique that can provide quick, in-situ, and real-time detections of headspace gas compositions is highly desirable. This report summarizes the results obtained from a Laboratory Directed Research & Development (LDRD) project entitled 'Potential Application of Microsensor Technology in Radioactive Waste Management with Emphasis on Headspace Gas Detection'. The objective of this project is to bridge the technical gap between the current status of microsensor development and the intended applications of these sensors in nuclear waste management. The major results are summarized below: {sm_bullet} A literature review was conducted on the regulatory requirements for headspace gas sampling/analysis in waste characterization and monitoring. The most relevant gaseous species and the related physiochemical environments were identified. It was found that preconcentrators might be needed in order for chemiresistor sensors to meet desired detection {sm_bullet} A long-term stability test was conducted for a polymer-based chemresistor sensor array. Significant drifts were observed over the time duration of one month. Such drifts should be taken into account for long-term in-situ monitoring. {sm_bullet} Several techniques were explored to improve the performance of sensor polymers. It has been demonstrated that freeze deposition of black carbon (CB)-polymer composite can effectively eliminate the so-called 'coffee ring' effect and lead to a desirable uniform distribution of CB particles in sensing polymer films. The optimal ratio of CB/polymer has been determined. UV irradiation has been shown to improve sensor sensitivity. {sm_bullet} From a large set of commercially available polymers, five polymers were selected to form a sensor array that was able to provide optimal responses to six target-volatile organic compounds (VOCs). A series of tests on the response of sensor array to various VOC concentrations have been performed. Linear sensor responses have been observed over the tested concentration ranges, although the responses over a whole concentration range are generally nonlinear. {sm_bullet} Inverse models have been developed for identifying individual VOCs based on sensor array responses. A linear solvation energy model is particularly promising for identifying an unknown VOC in a single-component system. It has been demonstrated that a sensor array as such we developed is able to discriminate waste containers for their total VOC concentrations and therefore can be used as screening tool for reducing the existing headspace gas sampling rate. {sm_bullet} Various VOC preconcentrators have been fabricated using Carboxen 1000 as an absorbent. Extensive tests have been conducted in order to obtain optimal configurations and parameter ranges for preconcentrator performance. It has been shown that use of preconcentrators can reduce the detection limits of chemiresistors by two orders of magnitude. The life span of preconcentrators under various physiochemical conditions has also been evaluated. {sm_bullet} The performance of Pd film-based H2 sensors in the presence of VOCs has been evaluated. The interference of sensor readings by VOC has been observed, which can be attributed to the interference of VOC with the H2-O2 reaction on the Pd alloy surface. This interference can be eliminated by coating a layer of silicon dioxide on sensing film surface. Our work has demonstrated a wide range of applications of gas microsensors in radioactive waste management. Such applications can poten

Davis, Chad Edward; Thomas, Michael Loren; Wright, Jerome L.; Pohl, Phillip Isabio; Hughes, Robert Clark; Wang, Yifeng; McGrath, Lucas K.; Ho, Clifford Kuofei; Gao, Huizhen

2004-09-01

284

Detection of Several Classes of Pesticides and Metabolites in Meconium by Gas Chromatography-Mass Spectrometry  

PubMed Central

A solid phase extraction method was developed to isolate multiple classes of parent pesticides from meconium. A methanolic/hydrochloric acid methyl ester derivatization with liquid-liquid extraction technique was also developed for the analysis of metabolites. Identification and quantitation was by electron impact gas chromatography-mass spectrometry. For the parent compounds and metabolites, recoveries in spiked meconium ranged between 72–109%, with coefficients of variation ranging from 1.55–16.92% and limits of detection between 0.01–4.15 ?g g?1. Meconium samples obtained from infants in the Philippines were assayed using these methods, and propoxur, cypermethrin, pretilachlor, malathion, 4,4?-dichlorodiphenyltrichloroethylene, bioallethrin, and cyfluthrin were detected.

Bielawski, D.; Ostrea, E.; Posecion, N.; Corrion, M.; Seagraves, J.

2007-01-01

285

Identification of volatiles by headspace gas chromatography with simultaneous flame ionization and mass spectrometric detection.  

PubMed

Volatiles are frequently abused as inhalants. The methods used for identification are generally nonspecific if analyzed concurrently with ethanol or require an additional analytical procedure that employs mass spectrometry. A previously published technique utilizing a capillary flow technology splitter to simultaneously quantitate and confirm ethyl alcohol by flame ionization and mass spectrometric detection after headspace sampling and gas chromatographic separation was evaluated for the detection of inhalants. Methanol, isopropanol, acetone, acetaldehyde, toluene, methyl ethyl ketone, isoamyl alcohol, isobutyl alcohol, n-butyl alcohol, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane (Norflurane, HFC-134a), chloroethane, trichlorofluoromethane (Freon(®)-11), dichlorodifluoromethane (Freon(®)-12), dichlorofluoromethane (Freon(®)-21), chlorodifluoromethane (Freon(®)-22) and 1,2-dichlorotetrafluoroethane (Freon(®)-114) were validated for qualitative identification by this method. The validation for qualitative identification included evaluation of matrix effects, sensitivity, carryover, specificity, repeatability and ruggedness/robustness. PMID:24005155

Tiscione, Nicholas B; Yeatman, Dustin Tate; Shan, Xiaoqin; Kahl, Joseph H

2013-09-04

286

A COST EFFECTIVE MULTI-SPECTRAL SCANNER FOR NATURAL GAS DETECTION  

SciTech Connect

The objective of this project is to design, fabricate and field demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first year of the project, a laboratory version of the multi-spectral scanner was designed, fabricated, and tested at En'Urga Inc. The multi-spectral scanner was also evaluated using a blind DoE study at RMOTC. The performance of the scanner was inconsistent during the blind DoE study. However, most of the leaks were outside the view of the multi-spectral scanner. Therefore, a definite evaluation of the capability of the scanner was not obtained. Despite the results, sufficient number of plumes was detected fully confirming the feasibility of the multi-spectral scanner. During the second year, a rugged prototype scanner will be developed and evaluated, both at En'Urga Inc. and any potential field sites.

Yudaya Sivathanu; Jongmook Lim; Vinoo Narayanan

2004-10-25

287

Detection of pristine gas two billion years after the Big Bang.  

PubMed

In the current cosmological model, only the three lightest elements were created in the first few minutes after the Big Bang; all other elements were produced later in stars. To date, however, heavy elements have been observed in all astrophysical environments. We report the detection of two gas clouds with no discernible elements heavier than hydrogen. These systems exhibit the lowest heavy-element abundance in the early universe, and thus are potential fuel for the most metal-poor halo stars. The detection of deuterium in one system at the level predicted by primordial nucleosynthesis provides a direct confirmation of the standard cosmological model. The composition of these clouds further implies that the transport of heavy elements from galaxies to their surroundings is highly inhomogeneous. PMID:22075722

Fumagalli, Michele; O'Meara, John M; Prochaska, J Xavier

2011-11-10

288

Determination of 17 ?-Estradiol in Rabbit Plasma by Gas Chromatography with Flame Ionization Detection  

PubMed Central

This article describes gas chromatography-flame ionization detection method for determination of 17 ?-estradiol in rabbit plasma. 17 ?-estradiol and internal standard progesterone were extracted from plasma using liquid–liquid extraction method. Linearity was found between 0.25 and 20 ?g/ml (r2=0.994) for plasma samples. Intra-day and inter-day precision, expressed as the relative standard deviation were less than 5.5%, and accuracy (relative error) was less than 3.5%. The mean recovery of 17 ?-estradiol samples was 94.4%. The limits of detection and quantification of method for plasma samples were 0.10 ?g/ml and 0.15 ?g/ml, respectively. Also, clinically used other 10 drugs were investigated to check for potential interferences and the method was successfully applied to the determination of 17 ?-estradiol in New Zealand white rabbits.

Yilmaz, B; Kadioglu, Y.

2012-01-01

289

Performance-enhanced "tunable" capillary microwave-induced plasma mass spectrometer for gas chromatography detection.  

PubMed

Improvements in the stability and performance of a capillary microwave-induced plasma-mass spectrometer (MIP-MS) were achieved by optimizing power transfer to the cavity using a tunable coaxial MIP. The MIP, operating at atmospheric pressure, was sustained with 30 mL/min He and 60 W of power. Measurement precision and sensitivity for the standard waveguide and coaxial systems were determined using 16 organochlorine pesticide solutions separated by gas chromatography (GC). The linear dynamic range obtained with the tunable MIP-MS extended over 3 orders of magnitude, a 10 time improvement with respect to the standard MIP. Detection limits were between 3 and 19 pg of Cl mol(-1) s(-1), 7 times lower than the detection limits obtained with the nontunable MIP-MS. Analysis of pesticides containing sulfur atoms was also possible, further demonstrating multielement MIP-MS detection. Excellent accuracy (10% recovery) and precision (5% RSD) were found for the detection of the pesticides in a petroleum-contaminated reference soil. By placing the GC column at the plasma expansion stage, molecular fragmentation of a mixture of volatile organic compounds was also demonstrated. With the MS operated in the selected ion monitoring mode, measurement sensitivity was approximately 500 pg/s per compound. PMID:10939373

Zapata, A M; Robbat, A

2000-07-15

290

Selective cavity-enhanced trace gas detection via diffusion time-of-fight  

NASA Astrophysics Data System (ADS)

A novel approach to optical detection of airborne explosive vapor using a combination of cavity enhanced ab- sorption spectroscopy (CEAS) and diusion time of ight (DiTOF) is reported. The direct optical detection of explosive vapors by absorption presents a number of unique challenges due to low vapor pressures of explosive compounds, a lack of resolved spectral features, and the presence of interfering species with overlapping absorp- tion spectra. By recording the changing optical absorption as sampled atmosphere diuses into an explosive-free buer gas, the concentration of explosive molecules may be determined using a Bayesian statistical signal process- ing technique. This technique avoids the need for laser wavelength scans while simultaneously providing robust background rejection. The use of xed laser wavelengths allows for the use of cavity-locked cavity ring-down or cavity-locked direct cavity transmission absorption measurements with high data acquisition rates and signi- cantly reduces the complexity of the laser system by eliminating the need for precision wavelength monitoring. This allows for the development of compact, eld deployable sensors based on this technique. Experimental demonstration of the simultaneous detection of multiple species of hydrocarbon tracer molecules at 4295 cm-1 will be reported. The results of the current work will be applied to the detection of TNT vapor to show a projected sensitivity of 2 pptv in a diesel exhaust background.

Miller, Anthony; Richman, Bruce; Viteri, C. Ricardo; McKeever, Jason

2012-05-01

291

Fourier transform infrared photoacoustic multicomponent gas spectroscopy with optical cantilever detection.  

PubMed

The sensitivity of photoacoustic spectroscopy was improved with the invention of optical cantilever detection (PAS-OCD). However, the ability of present PAS-OCD devices to carry out multicomponent detection is poor. To overcome this, a Fourier transform infrared photoacoustic spectrometer with optical cantilever detection (FT-IR-PAS-OCD) prototype was assembled. In this article, the first evaluation and performance tests of the prototype are described. Selectivity, sensitivity, and the linearity of the signal response are evaluated. The linear response was studied for methane and carbon dioxide and confirmed in the whole analyzed concentration range from 500 to 3500 ppm and from 2500 to 17500 ppm, respectively. The calculated signal-to-noise ratio (SNR) and limit of detection were 2027 and 0.5 ppm for methane and 1362 and 4 ppm for carbon dioxide, with a measurement time of 100 seconds. Selectivity was studied with a multicomponent gas mixture of propene, methane, carbon dioxide, and methylmercaptane. The results indicate that a quantitative analysis of all components in the mixture is possible using the FT-IR-PAS-OCD. PMID:20223064

Hirschmann, Christian Bernd; Uotila, Juho; Ojala, Satu; Tenhunen, Jussi; Keiski, Riitta Liisa

2010-03-01

292

Detection of greenhouse gas precursors from diesel engines using electrochemical and photoacoustic sensors.  

PubMed

Atmospheric pollution is one of the worst threats to modern society. The consequences derived from different forms of atmospheric pollution vary from the local to the global scale, with deep impacts on climate, environment and human health. Several gaseous pollutants, even when present in trace concentrations, play a fundamental role in important processes that occur in atmosphere. Phenomena such as global warming, photochemical smog formation, acid rain and the depletion of the stratospheric ozone layer are strongly related to the increased concentration of certain gaseous species in the atmosphere. The transport sector significantly produces atmospheric pollution, mainly when diesel oil is used as fuel. Therefore, new methodologies based on selective and sensitive gas detection schemes must be developed in order to detect and monitor pollutant gases from this source. In this work, CO(2) Laser Photoacoustic Spectroscopy was used to evaluate ethylene emissions and electrochemical analyzers were used to evaluate the emissions of CO, NO(x) and SO(2) from the exhaust of diesel powered vehicles (rural diesel with 5% of biodiesel, in this paper called only diesel) at different engine rotation speeds. Concentrations in the range 6 to 45 ppmV for ethylene, 109 to 1,231 ppmV for carbon monoxide, 75 to 868 ppmV for nitrogen oxides and 3 to 354 ppmV for sulfur dioxide were obtained. The results indicate that the detection techniques used were sufficiently selective and sensitive to detect the gaseous species mentioned above in the ppmV range. PMID:22163437

Mothé, Geórgia; Castro, Maria; Sthel, Marcelo; Lima, Guilherme; Brasil, Laisa; Campos, Layse; Rocha, Aline; Vargas, Helion

2010-11-01

293

Development of detection method with a magnetic field sensor for incomplete contact in gas insulated switches and bus connecting parts  

Microsoft Academic Search

This paper describes a detecting method of incomplete contact in gas insulated switches and bus connecting parts. The principle of the method is to measure the change in magnetic field caused by the current distribution at an abnormal contact point. Fundamental studies with small-size bus models have shown that incomplete contact can be reliably detected with an opto-magnetic sensor in

H. Fujinami; T. Takuma; T. Kawamoto

1995-01-01

294

Comparison of Detection Capability for Acoustic Thermography, Visual Inspection and Fluorescent Penetrant Inspection on Gas Turbine Components  

Microsoft Academic Search

The innovative NDE inspection system Acoustic Thermography is developed with Sonic Infrared (Sonic IR) technology. Since the probability of detection is sensitive to the flaw characteristics, the fabricated flaws could not simulated the nature flaws with accuracy. The study is focus on gas turbine blades with service induced fatigue cracks. The detection capability of this innovative NDE inspection system is

Y. Guo; F. R. Ruhge

2009-01-01

295

Fault detection and isolation in aircraft gas turbine engines. Part 2: validation on a simulation test bed  

Microsoft Academic Search

The first part of this two-part paper, which is a companion paper, has developed a novel concept of fault detection and isolation (FDI) in aircraft gas turbine engines. The FDI algorithms are built upon the statistical pattern recognition method of symbolic dynamic filtering (SDF) that is especially suited for real-time detection and isolation of slowly evolving anomalies in engine components,

S Sarkar; S Gupta; K Mukherjee; A Ray

2008-01-01

296

AIRBORNE, OPTICAL REMOTE SENSING OF METHANE AND ETHANE FOR NATURAL GAS PIPLINE LEAK DETECTION  

SciTech Connect

Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The third six-month technical report contains a summary of the progress made towards finalizing the design and assembling the airborne, remote methane and ethane sensor. The vendor has been chosen and is on contract to develop the light source with the appropriate linewidth and spectral shape to best utilize the Ophir gas correlation software. Ophir has expanded upon the target reflectance testing begun in the previous performance period by replacing the experimental receiving optics with the proposed airborne large aperture telescope, which is theoretically capable of capturing many times more signal return. The data gathered from these tests has shown the importance of optimizing the fiber optic receiving fiber to the receiving optic and has helped Ophir to optimize the design of the gas cells and narrowband optical filters. Finally, Ophir will discuss remaining project issues that may impact the success of the project.

Jerry Myers

2004-05-12

297

Xenon Additives Detection in Helium Micro-Plasma Gas Analytical Sensor  

NASA Astrophysics Data System (ADS)

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

Tsyganov, Alexander; Kudryavtsev, Anatoliy; Mustafaev, Alexander

2012-10-01

298

Detection of unburned fuel as contaminant in engine oil by a gas microsensor array  

NASA Astrophysics Data System (ADS)

We developed a novel method to detect the presence of unburned diesel fuel in used diesel fuel engine oil. The method is based on the use of an array of different gas microsensors based on metal oxide thin films deposited by sol-gel technique on Si substrates. The sensor array, exposed to the volatile chemical species of different diesel fuel engine oil samples contaminated in different percentages by diesel fuel, resulted to be appreciable sensitive to them. Principal Component Analysis (PCA) and Self-Organizing Map (SOM) applied to the sensor response data-set gave a first proof of the sensor array ability to discriminate among the different diesel fuel diluted lubricating oils. Moreover, in order to get information about the headspace composition of the diesel fuel-contaminated engine oils used for gas-sensing tests, we analyzed the engine oil samples by Static Headspace Solid Phase Micro Extraction/Gas Chromatograph/Mass Spectrometer (SHS-SPME/ GC/MS).

Capone, Simonetta; Zuppa, Marzia; Presicce, Dominique S.; Epifani, Mauro; Francioso, Luca; Siciliano, Pietro; Distante, C.

2007-06-01

299

Detection of trace gas emissions from point sources using shortwave infrared imaging spectrometry  

NASA Astrophysics Data System (ADS)

Existing spaceborne remote sensing provides an effective means of detecting continental-scale variation in trace gas concentrations, but does not permit mapping of local emissions from point sources. Point source emissions of methane (CH4), nitrous oxide (N2O) and particulates, often associated with combustion and carbon dioxide (CO2) emissions, have significant impacts on air quality. Using Airborne Visible InfraRed Imaging Spectrometer (AVIRIS) data and a cluster-tuned matched filter technique, we have mapped local CH4, N2O and CO2 emissions from terrestrial sources in the Los Angeles basin. CH4 anomalies were in close proximity to known and probable emission sources, including hydrocarbon storage tanks and gas flares. Multiple N2O and CH4 anomalies were detected at a wastewater treatment facility, while CH4 and CO2 anomalies were also identified at a large oil refinery. We discuss ongoing efforts to estimate CH4 concentrations using radiative transfer modeling and potential application of this technique to additional trace gasses with distinct absorption features. This method could be applied to data from existing airborne sensors and planned satellite missions like HyspIRI, thereby improving high resolution mapping of trace gasses and better constraining local sources.

Thorpe, A. K.; Roberts, D. A.; Dennison, P. E.; Bradley, E. S.; Funk, C. C.

2011-12-01

300

Detection and tracking of gas plumes in LWIR hyperspectral video sequence data  

NASA Astrophysics Data System (ADS)

Automated detection of chemical plumes presents a segmentation challenge. The segmentation problem for gas plumes is difficult due to the diffusive nature of the cloud. The advantage of considering hyperspectral images in the gas plume detection problem over the conventional RGB imagery is the presence of non-visual data, allowing for a richer representation of information. In this paper we present an effective method of visualizing hyperspectral video sequences containing chemical plumes and investigate the effectiveness of segmentation techniques on these post-processed videos. Our approach uses a combination of dimension reduction and histogram equalization to prepare the hyperspectral videos for segmentation. First, Principal Components Analysis (PCA) is used to reduce the dimension of the entire video sequence. This is done by projecting each pixel onto the first few Principal Components resulting in a type of spectral filter. Next, a Midway method for histogram equalization is used. These methods redistribute the intensity values in order to reduce icker between frames. This properly prepares these high-dimensional video sequences for more traditional segmentation techniques. We compare the ability of various clustering techniques to properly segment the chemical plume. These include K-means, spectral clustering, and the Ginzburg-Landau functional.

Gerhart, Torin; Sunu, Justin; Lieu, Lauren; Merkurjev, Ekaterina; Chang, Jen-Mei; Gilles, Jérôme; Bertozzi, Andrea L.

2013-05-01

301

AIRBORNE, OPTICAL REMOTE SENSING OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION  

SciTech Connect

Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. This six-month technical report summarizes the progress for each of the proposed tasks, discusses project concerns, and outlines near-term goals. Ophir has completed a data survey of two major natural gas pipeline companies on the design requirements for an airborne, optical remote sensor. The results of this survey are disclosed in this report. A substantial amount of time was spent on modeling the expected optical signal at the receiver at different absorption wavelengths, and determining the impact of noise sources such as solar background, signal shot noise, and electronic noise on methane and ethane gas detection. Based upon the signal to noise modeling and industry input, Ophir finalized the design requirements for the airborne sensor, and released the critical sensor light source design requirements to qualified vendors. Responses from the vendors indicated that the light source was not commercially available, and will require a research and development effort to produce. Three vendors have responded positively with proposed design solutions. Ophir has decided to conduct short path optical laboratory experiments to verify the existence of methane and absorption at the specified wavelength, prior to proceeding with the light source selection. Techniques to eliminate common mode noise were also evaluated during the laboratory tests. Finally, Ophir has included a summary of the potential concerns for project success and has established future goals.

Jerry Myers

2003-05-13

302

Limited Streamer Tube System for Detecting Contamination in the Gas Used in the BaBar Instrumented Flux Return  

SciTech Connect

The Resistive Plate Chambers (RPCs) initially installed in the Instrumented Flux Return (IFR) of the BABAR particle detector have proven unreliable and inefficient for detecting muons and neutral hadrons. In the summer of 2004, the BABAR Collaboration began replacing the RPCs with Limited Streamer Tubes (LSTs). LST operation requires a mixture of very pure gases and an operating voltage of 5500 V to achieve maximum efficiency. In the past, the gas supplies obtained by the BABAR Collaboration have contained contaminants that caused the efficiency of the IFR LSTs to drop from approximately 90% to approximately 60%. Therefore, it was necessary to develop a method for testing this gas for contaminants. An LST test system was designed and built using two existing LSTs, one placed 1 cm above the other. These LSTs detect cosmic muons in place of particles created during the BABAR experiment. The effect of gas contamination was mimicked by reducing the operating voltage of the test system in order to lower the detection efficiency. When contaminated gas was simulated, the coincidence rate and the percent coincidence between the LSTs in the test system dropped off significantly, demonstrating that test system can be used as an indicator of gas purity. In the fall of 2006, the LST test system will be installed in the gas storage area near the BABAR facility for the purpose of testing the gas being sent to the IFR.

Huntley, L.I.; /Franklin - Marshall Coll.

2006-08-30

303

A COST EFFECTIVE MULTI-SPECTRAL SCANNER FOR NATURAL GAS DETECTION  

SciTech Connect

The objective of this project is to design, fabricate and field demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first year of the project, a laboratory version of the multi-spectral scanner was designed, fabricated, and tested at En'Urga Inc. The multi-spectral scanner was also evaluated using a blind DoE study at RMOTC. The performance of the scanner was inconsistent during the blind DoE study. However, most of the leaks were outside the view of the multi-spectral scanner. Therefore, a definite evaluation of the capability of the scanner was not obtained. Despite the results, sufficient number of plumes was detected fully confirming the feasibility of the multi-spectral scanner. During the second year, the optical design of the scanner was changed to improve the sensitivity of the system. Laboratory tests show that the system can reliably detect small leaks (20 SCFH) at 30 to 50 feet. Electronic design of the scanner to make it a self standing sensor is currently in progress. During the last six months of the project, the electronic and mechanical design will be completed and evaluated at En'Urga Inc.

Yudaya Sivathanu; Jongmook Lim; Vinoo Narayanan; Seonghyeon Park

2005-04-15

304

Detection of cold gas releases in space via low-energy neutral atom imaging  

NASA Astrophysics Data System (ADS)

Low energy neutral atoms (LENAs) are produced in space plasmas by charge exchange between the ambient magnetospheric plasma ions and cold neutral atoms. Under normal conditions these cold neutrals come from the terrestrial geocorona, a shroud of few-eV hydrogen atoms surrounding the Earth. As a consequence of this charge exchange, it has become possible to remotely image many regions of the magnetosphere for the first time utilizing recently developed LENA imaging technology. In addition to the natural hydrogen geocorona, conventional explosions and maneuvering thruster firings can also introduce large amounts of cold gas into the space environment. In this paper we examine whether such potentially clandestine activities could also be remotely observed for the first time via LENA imaging. First, we examine the fluxes of LENAs produced in the space environment from a conventional explosion. Then we review the present state of the art in the emerging field of LENA detection and imaging. We conclude that the sensitivities for present LENA imager designs may be just adequate for detecting some mad-made releases. With additional improvements in LENA detection capabilities, this technique could become an important new method for monitoring for conventional explosions, as well as other man-made neutral releases, in the space environment.

McComas, David J.; Funsten, Herbert O.; Moore, Kurt R.; Scime, Earl E.; Thomsen, Michelle F.

1993-11-01

305

Strategies for Detecting Hidden Geothermal Systems by Near-Surface Gas Monitoring  

SciTech Connect

''Hidden'' geothermal systems are those systems above which hydrothermal surface features (e.g., hot springs, fumaroles, elevated ground temperatures, hydrothermal alteration) are lacking. Emissions of moderate to low solubility gases (e.g., CO2, CH4, He) may be one of the primary near-surface signals from these systems. Detection of anomalous gas emissions related to hidden geothermal systems may therefore be an important tool to discover new geothermal resources. This study investigates the potential for CO2 detection and monitoring in the subsurface and above ground in the near-surface environment to serve as a tool to discover hidden geothermal systems. We focus the investigation on CO2 due to (1) its abundance in geothermal systems, (2) its moderate solubility in water, and (3) the wide range of technologies available to monitor CO2 in the near-surface environment. However, monitoring in the near-surface environment for CO2 derived from hidden geothermal reservoirs is complicated by the large variation in CO2 fluxes and concentrations arising from natural biological and hydrologic processes. In the near-surface environment, the flow and transport of CO2 at high concentrations will be controlled by its high density, low viscosity, and high solubility in water relative to air. Numerical simulations of CO2 migration show that CO2 concentrations can reach very high levels in the shallow subsurface even for relatively low geothermal source CO2 fluxes. However, once CO2 seeps out of the ground into the atmospheric surface layer, surface winds are effective at dispersing CO2 seepage. In natural ecological systems in the absence of geothermal gas emissions, near-surface CO2 fluxes and concentrations are primarily controlled by CO2 uptake by photosynthesis, production by root respiration, and microbial decomposition of soil/subsoil organic matter, groundwater degassing, and exchange with the atmosphere. Available technologies for monitoring CO2 in the near-surface environment include (1) the infrared gas analyzer (IRGA) for measurement of concentrations at point locations, (2) the accumulation chamber (AC) method for measuring soil CO2 fluxes at point locations, (3) the eddy covariance (EC) method for measuring net CO2 flux over a given area, (4) hyperspectral imaging of vegetative stress resulting from elevated CO2 concentrations, and (5) light detection and ranging (LIDAR) that can measure CO2 concentrations over an integrated path. Technologies currently in developmental stages that have the potential to be used for CO2 monitoring include tunable lasers for long distance integrated concentration measurements and micro-electronic mechanical systems (MEMS) that can make widespread point measurements. To address the challenge of detecting potentially small-magnitude geothermal CO2 emissions within the natural background variability of CO2, we propose an approach that integrates available detection and monitoring methodologies with statistical analysis and modeling strategies. Within the area targeted for geothermal exploration, point measurements of soil CO2 fluxes and concentrations using the AC method and a portable IRGA, respectively, and measurements of net surface flux using EC should be made. Also, the natural spatial and temporal variability of surface CO2 fluxes and subsurface CO2 concentrations should be quantified within a background area with similar geologic, climatic, and ecosystem characteristics to the area targeted for geothermal exploration. Statistical analyses of data collected from both areas should be used to guide sampling strategy, discern spatial patterns that may be indicative of geothermal CO2 emissions, and assess the presence (or absence) of geothermal CO2 within the natural background variability with a desired confidence level. Once measured CO2 concentrations and fluxes have been determined to be of anomalous geothermal origin with high confidence, more expensive vertical subsurface gas sampling and chemical and isotopic analyses can be undertaken. Integrated analysis of all measurements will d

Lewicki, Jennifer L.; Oldenburg, Curtis M.

2004-12-15

306

Design and development of a novel nuclear magnetic resonance detection for the gas phase ions by magnetic resonance acceleration technique  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) technique is a well-established powerful tool to study the physical and chemical properties of a wide range of materials. However, presently, NMR applications are essentially limited to materials in the condensed phase. Although magnetic resonance was originally demonstrated in gas phase molecular beam experiments, no application to gas phase molecular ions has yet been demonstrated. Here, we present a novel principle of NMR detection for gas phase ions based on a ``magnetic resonance acceleration'' technique and describe the design and construction of an apparatus which we are developing. We also present an experimental technique and some results on the formation and manipulation of cold ion packets in a strong magnetic field, which are the key innovations to detect NMR signal using the present method. We expect this novel method to lead new realm for the study of mass-selected gas-phase ions with interesting applications in both fundamental and applied sciences.

Fuke, K.; Tona, M.; Fujihara, A.; Sakurai, M.; Ishikawa, H.

2012-08-01

307

A COST EFFECTIVE MULTI-SPECTRAL SCANNER FOR NATURAL GAS DETECTION  

SciTech Connect

The objective of this project is to design, fabricate and field demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first six months of the project, the design for a laboratory version of the multispectral scanner was completed. The optical, mechanical, and electronic design for the scanner was completed. The optical design was analyzed using Zeemax Optical Design software and found to provide sufficiently resolved performance for the scanner. The electronic design was evaluated using a bread board and very high signal to noise ratios were obtained. Fabrication of a laboratory version of the multi-spectral scanner is currently in progress. A technology status report and a research management plan was also completed during the same period.

Yudaya Sivathanu; Jongmook Lim; Vinoo Narayanan

2004-04-01

308

Detection of exhaled hydrogen sulphide gas in rats exposed to intravenous sodium sulphide  

PubMed Central

Background and purpose: Sodium sulphide (Na2S) disassociates to sodium (Na+) hydrosulphide, anion (HS?) and hydrogen sulphide (H2S) in aqueous solutions. Here we have established and characterized a method to detect H2S gas in the exhaled breath of rats. Experimental approach: Male rats were anaesthetized with ketamine and xylazine, instrumented with intravenous (i.v.) jugular vein catheters, and a tube inserted into the trachea was connected to a pneumotach connected to a H2S gas detector. Sodium sulphide, cysteine or the natural polysulphide compound diallyl disulphide were infused intravenously while the airway was monitored for exhaled H2S real time. Key results: Exhaled sulphide concentration was calculated to be in the range of 0.4–11 ppm in response to i.v. infusion rates ranging between 0.3 and 1.1 mg·kg?1·min?1. When nitric oxide synthesis was inhibited with N?-nitro-L-arginine methyl ester the amount of H2S exhaled during i.v. infusions of sodium sulphide was significantly increased compared with that obtained with the vehicle control. An increase in circulating nitric oxide using DETA NONOate [3,3-bis(aminoethyl)-1-hydroxy-2-oxo-1-triazene] did not alter the levels of exhaled H2S during an i.v. infusion of sodium sulphide. An i.v. bolus of L-cysteine, 1 g·kg?1, and an i.v. infusion of the garlic derived natural compound diallyl disulphide, 1.8 mg·kg?1·min?1, also caused exhalation of H2S gas. Conclusions and implications: This method has shown that significant amounts of H2S are exhaled in rats during sodium sulphide infusions, and the amount exhaled can be modulated by various pharmacological interventions.

Insko, Michael A; Deckwerth, Thomas L; Hill, Paul; Toombs, Christopher F; Szabo, Csaba

2009-01-01

309

Determination of levamisole in plasma and animal tissues by gas chromatography with thermionic specific detection.  

PubMed

A rapid and sensitive method has been developed for the determination of the anthelmintic levamisole in plasma and tissues from man and animals. The procedure involves the extraction of the drug and its internal standard from the biological material at alkaline pH, back-extraction into sulphuric acid and re-extraction into the organic phase (heptane-isoamyl alcohol). Several extraction steps can be omitted, however, whenever the gas chromatographic background permits and some operations can be simplified using Clin ElutTM extraction tubes. The analyses were carried out by gas chromatography using a nitrogen-selective thermionic specific detector. The detection limit was 5 ng, contained in 1 ml of plasma or in 1 g of the various tissues, and recoveries were sufficiently high (79-86%). The method was applied to human plasma samples in a comprehensive bioavailability study of levamisole in healthy volunteers, and to plasma and tissues in a residue trial in cattle. The effect of the blood collection technique on the plasma levels was also studied and pointed to decreased plasma concentrations when Vacutainer tubes were used. PMID:7263817

Woestenborghs, R; Michielsen, L; Heykants, J

1981-06-12

310

Energy Resolution and Counting Properties of Micro-Strip Gas Counter for X-Ray Detecting  

NASA Astrophysics Data System (ADS)

A two-dimensional micro-strip Gas Chamber (MSGC) with a 20 × 20 mm2 detection area had been developed. The MSGC had a thin diamond film of 10 ?m deposited on a silicon wafer as substrate and lots of micro-strip anode and cathode electrodes made by multi-chip module technology. Energy resolution and pulse signal under 5.9 keV 55Fe X-rays were measured by a multi-channel energy spectrometer with different voltage under room temperature in atmospheric pressure. Results indicated high signal-to-noise ratio, count rate ?103 Hz and stable gas gain of the MSGC were obtained. When Ar:CH4=90:10, drift voltage, cathode voltage and anode voltage was -1000 V, -650 V and 0 V, respectively. However, the energy resolution of 12.3% for 5.9 keV 55Fe X-rays was achieved. The effects of cathode voltage and drift voltage on energy resolution and count rate were also obtained.

Su, Qingfeng; Xia, Yiben; Wang, Linjun; Yang, Ying; Shi, Weimin

311

Microstrip gas chamber with individual read-out using two-level discriminators for neutron detection  

NASA Astrophysics Data System (ADS)

The microstrip gas chamber (MSGC) with an individual read-out and using two-level discriminators for each strip is proposed for neutron detection with a high spatial resolution. The system identifies secondary particles-protons and tritons-created in the nuclear reaction 3He+n-->p+T based on the difference in their track lengths, and determines the incident position of neutrons using suprathreshold signals from tritons. The new system selects the appropriate suprathreshold signals for proper identification from two-level discriminators according to the emission angles of the secondary particles. The calculated spatial resolution of the detector system using the two-level discriminators (Hi-InSPaD) was 0.5mm in full width at half maximum when the MSGC was operated in a gas condition of a mixture of 20% argon with helium-3 at 0.5MPa, when the strip pitches were 0.4mm in both x and y axes. The calculated spatial response of the detector to the point-incident neutrons was superior to a standard InSPaD system that uses one level of threshold discrimination, in terms of the peak counts (about twofold higher) and the peak shape and width.

Yamagishi, H.; Nakamura, T.; Masaoka, S.; Soyama, K.; Aizawa, K.

2004-08-01

312

Chemical warfare agent detection in complex environments with comprehensive two-dimensional gas chromatography  

NASA Astrophysics Data System (ADS)

Comprehensive two-dimensional gas chromatography (GCxGC) is an emerging technology for chemical separation that provides an order-of-magnitude increase in separation capacity over traditional gas chromatography. GCxGC separates chemical species with two capillary columns interfaced by two-stage thermal desorption. Because GCxGC is comprehensive and has high separation capacity, it can perform multiple traditional analytical methods with a single analysis. GCxGC has great potential for a wide variety of environmental sensing applications, including detection of chemical warfare agents (CWA) and other harmful chemicals. This paper demonstrates separation of nerve agents sarin and soman from a matrix of gasoline and diesel fuel. Using a combination of an initial column separating on the basis of boiling point and a second column separating on the basis of polarity, GCxGC clearly separates the nerve agents from the thousands of other chemicals in the sample. The GCxGC data is visualized, processed, and analyzed as a two-dimensional digital image using a software system for GCxGC image processing developed at the University of Nebraska - Lincoln.

Reichenbach, Stephen E.; Ni, Mingtian; Kottapalli, Visweswara; Visvanathan, Arvind; Ledford, Edward B., Jr.; Oostdijk, John; Trap, Henk C.

2003-08-01

313

Long-wave infrared imaging of vegetation for detecting leaking CO2 gas  

NASA Astrophysics Data System (ADS)

The commercial development of uncooled-microbolometer, long-wave infrared (LWIR) imagers, combined with advanced radiometric calibration methods developed at Montana State University, has led to new uses of thermal imagery in remote sensing applications. One specific novel use of these calibrated imagers is imaging of vegetation for CO2 gas leak detection. During a four-week period in the summer of 2011, a CO2 leak was simulated in a test field run by the Zero Emissions Research and Technology Center in Bozeman, Montana. An LWIR imager was deployed on a scaffold before and during the CO2 release, viewing a vegetation test area that included regions of high and low CO2 flux. Increased root-level CO2 concentration caused plant stress that led to reduced thermal regulation of the vegetation, which was consistent with increased diurnal variation of IR emission observed in this study. In a linear regression, the IR data were found to have a strong relationship to the CO2 emission and to be consistent with the location of leaking CO2 gas. Reducing the continuous data set to one image per day weakened the regression fit, but maintained sufficient significance to indicate that this method could be implemented with once-daily airborne images.

Johnson, Jennifer E.; Shaw, Joseph A.; Lawrence, Rick; Nugent, Paul W.; Dobeck, Laura M.; Spangler, Lee H.

2012-01-01

314

Detecting Gas Outflows in Type-2 AGNs Selected from the Sloan Digital Sky Survey  

NASA Astrophysics Data System (ADS)

Energetic outflow from active galactic nuclei (AGNs) may play a critical role in galaxy evolution (e.g., Silk & Rees 1998). We present a velocity diagnostic for detecting gas outflow in the narrow-line region of Type-2 AGNs using line-of-sight velocity offsets of the [O iii] ?5007 and H? emission lines with respect to the systemic velocity of stars in host galaxies (See Figure 1). We apply the diagnostics to nearby galaxies at 0.02 < z < 0.05, 3775 AGN-host and 907 star-forming galaxies as a comparison sample, which are selected from the Sloan Digital Sky Survey DR7. After obtaining a best-fit stellar population model for the continuum and a systemic velocity based on stellar lines, we subtract the stellar component to measure velocity offsets of each emission line. We find a sample of 169 AGN-host galaxies with outflow signatures, displaying a larger velocity shift of [O iii] than that of H?, as expected in a decelerating outflow model (Komossa et al. 2008). We find that the offset velocity of [O iii] increases with Eddington ratio, suggesting that gas outflow depends on the energetics of AGN.

Bae, Hyun-Jin; Woo, Jong-Hak; Oh, Semyeong

2013-03-01

315

Deep gas in the Barbados accretionary prism: Sources, migration, detection: Final report  

SciTech Connect

The project objectives are: (1) to detect the existence on Barbados of gas derived from underthrust or underplated sediments at the prism base (now at 20 to 25 km in depth); (2) to understand the conditions and processes of organic maturation within and below the accretionary prism and the evolution of migration plants and reservoirs for gas within this progressively deforming mass; (3) to consider further strategies and methodologies by which gases generated at deep and shallow depths may be discriminated; (4) to study processes of accretion and structure generated in an active intra-oceanic subduction zone (Lesser Antilles) with large influx of terrigenous sediments; and (5) to provide a modern analog for the structural and hydrocarbon evolution of ancient Cordilleran accretionary complexes that incorporate an abundance of terrigenous sediment. Contents of this report include: forearcs and hydrocarbons; forearcs in global context, Lesser Antilles forearc; geologic evolution of Barbados; organic and hydrocarbon contents; thermal; deformation and structures; fluid emission; applications to ancient US prisms; and conclusions.

Speed, R.C.

1987-06-01

316

Determination of sulfur dioxide in wine using headspace gas chromatography and electron capture detection.  

PubMed

Sulfites are routinely added as preservatives and antioxidants in wine production. By law, the total sulfur dioxide content in wine is restricted and therefore must be monitored. Currently, the method of choice for determining the total content of sulfur dioxide in wine is the optimised Monier-Williams method, which is time consuming and laborious. The headspace gas chromatographic method described in this study offers a fast and reliable alternative method for the detection and quantification of the sulfur dioxide content in wine. The analysis was performed using an automatic headspace injection sampler, coupled with a gas chromatograph and an electron capture detector. The method is based on the formation of gaseous sulfur dioxide subsequent to acidification and heating of the sample. In addition to free sulfur dioxide, reversibly bound sulfur dioxide in carbonyl compounds, such as acetaldehyde, was also measured with this method. A total of 20 wine samples produced using diverse grape varieties and vintages of varied provenance were analysed using the new method. For reference and comparison purposes, 10 of the results obtained by the proposed method were compared with those acquired by the optimised Monier-Williams method. Overall, the results from the headspace analysis showed good correlation (R = 0.9985) when compared with the conventional method. This new method requires minimal sample preparation and is simple to perform, and the analysis can also be completed within a short period of time. PMID:23176364

Aberl, A; Coelhan, M

2012-11-23

317

Detection of Dense Molecular Gas in Interarm Spurs in M51  

NASA Astrophysics Data System (ADS)

Spiral arm spurs are prominent features that have been observed in extinction and 8 ?m emission in nearby galaxies. In order to understand their molecular gas properties, we used the Owens Valley Radio Observatory (OVRO) to map the CO(1-0) emission in three spurs emanating from the inner northwestern spiral arm of M51. We report CO detections from all three spurs. The molecular gas mass and surface density are MH2~3×106 Msolar and ?H2~50 Msolar pc-2. Thus, relative to the spiral arms, the spurs are extremely weak features. However, since the spurs are extended perpendicular to the spiral arms for ~500 pc and contain adequate fuel for star formation, they may be the birthplace for observed interarm H II regions. This reduces the requirement for the significant time delay that would be otherwise needed if the interarm star formation was initiated in the spiral arms. Larger maps of galaxies at similar depth are required to further understand the formation and evolution of these spurs and their role in star formation-such data should be forthcoming with the new Combined Array for Research in Millimeter Astronomy (CARMA) and future Atacama Large Millimeter/submillimeter Array (ALMA) telescopes, and can be compared to several recent numerical simulations that have been examining the evolution of spiral arm spurs.

Corder, Stuartt; Sheth, Kartik; Scoville, Nicholas Z.; Koda, Jin; Vogel, Stuart N.; Ostriker, Eve

2008-12-01

318

Detection of abundant molecular gas in the UV-excess quasar Markarian 1014  

SciTech Connect

CO(1-0) emission has been detected from the UV-excess quasar Mrk 1014 ( = PG 0157+001 = IRAS 01572+0009) at z = 0.163. Assuming the same empirical relationship between CO brightness and H2 surface mass density as has been found for giant molecular clouds in the Milky Way, the mass of H2 gas is about 4 x 10 to the 10th solar masses more than 10 times the H2 content of the Galaxy. The infrared and molecular gas properties of Mrk 1014 are similar to other warm, ultraluminous infrared galaxies such as Mrk 231, and IRAS 15206+3342 (z = 0.125) from which CO(1-0) emission is also reported. The trigger for the intense infrared activity in both Mrk 1014 and IRAS 15206+3342 appears to be a recent galaxy merger. It is suggested that objects such as these represent an important link in the evolution of ultraluminous infrared galaxies into UV-excess quasars. 37 references.

Sanders, D.B.; Scoville, N.Z.; Soifer, B.T.

1988-12-01

319

Detection of abundant molecular gas in the UV-excess quasar Mrk 1014  

SciTech Connect

Carbon dioxide (1 yields 0) emission has been detected from the UV-excess quasar Mrk 1014 (=PG 0157+001=IRAS 01572+0009) at z=0.163. Assuming the same empirical relationship between CO brightness and H2 surface mass density as has been found for giant molecular clouds in the Milky Way, the mass of H2 gas is approximately 4 x 10 to the 10th solar masses, i.e., more than ten times the H2 content of our Galaxy. The infrared and molecular gas properties of Mrk 1014 are similar to other warm, ultraluminous infrared galaxies such as Mrk 231, and IRAS 15206+3342 (z=0.125) from which CO(1 yields 0) emission is also reported. The trigger for the intense infrared activity in both Mrk 1014 and IRAS 15206+3342 appears to be a recent galaxy merger. It is suggested that objects such as these represent an important link in the evolution of ultraluminous infrared galaxies into UV-excess quasars.

Sanders, D.B.; Scoville, N.Z.; Soifer, B.T.

1988-01-01

320

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

NASA Astrophysics Data System (ADS)

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

Dobi, Attila

2011-04-01

321

Oxygen gas concentration-detecting apparatus and air-fuel ratio-controlling apparatus using same in internal combustion engine  

SciTech Connect

An oxygen concentration-detecting apparatus is described comprising a ceramic substrate for generating an electromotive force between a first surface contacted with a reference gas and a second surface contacted with a gas to be detected according to the ratio of the concentration of oxygen gas O/sub 2/ between the two gases, a pair of electrode members formed at parts of the first and second surfaces, respectively, of the ceramic substrate, to take out the electromotive force as a detection signal, an oxidation catalyst layer arranged to cover the outer surface of the ceramic substrate and promote oxidation reaction of unburnt components, and a reduction catalyst layer arranged to cover an outer surface of the ceramic substrate and promote mainly reduction reaction of nitrogen oxides NO/sub x/.

Uchikawa, A.; Anbe, S.; Suwa, T.; Kawashima, M.; Yamada, T.

1988-09-27

322

Development of a Magnetic Coating for Gas Pipe Detection. Final Report May 1987-June 1988,  

National Technical Information Service (NTIS)

The inability to accurately locate plastic gas pipe after it is buried has been a troublesome problem since plastic pipe began being used for natural gas distribution. Electromagnetic pipe locaters have been available to the gas industry for decades. Howe...

W. L. Goodman

1989-01-01

323

Detection of liquid petroleum gas using mixed nanosized tungsten oxide-based thick-film semiconductor sensor  

Microsoft Academic Search

The thick-film semiconductor sensor for liquid petroleum gas (LPG) detection was fabricated using a mixed WO3-based sensor. We present the characterization of both their structural properties by means of XRD measurements and the electrical characteristics by using gas-sensing properties. The sensing characteristics such as sensitivity, working range, cross-sensitivity and response time were studied by using nanosized WO3-based mixed with different

G. N. Chaudhari; A. M. Bende; A. B. Bodade; S. S. Patil; S. V. Manorama

2006-01-01

324

Detection of human butyrylcholinesterase-nerve gas adducts by liquid chromatography–mass spectrometric analysis after in gel chymotryptic digestion  

Microsoft Academic Search

To verify the exposure to nerve gas, a method for detecting human butyrylcholinesterase (BuChE)-nerve gas adduct was developed using LC–electrospray mass spectrometry (ESI-MS). Purified human serum BuChE was incubated with sarin, soman or VX, and the adduct was purified by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and digested in gel by treatment with chymotrypsin. The resulting peptide mixture was subjected

Kouichiro Tsuge; Yasuo Seto

2006-01-01

325

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, EXPLOSIVES DETECTION TECHNOLOGY, SRI INSTRUMENTS, MODEL 8610C, GAS CHROMATOGRAPH/THERMIONIC IONIZATION DETECTION  

EPA Science Inventory

The SRI Model 86 1 OC gas chromatograph (GC) is a transportable instrument that can provide on-site analysis of soils for explosives. Coupling this transportable gas chromatograph with a thermionic ionization detector (TID) allows for the determination of explosives in soil matri...

326

Long-wave infrared imaging of vegetation for detecting leaking CO2 gas  

NASA Astrophysics Data System (ADS)

The commercial development of microbolometer uncooled long-wave thermal infrared imagers in conjuncture with advanced radiometric calibration methods developed at Montana State University has led to new uses of thermal imagery in remote sensing applications. A novel use of these calibrated imagers is imaging of vegetation for CO2 gas leak detection. During a four-week period in the summer of 2011, a CO2 leak was simulated in a test field run by the Zero Emissions Research and Technology Center in Bozeman, Montana. Thermal infrared images were acquired, along with visible and near-infrared reflectance images, of the exposed vegetation and healthy control vegetation. The increased root-level CO2 concentration causes plant stress that results in reduced thermal regulation of the vegetation, which is detectable as an increased diurnal variation of infrared emission. . In a linear regression, the infrared data were found to have a strong coefficient of determination and clearly show the effect of the CO2 on the vegetation.

Johnson, Jennifer E.; Shaw, Joseph A.; Lawrence, Rick L.; Nugent, Paul W.; Dobeck, Laura M.; Spangler, Lee H.

2012-10-01

327

Towards smaller and faster gas chromatography-mass spectrometry systems for field chemical detection.  

PubMed

Gas chromatography-mass spectrometry (GC-MS) is already an important laboratory method, but new sampling techniques and column heating approaches will expand and improve its usefulness for detection and identification of unknown chemicals in field settings. In order to demonstrate commercially-available technical advances for both sampling and column heating, we used solid phase microextraction (SPME) sampling of both water and air systems, followed by immediate analysis with a resistively heated analytical column and mass spectrometric detection. High-concern compounds ranging from 140 to 466 amu were analyzed to show the applicability of these techniques to emergency situations impacting public health. A field portable (about 35 kg) GC-MS system was used for analysis of water samples with a resistively heated analytical column externally mounted as a retrofit using the air bath oven of the original instrument design to heat transfer lines. The system used to analyze air samples included a laboratory mass spectrometer with a dedicated resistive column heating arrangement (no legacy air bath column oven). The combined sampling and analysis time was less than 10 min for both air and water sample types. By combining dedicated resistive column heating with smaller mass spectrometry systems designed specificallyfor use in the field, substantially smaller high performance field-portable instrumentation will be possible. PMID:15844534

Smith, P A; Sng, M T; Eckenrode, B A; Leow, S Y; Koch, D; Erickson, R P; Jackson Lepage, C R; Hook, G L

2005-03-01

328

Nonlinear Bayesian Algorithms for Gas Plume Detection and Estimation from Hyper-spectral Thermal Image Data  

PubMed Central

This paper presents a nonlinear Bayesian regression algorithm for detecting and estimating gas plume content from hyper-spectral data. Remote sensing data, by its very nature, is collected under less controlled conditions than laboratory data. As a result, the physics-based model that is used to describe the relationship between the observed remote-sensing spectra, and the terrestrial (or atmospheric) parameters that are estimated is typically littered with many unknown “nuisance” parameters. Bayesian methods are well-suited for this context as they automatically incorporate the uncertainties associated with all nuisance parameters into the error estimates of the parameters of interest. The nonlinear Bayesian regression methodology is illustrated on simulated data from a three-layer model for longwave infrared (LWIR) measurements from a passive instrument. The generated LWIR scenes contain plumes of varying intensities, and this allows estimation uncertainty and probability of detection to be quantified. The results show that this approach should permit more accurate estimation as well as a more reasonable description of estimate uncertainty. Specifically, the methodology produces a standard error that is more realistic than that produced by matched filter estimation.

Heasler, Patrick; Posse, Christian; Hylden, Jeff; Anderson, Kevin

2007-01-01

329

Determination of eight synthetic pyrethroids in bovine fat by gas chromatography with electron capture detection.  

PubMed

Synthetic pyrethroids are among the most widely used classes of insecticides, and their uses are varied, including plant protection, animal dips, and as a treatment for human clothing and bedding in very hot climates. Veterinary applications include ear tags, pour-on formulations, sprays, and dips. Persistent residues have been reported in livestock, and routine monitoring programs in other countries have found detectable residues of various pyrethroids in fat. A method has been developed using solid-phase extraction that reduces the quantities of solvents used, the time required, and the amount of glassware used compared to an earlier method on which it was based. The scope of analytes tested included the 5 compounds cited in the earlier method (flucythrinate, permethrin, cypermethrin, fenvalerate, and deltamethrin) and, in addition, cyfluthrin, lambda-cyhalothrin, and fluvalinate. Sample extracts were analyzed by gas chromatography with electron capture detection using selected chromatographic peaks characteristic of each compound. Limits of quantification for the compounds were from 25-50 microg/kg, with a linear response for all compounds to 200 microg/kg. Recoveries ranged from 80 to 123%. PMID:17042195

Akre, Christine J; MacNeil, James D

330

Microphotonic sensors for the rapid detection of the presence of explosive gas mixtures  

NASA Astrophysics Data System (ADS)

A first generation, microphotonic sensor for rapid (10 ms response time) measurement of vapors from the hydrocarbon-based fuels JP-8, DF-2, and gasoline has been developed at the U.S. Army Research Laboratory. This sensor is based upon a previously reported laser mixing technique that uses two tunable diode lasers emitting in the near-infrared spectral region to measure concentrations of gases having unstructured absorption spectra. The fiber-mixed laser beam consists of two wavelengths, one of which is absorbed by the fuel vapor, and one of which is not absorbed. By sinusoidally modulating the power of the two lasers at the same frequency but 180 degrees out of phase, a sinusoidal signal is generated at the detector (when the target gas is present in the line of sight). The signal amplitude, measured using standard phase sensitive detection techniques, is proportional to fuel vapor concentration. A second generation sensor, designed to measure the full envelope of the first overtone C-H vibrations in middle distillate fuels is currently being developed. Both sensors are described. Limits of detection using the first generation sensor are reported for vapors of the three fuels studied.

McNesby, Kevin L.; Miziolek, Andrzej W.

2002-02-01

331

[Determination and distribution of sulfur compounds in coked gasoline by gas chromatography-sulfur chemiluminescence detection].  

PubMed

The method for the separation and determination of sulfur compounds in coked gasoline by gas chromatography-sulfur chemiluminescence detection (GC-SCD) was established. Seventy-four sulfur compounds including hydrogen sulfide, mercaptans, sulfides, disulfides, thiophene, alkyl thiophenes, benzothiophene, alkyl benzothiophenes in a coked gasoline sample were identified by standard samples and past identified results. The retention indexes of different sulfur compounds in coked gasoline under programmed temperature condition were calculated based on the retention times of hydrosulfide, ethyl mercaptan, n-propyl mercaptan, thiophene, 2-methyl thiophene, 2-ethylthiophene, 2-propylthiophene, C4-thiophene (t(R) = 40.28 min), benzothiophene, and methylbenzothiophene (t(R) = 58.13 min). The relative standard deviations of the determination results of main sulfur compounds (isopropyl mercaptan, n-propyl mercaptan, n-butyl mercaptan, 2-methylthiophene, 3-methylthiophene, 2, 4-dimethylthiophene, 2,3,4-trimethylthiophene) in coked gasoline were less than 5%, and the detection limit for sulfur was 0.05 mg/L. The linear range of sulfur was 0.2 - 400 mg/L for each sulfur compounds (r2 = 0. 999). The contents of sulfur compounds, especially the content of mercaptan, are much more than those in the catalytic gasoline. There is also a big difference in the sulfur contents between 2-methylthiophene and 3-methylthiophene. The data can be useful for the study of hydrodesulfurizing catalyst and industrial process planning. PMID:17679435

Yang, Yongtan; Wang, Zheng

2007-05-01

332

The gas-liquid chromatograph and the electron capture detection in equine drug testing.  

PubMed Central

Three gas-liquid chromatographic (G.L.C.) procedures discussed have been designed around the four "esses" of detection tests--speed, sensitivity, simplicity, and specificity. These techniques are admirably applicable to the very low plasma drug levels encountered in blood testing under pre-race conditions. The methods are equally applicable to post-race testing procedures, where both blood and urine samples are tested. Drugs can only rarely be detected by the electron capture detector (E.C.D.) without a prior derivatization step, which conveys to the drug(s) high electron affinity. Because of broad applicability, two derivatizing agents, heptafluorobutyric (HFBA) and pentafluorpropionic (PFPA) anhydrides are employed. The three techniques, allowing broad coverage of various drug classes are: 1) direct derivatization of drugs to form strongly electron capturing amides and esters. 2) reductive fragmentation of drugs with lithium aluminum hydride to form alcohols, with conversion to ester derivatives. 3) oxidative fragmentation of drugs with potassium dichromate to form derivatizable groups, followed by direct derivatization.

Blake, J. W.; Tobin, T.

1976-01-01

333

Lung cancer detection by proton transfer reaction mass-spectrometric analysis of human breath gas  

NASA Astrophysics Data System (ADS)

Background Determination of the diagnostic usefulness of proton transfer reaction mass spectrometry (PTR-MS) for detecting primary lung cancer through analysis of volatile organic compounds (VOCs) in exhaled human breath was demonstrated in this investigation. Unlike, for example, gas-chromatographic analyses, PTR-MS can be used without time-consuming preconcentration of the gas samples.Methods By means of PTR-MS, exhaled breath samples from primary lung cancer patients (n = 17) were analyzed and compared with both an overall control collective (controls total, n = 170) and three sub-collectives: hospital personnel (controls hospital, n = 35), age-matched persons (controls age, n = 25), and smokers (controls s, n = 60), respectively.Results Among the VOCs present at reasonably high concentrations, the ones leading to the product ion at m/z = 31 (VOC-31, tentatively protonated formaldehyde) and m/z = 43 (VOC-43, tentatively a fragment of protonated iso-propanol), were found at significantly higher concentrations in the breath gas of the primary lung cancer patients as compared to the healthy controls at the following median concentrations (with interquartile distance, iqr): For VOC-31 the median concentrations were 7.0 ppb (iqr, 15.5 ppb) versus 3.0 ppb (iqr, 1.9 ppb) with P < 10-4. For VOC-43 the median concentrations were 244.1 ppb (iqr, 236.2 ppb) versus 94.1 ppb (iqr, 55.2 ppb) with P < 10-6. The discriminative power between the two collectives was further assessed by ROC-curves obtained upon variation of the chosen threshold concentration and by Fisher's Quadratic Discriminant Method.Conclusions Within the limits of pilot study, VOC-31 and -43 were found to best discriminate between exhaled breath of primary lung cancer cases and healthy controls. Simple and time-saving breath gas analysis by PTR-MS makes this method attractive for a larger clinical evaluation. It may become a new valuable tool for diagnosing primary lung cancer.

Wehinger, Andreas; Schmid, Alex; Mechtcheriakov, Sergei; Ledochowski, Maximilian; Grabmer, Christoph; Gastl, Guenther A.; Amann, Anton

2007-08-01

334

Hydroacoustic detection and quantification of free gas -methane bubbles in the ocean  

Microsoft Academic Search

Extensive methane release as a free gas phase from cold vents is well known from deep (>2000m) and shallow (10s of meters) water depths. Supposedly, much more methane is transported into the water column by free gas than by dissolved gas, which is oxidized by anaerobic and aerobic processes and partly precipitated as carbonate. Rising gas bubbles are not affected

J. Greinert; Y. Artemov; P. Gimpel

2003-01-01

335

Derivation of New Emission Factors for Quantification of Mass Emissions When Using Optical Gas Imaging for Detecting Leaks  

Microsoft Academic Search

This paper describes the development of new “leak\\/no-leak” emission factors that are suitable for estimating facilities’ fugitive emissions when using an alternative work practice (AWP) that is based on optical gas imaging technology for detecting leaking piping system components. These emission factors were derived for valves, pumps, and connectors\\/flanges for instrument leak detection thresholds ranging from 3 to 60 g\\/hr

Miriam Lev-On; David Epperson; Jeffrey Siegell; Karin Ritter; Norman Robinson; Dana Trimble; Steven Kohl; John Watson; L.-W. Chen; M. C. Chang; Hsing-Wang Li; Yee-Lin Wu; Wen-Jhy Lee; Guo-Ping Chang-Chien; Joao Gomes; Joana Nascimento; Helena Rodrigues; David Schaad; James Halley; Vince Alaimo; Hal Taback; Yu Zhou; Lixin Fu; Linglin Cheng; Pao-Wen Liu; Daniel Brady; Gregory Pratt; Qingzhong Yuan; Kalliat Valsaraj; Danny Reible; Clinton Willson; Wipada Sanongraj; Yongsheng Chen; John Crittenden; Hugo Destaillats; David Hand; David Perram; Roy Taylor; Sangil Lee; Armistead Russell; Karsten Baumann

2007-01-01

336

Novel SnO 2-based gas sensors promoted with metal oxides for the detection of dichloromethane  

Microsoft Academic Search

A SnO2-based recoverable thick-film gas sensor was developed in this study for the detection of dichloromethane (DCM) of ppb level at 350°C. The response of the SnO2 sensor decreased gradually during multiple cycles of detection and recovery, while the response of the SnO2-based sensor, promoted simultaneously with Mo and Ni, was maintained during multiple cycles without deactivation. In particular, the

Soo Chool Lee; Ho Yun Choi; Soo Jae Lee; Woo Suk Lee; Jeung Soo Huh; Duk Dong Lee; Jae Chang Kim

2009-01-01

337

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Remote laser detection of natural gas leakages from pipelines  

Microsoft Academic Search

A differential absorption lidar based on a tunable TEA CO2 laser emitting at 42 lines of the 'hot' 0111 --- 1110 band in the range from 10.9 to 11.4 mum is developed for detecting natural gas leakages from oil pipelines by measuring the ethane content in the atmosphere. The ethane detection sensitivity is 0.9 ppm km. The presence of methane

V. O. Petukhov; V. A. Gorobets; Yu M. Andreev; G. V. Lanskii

2010-01-01

338

Remarks on detecting high-energy deuterium–tritium fusion gamma rays using a gas Cherenkov detector  

Microsoft Academic Search

As fusion ignition conditions are approached using the national ignition facility (NIF), independent high-bandwidth gamma-ray fusion burn measurements become essential complements to information obtained from neutron diagnostics. The 16.75-MeV gamma rays that accompany deuterium–tritium (d+t) fusion can be detected using a high-bandwidth gaseous carbon dioxide Cherenkov threshold detector. The detection energy threshold was set by the CO2 gas pressure. A

J. M. Mack; R. R. Berggren; S. E. Caldwell; C. R. Christensen; S. C. Evans; J. R. Faulkner Jr.; R. L. Griffith; G. M. Hale; R. S. King; D. K. Lash; R. A. Lerche; J. A. Oertel; D. M. Pacheco; C. S. Young

2006-01-01

339

Comparison of Detection Capability for Acoustic Thermography, Visual Inspection and Fluorescent Penetrant Inspection on Gas Turbine Components  

NASA Astrophysics Data System (ADS)

The innovative NDE inspection system Acoustic Thermography is developed with Sonic Infrared (Sonic IR) technology. Since the probability of detection is sensitive to the flaw characteristics, the fabricated flaws could not simulated the nature flaws with accuracy. The study is focus on gas turbine blades with service induced fatigue cracks. The detection capability of this innovative NDE inspection system is compared with two traditional NDE methods: Visual Inspection and Fluorescent Penetrant Inspection. POD curves for each technique were generated and compared.

Guo, Y.; Ruhge, F. R.

2009-03-01

340

Gas flow proportional detection system for the determination of boron in aerosol samples and other sample types  

Microsoft Academic Search

This work describes the design, fabrication, and testing of a lucite bodied proportional gas detection system for the analysis of boron in selected samples via detection of the charged particles produced in the ¹°B(n,..cap alpha..)⁷Li reaction induced by thermal neutrons. The detector was designed for internal placement of samples; the sample types of major interest were airborne aerosols collected on

Chabot

1985-01-01

341

A continuously tunable long-wavelength cw IR source for high-resolution spectroscopy and trace-gas detection  

Microsoft Academic Search

A new widely tuna¤le source in the infrared for use in high-resolution spectroscopy and trace-gas detection is described. This spectroscopic source is based on Difference Frequency Generation (DFG) in gallium selenide (GaSe) and is continuously tunable in the 8.8-15.0rwm wavelength region. Such a DFG source operates at room temperature which makes it a useful alternative to a lead-salt diode-laser-based detection

Wade C. Eckhoff; Roger S. Putnam; Shunxi Wang; Robert F. Curl; Frank K. Tittel

1996-01-01

342

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

DOEpatents

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

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

2010-08-24

343

Development of a Chemiluminescence Method for Gas-Phase HO2 Detection  

NASA Astrophysics Data System (ADS)

Hydroperoxyl Radical (HO2) is a highly reactive intermediate species that participates in photochemical processes in the troposphere. Accurate measurement of HO2 will facilitate the verification of the ozone production mechanism used by the atmospheric chemistry community. HO2 is also the major source of H2O2, which is responsible for the oxidation of SO2 in droplets. Here, we describe a new HO2 detection method based on flow injection analysis (FIA) with a chemiluminescence detector. Gas-phase HO2 is first scrubbed into a pH 9 borax buffer solution, then injected into a chemiluminescence detector, where HO2 and its conjugate base O2- react with MCLA, a synthetic analog of the luciferin from the crustacean Cypridina, to emit light at 465 nm. This technique shows high sensitivity (DL = 0.1 nM in liquid phase or 1 pptv in gas phase) and selectivity for the HO2 / O2- system. A unique feature of our technique is the calibration with a radiolytic method that uses a 60Co gamma ray source to quantitatively produce stable aqueous HO2 / O2- standards. This calibration method is highly reproducible, producing an instrument response that varies less than 5% from day to day. We tested our instrument in the meteorology field at Brookhaven National Laboratory (BNL), which is considered a clean remote rural site with background ozone levels about 30 ppbv. On July 17, 2003, a clear sunny day, with a steady NW wind, HO2 started to build up after sunrise and reached a maximum of 9 pptv at about 3 pm local time, approximately two hours after the maximum solar intensity. Our technique has the advantages of simplicity, low cost and ease of operation. It is especially suitable for field measurements, where space and energy resources are usually limited.

Zheng, J.; Lloyd, J.; Springston, S.

2003-12-01

344

Detection of DEMP vapors using SnO 2-based gas sensors: understanding of the chemical reactional mechanism  

Microsoft Academic Search

Tin dioxide-based gas sensors make it possible to detect diethyl methyl phosphonate vapors (DEMP). However, the responses present drifts that can be observed vs. time. Such a problem raises the question of the reliability of these devices. The results presented in this article are two-fold: first, they are concerned with the study of the thermal degradation of DEMP by thermal

F. Berger; E. Brunol; R. Planade; A. Chambaudet

2003-01-01

345

CAPILLARY GAS CHROMATOGRAPHY-ATOMIC EMISSION DETECTION METHOD FOR THE DETERMINATION OF PENTYLATED ORGANOTIN COMPOUNDS: INTERLABORATORY STUDY  

EPA Science Inventory

A capillary gas chromatography-atomic emission detection (GC-AED) method was developed for the U. S. Environmental Protection Agency's Environmental Monitoring Systems Laboratory in Las Vegas, NV, for determination of selected organotin compounds. Here we report on an interlabora...

346

Assessment of technology for detection of stress corrosion cracking in gas pipelines. Final report, July 1993March 1994  

Microsoft Academic Search

The objective of the project was to assess the nondestructive evaluation (NDE) technology that may be applied to natural gas steel pipelines for the detection of stress corrosion cracking (SCC). In particular, the application of such technology would be from the inside of the pipe while the pipeline is in service, and inspection commonly called in-line inspection (ILI). The assessment

A. E. Crouch; C. M. Teller; J. L. Fisher; G. M. Light; C. M. Fortunko

1994-01-01

347

Qualitative analysis of contaminated environmental extracts by multidimensional gas chromatography with infrared and mass spectral detection (MDGC-IR-MS)  

Microsoft Academic Search

The use of capillary gas chromatography in conjunction with spectral detection has been utilized for several years for both quantitative and qualitative analyses of environmental extracts. Unfortunately, in some extreme cases, Chromatographic peak overlap precludes the accurate identification of many of the components, and alternative separation strategies employing multidimensional techniques must be utilized to improve the qualitative information. This study

Kevin A. Krock; Charles L. Wilkins

1996-01-01

348

Fast gas chromatography with luminol chemiluminescence detection for the simultaneous determination of nitrogen dioxide and peroxyacetyl nitrate in the atmosphere  

Microsoft Academic Search

An instrument has been designed and constructed for the simultaneous determination of nitrogen dioxide (NO2) and peroxyacetyl nitrate (PAN) in atmospheric samples. The instrument's design is based on separation by fast gas chromatography (GC) with a 30 ft capillary column (DB-1) followed by detection by luminol chemiluminescence. The chemiluminescent reaction between NO2 or PAN and luminol takes place at the

Nancy A. Marley; Jeffrey S. Gaffney; Robert V. White; Luis Rodriguez-Cuadra; Scott E. Herndon; Ed Dunlea; Rainer M. Volkamer; Luisa T. Molina; Mario J. Molina

2004-01-01

349

The portable gas chromatograph OralChroma™: a method of choice to detect oral and extra-oral halitosis  

Microsoft Academic Search

It is now generally accepted that the volatile sulfur compounds (VSCs) hydrogen sulfide, methyl mercaptan and dimethyl sulfide are the main contributors to halitosis when of oropharyngeal origin. Gas chromatography using a specific sulfur detector is the most appropriate method to detect halitosis of different origin (intra-oral and extra-oral halitosis) and should be considered as the gold standard. However, a

A Tangerman; E G Winkel

2008-01-01

350

Potentialities of gaseous biomarkers detection against the main atmospheric components with gas analyzer based on CO2 laser  

NASA Astrophysics Data System (ADS)

Potentialities of detection of minor gases characterizing the biosystem-atmosphere gas exchange, such as C2H4, N2O, NH3, H2O2, using a gas-analyzer based on waveguide CO2 laser with discrete frequency tuning are studied numerically. The measured signal is recorded over the whole laser frequency scan for 9-?m or 10-?m transitions, i.e. for 25-30 generation lines. An effect of interference of the main gaseous atmospheric components H2O and CO2 on the minor gas detection limit and the uncertainty in the retrieved concentration is analyzed. Absorption coefficients of atmospheric gases at CO2 laser lines are calculated using the HITRAN-2004 spectral database and the CKD water vapor continuum model. Aerosol effect is not taken into account.

Nikiforova, O. Yu.; Ptashnik, I. V.

2006-11-01

351

Hydrogen analysis in metal samples by selective detection method utilizing TEA CO2 laser-induced He gas plasma  

NASA Astrophysics Data System (ADS)

When a Transversely Excited Atmospheric (TEA) CO2 laser (energy of 1.5 J, pulse duration of 200 ns) was focused on a metal sample surface containing hydrogen (H) in He gas at 1 atm, a strong helium gas plasma was produced and only H atoms came out of the sample. The H atoms then moved into the helium gas plasma to be excited through meta-stable helium atoms. Using this technique, an excellent linear calibration curve with zero intercept was made using zircalloy-2 samples containing H (100-600 ppm), where the compensation method was made using an emission intensity of O I 777.1 nm in order to subtract the H emission intensity coming from unwanted H2O. It should be emphasized that this technique has a possibility to realize highly sensitive analysis of H with a detection limit of less than 1 ppm because of its selective detection.

Lie, Zener Sukra; Khumaeni, Ali; Maruyama, Tadashi; Fukumoto, Ken-Ichi; Niki, Hideaki; Kagawa, Kiichiro

2010-11-01

352

Temperature-programmable resistively heated micromachined gas chromatography and differential mobility spectrometry detection for the determination of non-sulfur odorants in natural gas.  

PubMed

A portable, fast gas chromatographic method for the direct measurement of the parts per billion level of sulfur-free odorants in commercially available natural gas is introduced. The approach incorporates a resistively heated, temperature-programmable silicon micromachined gas chromatograph that employs a standard capillary column for the fast separation of methyl and ethyl acrylate from the natural gas matrix. The separation approach is coupled to a micromachined differential mobility detector to enhance analyte detectability, and the overall selectivity obtained against the matrix is described. A complete analysis can be conducted in less than 70 s. Furthermore, these two compounds can be measured accurately in the presence of other common volatile sulfur-based odorants such as alkyl mercaptans and alkyl sulfides. Repeatability of less than 3% RSD (n = 20) over a range from 0.5 to 5 ppm was obtained with a limit of detection for the target compounds at 50 ppb (v/v) and a linear range from 0.5 to 50 ppm with a correlation coefficient of at least 0.997. PMID:23427942

Luong, J; Gras, R; Cortes, H J; Shellie, R A

2013-03-07

353

Molecular gas in NUclei of GAlaxies (NUGA): VI. Detection of a molecular gas disk/torus via HCN in the Seyfert 2 galaxy NGC 6951?  

NASA Astrophysics Data System (ADS)

Context: Several studies of nearby active galaxies indicate significantly higher HCN-to-CO intensity ratios in AGN (e.g., NGC 1068) than in starburst (e.g., M 82) environments. HCN enhancement can be caused by many different effects, such as higher gas densities and/or temperatures, UV/X-ray radiation, and non-collisional excitation. As active galaxies often exhibit intense circumnuclear star formation, high angular resolution/high sensitivity observations are of paramount importance to disentangling the influence of star formation from that of nuclear activity on the chemistry of the surrounding molecular gas. The tight relation of HCN enhancement and nuclear activity may qualify HCN as an ideal tracer of molecular gas close to the AGN, providing complementary and additional information to that gained via CO. Aims: NGC 6951 houses nuclear and starburst activity, making it an ideal testbed in which to study the effects of different excitation conditions on the molecular gas. Previous lower angular resolution/sensitivity observations of HCN(1-0) carried out with the Nobeyama Millimeter array by Kohno et al. (1999a, ApJ, 511, 157) led to the detection of the starburst ring, but no central emission has been found. Our aim was to search for nuclear HCN emission and, if successful, for differences of the gas properties of the starburst ring and the nucleus. Methods: We used the new A, B, C and D configurations of the IRAM PdBI array to observe HCN(1-0) in NGC 6951 at high angular resolution (1'' ?96 pc) and sensitivity. Results: We detect very compact (?50 pc) HCN emission in the nucleus of NGC 6951, supporting previous hints of nuclear gas structure. Our observations also reveal HCN emission in the starburst ring and resolve it into several peaks, leading to a higher coincidence between the HCN and CO distributions than previously reported by Kohno et al. (1999a). Conclusions: We find a significantly higher HCN-to-CO intensity ratio (?0.4) in the nucleus than in the starburst ring (0.02-0.05). As for NGC 1068, this might result from a higher HCN abundance in the centre due to an X-ray dominated gas chemistry, but a higher gas density/temperature or additional non-collisional excitation of HCN cannot be entirely ruled out, based on these observations. The compact HCN emission is associated with rotating gas in a circumnuclear disk/torus. Based on observations carried out with the IRAM Plateau de Bure Interferometer (PdBI). IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

Krips, M.; Neri, R.; García-Burillo, S.; Combes, F.; Schinnerer, E.; Baker, A. J.; Eckart, A.; Boone, F.; Hunt, L.; Leon, S.; Tacconi, L. J.

2007-06-01

354

Selective Detection of Formaldehyde Gas Using a Cd-Doped TiO2-SnO2 Sensor  

PubMed Central

We report the microstructure and gas-sensing properties of a nonequilibrium TiO2-SnO2 solid solution prepared by the sol-gel method. In particular, we focus on the effect of Cd doping on the sensing behavior of the TiO2-SnO2 sensor. Of all volatile organic compound gases examined, the sensor with Cd doping exhibits exclusive selectivity as well as high sensitivity to formaldehyde, a main harmful indoor gas. The key gas-sensing quantities, maximum sensitivity, optimal working temperature, and response and recovery time, are found to meet the basic industrial needs. This makes the Cd-doped TiO2-SnO2 composite a promising sensor material for detecting the formaldehyde gas.

Zeng, Wen; Liu, Tianmo; Wang, Zhongchang; Tsukimoto, Susumu; Saito, Mitsuhiro; Ikuhara, Yuichi

2009-01-01

355

Detection of the abnormal events along the oil and gas pipeline and multi-scale chaotic character analysis of the detected signals  

Microsoft Academic Search

This paper studies the monitoring principle of abnormal events along oil and gas pipelines, which is conducted by a Mach–Zehnder optical fiber interferometer based distributed optical fiber pipeline pre-warning system. The detected signals of three typical abnormal events are analyzed by a multi-scale chaotic character analysis method based on orthogonal wavelet packet decomposition. In this pre-warning system, an optical cable

Zhigang Qu; Yan Zhou; Zhoumo Zeng; Hao Feng; Yu Zhang; Shijiu Jin

2008-01-01

356

Remote detection NMR imaging of gas phase hydrogenation in microfluidic chips.  

PubMed

The heterogeneous hydrogenation reaction of propene into propane in microreactors is studied by remote detection (RD) nuclear magnetic resonance (NMR). The reactors consist of 36 parallel microchannels (50 × 50 ?m(2) cross sections) coated with a platinum catalyst. We show that RD NMR is capable of monitoring reactions with sub-millimeter spatial resolution over a field-of-view of 30 × 8 mm(2) with a steady-state time-of-flight time resolution in the tens of milliseconds range. The method enables the visualization of active zones in the reactors, and time-of-flight is used to image the flow velocity variations inside the reactor. The overall reaction yields determined by NMR varied from 10% to 50%, depending on the flow rate, temperature and length of the reaction channels. The reaction yield was highest for the channels with the lowest flow velocity. Propane T1 relaxation time in the channels, estimated by means of RD NMR images, was 270 ± 18 ms. No parahydrogen-induced polarization (PHIP) was observed in experiments carried out using parahydrogen-enriched H2, indicating fast spreading of the hydrogen atoms on the sputtered Pt surface. In spite of the low concentration of gases, RD NMR made imaging of gas phase hydrogenation of propene in microreactors feasible, and it is a highly versatile method for characterizing on-chip chemical reactions. PMID:23435499

Zhivonitko, Vladimir V; Telkki, Ville-Veikko; Leppäniemi, Jarmo; Scotti, Gianmario; Franssila, Sami; Koptyug, Igor V

2013-04-21

357

Automated thermochemolysis reactor for detection of Bacillus anthracis endospores by gas chromatography-mass spectrometry.  

PubMed

An automated sample preparation system was developed and tested for the rapid detection of Bacillus anthracis endospores by gas chromatography-mass spectrometry (GC-MS) for eventual use in the field. This reactor is capable of automatically processing suspected bio-threat agents to release and derivatize unique chemical biomarkers by thermochemolysis (TCM). The system automatically controls the movement of sample vials from one position to another, crimping of septum caps onto the vials, precise delivery of reagents, and TCM reaction times and temperatures. The specific operations of introduction of sample vials, solid phase microextraction (SPME) sampling, injection into the GC-MS system, and ejection of used vials from the system were performed manually in this study, although they can be integrated into the automated system. Manual SPME sampling is performed by following visual and audible signal prompts for inserting the fiber into and retracting it from the sampling port. A rotating carousel design allows for simultaneous sample collection, reaction, biomarker extraction and analysis of sequential samples. Dipicolinic acid methyl ester (DPAME), 3-methyl-2-butenoic acid methyl ester (a fragment of anthrose) and two methylated sugars were used to compare the performance of the autoreactor with manual TCM. Statistical algorithms were used to construct reliable bacterial endospore signatures, and 24 out of 25 (96%) endospore-forming Bacillus species were correctly identified in a statistically designed test. PMID:23601976

Li, Dan; Rands, Anthony D; Losee, Scott C; Holt, Brian C; Williams, John R; Lammert, Stephen A; Robison, Richard A; Tolley, H Dennis; Lee, Milton L

2013-03-13

358

Nonlinear Bayesian Algorithms for Gas Plume Detection and Estimation from Hyper-spectral Thermal Image Data  

SciTech Connect

This paper presents a nonlinear Bayesian regression algorithm for the purpose of detecting and estimating gas plume content from hyper-spectral data. Remote sensing data, by its very nature, is collected under less controlled conditions than laboratory data. As a result, the physics-based model that is used to describe the relationship between the observed remotesensing spectra, and the terrestrial (or atmospheric) parameters that we desire to estimate, is typically littered with many unknown "nuisance" parameters (parameters that we are not interested in estimating, but also appear in the model). Bayesian methods are well-suited for this context as they automatically incorporate the uncertainties associated with all nuisance parameters into the error estimates of the parameters of interest. The nonlinear Bayesian regression methodology is illustrated on realistic simulated data from a three-layer model for longwave infrared (LWIR) measurements from a passive instrument. This shows that this approach should permit more accurate estimation as well as a more reasonable description of estimate uncertainty.

Heasler, Patrick G.; Posse, Christian; Hylden, Jeff L.; Anderson, Kevin K.

2007-06-13

359

High Sensitivity Gas Detection Using a Macroscopic Three-Dimensional Graphene Foam Network  

PubMed Central

Nanostructures are known to be exquisitely sensitive to the chemical environment and offer ultra-high sensitivity for gas-sensing. However, the fabrication and operation of devices that use individual nanostructures for sensing is complex, expensive and suffers from poor reliability due to contamination and large variability from sample-to-sample. By contrast, conventional solid-state and conducting-polymer sensors offer excellent reliability but suffer from reduced sensitivity at room-temperature. Here we report a macro graphene foam-like three-dimensional network which combines the best of both worlds. The walls of the foam are comprised of few-layer graphene sheets resulting in high sensitivity; we demonstrate parts-per-million level detection of NH3 and NO2 in air at room-temperature. Further, the foam is a mechanically robust and flexible macro-scale network that is easy to contact (without Lithography) and can rival the durability and affordability of traditional sensors. Moreover, Joule-heating expels chemisorbed molecules from the foam's surface leading to fully-reversible and low-power operation.

Yavari, Fazel; Chen, Zongping; Thomas, Abhay V.; Ren, Wencai; Cheng, Hui-Ming; Koratkar, Nikhil

2011-01-01

360

High sensitivity gas detection using a macroscopic three-dimensional graphene foam network.  

PubMed

Nanostructures are known to be exquisitely sensitive to the chemical environment and offer ultra-high sensitivity for gas-sensing. However, the fabrication and operation of devices that use individual nanostructures for sensing is complex, expensive and suffers from poor reliability due to contamination and large variability from sample-to-sample. By contrast, conventional solid-state and conducting-polymer sensors offer excellent reliability but suffer from reduced sensitivity at room-temperature. Here we report a macro graphene foam-like three-dimensional network which combines the best of both worlds. The walls of the foam are comprised of few-layer graphene sheets resulting in high sensitivity; we demonstrate parts-per-million level detection of NH(3) and NO(2) in air at room-temperature. Further, the foam is a mechanically robust and flexible macro-scale network that is easy to contact (without Lithography) and can rival the durability and affordability of traditional sensors. Moreover, Joule-heating expels chemisorbed molecules from the foam's surface leading to fully-reversible and low-power operation. PMID:22355681

Yavari, Fazel; Chen, Zongping; Thomas, Abhay V; Ren, Wencai; Cheng, Hui-Ming; Koratkar, Nikhil

2011-11-23

361

High Sensitivity Gas Detection Using a Macroscopic Three-Dimensional Graphene Foam Network  

NASA Astrophysics Data System (ADS)

Nanostructures are known to be exquisitely sensitive to the chemical environment and offer ultra-high sensitivity for gas-sensing. However, the fabrication and operation of devices that use individual nanostructures for sensing is complex, expensive and suffers from poor reliability due to contamination and large variability from sample-to-sample. By contrast, conventional solid-state and conducting-polymer sensors offer excellent reliability but suffer from reduced sensitivity at room-temperature. Here we report a macro graphene foam-like three-dimensional network which combines the best of both worlds. The walls of the foam are comprised of few-layer graphene sheets resulting in high sensitivity; we demonstrate parts-per-million level detection of NH3 and NO2 in air at room-temperature. Further, the foam is a mechanically robust and flexible macro-scale network that is easy to contact (without Lithography) and can rival the durability and affordability of traditional sensors. Moreover, Joule-heating expels chemisorbed molecules from the foam's surface leading to fully-reversible and low-power operation.

Yavari, Fazel; Chen, Zongping; Thomas, Abhay V.; Ren, Wencai; Cheng, Hui-Ming; Koratkar, Nikhil

2011-11-01

362

Naturally fractured tight gas reservoir detection optimization. Annual report, September 1993--September 1994  

SciTech Connect

This report is an annual summarization of an ongoing research in the field of modeling and detecting naturally fractured gas reservoirs. The current research is in the Piceance basin of Western Colorado. The aim is to use existing information to determine the most optimal zone or area of fracturing using a unique reaction-transport-mechanical (RTM) numerical basin model. The RTM model will then subsequently help map subsurface lateral and vertical fracture geometries. The base collection techniques include in-situ fracture data, remote sensing, aeromagnetics, 2-D seismic, and regional geologic interpretations. Once identified, high resolution airborne and spaceborne imagery will be used to verify the RTM model by comparing surficial fractures. If this imagery agrees with the model data, then a further investigation using a three-dimensional seismic survey component will be added. This report presents an overview of the Piceance Creek basin and then reviews work in the Parachute and Rulison fields and the results of the RTM models in these fields.

NONE

1994-10-01

363

Determination of tobacco alkaloids by gas chromatography with nitrogen-phosphorus detection.  

PubMed

An improved method, gas chromatography (GC) with nitrogen-phosphorus detection (NPD), has been used for determination of alkaloids in green and cured tobacco. Tobacco alkaloids of interest included nicotine, nornicotine, myosmine, anabasine, and anatabine. Tobacco samples were treated with a small quantity of aqueous ammonia solution to "loosen" tobacco tissue and to adjust pH, then extracted with solvent. The composition of the extraction solvent solution affected recoveries of the alkaloids, particularly nornicotine, and also contributed to other phenomena such as carry-over in the injection liner and "quenching" of the nitrogen-phosphorus detector. Use of a packed injection liner (e.g. with Carbowax-KOH on Chromosorb) to reduce carry-over was studied. Quenching of the nitrogen-phosphorus detector was eliminated by reducing the injection volume (i.e. increasing the split ratio), by use of a packed injection liner, and by reducing the amount of pretreatment with aqueous ammonia. A narrow bore capillary column (i.e. 0.18 mm id) was used to improve sensitivity and resolution and to increase the speed of GC analysis. An internal standard, 2,4'-dipyridyl, was used for quantitative measurement of these tobacco alkaloids. PMID:12194047

Yang, S S; Smetena, I; Huang, C B

2002-07-27

364

Short-Time-Response measurements of nitrogen dioxide and peroxyacetyl nitrate by fast capillary gas chromatography with luminol detection.  

SciTech Connect

The interaction of hydrocarbons and nitrogen oxides in sunlight to produce photochemical smog has been well studied over the years. In the past, the workhorse for the measurement of NO{sub 2}and NO was the chemiluminescent reaction with ozone. This method has detection limits of approximately 0.5 ppb in most commercial instruments, but it cannot detect NO{sub 2} directly; the instrument detects NO and uses hot catalytic surfaces to decompose all other nitrogen oxides (including NO{sub 2}) to NO for detection (l). The main problem with the method is the inherent difficulty in detecting excited NO{sub 2}, which emits over a broad region beginning at approximately 660 nm and has a maximum at 1270 nm, thus requiring a red-shifted photomultiplier for detection. The use of luminol for direct chemiluminescent detection of NO{sub 2} was demonstrated to have greater inherent sensitivity (detection limits of 5 ppt) than the indirect ozone chemiluminescence detection (2). In the luminol system, a gas-liquid reaction leads to light emission with a maximum at approximately 425 nm, at the maximum sensitivity for most photomultiplier tubes. This emission is responsible for the increased detection sensitivities. The biggest problem with this method for direct measurement of NO{sub 2} has been interference due to other soluble oxidants, particularly peroxyacyl nitrates (PANs).

Marley, N. A.; Gaffney, J. S.; Drayton, P. J.

2000-12-07

365

Gas seeps in Lake Baikal—detection, distribution, and implications for water column mixing  

NASA Astrophysics Data System (ADS)

Echo sounders served to locate a large number of shallow- and deepwater gas seeps at the bottom of all three basins of Lake Baikal during the years 2005 to 2008. A substantial proportion of the shallow gas seeps was located near the delta of the Selenga River, and at the Posolskii uplift. Deepwater gas seeps were recorded at the lake bed both inside and outside of areas where a bottom-simulating reflector was identified in seismic profiles. By monitoring the activity of gas emissions at the gas seeps, times of episodic gas ebullition could be distinguished from times of persistent gas bubble streams. A maximum gas flare height of more than 950 m above the bottom was recorded at the St. Petersburg mud volcano located in the central basin of Lake Baikal. Based on calculations from echo sounder data, the ascent velocity of gas bubbles reached 40 cm/s. In the area of gas seepage, there was a thick near-bottom layer, in which the gradient of water temperature was equal to the adiabatic gradient. This implies complete mixing of the water close to the lake bed, resulting from ascending gas bubbles released at seep sites. Analyses of vertical temperature profiles indicate possibly localized upwelling up to the lake surface when gas emissions are intensive.

Granin, Nikolay Grigorievich; Makarov, Mikhail M.; Kucher, Konstantin M.; Gnatovsky, Ruslan Y.

2010-06-01

366

High-resolution seismic detection of shallow natural gas beneath Hutchinson, Kansas  

USGS Publications Warehouse

Two high-resolution seismic reflection surveys were conducted to identify shallow natural gas that had caused explosions in Hutchinson, Kansas, in January 2001. Gas presence is associated with both a bright spot and a dim-out on the seismic reflection profiles. Core and log data from wells drilled to vent the gas indicate that the gas-bearing interval corresponds to thin dolomite layers, which have higher P-wave velocities than the surrounding shales. Gas in fractures can reduce the velocity of the dolomite interval to that of the shales (or lower). Depending on the magnitude of the velocity change, either a dim-out or bright spot is produced. Sonic logs from gas-bearing vent wells, recorded after venting of gas, show no anomalous velocity, indicating that as gas dissipates, any associated seismic anomaly will be reduced. Lateral variations in the seismic properties of the gas-bearing interval and adjacent strata (namely, variations in dolomite and shale content) also have a significant effect on the seismic signature of the interval, mimicking the effect of a small amount of gas. Only where the gas zone is relatively thick (2-3 m; 7-10 ft), creating a high-amplitude negative seismic reflection, is the seismic signature diagnostic of gas. Therefore, whereas the dim-outs observed on the seismic reflection profiles may be the result of gas presence, they are equally well explained by lateral variations in lithology. Dim-outs should not be used in the Hutchinson area as an indicator of gas. The observed bright spot, however, is most likely a unique gas response. Copyright ?? 2004. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Nissen, S. E.; Watney, W. L.; Xia, J.

2004-01-01

367

Comparison of breath and in-mouth collection for the measurement of oral malodorous compounds by gas chromatography using sulfur chemiluminescence detection  

Microsoft Academic Search

Volatile sulfur compounds (VSCs), specifically hydrogen sulfide, methyl mercaptan and dimethyl sulfide, are generally considered to be the primary volatiles responsible for 'morning' malodors in breath. To date, the 'gold standard' for detecting VSC concentrations in breath is the use of gas chromatography coupled with sulfur chemiluminescence detection. Breath gas is often collected in a polypropylene syringe and then aliquots

Debbie J. Paetznick; G. A. Reineccius; T. L. Peppard; J. M. Herkert; P. Lenton

2010-01-01

368

Comparison of breath and in-mouth collection for the measurement of oral malodorous compounds by gas chromatography using sulfur chemiluminescence detection  

Microsoft Academic Search

Volatile sulfur compounds (VSCs), specifically hydrogen sulfide, methyl mercaptan and dimethyl sulfide, are generally considered to be the primary volatiles responsible for ‘morning’ malodors in breath. To date, the ‘gold standard’ for detecting VSC concentrations in breath is the use of gas chromatography coupled with sulfur chemiluminescence detection. Breath gas is often collected in a polypropylene syringe and then aliquots

Debbie J Paetznick; G A Reineccius; T L Peppard; J M Herkert; P Lenton

2010-01-01

369

Sputtered gas-phase dianions detected by high-sensitivity mass spectrometry  

NASA Astrophysics Data System (ADS)

The detection of small doubly-charged molecular anions by means of highly sensitive mass spectrometry is discussed. The production of these gas-phase dianions is accomplished by sputtering the specimen with Cs + ions with an energy of a few keV. It is demonstrated that dianions can be detected most easily when the molecular ion has an odd total mass; then, the dianions will show up at half-integral mass numbers in the mass spectrum. In addition, the agreement of the relative abundances of several isotopomers of a dianion with the nominal isotopic pattern corroborates the identification of a dianionic species in the mass spectrum. These features are exemplified by monitoring mixed silicon-oxygen dianions of the general form OO52-[28], Sn2-[29], SiC62-[30], BeCn2-[31], and PtX62- (X = F, Cl, Br) [32]. More recent work of this group investigated the existence of long-lived dianions containing tetrahedrally coordinated oxygen atoms, namely, O(C)42- and O(BN)42-[33], of cyclic carbon cluster dianions [34], of tetraborates [35], of derivatives of the closo-hexaborate dianion BH62-[36], and of aromatic dianions [37]. Apart from identifying (meta)stable dianions, these computations indicated a possible general formation principle: small dianions are expected to be particularly stable if they consist of a central, at least partially positively charged atom and several equivalent negatively charged ligands [2,6,30,38]. Furthermore, it was pointed out [31,39,40] that for multiply charged anions a repulsive Coulomb barrier for electron emission exists which may result in small metastable dianions which can be detected by mass spectrometry. In fact, the existence of such a Coulomb barrier was inferred from various experiments [41-47]. Apart from dianions, Cederbaum and coworkers studied different small MCAs [19,24,25,48-50]. Theoretical work by other groups [51-59] corroborated and diversified these results. Following the experimental detection of Cn2-[12], several different types of other dianions were produced by means of sputtering: SiCn2- ( n = 6, 8, 10) [60], BeCn2- (4 ? n ? 14) [61,62], OCn2- (5 ? n ? 19) [63,64], SCn2- (6 ? n ? 18) [65], BeF42- and, MgF42-[66], CaF42-[67], HfF62-[68], ZrF62-[65], LiF32-[69], BeOn2- ( n = 4, 6), and CuBeO42-[70], as well as a few others [65,71]. However, also a considerable number of unsuccessful searches for dianions were reported [13,65,68,72]. Apart from sputtering, other ways of dianion formation were employed: Oxygen cluster (O)n2- ( n = 3, 5, 7, 9) were formed by electron attachment to an O 2 beam [73]. Electrospray ionization was used to produce various dianions, e.g., SO42-·nHO, SO62-·nHO, and SO82-·nHO[74], MX42- (M = Pd, Pt; X = Cl, Br) [43,44,75], MX62- (M = Re, Os, Ir, Pt; X = Cl, Br) [43,76], ZrF62-[77] or aliphatic dicarboxylate dianions [78-80]. While fullerene dianions (with n = 70-124) [81] and even C603- and C604-[82] could be produced by electrospray mass spectrometry, no C602- dianions were observed in these studies. Doubly-charged C602- and C702- ions have been produced also by laser desorption[83,84] or by collisions with Na atoms [85] whereas CF482-[41], C842-[42], C762-[86], and C702-[87] could be formed by electron attachment. More recently, dianions and even trianions of large metal clusters (some 30 or more constituents) could be produced by laser ablation [88] or by metal evaporation and subsequent electron attachment[89-92]. The aim of the present work is to discuss the production of dianions in the gas phase by sputtering and to describe their detection both in conventional mass spectrometers, operated at ion-beam energies of a few keV and in high-energy mass spectrometry. For the former, the pertinent aspects will be illustrated by means of a new class of molecular dianions, OO72-. Three distinct peaks at half-integral mass numbers are seen in the spectrum, at 98.5, 99.5, and 100.5 amu; their relative intensities are 1:9.0 × 10 -2:1.7 × 10 -3. Following the above argument, we can assume that these are caused by dianions with an odd total mass. Bot

Gnaser, Hubert; Golser, Robin

2006-10-01

370

A broadband absorption spectrometer using light emitting diodes for ultrasensitive, in situ trace gas detection  

NASA Astrophysics Data System (ADS)

A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) broadband cavity enhanced absorption spectroscopy (BBCEAS) is used to quantify the concentration of gases in sample mixtures from their characteristic absorption features, and (ii) periodic measurements of the cavity mirrors' reflectivity are made using step-scan phase shift cavity ringdown spectroscopy (PSCRDS). The latter PSCRDS method provides a stand-alone alternative to the more usual method of determining mirror reflectivities by measuring BBCEAS absorption spectra for calibration samples of known composition. Moreover, the instrument's two modes of operation use light from the same light emitting diode transmitted through the cavity in the same optical alignment, hence minimizing the potential for systematic errors between mirror reflectivity determinations and concentration measurements. The ability of the instrument to quantify absorber concentrations is tested in instrument intercomparison exercises for NO2 (versus a laser broadband cavity ringdown spectrometer) and for H2O (versus a commercial hygrometer). A method is also proposed for calculating effective absorption cross sections for fitting the differential structure in BBCEAS spectra due to strong, narrow absorption lines that are under-resolved and hence exhibit non-Beer-Lambert law behavior at the resolution of the BBCEAS measurements. This approach is tested on BBCEAS spectra of water vapor's 4v+? absorption bands around 650 nm. The most immediate analytical application of the present instrument is in quantifying the concentration of reactive trace gases in the ambient atmosphere. The instrument's detection limits for NO3 as a function of integration time are considered in detail using an Allan variance analysis. Experiments under laboratory conditions produce a 1? detection limit of 0.25 pptv for a 10 s acquisition time, which improves with further signal averaging to 0.09 pptv in 400 s. Finally, an example of the instrument's performance under field work conditions is presented, in this case of measurements of the sum of NO3+N2O5 concentrations in the marine boundary layer acquired during the Reactive Halogens in the Marine Boundary Layer field campaign.

Langridge, Justin M.; Ball, Stephen M.; Shillings, Alexander J. L.; Jones, Roderic L.

2008-12-01

371

A broadband absorption spectrometer using light emitting diodes for ultrasensitive, in situ trace gas detection.  

PubMed

A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) broadband cavity enhanced absorption spectroscopy (BBCEAS) is used to quantify the concentration of gases in sample mixtures from their characteristic absorption features, and (ii) periodic measurements of the cavity mirrors' reflectivity are made using step-scan phase shift cavity ringdown spectroscopy (PSCRDS). The latter PSCRDS method provides a stand-alone alternative to the more usual method of determining mirror reflectivities by measuring BBCEAS absorption spectra for calibration samples of known composition. Moreover, the instrument's two modes of operation use light from the same light emitting diode transmitted through the cavity in the same optical alignment, hence minimizing the potential for systematic errors between mirror reflectivity determinations and concentration measurements. The ability of the instrument to quantify absorber concentrations is tested in instrument intercomparison exercises for NO(2) (versus a laser broadband cavity ringdown spectrometer) and for H(2)O (versus a commercial hygrometer). A method is also proposed for calculating effective absorption cross sections for fitting the differential structure in BBCEAS spectra due to strong, narrow absorption lines that are under-resolved and hence exhibit non-Beer-Lambert law behavior at the resolution of the BBCEAS measurements. This approach is tested on BBCEAS spectra of water vapor's 4v+delta absorption bands around 650 nm. The most immediate analytical application of the present instrument is in quantifying the concentration of reactive trace gases in the ambient atmosphere. The instrument's detection limits for NO(3) as a function of integration time are considered in detail using an Allan variance analysis. Experiments under laboratory conditions produce a 1sigma detection limit of 0.25 pptv for a 10 s acquisition time, which improves with further signal averaging to 0.09 pptv in 400 s. Finally, an example of the instrument's performance under field work conditions is presented, in this case of measurements of the sum of NO(3)+N(2)O(5) concentrations in the marine boundary layer acquired during the Reactive Halogens in the Marine Boundary Layer field campaign. PMID:19123548

Langridge, Justin M; Ball, Stephen M; Shillings, Alexander J L; Jones, Roderic L

2008-12-01

372

A broadband absorption spectrometer using light emitting diodes for ultrasensitive, in situ trace gas detection  

SciTech Connect

A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) broadband cavity enhanced absorption spectroscopy (BBCEAS) is used to quantify the concentration of gases in sample mixtures from their characteristic absorption features, and (ii) periodic measurements of the cavity mirrors' reflectivity are made using step-scan phase shift cavity ringdown spectroscopy (PSCRDS). The latter PSCRDS method provides a stand-alone alternative to the more usual method of determining mirror reflectivities by measuring BBCEAS absorption spectra for calibration samples of known composition. Moreover, the instrument's two modes of operation use light from the same light emitting diode transmitted through the cavity in the same optical alignment, hence minimizing the potential for systematic errors between mirror reflectivity determinations and concentration measurements. The ability of the instrument to quantify absorber concentrations is tested in instrument intercomparison exercises for NO{sub 2} (versus a laser broadband cavity ringdown spectrometer) and for H{sub 2}O (versus a commercial hygrometer). A method is also proposed for calculating effective absorption cross sections for fitting the differential structure in BBCEAS spectra due to strong, narrow absorption lines that are under-resolved and hence exhibit non-Beer-Lambert law behavior at the resolution of the BBCEAS measurements. This approach is tested on BBCEAS spectra of water vapor's 4v+{delta} absorption bands around 650 nm. The most immediate analytical application of the present instrument is in quantifying the concentration of reactive trace gases in the ambient atmosphere. The instrument's detection limits for NO{sub 3} as a function of integration time are considered in detail using an Allan variance analysis. Experiments under laboratory conditions produce a 1{sigma} detection limit of 0.25 pptv for a 10 s acquisition time, which improves with further signal averaging to 0.09 pptv in 400 s. Finally, an example of the instrument's performance under field work conditions is presented, in this case of measurements of the sum of NO{sub 3}+N{sub 2}O{sub 5} concentrations in the marine boundary layer acquired during the Reactive Halogens in the Marine Boundary Layer field campaign.

Langridge, Justin M.; Shillings, Alexander J. L.; Jones, Roderic L. [Department of Chemistry, University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Ball, Stephen M. [Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

2008-12-15

373

Sampling and analysis of butyltin compounds in air using gas chromatography and flame photometric detection.  

PubMed

Organotin compounds are used in a variety of applications including stabilizers, catalysts, antifouling agents, and biocides. Because of the widespread use of organotin compounds in industry and their wide range of toxic effects, it is important to measure worker exposure to specific organotin compounds. Three butyltin compounds were selected for this study--butyltin trichloride, dibutyltin dichloride, and tributyltin chloride. These three compounds are typically present in the same work environment; therefore, developing a sampling and analytical method that would allow all three butyltin compounds to be sampled and analyzed simultaneously was desired. A derivatization procedure using sodium tetraethylborate (STEB) was selected for study and validation. The validation study demonstrated that sampling using the Occupational Safety and Health Administration (OSHA) Versatile Sampler (OVS) with XAD-2 resin sorbent and analysis using gas chromatography/flame photometric detection (GC/FPD) can be used to evaluate worker exposures to specific butyltin chlorides over the range of 5 to 270 micrograms/m3 collected at a flowrate of 0.25 L/min over a 3-hour period for a 45-L air sample. Breakthrough studies at 1.5 times the occupational exposure guideline (OEG) of 0.05 mg/m3 showed that samples could be collected at flowrates up to 0.5 L/min for 12 hours without breakthrough. The 14-day storage stability study showed apparent degradation of tributyltin and monobutyltin within a 3-day storage period at both ambient and refrigerated temperatures. There was no further degradation from 3 to 14 days. The stability of dibutyltin was unaffected by storage condition over the 14-day storage study. Subsequent stability studies incorporating a spiking solution control sample were conducted extending the stability study out to 27 days. These data show that all three butyltins were stable at either ambient or refrigerated conditions. PMID:15202157

Boraiko, Carol; Yoder, Raymond; Cooper, Jeffrey; Lieckfield, Robert; Remski, Mary

2004-01-01

374

Gas chromatography with flame ionization detection for determination of additives in an electrolytic Zn bath.  

PubMed

The monitoring of additives in electrolytic baths is a fundamental task for proper coatings. Among the additives used in zinc baths, benzylideneacetone (BDA), benzoic acid (BA) and polyethylene glycol 400 (PEG400) are easily found. This paper deals with the possibilities of handling the bath sample before it is taken to a gas chromatograph (GC) in order to follow the additives concentration along the bath life. The applied techniques include solid phase extraction (SPE), solvent extraction (SE), static headspace (SHS), direct injection (DI) and headspace solid phase microextraction (HS-SPME) recoveries up to 6:1, 14:1, 9:1, 1:1 and 80:1 respectively have been obtained. Internal standards have been found for every case. Advantages and disadvantages of the techniques are collected. In this paper DI and HS-SPME have finally been applied, though none of them is able for PEG400 determination. DI provides quantitative information for BA (limit of detection, LOD, 1.6 gL(-1)) and BDA (LOD, 0.09 gL(-1)); HS-SPME only provides quantitative information for BDA (LOD, 0.05 gL(-1)). Taking into account that PEG400 and BA do not practically change with the use of the bath, that DI is very quick and simple and that no significant differences with spectrophotometric results have been found, DI is recommended for the monitoring of BA and BDA along the zinc bath life. This should be considered a technique for process analysis for these additives. PMID:22885048

Barriola, Ainara; Ostra, Miren; Ubide, Carlos

2012-07-28

375

Gas seeps in Lake Baikal—detection, distribution, and implications for water column mixing  

Microsoft Academic Search

Echo sounders served to locate a large number of shallow- and deepwater gas seeps at the bottom of all three basins of Lake\\u000a Baikal during the years 2005 to 2008. A substantial proportion of the shallow gas seeps was located near the delta of the\\u000a Selenga River, and at the Posolskii uplift. Deepwater gas seeps were recorded at the lake

Nikolay Grigorievich Granin; Mikhail M. Makarov; Konstantin M. Kucher; Ruslan Y. Gnatovsky

2010-01-01

376

[Mid-infrared distributed-feedback quantum cascade laser-based photoacoustic detection of trace methane gas].  

PubMed

There have been considerable interests in methane detection based on infrared absorption spectroscopy for industrial and environment monitoring. The authors report on the realization of photoacoustic detection of methane (CH4) using mid-infrared distributed-feedback quantum cascade laser (DFB-QCL). The absorption line at 1316.83 cm(-1) was selected for CH4 detection, which can be reached by the self-manufactured DFB-QCL source operating in pulsed mode near 7.6 microm at room-temperature. The CH4 gas is filled to a Helmholtz resonant photoacoustic cell, which was equipped with a commercial electret microphone. The DFB-QCL was operated at 234 Hz with an 80 mW optical peak power. A detection limit of 189 parts per billion in volume was derived when the signal-to-noise ratio equaled 1. PMID:22827065

Tan, Song; Liu, Wan-feng; Wang, Li-jun; Zhang, Jin-chuan; Li, Lu; Liu, Jun-qi; Liu, Feng-qi; Wang, Zhan-guo

2012-05-01

377

Selective and sensitive chromogenic detection of cyanide and HCN in solution and in gas phase.  

PubMed

Two triphenylmethane based chemodosimeters for selective and chromogenic sensing of cyanide anions in aqueous environments and of hydrogen cyanide in gas phase were prepared and studied. PMID:23680816

Gotor, Raúl; Costero, Ana M; Gil, Salvador; Parra, Margarita; Martínez-Máñez, Ramón; Sancenón, Félix; Gaviña, Pablo

2013-05-17

378

Handheld, battery-powered near-IR TDL sensor for stand-off detection of gas and vapor plumes  

NASA Astrophysics Data System (ADS)

A handheld, battery-powered tunable-diode-laser sensor platform is described. The sensor is based on frequency modulation (FM) spectroscopy using near-IR diode lasers and passive topographic backscatter from common environmental targets such as buildings, ground and foliage. A specific application to the detection of methane using a 1.65-micron diode laser is described in detail, showing a detection sensitivity sufficient to identify typical leaks from buried residential natural gas service lines at stand-off distances up to 30 m. Signal and noise sources are analyzed in detail, along with laboratory and field-test data, including known service leaks.

Wainner, R. T.; Green, B. D.; Allen, M. G.; White, M. A.; Stafford-Evans, J.; Naper, R.

379

A simple and sensitive quantitation of N,N-dimethyltryptamine by gas chromatography with surface ionization detection.  

PubMed

A simple and sensitive method for determination of N,N-dimethyltryptamine (DMT) by gas chromatography (GC) with surface ionization detection (SID) is presented. Whole blood or urine, containing DMT and gramine (internal standard), was subjected to solid-phase extraction with a Sep-Pak C18 cartridge before analysis by GC-SID. The calibration curve was linear in the DMT range of 1.25-20 ng/mL blood or urine. The detection limit of DMT was about 0.5 ng/mL (10 pg on-column). The recovery of both DMT and gramine spiked in biological fluids was above 86%. PMID:9013290

Ishii, A; Seno, H; Suzuki, O; Hattori, H; Kumazawa, T

380

Polymer/Ordered mesoporous carbon nanocomposite platelets as superior sensing materials for gas detection with surface acoustic wave devices.  

PubMed

We have prepared nanocomposites of polymers and platelet CMK-5-like carbon and have demonstrated their superior performance for gravimetric gas detection. The zirconium-containing platelet SBA-15 was used as hard template to prepare CMK-5-like carbon, which was then applied as a lightweight and high-surface-area scaffold for the growth of polymers by radical polymerization. Mesoporous nanocomposites composed of four different polymers were used as sensing materials for surface acoustic wave devices to detect ppm-level ammonia gas. The sensors showed much better sensitivity and reversibility than those coated with dense polymer films, and the sensor array could still generate a characteristic pattern for the analyte with a concentration of 16 ppm. The results show that the nanocomposite sensing materials are promising for highly sensitive gravimetric-type electronic nose applications. PMID:22835071

Ku, Pei-Hsin; Hsiao, Chen-Yun; Chen, Mei-Jing; Lin, Tai-Hsuan; Li, Yi-Tian; Liu, Szu-Chieh; Tang, Kea-Tiong; Yao, Da-Jeng; Yang, Chia-Min

2012-07-26

381

Detection of more than 50 substituted phenols as their t-butyldimethylsilyl derivatives using gas chromatography-mass spectrometry  

Microsoft Academic Search

More than 50 substituted phenols have been derivatized successfully with N-(t-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA) by forming their t-butyldimethylsilyl derivatives. The study included 21 chlorinated phenols, 13 nitrophenols, 3 aminophenols, 4 alkylphenols, o-phenylphenol, the non-substituted phenol and some other substituted phenols including six phenolic pesticides. The determination and detection of the derivatives were performed by capillary gas chromatography-mass spectrometry. The mass spectra of

Thomas Heberer; Hans-Juergen Stan

1997-01-01

382

Headspace Liquid-Phase Microextraction of Short-Chain Fatty Acids in Plasma, and Gas Chromatography with Flame Ionization Detection  

Microsoft Academic Search

A novel method for analysis of short-chain fatty acids (SCFA) in blood plasma has been developed by combining headspace liquid-phase microextraction (HS-LPME) and gas chromatography with flame ionization detection. HS-LPME conditions, for example working solution volume, salt concentration, and extraction temperature and time, were optimized by means of an L9 (34) orthogonal array design. The effects on extraction efficiency of

L. Tan; X. P. Zhao; X. Q. Liu; H. X. Ju; J. S. Li

2005-01-01

383

Lard detection based on fatty acids profile using comprehensive gas chromatography hyphenated with time-of-flight mass spectrometry  

Microsoft Academic Search

Comprehensive gas chromatography hyphenated with time-of-flight mass spectrometry was applied to detect the differences between lard (LA) and three other commonly animal-derived fats, namely cattle fat (CA), chicken fat (CF) and goat fat (GF). Combination of two different microbore columns (SLB-5ms and DB-wax) allowed the discrimination of lard from other animal fats by three fatty acid methyl esters (FAMEs) constituents

Dias Indrasti; Yaakob B. Che Man; Shuhaimi Mustafa; Dzulkifly Mat Hashim

2010-01-01

384

Kinetics of Ethanol and Acetaldehyde Production in Fermenting Wheat Dough by Laser-Based Trace Gas Detection  

Microsoft Academic Search

The fermentation process of wheat dough was studied by laser-based trace gas detection. A CO-laser-driven photoacoustic spectrometer was used to monitor simultaneously, in real time, the ethanol and acetaldehyde production rates of two commercial types of active dry yeast (Saccharomyces cerevisiae) in wheat dough substrates. Both types of yeast, Oand B, produced ethanol for 5 hours. Acetaldehyde was yielded only

S. Tomás; F. J. M. Harren

2001-01-01

385

A continuously tunable long-wavelength cw IR source for high-resolution spectroscopy and trace-gas detection  

Microsoft Academic Search

A new widely tunable source in the infrared for use in high-resolution spectroscopy and trace-gas detection is described. This spectroscopic source is based on Difference Frequency Generation (DFG) in gallium selenide (GaSe) and is continuously tunable in the 8.8 15.0 mum wavelength region. Such a DFG source operates at room temperature which makes it a useful alternative to a lead-salt

Wade C. Eckhoff; Roger S. Putnam; Shunxi Wang; Robert F. Curl; Frank K. Tittel

1996-01-01

386

A continuously tunable long-wavelength cw IR source for high-resolution spectroscopy and trace-gas detection  

Microsoft Academic Search

A new widely tunable source in the infrared for use in high-resolution spectroscopy and trace-gas detection is described. This spectroscopic source is based on Difference Frequency Generation (DFG) in gallium selenide (GaSe) and is continuously tunable in the 8.8–15.0 µm wavelength region. Such a DFG source operates at room temperature which makes it a useful alternative to a lead-salt diode-laser-

Wade C. Eckhoff; Roger S. Putnam; Shunxi Wang; Robert F. Curl; Frank K. Tittel

1996-01-01

387

Long-term detection of clenbuterol in human scalp hair by gas chromatography–high-resolution mass spectrometry  

Microsoft Academic Search

A method for the detection of clenbuterol in human scalp hair by gas chromatography–high-resolution mass spectrometry (GC–HRMS) is described. The sample preparation involved chemical digestion of the protein structure, which was achieved by incubating the hair with 1 M KOH at 70°C. A single extraction step with tert.-butyl methyl ether provided approximately 90% of the analyte, which was dried and

M. Machnik; H. Geyer; S Horning; A. Breidbach; P. Delahaut; W. Schänzer

1999-01-01

388

The portable gas chromatograph OralChroma™: a method of choice to detect oral and extra-oral halitosis.  

PubMed

It is now generally accepted that the volatile sulfur compounds (VSCs) hydrogen sulfide, methyl mercaptan and dimethyl sulfide are the main contributors to halitosis when of oropharyngeal origin. Gas chromatography using a specific sulfur detector is the most appropriate method to detect halitosis of different origin (intra-oral and extra-oral halitosis) and should be considered as the gold standard. However, a gas chromatograph is an expensive apparatus and needs trained personnel. The less specific Halimeter is the most used apparatus in halitosis research. In this study a newly developed portable gas chromatograph, the OralChroma™ (Abilit Corporation, Japan), was evaluated for use in the field of halitosis. The results show that the OralChroma is a very sensitive apparatus for measuring VSCs. Just like standard gas chromatography, it can perfectly differentiate between intra-oral and extra-oral blood-borne halitosis, while the Halimeter can only detect intra-oral halitosis. The hardware of the OralChroma meets all the needs for becoming the apparatus of choice in the field of halitosis. However, the software needs a major revision. Sometimes, the concentrations given for the different VSCs are completely incorrect due to a wrong assignment of the place of the VSCs in the chromatogram. PMID:21386154

Tangerman, A; Winkel, E G

2008-03-07

389

Detection and quantification of fugitive emissions from Colorado oil and gas production operations using remote monitoring  

EPA Science Inventory

Western states contain vast amounts of oil and gas production. For example, Weld County Colorado contains approximately 25,000 active oil and gas well sites with associated production operations. There is little information on the air pollutant emission potential from this source...

390

Polymer coated quartz crystal microbalance sensors for detection of volatile organic compounds in gas mixtures  

Microsoft Academic Search

By coating different conducting polymers of thiophene and its derivatives on quartz crystal microbalance (QCM) sensor surfaces, new novel QCM gas sensors have been produced in two simple ways, which could classify testing gas samples of volatile organic compounds (VOCs) gases. Principle components analysis (PCA) has been performed based on the QCM measurement results, which shows that our QCM sensors

Pengchao Si; John Mortensen; Alexei Komolov; Jens Denborg; Preben Juul Møller

2007-01-01

391

Gas chromatography negative ion chemical ionization mass spectrometry: application to the detection of alkyl nitrates and halocarbons in the atmosphere.  

PubMed

Alkyl nitrates and very short-lived halocarbon species are important atmospheric trace gas species that are present in the low to sub parts per trillion concentration range. This presents an analytical challenge for their detection and quantification that requires instrumentation with high sensitivity and selectivity. In this paper, we present a new in situ gas chromatograph negative ion chemical ionization mass spectrometer (GC/NICI-MS) coupled to a non-cryogen sample pre-concentration system. This instrument, with detection limits of <0.01 ppt, is capable of detecting and quantifying a large suite of alkyl nitrate and halocarbon species with high sensitivity and precision. The effects of ion source temperature and reagent gas pressure on the ionization efficiency of the NICI mode are investigated and the results are used to optimize the sensitivity. The NICI mode is compared to the more frequently used electron impact (EI) ionization and the enhancements in sensitivity are presented for all the calibrated compounds. PMID:18586255

Worton, David R; Mills, Graham P; Oram, David E; Sturges, William T

2008-06-18

392

CW DFB RT diode laser-based sensor for trace-gas detection of ethane using a novel compact multipass gas absorption cell  

NASA Astrophysics Data System (ADS)

The development of a continuous wave, thermoelectrically cooled (TEC), distributed feedback diode laser-based spectroscopic trace-gas sensor for ultra-sensitive and selective ethane (C2H6) concentration measurements is reported. The sensor platform used tunable diode laser absorption spectroscopy (TDLAS) and wavelength modulation spectroscopy as the detection technique. TDLAS was performed using an ultra-compact 57.6 m effective optical path length innovative spherical multipass cell capable of 459 passes between two mirrors separated by 12.5 cm and optimized for the 2.5-4 ?m range TEC mercury-cadmium-telluride detector. For an interference-free C2H6 absorption line located at 2,976.8 cm-1, a 1? minimum detection limit of 740 pptv with a 1 s lock-in amplifier time constant was achieved.

Krzempek, Karol; Jahjah, Mohammad; Lewicki, Rafa?; Stefa?ski, Przemys?aw; So, Stephen; Thomazy, David; Tittel, Frank K.

2013-06-01

393

CW DFB RT diode laser based sensor for trace-gas detection of ethane using novel compact multipass gas absorption cell  

NASA Astrophysics Data System (ADS)

The development of a continuous wave (CW), thermoelectrically cooled (TEC), distributed feedback (DFB) laser diode based spectroscopic trace-gas sensor for ultra sensitive and selective ethane (C2H6) concentration measurements is reported. The sensor platform used tunable laser diode absorption spectroscopy (TDLAS) and wavelength modulation spectroscopy (WMS) as the detection technique. TDLAS was performed with an ultra-compact 57.6 m effective optical path length innovative spherical multipass cell capable of 459 passes between two mirrors separated by 12.5 cm. For an interference free C2H6 absorption line located at 2976.8 cm-1 a 1? minimum detection limit of 130 pptv with a 1 second lock-in amplifier time constant was achieved.

Jahjah, Mohammad; Lewicki, Rafal; Tittel, Frank K.; Krzempek, Karol; Stefanski, Przemyslaw; So, Stephen; Thomazy, David

2013-01-01

394

Development of a high-performance microstrip gas chamber with a capability of track discrimination for neutron detection  

NASA Astrophysics Data System (ADS)

A microstrip gas chamber (MSGC) with a capability of track discrimination for neutron detection was developed whilst ensuring the stability of the MSGC and fulfilling the specifications required for detectors used in high-flux reactors and high-intensity pulsed-neutron sources. The developed two-dimensional detector system comprises an MSGC with individual signal channel read-outs and a new instrument system with a capability of secondary-particle discrimination (InSPaD). The InSPaD identifies the particles-proton and triton-created in the nuclear reaction 3He+n-->p+T by a simple, fast and cost-effective method using the difference in the track length, and it allows using a small amount of heavy gas such as C2H6 with helium-3 as the filling gas for achieving a high spatial resolution. We describe the concept and design of the developed detector system and show some basic experimental results supporting the feasibility of the detector system with the InSPaD, including the gas gain of the MSGC, spatial uniformity of the gas gain, and pulse-height distribution along the tracks of the secondary particles created in neutron events.

Nakamura, T.; Yamagishi, H.; Masaoka, S.; Soyama, K.; Aizawa, K.

2004-08-01

395

Final design review report for the RMCS Flammable Gas Detection Interlock  

SciTech Connect

This report document the completion of the formal design review for the RMCS (Rotary Mode Core Sampling) flammable gas detector interlock. This hydrogen/flammable gas interlock, a proposed addition to the RMCS system portable exhauster, in intended to support core sampling operations in waste tanks requiring flammable gas controls. The objective of this review was to approve new drawings at the 100% design completion state. The conclusion reached by the review committee was that the design was acceptable and efforts should continue toward fabrication and delivery.

Corbett, J.E., Westinghouse Hanford

1996-08-20

396

Gas Chromatographic Detection of in Vitro and in Vivo Activities of Certain Canine Viruses.  

National Technical Information Service (NTIS)

Gas chromatograms prepared from dog kidney cell cultures infected with individual strains of canine infectious hepatitis, herpes, distemper, and parainfluenza viruses contained compounds not present in uninoculated cultures. Metabolites were observed in c...

B. M. Mitruka L. E. Carmichael M. Alexander

1969-01-01

397

Naturally fractured tight gas reservoir detection optimization. Quarterly report, January--March 1995.  

National Technical Information Service (NTIS)

This report describes progress in five projects: (1) Geologic assessment of the Piceance Basin; (2) Regional stratigraphic studies, Upper Cretaceous Mesaverde Group, southern Piceance Basin, Colorado; (3) Structurally controlled and aligned tight gas rese...

1995-01-01

398

Chemical warfare agent detection in complex environments with comprehensive two-dimensional gas chromatography  

Microsoft Academic Search

Comprehensive two-dimensional gas chromatography (GCxGC) is an emerging technology for chemical separation that provides an order-of-magnitude increase in separation capacity over traditional gas chromatography. GCxGC separates chemical species with two capillary columns interfaced by two-stage thermal desorption. Because GCxGC is comprehensive and has high separation capacity, it can perform multiple traditional analytical methods with a single analysis. GCxGC has great

Stephen E. Reichenbach; Mingtian Ni; Visweswara Kottapalli; Arvind Visvanathan; Edward B. Ledford Jr.; John Oostdijk; Henk C. Trap

2003-01-01

399

Performance improvements of widely tunable lasers for multi gas species detection and analysis  

NASA Astrophysics Data System (ADS)

Widely tunable lasers support certain characteristics which out perform DFB technology for the sensing of gas species in the NIR spectral region. Reduced frequency tuning variation and almost zero residual amplitude modulation (RAM) are investigated. The current report illustrates how 18 individual gas absorption lines can be interrogated using a single laser source over a 40nm wavelength range, where RAM and FM non-linearity never exceed 5% and 13 % respectively. Comparison with DFB technology is made.

Ryan, Neil; McDonald, David; Lavin, Adrian

2005-06-01

400

Fracture detection, mapping, and analysis of naturally fractured gas reservoirs using seismic technology. Final report, November 1995  

SciTech Connect

Many basins in the Rocky Mountains contain naturally fractured gas reservoirs. Production from these reservoirs is controlled primarily by the shape, orientation and concentration of the natural fractures. The detection of gas filled fractures prior to drilling can, therefore, greatly benefit the field development of the reservoirs. The objective of this project was to test and verify specific seismic methods to detect and characterize fractures in a naturally fractured reservoir. The Upper Green River tight gas reservoir in the Uinta Basin, Northeast Utah was chosen for the project as a suitable reservoir to test the seismic technologies. Knowledge of the structural and stratigraphic geologic setting, the fracture azimuths, and estimates of the local in-situ stress field, were used to guide the acquisition and processing of approximately ten miles of nine-component seismic reflection data and a nine-component Vertical Seismic Profile (VSP). Three sources (compressional P-wave, inline shear S-wave, and cross-line, shear S-wave) were each recorded by 3-component (3C) geophones, to yield a nine-component data set. Evidence of fractures from cores, borehole image logs, outcrop studies, and production data, were integrated with the geophysical data to develop an understanding of how the seismic data relate to the fracture network, individual well production, and ultimately the preferred flow direction in the reservoir. The multi-disciplinary approach employed in this project is viewed as essential to the overall reservoir characterization, due to the interdependency of the above factors.

NONE

1995-10-01

401

Development of a tunable mid-IR difference frequency laser source for highly sensitive airborne trace gas detection  

NASA Astrophysics Data System (ADS)

The development of a compact tunable mid-IR laser system at 3.5 ?m for quantitative airborne spectroscopic trace gas absorption measurements is reported. The mid-IR laser system is based on difference frequency generation (DFG) in periodically poled LiNbO3 and utilizes optical fiber amplified near-IR diode and fiber lasers as pump sources operating at 1083 nm and 1562 nm, respectively. This paper describes the optical sensor architecture, performance characteristics of individual pump lasers and DFG, as well as its application to wavelength modulation spectroscopy employing an astigmatic Herriott multi-pass gas absorption cell. This compact system permits detection of formaldehyde with a minimal detectable concentration (1? replicate precision) of 74 parts-per-trillion by volume (pptv) for 1 min of averaging time and was achieved using calibrated gas standards, zero air background and rapid dual-beam subtraction. This corresponds to a pathlength-normalized replicate fractional absorption sensitivity of 2.5×10-10 cm-1.

Richter, D.; Fried, A.; Wert, B. P.; Walega, J. G.; Tittel, F. K.

402

System for rapid detection and mapping of gas plumes on 100 m scales: examination of some technical and economic issues  

NASA Astrophysics Data System (ADS)

We consider the design of a system combining computed tomography and Fourier Transform Infrared Spectroscopy (CT/FTIR) to detect and map the concentration of multicontaminant gas plumes in ambient air over a 100 m square area. Several factors affecting the accuracy of the reconstructed map and the detection limits that can be achieved in the field are discussed. The estimated cost and capabilities of the system are compared with those of a more conventional gas monitoring system that might operate over a similar spatial extent. The paper includes a description of a proposed system that is designed to produce a map of multiple gaseous contaminants with a resolution of 12 m X 12 m in a time of approximately 10 minutes by sequentially measuring the contaminant concentrations along 48 intersecting beam paths and then reconstructing the map using a CT algorithm adapted to detect Gaussian plumes. The optical elements consist of an FTIR mounted on a steerable telescope platform, a second remote steerable mirror platform, and 32 fixed retro-reflectors.

Fischer, Marc L.; Drescher, Anushka C.; Gadgil, Ashok J.; Yost, Michael G.

1995-05-01

403

Fast gas chromatography with luminol chemiluminescence detection for the simultaneous determination of nitrogen dioxide and peroxyacetyl nitrate in the atmosphere  

NASA Astrophysics Data System (ADS)

An instrument has been designed and constructed for the simultaneous determination of nitrogen dioxide (NO2) and peroxyacetyl nitrate (PAN) in atmospheric samples. The instrument's design is based on separation by fast gas chromatography (GC) with a 30 ft capillary column (DB-1) followed by detection by luminol chemiluminescence. The chemiluminescent reaction between NO2 or PAN and luminol takes place at the gas-liquid interface on the surface of a solid support. The chemiluminescent emission at 425 nm is detected with a photon counting module. The instrument is controlled by a 1.8 GHz Notebook computer with a WINDOWS 2000 operating system and a custom software application programmed in LABVIEW. Detection limits are in the low parts per trillion (ppt) with a time resolution of 30 s to 1 min. The instrument was operated during the Mexico City Metropolitan Area/Mexico City Megacity 2003 collaborative air quality study. Results for NO2 from this fast GC method were compared with results from a co-located differential optical absorption spectrometer (DOAS) and a tunable diode laser absorption spectromenter (TDLAS). The results support the application of the new luminol-based instrument for atmospheric measurements.

Marley, Nancy A.; Gaffney, Jeffrey S.; White, Robert V.; Rodriguez-Cuadra, Luis; Herndon, Scott E.; Dunlea, Ed; Volkamer, Rainer M.; Molina, Luisa T.; Molina, Mario J.

2004-11-01

404

Detection of Noble Gas Radionuclides from an Underground Nuclear Explosion During a CTBT On-Site Inspection  

NASA Astrophysics Data System (ADS)

The development of a technically sound approach to detecting the subsurface release of noble gas radionuclides is a critical component of the on-site inspection (OSI) protocol under the Comprehensive Nuclear Test Ban Treaty. In this context, we are investigating a variety of technical challenges that have a significant bearing on policy development and technical guidance regarding the detection of noble gases and the creation of a technically justifiable OSI concept of operation. The work focuses on optimizing the ability to capture radioactive noble gases subject to the constraints of possible OSI scenarios. This focus results from recognizing the difficulty of detecting gas releases in geologic environments—a lesson we learned previously from the non-proliferation experiment (NPE). Most of our evaluations of a sampling or transport issue necessarily involve computer simulations. This is partly due to the lack of OSI-relevant field data, such as that provided by the NPE, and partly a result of the ability of computer-based models to test a range of geologic and atmospheric scenarios far beyond what could ever be studied by field experiments, making this approach very highly cost effective. We review some highlights of the transport and sampling issues we have investigated and complete the discussion of these issues with a description of a preliminary design for subsurface sampling that addresses some of the sampling challenges discussed here.

Carrigan, Charles R.; Sun, Yunwei

2012-08-01

405

Chemotaxonomic differentiation of legionellae by detection and characterization of aminodideoxyhexoses and other unique sugars using gas chromatography-mass spectrometry.  

PubMed Central

Legionellae have been differentiated previously by analyzing their carbohydrate contents by gas chromatography with flame ionization detection. In the present study, total ion mode gas chromatography-mass spectrometry (GC-MS) was used to detect a number of unusual sugars, including one that is structurally related to O-methyldideoxyheptoses. Increased sensitivity and selectivity for carbohydrate detection was achieved by selected ion-monitoring GC-MS. Two of the uncommon sugars previously discovered in the legionellae (X1 and X2) were identified as quinovosamine and fucosamine, respectively. Legionella pneumophila contained rhamnose and quinovosamine but not the quinovosamine isomer fucosamine. Tatlockia micdadei and Legionella maceachernii contained large amounts of rhamnose, fucose, and fucosamine but not quinovosamine. These two species were the only legionellae studied that contained another unusual sugar that is referred to as X3, pending determination of its structure. Fluoribacter dumoffi, Fluoribacter bozemanae, and Legionella anisa were varied in their carbohydrate contents, both within and between species, but could be distinguished from L. pneumophila and the T. micdadei and L. maceachernii group. Fluoribacter gormanii was unique among the legionellae in that it lacked both quinovosamine and fucosamine. Legionella jordanis contained other unusual carbohydrates in addition to quinovosamine. GC-MS may have wide application in the differentiation of bacterial species.

Fox, A; Rogers, J C; Fox, K F; Schnitzer, G; Morgan, S L; Brown, A; Aono, R

1990-01-01

406

Multiphase imaging of gas flow in a nanoporous material usingremote detection NMR  

SciTech Connect

Pore structure and connectivity determine how microstructured materials perform in applications such as catalysis, fluid storage and transport, filtering, or as reactors. We report a model study on silica aerogel using a recently introduced time-of-flight (TOF) magnetic resonance imaging technique to characterize the flow field and elucidate the effects of heterogeneities in the pore structure on gas flow and dispersion with Xe-129 as the gas-phase sensor. The observed chemical shift allows the separate visualization of unrestricted xenon and xenon confined in the pores of the aerogel. The asymmetrical nature of the dispersion pattern alludes to the existence of a stationary and a flow regime in the aerogel. An exchange time constant is determined to characterize the gas transfer between them. As a general methodology, this technique provides new insights into the dynamics of flow in porous media where multiple phases or chemical species may be present.

Harel, Elad; Granwehr, Josef; Seeley, Juliette A.; Pines, Alex

2005-10-03

407

Detection of hydrogen gas-producing anaerobes in refuse-derived fuel (RDF) pellets.  

PubMed

Recently, we reported that refuse-derived fuel (RDF) pellets contain a relatively high number of viable bacterial cells and that these bacteria generate heat and hydrogen gas during fermentation under wet conditions. In this study we analyzed bacterial cell numbers of RDF samples manufactured with different concentrations of calcium hydroxide, which is usually added to waste materials for the prevention of rotting of food wastes and the acceleration of drying of solid wastes, and determined the amount of hydrogen gas produced by them under wet conditions. Furthermore, we analyzed microflora of the RDF samples before and during fermentation by denaturing gradient gel electrophoresis of 16S rDNA followed by sequencing. We found that the RDF samples contained various kinds of clostridia capable of producing hydrogen gas. PMID:16306688

Sakka, Makiko; Kimura, Tetsuya; Ohmiya, Kunio; Sakka, Kazuo

2005-11-01

408

Use of a MicroStrip Gas Chamber conductive capillary plate for time-resolved X-ray area detection  

NASA Astrophysics Data System (ADS)

The stable operation of MicroStrip Gas Chamber (MSGC) was successfully performed using glass capillary plate as an intermediate gas multiplier. Detection area of 95mm2 was available and fine position resolution of 90?m using digital readout was attained. A charge-up problem of capillary plate under intense radiation source was perfectly removed by surface conductivity inside of capillaries. The quantitative measurements using MSGC is now available in X-ray imaging. This paper also presents novel applications of X-ray diffraction studies and their preliminary results using an MSGC. Rapid measurements for X-ray crystallography of the order of a few tens of seconds were attained successfully.

Ochi, Atsuhiko; Tanimori, Toru; Nishi, Yuji; Nishi, Yasuro; Nagayoshi, Tsutomu; Ohashi, Yuji; Uekusa, Hidehiro; Toyokawa, Hidenori

2002-01-01

409

Laboratory Studies Of Titan Haze: Simultaneous In Situ Detection Of Gas And Particle Species  

NASA Astrophysics Data System (ADS)

Analyses of data obtained by multiple instruments carried by Cassini and Huygens have increased our knowledge of the composition of Titan’s atmosphere. While a wealth of new information about the aerosols in Titan’s atmosphere was obtained, their composition is still not well constrained. Laboratory experiments will therefore play a key role in furthering our understanding of the chemical processes resulting in the formation of haze in Titan’s atmosphere and its possible composition. We have obtained simultaneous in situ measurements of the gas- and particle-phase compositions produced by our Titan atmosphere simulation experiments (see e.g. [1]). The gas phase composition was measured using a Proton-Transfer Ion-Trap Mass Spectrometer (PIT-MS) and the aerosol composition was measured using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). This complementary set of measurements will allow us to address the partitioning of gas- and aerosol-phase species. Knowledge of the gas phase composition in which the particles in our experiments form allows both for better comparison to the chemistry that is occurring in Titan’s atmosphere and for enabling more accurate determination of the possible pathways involved in the transition from gas phase to aerosol. We will compare the results from experiments that used two different initial gas mixtures (98% N2/2% CH4 and 98%N2/2%CH4/50 ppm CO) and two different energy sources to initiate the chemical reactions that result in particle formation (spark discharge using a Tesla coil or FUV irradiation from a deuterium lamp (115-400 nm)). [1] Trainer, M.G., et al. (2012) Astrobiology, 12, 315-326. SMH is supported by NSF Astronomy and Astrophysics Postdoctoral Fellowship AST-1102827.

Horst, Sarah; Li, R.; Yoon, H.; Hicks, R.; de Gouw, J.; Tolbert, M.

2012-10-01

410

Detection and tracking of gas clouds in an urban area by imaging infrared spectroscopy  

NASA Astrophysics Data System (ADS)

The release of toxic industrial compounds in urban areas is a threat for the population and the environment. In order to supply emergency response forces with information about the released compounds after accidents or terrorist attacks, monitoring systems such as the scanning imaging spectrometer SIGIS 2 or the hyperspectral imager HI 90 were developed. Both systems are based on the method of infrared spectroscopy. The systems were deployed to monitor gas clouds released in the harbor area of Hamburg. The gas clouds were identified, visualized and quantified from a distance in real time. Using data of two systems it was possible to identify contaminated areas and to determine the source location.

Sabbah, Samer; Rusch, Peter; Gerhard, Jörn-Hinnrich; Harig, Roland

2013-05-01

411

Multiscale rock-physics templates for gas detection in carbonate reservoirs  

NASA Astrophysics Data System (ADS)

The heterogeneous distribution of fluids in patchy-saturated rocks generates significant velocity dispersion and attenuation of seismic waves. The mesoscopic Biot-Rayleigh theory is used to investigate the relations between wave responses and reservoir fluids. Multiscale theoretical modeling of rock physics is performed for gas/water saturated carbonate reservoirs. Comparisons with laboratory measurements, log and seismic data validate the rock physics template. Using post-stack and pre-stack seismic inversion, direct estimates of rock porosity and gas saturation of reservoirs are obtained, which are in good agreement with oil production tests of the wells.

Ba, Jing; Cao, Hong; Carcione, José M.; Tang, Gang; Yan, Xin-Fei; Sun, Wei-tao; Nie, Jian-xin

2013-06-01

412

Validation of a method to detect cocaine and its metabolites in nails by gas chromatography-mass spectrometry.  

PubMed

The objective of the present work was to compare previously published methods and provide validation data to detect simultaneously cocaine (COC), benzoylecgonine (BE) and norcocaine (NCOC) in nail. Finger and toenail samples (5mg) were cut in very small pieces and submitted to an initial procedure for external decontamination. Methanol (3 ml) was used to release analytes from the matrix. A cleanup step was performed simultaneously by solid-phase extraction (SPE) and the residue was derivatized with pentafluoropropionic anhydride/pentafluoropropanol (PFPA/PFP). Gas chromatography-mass spectrometry (GC-MS) was used to detect the analytes in selected ion monitoring mode (SIM). Confidence parameters of validation of the method were: recovery, intra- and inter-assay precision, as well as limit of detection (LOD) of the analytes. The limits of detection were: 3.5 ng/mg for NCOC and 3.0 ng/mg for COC and BE. Good intra-assay precision was observed for all detected substances (coefficient of variation (CV)<11%). The inter-assay precision for norcocaine and benzoylecgonine were <4%. For intra- and inter-assay precision deuterated internal standards were used. Toenail and fingernail samples from eight declared cocaine users were submitted to the validated method. PMID:16183230

Valente-Campos, Simone; Yonamine, Mauricio; de Moraes Moreau, Regina Lucia; Silva, Ovandir Alves

2005-09-23

413

Ultralow-limit gas detection in nano-dumbbell polymer sensor via electrospinning  

NASA Astrophysics Data System (ADS)

Nano-dumbbells via electrospinning: controllable nano-dumbbells are fabricated via electrospinning. The weight block parts and the length of nanowires between them can be adjusted through changing the experimental conditions. This nanostructure enables ultralow-limit gas sensing properties of the resulting polypyrrole-based microsensor.

Xue, Mianqi; Li, Fengwang; Wang, Yue; Cai, Xiaojing; Pan, Feng; Chen, Jitao

2013-02-01

414

Development of Oxide Semiconductor Thick Film Gas Sensor for the Detection of Total Volatile Organic Compounds  

Microsoft Academic Search

After an amendment of Building Standards Law in 2003, the installation of the ventilator is compulsory in the newly built house. Because many persons suffer from indoor-air pollutants caused by the volatile organic compounds (VOCs). The final purpose of this research is to develop the gas sensor which can monitor the gross weight of VOC gases indoors and then to

Masahiro Kadosaki; Yuichi Sakai; Ikuo Tamura; Ichiro Matsubara; Toshio Itoh

2008-01-01

415

Transesophageal Echocardiographic Detection of Gas Embolism and Cardiac Valvular Dysfunction During Laparoscopic Nephrectomy  

Microsoft Academic Search

We used transesophageal echocardiography (TEE) to monitor venous gas embolism, cardiac performance, and the hemodynamic effects of positioning and pneu- moperitoneum in 16 healthy kidney donors undergo- ing laparoscopic nephrectomy. A four-chamber view was used continuously, except at predetermined inter- vals, when a complete TEE examination for cardiac function was performed. Other clinical variables re- corded include systolic, diastolic, and

Brenda G. Fahy; Jawad U. Hasnain; John L. Flowers; Jeffrey S. Plotkin; Patrick Odonkor; Mary K. Ferguson

1999-01-01

416

Alternating current plasma detector for selective mercury detection in gas chromatography  

Microsoft Academic Search

Gas chromatograpy (GC) coupled with element-specific detectors has been employed in many applications to simplify the interpretation of complex chromatograms. Desirable characteristic of an element-specific detector are that it should be highly specific for a wide range of elements, sensitive for these elements over a wide linear range, simple to construct and maintain, and stable under many application conditions. This

Robert B. Costanzo; Eugene F. Barry

1988-01-01

417

Detection of Hydrogen Gas-Producing Anaerobes in Refuse-Derived Fuel (RDF) Pellets  

Microsoft Academic Search

Recently, we reported that refuse-derived fuel (RDF) pellets contain a relatively high number of viable bacterial cells and that these bacteria generate heat and hydrogen gas during fermentation under wet conditions. In this study we analyzed bacterial cell numbers of RDF samples manufactured with different concentrations of calcium hydroxide, which is usually added to waste materials for the prevention of

Makiko SAKKA; Tetsuya KIMURA; Kunio OHMIYA; Kazuo SAKKA

2005-01-01

418

Compression as a Tool to Detect Bose Glass in a Cold Atomic Gas  

SciTech Connect

We suggest that measuring the variation of the radius of an atomic cloud when the harmonic trap confinement is varied makes it possible to monitor the disappearance of the insulating Mott phase of an ultracold atomic gas trapped in a disordered optical lattice. This paves the way for an unambiguous identification of a Bose glass phase in the system.

Delande, Dominique [Laboratoire Kastler-Brossel, Universite Pierre et Marie Curie-Paris 6, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Zakrzewski, Jakub [Laboratoire Kastler-Brossel, Universite Pierre et Marie Curie-Paris 6, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Instytut Fizyki imienia Mariana Smoluchowskiego and Mark Kac Complex Systems Research Center, Uniwersytet Jagiellonski, ulica Reymonta 4, PL-30-059 Krakow (Poland)

2009-02-27

419

Tin oxide nanowire sensors for highly sensitive detection of the toxic gas H2S  

NASA Astrophysics Data System (ADS)

We have realized gas sensor devices, which are based on a single SnO2-nanowire or a multiple SnO2-nanowire network as gas sensing components and are very sensitive to the toxic gas H2S. The nanowires are fabricated in a two-step atmospheric pressure synthesis process directly on the Si-chip by spray pyrolysis and subsequent annealing. Exposure of the single SnO2-nanowire sensor H2S with a concentration of only 1.4 ppm decreases the resistance by ~ 30%, while the multiple SnO2-nanowire network sensor exhibits a resistance decrease by ~ 90%. The nanowire sensors have extraordinary sensitivity with resolution limit in the ppb range and are able to measure concentrations well below the threshold limit value of 10 ppm. Due to their high performance the nanowire based sensors are basically suited for the realization of smart gas sensing devices for personal safety issues as well as industrial applications.

Köck, A.; Brunet, E.; Mutinati, G. C.; Maier, T.; Steinhauer, S.

2011-05-01

420

Gas sensors development using supercritical fluid technology to detect the ripeness of bananas  

Microsoft Academic Search

This work reports the development of gas sensors with three different techniques applied to sensor coating with conducting polymer polyaniline (PANI) by: in situ polymerization, RESS (rapid expansion of supercritical solutions) of polyaniline doped with dodecyl benzene sulphonic acid (DBSA) in pressurized fluid, and precipitation. The two latter sensors were obtained through micro\\/nanoparticle deposition onto interdigitated line patterns of graphite

C. Steffens; E. Franceschi; F. C. Corazza; P. S. P. Herrmann Jr.; J. Vladimir Oliveira

2010-01-01

421

A seismic survey to detect natural gas hydrate in the East Sea of Korea  

Microsoft Academic Search

Recently, several countries have conducted projects to explore and develop natural gas hydrate, which is one of the new alternative energy resources for the future. In Korea, a five-year national research project was initiated in 2000. As part of this project, a seismic survey was performed in the East Sea of Korea to quantify the potential magnitude and distribution of

Jeong Hwan Lee; Young Soon Baek; Byong Jae Ryu; Michael Riedel; Roy D. Hyndman

2005-01-01

422

Determination of nine organophosphorus pesticides in cereals and kidney beans by capillary gas chromatography with flame photometric detection.  

PubMed

A method is developed for the determination of nine organophosphorus pesticide residues in cereals and kidney beans by capillary gas chromatography with flame-photometric detection. In this method, dichloromethane is used for clean-up after liquid-liquid extraction. It is shown that good separations are obtained using a fused-silica capillary column (DB-1701) by the optimized temperature program. In the spiked levels of 0.012-0.43 mg/kg, the recoveries are from 83.7% to 107%, with the relative standard deviation between 3.2% and 13% and limits of detection from 8.2 to 15 microg/kg. The method is rapid, sensitive, and practical. PMID:16176643

Tang, Bo; Zhang, Jin-E; Zang, Li-Guo; Zhang, Yao-Zhong; Li, Xiang-Yang; Zhou, Li

2005-08-01

423

Determination of carphedon in human urine by solid-phase microextraction using capillary gas chromatography with nitrogen-phosphorus detection.  

PubMed

Carphedon is a phenyl derivative of nootropil and is effective in increasing physical endurance and cold resistance, and is used for amnesia treatment. Carphedon was extracted from human urine samples by solid-phase microextraction with a 65 microns carbowax-divinylbenzene-coated fiber. This analysis was performed by using capillary gas chromatography with nitrogen-phosphorus detection and optimized at pH 9.6, 30% NaCl, immersion time 10 min and desorption in the GC injector at 250 degrees C for 3 min. The regression equation for carphedon showed good linearity in the range from 0.1 to 10 micrograms ml-1 for human urine samples. The limit of detection was 0.01 microgram ml-1. The developed method is more sensitive and simpler in sample preparation than liquid-liquid extraction and can be applied to doping analysis for stimulants. PMID:10746314

Kim, S; Park, J H; Myung, S W; Lho, D S

1999-11-01

424

Electrospray mass spectrometric detection of products and short-lived intermediates in aqueous aerosol microdroplets exposed to a reactive gas.  

PubMed

The intermediates ISO3- (m/z=207) and IS2O3- (m/z=239) generated in aqueous (NaI/Na2S2O3) microdroplets traversing dilute O3 gas plumes are detected via online electrospray mass spectrometry within approximately 1 ms, and their stabilities gauged by collisionally induced dissociation. The simultaneous detection of anionic reactants and the S2O62-, HSO4-, IO3-, and I3- products as a function of experimental conditions provides evidence of genuinely interfacial reaction kinetics. Although O3(aq) reacts about 3 times faster with I- than with S2O32- in bulk solution, only S2O32- is significantly depleted in the interfacial layers of [I-]/[S2O32-]=10 microdroplets below [O3(g)] approximately 50 ppm. PMID:18004824

Enami, S; Vecitis, C D; Cheng, J; Hoffmann, M R; Colussi, A J

2007-11-16

425

Spatial precision of H1 radial wire drift chambers using gas mixtures suitable for transition radiation detection  

NASA Astrophysics Data System (ADS)

Results are presented from calibration and tests of a radial wire drift chamber for the H1 experiment at the HERA ep collider. The chambers form part of the H1 forward track detector (FTD) and are designed both to determine accurate vector track segments and to identify simultaneously electrons by means of dE/dx measurement and transition radiation (TR) detection. The spatial reconstruction accuracy (from drift timing and charge division) has been investigated using gas mixtures suitable for TR X-ray detection. A novel technique for enhancing the precision of determination of the radial (non-drift) coordinate of each track using the drift cell geometry is evaluated. A brief summary of the performance of the three radial wire chambers in the FTD is given.

Bailey, J. M.; Beck, G. A.; Burke, S.; Dainton, J. B.; Gabathuler, E.; Gillespie, D. M.; Goodall, A. M.; Martin, R.; Maxfield, S. J.; McMahon, S. J.; Morton, J. M.; Patel, G. D.; Sankey, D. P. C.; Womersley, L. A.; Grässler, H.; Hohlmann, M.; Kemmerling, G.; Masson, S.; Pilgram, W.; Struczinski, W.; Kolya, S.; Clarke, D.; Flower, P. S.; Hill, D.; Marshall, R.

1992-12-01

426

Development of Peptide Nanotube-Modified Biosensors for Gas-Phase Organophosphate Detection.  

National Technical Information Service (NTIS)

Vapor-phase detection of the model organophosphate malathion was achieved using enzymes encapsulated in peptide nanotubes and attached to gold screen-printed electrodes. Malathion was chosen as the model for this experiment because its binding mechanism w...

P. A. Baker

2013-01-01

427

Detection of Soil Microogarnisms in Situ by Combined Gas Chromatography Mass Spectrometry.  

National Technical Information Service (NTIS)

Experimental tests were made to determine whether analysis of volatile metabolic products, formed in situ, is a viable procedure for an extraterrestrial life detection system. Laboratory experiments, carried out under anaerobic conditions with addition of...

M. Alexander J. M. Duxbury A. J. Francis J. Adamson

1972-01-01

428

Detection of Breast Masses in Mammogram Images Using Growing Neural Gas Algorithm and Ripley's K Function  

Microsoft Academic Search

Breast cancer is a serious public health problem in several countries. Computer-aided detection\\/diagnosis systems (CAD\\/CADx)\\u000a have been used with relative success in aid of health care professionals. The goal of such systems is not to replace the professionals,\\u000a but to join forces in order to detect the different types of cancer at an early stage. The main contribution of this

Leonardo De Oliveira Martins; Aristófanes Corrêa Silva; Anselmo Cardoso De Paiva; Marcelo Gattass

2009-01-01

429

Optical fibre sensor coated with porous silica layers for gas and chemical vapour detection  

Microsoft Academic Search

Fibre optic sensors have been conceived in new technologies for detecting very small amounts of chemical, gaseous and biological species. Recently, new polymer-clad silica (PCS) fibres coated with thin porous silica layers have been developed. These porous layers have been prepared by the sol-gel method using the dip-coating technique. In this work, this new material has been investigated for detecting

A. Abdelghani; J. M. Chovelon; N. Jaffrezic-Renault; M. Lacroix; H. Gagnaire; C. Veillas; B. Berkova; M. Chomat; V. Matejec

1997-01-01

430

Detection of a Circumstellar Gas around DM Tauri: A Protoplanetary Disk around a Single Star?  

Microsoft Academic Search

Sensitive molecular line observations carried out with the Nobeyama 45 m telescope have resulted in the detection of the 12CO (J = 1-0) and 13CO (J = 1-0) emission centered on the young, classical T Tauri star, DM Tau. The derived peak antenna temperatures are 0.3 K in 12CO and 0.1 K in 13CO. No C18O emission was detected at

Toshihiro Handa; Shoken M. Miyama; Takuya Yamashita; Toshihiro Omodaka; Yoshimi Kitamura; Masahiko Hayashi; Toshikazu Onishi; Ronald L. Snell; Stephen E. Strom; Karen M. Strom; Michael F. Skrutskie; Suzan Edwards; Nagayoshi Ohashi; Kazuyoshi Sunada; Masao Saito; Yasuo Fukui; Akira Mizuno; Jun-Ichi Watanabe; Hirokazu Kataza

1995-01-01

431

Photoionization\\/flame-ionization detection of atmospheric hydrocarbons after capillary gas chromatography  

Microsoft Academic Search

A ''gastight, low-volume'' photoionization detector (PID) has been constructed for the purpose of detecting trace hydrocarbons in atmospheric samples. This modified PID, in tandem with an FID (flame-ionization detector), was tested by use of a standard gaseous mixture of aromatics, alkenes, and alkanes. The average minimum detectable amounts for the PID were found to be 1.2 pg for aromatics, 2.0

Winai. Nutmagul; Dagmar R. Cronn; Herbert H. Hill

1983-01-01

432

Open-path trace gas detection of ammonia based on cavity-enhanced absorption spectroscopy  

NASA Astrophysics Data System (ADS)

A compact open-path optical ammonia detector is developed. A tunable external-cavity diode laser operating at 1.5 ?m is used to probe absorptions of ammonia via the cavity-enhanced absorption (CEA) technique. The detector is tested in a climate chamber. The sensitivity and linearity of this system are studied for ammonia and water at atmospheric pressure. A cluster of closely spaced rovibrational overtone and combination band transitions, observed as one broad absorption feature, is used for the detection of ammonia. On these molecular transitions a detection limit of 100 ppb (1 s) is determined. The ammonia measurements are calibrated independently with a chemiluminescence monitor. Compared to other optical open-path detection methods in the 1-2 ?m region, the present result shows an improved sensitivity for contactless ammonia detection by over one order of magnitude. Using the same set-up, a detection limit of 100 ppm (1 s) is determined for the detection of water at atmospheric pressure.

Peeters, R.; Berden, G.; Apituley, A.; Meijer, G.

433

Multiphase High-Velocity Gas Detected within 7 kpc Toward the M13 Globular Cluster  

NASA Astrophysics Data System (ADS)

We present medium-resolution ultraviolet interstellar absorption measurements recorded with the HST-COS and FUSE spectrographs toward the post-AGB star Barnard 29 in the M13 globular cluster. Inspection of the UV spectra has revealed absorption at V˜-60 km s in the absorption profiles of the C I, C II, C, C IV, N I, N II, N V, O I, ALII, Si II, Si IV, S II and Fe II ions. This component can be associated with an intermediate-velocity cloud (IVC), previously identified by both radio and visible observations. More importantly, these data have newly revealed high-velocity absorption at V=-121±3 km s in the UV ions of C II, C III, C IV, N II, Si II, and Si IV. This absorption is thought to arise in a highly ionized, multiphase high-velocity cloud (HVC) located a distance of 0.46gas in the ISM such as Na I, N I or O I. This makes it one of the four nearest highly ionized HVCs yet discovered. The observed column density ratios of the H V components to the C IV and Si IV lines are consistent with values predicted for a turbulent mixing layer or shock ionization of a gas cloud. We have derived estimates of the abundance ratios of C and Si with respect to N relative to their corresponding solar values. Our results indicate values of [Si/N]>+0.40±0.21 and [C/N]=+0.10±0.25 for the HVC gas component. These values indicate that the H V gas has higher than solar relative abundances, consistent with gas of a supersolar metallicity. Several other highly ionized HVCs with distances of less than 7.5 kpc have recently been shown to possess similarly high-metallicity values that are consistent with an origin in condensing returning gas from a galactic fountain.

Welsh, Barry Y.; Wheatley, Jonathan; Lallement, Rosine

2011-08-01

434

Detection system for a gas chromatograph. [. cap alpha. -methylnaphthalene,. beta. -methylnapthalene  

DOEpatents

A method and apparatus are described for the quantitative analysis of vaporizable compounds, and in particular of polycyclic aromatic hydrocarbons which may be induced to fluoresce. The sample to be analyzed is injected into a gas chromatography column and is eluted through a narrow orifice into a vacuum chamber. The free expansion of the eluted sample into the vacuum chamber creates a supersonic molecular beam in which the sample molecules are cooled to the extent that the excited vibrational and rotational levels are substantially depopulated. The cooled molecules, when induced to fluoresce by laser excitation, give greatly simplified spectra suitable for analytical purposes. The laser induced fluorimetry provides great selectivity, and the gas chromatograph provides quantitative transfer of the sample to the molecular beam. 3 figures, 2 tables.

Hayes, J.M.; Small, G.J.

1982-04-26

435

Potential of solid phase microextraction and gas chromatography for quarantine-required detection of wood packaging in shipping containers.  

PubMed

Solid phase microextraction (SPME) coupled with gas chromatography (GC) was used to detect terpene hydrocarbons inside shipping containers entering New Zealand. The utility of this system for the rapid detection of undeclared wood packaging for quarantine purposes was demonstrated. A portable dynamic air-sampling device was built to house a SPME fibre and allow the air from shipping containers to be sampled. The effects of sample flow rate and sampling time were investigated and sampling conditions of 100 mL/min for 30 s were chosen to keep sampling within the linear range. A CV of less than 15% (n = 12) was obtained for all the compounds analysed under these conditions. To obtain an estimate for the limit of detection (LOD) for the terpene hydrocarbons of interest, small quantities of lime oil were placed in an empty shipping container and the air inside was analysed. LOD (S/N = 3) was estimated to be in the order of 50-100 ng/L of air using GC with flame ionisation detection (GC-FID). Finally, the device was tested in fully laden containers and was shown to be effective for trapping terpene hydrocarbons indicative of wood packaging. PMID:17566339

More, Nicole A; Braggins, Terry J; Goldson, Stephen L

2007-05-01

436

Pulsed Quantum-Cascade Laser-Based Sensor for Trace-Gas Detection of Carbonyl Sulfide  

Microsoft Academic Search

Simultaneous exhaled carbonyl sulfide (OCS) and carbon dioxide concentration measurements in human breath are demonstrated with a compact pulsed quantum-cascade laser-based gas sensor. We achieved a noise-equivalent sensitivity (1sigma) of 1.2 parts per billion by measuring a well-isolated OCS P(11) absorption line in the nu3 band at 2057.6 cm^-1 using an astigmatic Herriott cell of 36-m optical path length and

Gerard Wysocki; Matt McCurdy; Stephen So; Damien Weidmann; Chad Roller; Robert F. Curl; Frank K. Tittel

2004-01-01

437

Application of pyrolysis-capillary gas chromatography with NPD detection in thermal degradation of polyphosphazenes study  

Microsoft Academic Search

Polyphosphazenes represent a unique class of polymers with a backbone composed of alternating phosphorous and nitrogen atoms.\\u000a The thermal behaviour and decomposition of a variety of polyphosphazenes depends on the type of side groups present. Especially\\u000a those that bear aryloxy side groups, possess a high temperature stability as well as excellent flame resistance. Pyrolysis-capillary\\u000a gas chromatography has been used in

Jürgen Paulsdorf; Hans-Dieter Wiemhöfer; Andrej Orinák; Petr Zámostný; Zden?k B?lohlav; David Baxter

2007-0