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Sample records for flame ionization detection

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

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

    2013-10-01

    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.

  2. Gas chromatography with simultaneous detection: Ultraviolet spectroscopy, flame ionization, and mass spectrometry.

    Gras, Ronda; Luong, Jim; Haddad, Paul R; Shellie, Robert A

    2018-05-08

    An effective analytical strategy was developed and implemented to exploit the synergy derived from three different detector classes for gas chromatography, namely ultraviolet spectroscopy, flame ionization, and mass spectrometry for volatile compound analysis. This strategy was achieved by successfully hyphenating a user-selectable multi-wavelength diode array detector featuring a positive temperature coefficient thermistor as an isothermal heater to a gas chromatograph. By exploiting the non-destructive nature of the diode array detector, the effluent from the detector was split to two parallel detectors; namely a quadrupole mass spectrometer and a flame ionization detector. This multi-hyphenated configuration with the use of three detectors is a powerful approach not only for selective detection enhancement but also for improvement in structural elucidation of volatile compounds where fewer fragments can be obtained or for isomeric compound analysis. With the diode array detector capable of generating high resolution gas phase spectra, the information collected provides useful confirmatory information without a total dependence on the chromatographic separation process which is based on retention time. This information-rich approach to chromatography is achieved without incurring extra analytical time, resulting in improvements in compound identification accuracy, analytical productivity, and cost. Chromatographic performance obtained from model compounds was found to be acceptable with a relative standard deviation of the retention times of less than 0.01% RSD, and a repeatability at two levels of concentration of 100 and 1000 ppm (v/v) of less than 5% (n = 10). With this configuration, correlation of data between the three detectors was simplified by having near identical retention times for the analytes studied. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Ethanol analysis by headspace gas chromatography with simultaneous flame-ionization and mass spectrometry detection.

    Tiscione, Nicholas B; Alford, Ilene; Yeatman, Dustin Tate; Shan, Xiaoqin

    2011-09-01

    Ethanol is the most frequently identified compound in forensic toxicology. Although confirmation involving mass spectrometry is desirable, relatively few methods have been published to date. A novel technique utilizing a Dean's Switch to simultaneously quantitate and confirm ethyl alcohol by flame-ionization (FID) and mass spectrometric (MS) detection after headspace sampling and gas chromatographic separation is presented. Using 100 μL of sample, the limits of detection and quantitation were 0.005 and 0.010 g/dL, respectively. The zero-order linear range (r(2) > 0.990) was determined to span the concentrations of 0.010 to 1.000 g/dL. The coefficient of variation of replicate analyses was less than 3.1%. Quantitative accuracy was within ±8%, ±6%, ±3%, and ±1.5% at concentrations of 0.010, 0.025, 0.080, and 0.300 g/dL, respectively. In addition, 1,1-difluoroethane was validated for qualitative identification by this method. The validated FID-MS method provides a procedure for the quantitation of ethyl alcohol in blood by FID with simultaneous confirmation by MS and can also be utilized as an identification method for inhalants such as 1,1-difluoroethane.

  4. Tandem sulfur chemiluminescence and flame ionization detection with planar microfluidic devices for the characterization of sulfur compounds in hydrocarbon matrices.

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

    2013-07-05

    The detection of sulfur compounds in different hydrocarbon matrices, from light hydrocarbon feedstocks to medium synthetic crude oil feeds provides meaningful information for optimization of refining processes as well as demonstration of compliance with petroleum product specifications. With the incorporation of planar microfluidic devices in a novel chromatographic configuration, sulfur compounds from hydrogen sulfide to alkyl dibenzothiophenes and heavier distributions of sulfur compounds over a wide range of matrices spanning across a boiling point range of more than 650°C can be characterized, using one single analytical configuration in less than 25min. In tandem with a sulfur chemiluminescence detector for sulfur analysis is a flame ionization detector. The flame ionization detector can be used to establish the boiling point range of the sulfur compounds in various hydrocarbon fractions for elemental specific simulated distillation analysis as well as profiling the hydrocarbon matrices for process optimization. Repeatability of less than 3% RSD (n=20) over a range of 0.5-1000 parts per million (v/v) was obtained with a limit of detection of 50 parts per billion and a linear range of 0.5-1000 parts per million with a correlation co-efficient of 0.998. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. The characterization of petroleum and creosote-contaminated soils: Class component analysis by thin layer chromatography with flame ionization detection

    Pollard, S.J.T.; Hrudey, S.E.; Fuhr, B.J.; Alex, R.F.; Holloway, L.R.

    1992-01-01

    The assessment and reclamation of coal tar, creosote and petroleum-contaminated sites is emerging as a major challenge to industry and the federal and provincial Canadian governments. Contaminants frequently include polynuclear aromatic compounds (PAH), several high molecular weight analogues of which are documented carcinogens. Adaptation of thin layer chromatography with flame ionization detection for the analysis of hydrocarbon-contaminated soils is described. The method is directly applicable to the analysis of oily waste extracts from petroleum and creosote wood preservative site soils and is capable of distinguishing between the saturate, aromatic and polar components of waste residues. The method provides a rapid, low cost class component analysis of heavy hydrocarbon waste extracts and is particularly useful for estimating the extent of weathering experienced by chronically exposed hydrocarbon wastes in the soil environment. As such, it is useful as a screening tool for a preliminary assessment of the biotreatability or inherent recalcitrance of hydrocarbon waste mixtures. 11 refs., 5 figs

  6. Ultrasound extraction and thin layer chromatography-flame ionization detection analysis of the lipid fraction in marine mucilage samples.

    Mecozzi, M; Amici, M; Romanelli, G; Pietrantonio, E; Deluca, A

    2002-07-19

    This paper reports an analytical procedure based on ultrasound to extract lipids in marine mucilage samples. The experimental conditions of the ultrasound procedure (solvent and time) were identified by a FT-IR study performed on different standard samples of lipids and of a standard humic sample, before and after the sonication treatment. This study showed that diethyl ether was a more suitable solvent than methanol for the ultrasonic extraction of lipids from environmental samples because it allowed to minimize the possible oxidative modifications of lipids due to the acoustic cavitation phenomena. The optimized conditions were applied to the extraction of total lipid amount in marine mucilage samples and TLC-flame ionization detection analysis was used to identify the relevant lipid sub-fractions present in samples.

  7. Determination of free amino compounds in betalainic fruits and vegetables by gas chromatography with flame ionization and mass spectrometric detection.

    Kugler, Florian; Graneis, Stephan; Schreiter, Pat P-Y; Stintzing, Florian C; Carle, Reinhold

    2006-06-14

    Amino acids and amines are the precursors of betalains. Therefore, the profiles of free amino compounds in juices obtained from cactus pears [Opuntia ficus-indica (L.) Mill. cv. Bianca, cv. Gialla, and cv. Rossa], pitaya fruits [Selenicereus megalanthus (K. Schumann ex Vaupel) Moran, Hylocereus polyrhizus (Weber) Britton & Rose, and Hylocereus undatus (Haworth) Britton & Rose], and in extracts from differently colored Swiss chard [Beta vulgaris L. ssp. cicla (L.) Alef. cv. Bright Lights] petioles and red and yellow beets (B. vulgaris L. ssp. vulgaris var. conditiva Alef. cv. Burpee's Golden) were investigated for the first time. Amino compounds were derivatized with propyl chloroformate. While gas chromatography (GC) with mass spectrometry was used for peak assignment, GC flame ionization detection was applied for quantification of individual compounds. Whereas proline was the major free amino compound of cactus pear and pitaya fruit juices, glutamine dominated in Swiss chard stems and beets, respectively. Interestingly, extremely high concentrations of dopamine were detected in Swiss chard stems and beets. Furthermore, the cleavage of betaxanthins caused by derivatization in alkaline reaction solutions is demonstrated for the first time. Amino acids and amines thus released might increase the actual free amino compound contents of the respective sample. To evaluate the contribution of betaxanthin cleavage to total amino acid and amine concentration, isolated betaxanthins were derivatized according to the "EZ:faast" method prior to quantification of the respective amino compounds released. On a molar basis, betaxanthin contribution to overall amino compound contents was always below 6.4%.

  8. Combined Determination of Poly-β-Hydroxyalkanoic and Cellular Fatty Acids in Starved Marine Bacteria and Sewage Sludge by Gas Chromatography with Flame Ionization or Mass Spectrometry Detection

    Odham, Göran; Tunlid, Anders; Westerdahl, Gunilla; Mårdén, Per

    1986-01-01

    Extraction of lipids from bacterial cells or sewage sludge samples followed by simple and rapid extraction procedures and room temperature esterification with pentafluorobenzylbromide allowed combined determinations of poly-β-hydroxyalkanoate constituents and fatty acids. Capillary gas chromatography and flame ionization or mass spectrometric detection was used. Flame ionization permitted determination with a coefficient of variation ranging from 10 to 27% at the picomolar level, whereas quantitative chemical ionization mass spectrometry afforded sensitivities for poly-β-hydroxyalkanoate constituuents in the attomolar range. The latter technique suggests the possibility of measuring such components in bacterial assemblies with as few as 102 cells. With the described technique using flame ionization detection, it was possible to study the rapid formation of poly-β-hydroxyalkanoate during feeding of a starved marine bacterium isolate with a complex medium or glucose and correlate the findings to changes in cell volumes. Mass spectrometric detection of short β-hydroxy acids in activated sewage sludge revealed the presence of 3-hydroxybutyric, 3-hydroxyhexanoic, and 3-hydroxyoctanoic acids in the relative proportions of 56, 5 and 39%, respectively. No odd-chain β-hydroxy acids were found. PMID:16347181

  9. Seasonal variation of gastroprotective terpenoids in Maytenus robusta (Celastraceae) quantified by gas chromatography-flame ionization detection (GC-FID).

    Zermiani, Tailyn; Junior, Antonio A S; Ferreira, Renê A; Wagner, Theodoro M; Machado, Marina S; Cechinel-Filho, Valdir; Niero, Rivaldo

    2016-11-01

    The triterpenes friedelin (1), β-friedelinol (2) and 3,15-dioxo-21α-hydroxyfriedelane (3) in the aerial parts of Maytenus robusta, a Brazilian medicinal plant with antiulcer potential, were seasonally quantified by gas chromatography flame-ionization detection (GC-FID) using an external standard. The method was found to be linear, precise and sensitive. Compounds 1 and 2 were found in M. robusta leaves and branches, with highest concentrations in the leaves collected in autumn, i.e. 3.21 ± 0.16 and 12.60 ± 1.49 mg g-1 dry weight of 1 and 2, respectively. On the other hand, compound 3 was found only in the branches, with the highest concentrations in winter and autumn (0.21 ± 0.01 and 0.20 ± 0.02 mg g-1). The results allow to define the optimal season and plant parts for the collection of M. robusta as a phytotherapeutic drug.

  10. Simultaneous determination of methanol, acetaldehyde, acetone, and ethanol in human blood by gas chromatography with flame ionization detection.

    Schlatter, J; Chiadmi, F; Gandon, V; Chariot, P

    2014-01-01

    Methanol, acetaldehyde, acetone, and ethanol, which are commonly used as biomarkers of several diseases, in acute intoxications, and forensic settings, can be detected and quantified in biological fluids. Gas chromatography (GC)-mass spectrometry techniques are complex, require highly trained personnel and expensive materials. Gas chromatographic determinations of ethanol, methanol, and acetone have been reported in one study with suboptimal accuracy. Our objective was to improve the assessment of these compounds in human blood using GC with flame ionization detection. An amount of 50 µl of blood was diluted with 300 µl of sterile water, 40 µl of 10% sodium tungstate, and 20 µl of 1% sulphuric acid. After centrifugation, 1 µl of the supernatant was injected into the gas chromatograph. We used a dimethylpolysiloxane capillary column of 30 m × 0.25 mm × 0.25 µm. We observed linear correlations from 7.5 to 240 mg/l for methanol, acetaldehyde, and acetone and from 75 to 2400 mg/l for ethanol. Precision at concentrations 15, 60, and 120 mg/l for methanol, acetaldehyde, and acetone and 150, 600, and 1200 mg/ml for ethanol were 0.8-6.9%. Ranges of accuracy were 94.7-98.9% for methanol, 91.2-97.4% for acetaldehyde, 96.1-98.7% for acetone, and 105.5-111.6% for ethanol. Limits of detection were 0.80 mg/l for methanol, 0.61 mg/l for acetaldehyde, 0.58 mg/l for acetone, and 0.53 mg/l for ethanol. This method is suitable for routine clinical and forensic practices.

  11. Quantitative Analysis of Humectants in Tobacco Products Using Gas Chromatography (GC with Simultaneous Mass Spectrometry (MSD and Flame Ionization Detection (FID

    Rainey CL

    2014-12-01

    Full Text Available This paper describes the modification of an existing gas chromatographic (GC method to incorporate simultaneous mass spectrometric (MSD and flame ionization detection (FID into the analysis of tobacco humectants. Glycerol, propylene glycol, and triethylene glycol were analyzed in tobacco labeled as roll-your-own (RYO, cigar, cigarette, moist snuff, and hookah tobacco. Tobacco was extracted in methanol containing 1,3-butanediol (internal standard, filtered, and separated on a 15 m megabore DB-Wax column. Post-column flow was distributed using a microfluidic splitter between the MSD and FID for simultaneous detection. The limits of detection for the FID detector were 0.5 μg/mL (propylene glycol and triethylene glycol and 0.25 μg/mL (glycerol with a linear range of 2-2000 μg/mL (propylene glycol and triethylene glycol and 1-4000 μg/mL (glycerol. The limits of detection for the MSD detector were 2 μg/mL (propylene glycol and triethylene glycol and 4 μg/mL (glycerol with a linear range of 20-2000 μg/mL (propylene glycol and triethylene glycol and 40-4000 μg/mL (glycerol. Significant improvement in the sensitivity of the MSD can be achieved by employing selective ion monitoring (SIM detection mode. Although a high degree of correlation was observed between the results from FID and MSD analyses, marginal chromatographic resolution between glycerol and triethylene glycol limits the applicability of FID to samples containing low levels of both of these humectants. Utilizing MSD greatly improves the reliability of quantitative results because compensation for inadequate chromatographic resolution can be accomplished with mass selectivity in detection.

  12. On-line purge-and-trap-gas chromatography with flame ionization detection as an alternative analytical method for dimethyl sulphide trace release from marine algae

    Careri, M.; Musci, M.; Bianchi, F.; Mucchino, C. [Parma Univ., Parma (Italy). Dipt. di Chimica Generale ed Inorganica, Chimica Analitica e Chimica Fisica; Azzoni, R.; Viaroli, P. [Parma Univ., Parma (Italy). Dipt. di Scienze Ambientali

    2001-10-01

    The release of dimethyl sulphide (DMS) by the seaweed Ulva spp at trace level was studied in aqueous solutions at different salinities, temperature and light intensities. For this purpose, the purge-and-trap technique combined with gas chromatography-flame ionization detection was used. The analytical method was evaluated in terms of linearity range, limit of detection, precision and accuracy by considering 10% (w/v) and 30% (w/v) synthetic seawater as aqueous matrices. Calculation of the recovery function evidenced a matrix influence. The method of standard addition was then used for an accurate determination of DMS in synthetic seawater reproduction the matrix effect. DMS fluxes were analysed in batch cultures of Ulva spp reproducing the conditions which usually occur in the Sacca di Goro lagoon (Northern Adriatic Sea, Italy). [Italian] Il rilascio di dimetilsolfuro (DMS) in tracce da parte della macroalga Ulva spp e' stato studiato in soluzioni acquose di differente salinita' mediante la tecnica purge-and-trap accoppiata on-line alla gascromatografia con rivelazione a ionizzazione di fiamma (GC-FID). Il metodo analitico e' stato validato in termini di linearita' di risposta, di limite di rivelabilita', precisione e accuratezza considerando come matrice acqua di mare sintetica a diversa salinita' (10%0 m/v e 30%0 m/v). Il calcolo della funzione di recupero ha consentito di verificare la presenza di errori sistematici dovuti all'effetto matrice. Il metodo sviluppato e' stato quindi applicato a matrici ambientali allo scopo di verificare il rilascio di DMS da parte di Ulva spp, operando in condizioni ambientali simili a quelle che si verificano nella Sacca di Goro (Ferrara, Italia).

  13. Reversed phase liquid chromatography with UV absorbance and flame ionization detection using a water mobile phase and a cyano propyl stationary phase Analysis of alcohols and chlorinated hydrocarbons.

    Quigley, W W; Ecker, S T; Vahey, P G; Synovec, R E

    1999-10-01

    The development of liquid chromatography with a commercially available cyano propyl stationary phase and a 100% water mobile phase is reported. Separations were performed at ambient temperature, simplifying instrumental requirements. Excellent separation efficiency using a water mobile phase was achieved, for example N=18 800, or 75 200 m(-1), was obtained for resorcinol, at a retention factor of k'=4.88 (retention time of 9.55 min at 1 ml min(-1) for a 25 cmx4.6 mm i.d. column, packed with 5 mum diameter particles with the cyano propyl stationary phase). A separation via reversed phase liquid chromatography (RP-LC) with a 100% water mobile phase of six phenols and related compounds was compared to a separation of the same compounds by traditional RP-LC, using octadecylsilane (ODS), i.e. C18, bound to silica and an aqueous mobile phase modified with acetonitrile. Nearly identical analysis time was achieved for the separation of six phenols and related compounds using the cyano propyl stationary phase with a 100% water mobile phase, as compared to traditional RP-LC requiring a relatively large fraction of organic solvent modifier in the mobile phase (25% acetonitrile:75% water). Additional understanding of the retention mechanism with the 100% water mobile phase was obtained by relating measured retention factors of aliphatic alcohols, phenols and related compounds, and chlorinated hydrocarbons to their octanol:water partition coefficients. The retention mechanism is found to be consistent with a RP-LC mechanism coupled with an additional retention effect due to residual hydroxyl groups on the cyano propyl stationary phase. Advantages due to a 100% water mobile phase for the chemical analysis of alcohol mixtures and chlorinated hydrocarbons are reported. By placing an absorbance detector in-series and preceding a novel drop interface to a flame ionization detector (FID), selective detection of a separated mixture of phenols and related compounds and aliphatic

  14. Flame Atmospheric Pressure Chemical Ionization Coupled with Negative Electrospray Ionization Mass Spectrometry for Ion Molecule Reactions.

    Cheng, Sy-Chyi; Bhat, Suhail Muzaffar; Shiea, Jentaie

    2017-07-01

    Flame atmospheric pressure chemical ionization (FAPCI) combined with negative electrospray ionization (ESI) mass spectrometry was developed to detect the ion/molecule reactions (IMRs) products between nitric acid (HNO 3 ) and negatively charged amino acid, angiotensin I (AI) and angiotensin II (AII), and insulin ions. Nitrate and HNO 3 -nitrate ions were detected in the oxyacetylene flame, suggesting that a large quantity of nitric acid (HNO 3 ) was produced in the flame. The HNO 3 and negatively charged analyte ions produced by a negative ESI source were delivered into each arm of a Y-shaped stainless steel tube where they merged and reacted. The products were subsequently characterized with an ion trap mass analyzer attached to the exit of the Y-tube. HNO 3 showed the strongest affinity to histidine and formed (M histidine -H+HNO 3 ) - complex ions, whereas some amino acids did not react with HNO 3 at all. Reactions between HNO 3 and histidine residues in AI and AII resulted in the formation of dominant [M AI -H+(HNO 3 )] - and [M AII -H+(HNO 3 )] - ions. Results from analyses of AAs and insulin indicated that HNO 3 could not only react with basic amino acid residues, but also with disulfide bonds to form [M-3H+(HNO 3 ) n ] 3- complex ions. This approach is useful for obtaining information about the number of basic amino acid residues and disulfide bonds in peptides and proteins. Graphical Abstract ᅟ.

  15. Determination of valproic acid in human plasma using dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection

    Fazeli-Bakhtiyari, Rana; Panahi-Azar, Vahid; Sorouraddin, Mohammad Hossein; Jouyban, Abolghasem

    2015-01-01

    Objective(s): Dispersive liquid-liquid microextraction coupled with gas chromatography (GC)-flame ionization detector was developed for the determination of valproic acid (VPA) in human plasma. Materials and Methods: Using a syringe, a mixture of suitable extraction solvent (40 µl chloroform) and disperser (1 ml acetone) was quickly added to 10 ml of diluted plasma sample containing VPA (pH, 1.0; concentration of NaCl, 4% (w/v)), resulting in a cloudy solution. After centrifugation (6000 rpm for 6 min), an aliquot (1 µl) of the sedimented organic phase was removed using a 1-µl GC microsyringe and injected into the GC system for analysis. One variable at a time optimization method was used to study various parameters affecting the extraction efficiency of target analyte. Then, the developed method was fully validated for its accuracy, precision, recovery, stability, and robustness. Results: Under the optimum extraction conditions, good linearity range was obtained for the calibration graph, with correlation coefficient higher than 0.998. Limit of detection and lower limit of quantitation were 3.2 and 6 μg/ml, respectively. The relative standard deviations of intra and inter-day analysis of examined compound were less than 11.5%. The relative recoveries were found in the range of 97 to 107.5%. Finally, the validated method was successfully applied to the analysis of VPA in patient sample. Conclusion: The presented method has acceptable levels of precision, accuracy and relative recovery and could be used for therapeutic drug monitoring of VPA in human plasma. PMID:26730332

  16. Magnetic covalent triazine framework for rapid extraction of phthalate esters in plastic packaging materials followed by gas chromatography-flame ionization detection.

    Yan, Zijun; He, Man; Chen, Beibei; Gui, Bo; Wang, Cheng; Hu, Bin

    2017-11-24

    Covalent triazine frameworks (CTFs), featuring with high surface area, good thermal, chemical and mechanical stability, are good adsorbents in sample pretreatment. Herein, magnetic CTFs/Ni composite was prepared by in situ reduction of nickel ions on CTFs matrix with a solvothermal method. The prepared CTFs/Ni composite exhibited good preparation reproducibility, high chemical stability, and high extraction efficiency for targeted phthalate esters (PAEs) due to π-π interaction and hydrophobic effect. The porous structure of CTFs/Ni composite benefited the fast transfer of target PAEs from aqueous solution to the adsorbents, and the integrated magnetism contributed to the rapid separation of adsorbents from sample and elution solution. Based on it, a novel method of magnetic solid phase extraction (MSPE) combined with gas chromatography-flame ionization detector (GC-FID) was developed for the analysis of PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-2-ethylhexl phthalate (DEHP), and di-n-octyl phthalate (DNOP) in plastic packaging materials. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) for six PAEs were found to be in the range of 0.024-0.085mg/kg. The linear range was 0.32-16mg/kg for DMP, DEP, 0.08-80mg/kg for DBP, 0.16-32mg/kg for BBP, DEHP, and 0.32-32mg/kg for DNOP, respectively. The enrichment factors ranged from 59 to 88-fold (theoretical enrichment factor was 133-fold). The proposed method was successfully applied to the analysis of PAEs in various plastic packaging materials with recoveries in the range of 70.6-119% for the spiked samples. This method is characterized with short operation time, high sensitivity, low consumption of harmful organic solvents and can be extended to the analysis of other trace aromatic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Qualitative and quantitative analysis of pyrolysis oil by gas chromatography with flame ionization detection and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry.

    Sfetsas, Themistoklis; Michailof, Chrysa; Lappas, Angelos; Li, Qiangyi; Kneale, Brian

    2011-05-27

    Pyrolysis oils have attracted a lot of interest, as they are liquid energy carriers and general sources of chemicals. In this work, gas chromatography with flame ionization detector (GC-FID) and two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) techniques were used to provide both qualitative and quantitative results of the analysis of three different pyrolysis oils. The chromatographic methods and parameters were optimized and solvent choice and separation restrictions are discussed. Pyrolysis oil samples were diluted in suitable organic solvent and were analyzed by GC×GC-TOFMS. An average of 300 compounds were detected and identified in all three samples using the ChromaToF (Leco) software. The deconvoluted spectra were compared with the NIST software library for correct matching. Group type classification was performed by use of the ChromaToF software. The quantification of 11 selected compounds was performed by means of a multiple-point external calibration curve. Afterwards, the pyrolysis oils were extracted with water, and the aqueous phase was analyzed both by GC-FID and, after proper change of solvent, by GC×GC-TOFMS. As previously, the selected compounds were quantified by both techniques, by means of multiple point external calibration curves. The parameters of the calibration curves were calculated by weighted linear regression analysis. The limit of detection, limit of quantitation and linearity range for each standard compound with each method are presented. The potency of GC×GC-TOFMS for an efficient mapping of the pyrolysis oil is undisputable, and the possibility of using it for quantification as well has been demonstrated. On the other hand, the GC-FID analysis provides reliable results that allow for a rapid screening of the pyrolysis oil. To the best of our knowledge, very few papers have been reported with quantification attempts on pyrolysis oil samples using GC×GC-TOFMS most of which make use of the

  18. Non-polar lipids characterization of Quinoa (Chenopodium quinoa) seed by comprehensive two-dimensional gas chromatography with flame ionization/mass spectrometry detection and non-aqueous reversed-phase liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection.

    Fanali, Chiara; Beccaria, Marco; Salivo, Simona; Tranchida, Peter; Tripodo, Giusy; Farnetti, Sara; Dugo, Laura; Dugo, Paola; Mondello, Luigi

    2015-07-08

    A chemical characterization of major lipid components, namely, triacylglycerols, fatty acids and the unsaponifiable fraction, in a Quinoa seed lipids sample is reported. To tackle such a task, non-aqueous reversed-phase high-performance liquid chromatography with mass spectrometry detection was employed. The latter was interfaced with atmospheric pressure chemical ionization for the analysis of triacylglycerols. The main triacylglycerols (>10%) were represented by OLP, OOL and OLL (P = palmitoyl, O = oleoyl, L = linoleoyl); the latter was present in the oil sample at the highest percentage (18.1%). Furthermore, fatty acid methyl esters were evaluated by gas chromatography with flame ionization detection. 89% of the total fatty acids was represented by unsaturated fatty acid methyl esters with the greatest percentage represented by linoleic and oleic acids accounting for approximately 48 and 28%, respectively. An extensive characterization of the unsaponifiable fraction of Quinoa seed lipids was performed for the first time, by using comprehensive two-dimensional gas chromatography with dual mass spectrometry/flame ionization detection. Overall, 66 compounds of the unsaponifiable fraction were tentatively identified, many constituents of which (particularly sterols) were confirmed by using gas chromatography with high-resolution time-of-flight mass spectrometry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Detection of ionized foods

    Beerens, H.

    1986-01-01

    Irradiated foods and feed might be identified with two kinds of tests: 1. biochemical: detection of specific products are not yet available 2. microbiological: when a microbial species dissapears from a sample of food i.e. it is not detectable after enrichment (for instance Coliforms in hamburgers) it is likely that the sample has been ionized [fr

  20. Resonance ionization detection of combustion radicals

    Cool, T.A. [Cornell Univ., Ithaca, NY (United States)

    1993-12-01

    Fundamental research on the combustion of halogenated organic compounds with emphasis on reaction pathways leading to the formation of chlorinated aromatic compounds and the development of continuous emission monitoring methods will assist in DOE efforts in the management and disposal of hazardous chemical wastes. Selective laser ionization techniques are used in this laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames.

  1. Field survey of Canadian background soils: Implications for a new mathematical gas chromatography-flame ionization detection approach for resolving false detections of petroleum hydrocarbons in clean soils.

    Kelly-Hooper, Francine; Farwell, Andrea J; Pike, Glenna; Kennedy, Jocelyn; Wang, Zhendi; Grunsky, Eric C; Dixon, D George

    2014-08-01

    The reference method for the Canada-wide standard (CWS) for petroleum hydrocarbons (PHCs) in soil provides laboratories with methods for generating accurate and reproducible soil analysis results. The CWS PHC tier 1 generic soil-quality guidelines apply to 4 carbon ranges/fractions: F1 (C6-C10), F2 (C10-C16), F3 (C16-C34), and F4 (>C34). The methods and guidelines were developed and validated for soils with approximately 5% total organic carbon (TOC). However, organic soils have much higher TOC levels because of biogenic organic compounds (BOCs) originating from sources such as plant waxes and fatty acids. Coextracted BOCs can have elevated F2-F4 concentrations, which can cause false exceedances of PHC soil guidelines. The present study evaluated false PHC detections in soil samples collected from 34 background sites. The list of analytes included soil type, TOC, polycyclic aromatic hydrocarbons (PAHs), F2, F3, F4, F3a (C16-C22), and F3b (C22-C34). Soils with 3% to 41% TOC falsely exceeded the CWS PHC 300 mg/kg F3 coarse soil guideline. It was previously demonstrated that clean peat had F2:F3b ratios of less than 0.10, while crude oil spiked peat and spiked sand had higher ratios of greater than 0.10. In the present background study, all of the clean organic soils with at least 300 mg/kg F3 had F2:F3b ratios of less than 0.10, which indicated false guideline exceedances. Clean inorganic soils had low F3 concentrations, resulting in high F2:F3b ratios of greater than 0.10. Validation field studies are required to determine if the F2:F3b 0.10 PHC presence versus absence threshold value is applicable to crude oil- and diesel-contaminated sites. © 2014 SETAC.

  2. Use of a radio-frequency resonance circuit in studies of alkali ionization in flames

    Borgers, A.J.

    1978-01-01

    The construction of a radio-frequency resonance system and its use in the study of alkali metal ionization in flames is described. The author re-determines the values of the alkali ionization rate constants for a CO flame with N 2 as diluent gas of known temperature using the RF resonance method. (Auth.)

  3. Progress on resonance ionization detection of combustion radicals

    Cool, T.A.

    1994-01-01

    Selective laser ionization techniques are used in our laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames. The progress made on the following three separate experiments during the past year is briefly described in this report. Flame Radical Concentration Measurements with VUV Spectroscopy; observation of hyperfine quantum beats in cyanogen; and the spectroscopy of the ClCO radical

  4. Homogeneous liquid-liquid extraction (HoLLE) via flotation combined with gas chromatography-flame ionization detection as a very simple, rapid and sensitive method for the determination of fenitrothion in water samples.

    Mashayekhi, Hossein Ali

    2013-01-01

    Homogeneous liquid-liquid extraction via flotation assistance (HoLLE-FA) and gas chromatography-flame ionization detection (GC-FID) was presented for the extraction and determination of fenitrothion in water samples. In this work, a rapid, simple and efficient HoLLE-FA method was developed based on applying low-density organic solvents without employing centrifugation. A special extraction cell was designed to facilitate the collection of low-density solvent extraction in the determination of fenitrothion in water samples. The water sample solution was added into an extraction cell that contained an appropriate mixture of extraction and homogeneous solvents. By using air flotation, the organic solvent was collected at the conical part of the designed cell. Under the optimum conditions, the method performance was studied in terms of the linear dynamic range (LDR from 1.0 up to 100 μg L⁻¹), linearity (r² > 0.998), and precision (repeatability extraction and determination of fenitrothion in three different water samples.

  5. The analysis of semi-volatile and non-volatile petroleum hydrocarbons in a soil/sediment matrix by capillary column gas chromatography/flame ionization detection (GC/FID)

    George, J.E. III; Thoma, J.J.; Hastings, M.

    1990-01-01

    A comprehensive analysis for semi-volatile and non-volatile fractions of petroleum hydrocarbons can be achieved by a solvent extraction/concentration techniques that will effectively extract these high molecular weight fractions from a soil matrix. The prepared extract is then injected directly into a gas chromatograph equipped with a capillary column and flame ionization detector. This technique applies to the following types of commercially available petroleum hydrocarbons: Diesel Nos. 2,4,5, and 6, fuel oils and several grades of lubrication oil. The identification of a particular petroleum hydrocarbon is determined visually by comparison of the samples with known hydrocarbon standards. Accurate quantitation of the chromatograms is possible by using peak area summation and the presence of an internal standard. The practical quantitation limit for the method is 10 mg/Kg for most fuel types. This paper presents a method for determining the concentration of these fuel types in soil. Data will be presented only on 10W40 lubrication oil in terms of method validation, calibration, percent recovery, and method detection limits. A discussion of the quatitation techniques used will also be included

  6. Use of a radio-frequency resonance circuit in studies of alkali ionization in flames

    Borgers, A.J.

    1978-01-01

    The context of the investigations are outlined with a short review about recent flame studies at Utrecht University and a discussion about discrepancies and agreements in the literature concerning alkali ionization in flames. The measuring technique chosen is described and the general design of the radio-frequency resonance system presented. The optical track measurements and the theoretical calculations of flame rise velocity are dealt with. The collisional ionization rate constants for Na, K and Cs are determined. The collisional-ionization rate constant for lithium is treated separately by reason of the hydroxide formation. Finally a theoretical model for the conducting flame in a weak, alternating electric field is developed. The relation betaeen the admittance and the flame conductivity in first order approximations is derived. (Auth.)

  7. Lab-In-Syringe automation of stirring-assisted room-temperature headspace extraction coupled online to gas chromatography with flame ionization detection for determination of benzene, toluene, ethylbenzene, and xylenes in surface waters.

    Horstkotte, Burkhard; Lopez de Los Mozos Atochero, Natalia; Solich, Petr

    2018-06-22

    Online coupling of Lab-In-Syringe automated headspace extraction to gas chromatography has been studied. The developed methodology was successfully applied to surface water analysis using benzene, toluene, ethylbenzene, and xylenes as model analytes. The extraction system consisted of an automatic syringe pump with a 5 mL syringe into which all solutions and air for headspace formation were aspirated. The syringe piston featured a longitudinal channel, which allowed connecting the syringe void directly to a gas chromatograph with flame ionization detector via a transfer capillary. Gas injection was achieved via opening a computer-controlled pinch valve and compressing the headspace, upon which separation was initialized. Extractions were performed at room temperature; yet sensitivity comparable to previous work was obtained by high headspace to sample ratio V HS /V Sample of 1.6:1 and injection of about 77% of the headspace. Assistance by in-syringe magnetic stirring yielded an about threefold increase in extraction efficiency. Interferences were compensated by using chlorobenzene as an internal standard. Syringe cleaning and extraction lasting over 10 min was carried out in parallel to the chromatographic run enabling a time of analysis of <19 min. Excellent peak area repeatabilities with RSD of <4% when omitting and <2% RSD when using internal standard corrections on 100 μg L -1 level were achieved. An average recovery of 97.7% and limit of detection of 1-2 μg L -1 were obtained in analyses of surface water. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Ionization detection system for aerosols

    Jacobs, M.E.

    1977-01-01

    This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system utilizes a measuring ionization chamber which is modified to minimize false alarms and reductions in sensitivity resulting from changes in ambient temperature. In the preferred form of the modification, an annular radiation shield is mounted about the usual radiation source provided to effect ionization in the measuring chamber. The shield is supported by a bimetallic strip which flexes in response to changes in ambient temperature, moving the shield relative to the source so as to vary the radiative area of the source in a manner offsetting temperature-induced variations in the sensitivity of the chamber. 8 claims, 7 figures

  9. Development of gas chromatography-flame ionization detection system with a single column and liquid nitrogen-free for measuring atmospheric C2-C12 hydrocarbons.

    Liu, Chengtang; Mu, Yujing; Zhang, Chenglong; Zhang, Zhibo; Zhang, Yuanyuan; Liu, Junfeng; Sheng, Jiujiang; Quan, Jiannong

    2016-01-04

    A liquid nitrogen-free GC-FID system equipped with a single column has been developed for measuring atmospheric C2-C12 hydrocarbons. The system is consisted of a cooling unit, a sampling unit and a separation unit. The cooling unit is used to meet the temperature needs of the sampling unit and the separation unit. The sampling unit includes a dehydration tube and an enrichment tube. No breakthrough of the hydrocarbons was detected when the temperature of the enrichment tube was kept at -90 °C and sampling volume was 400 mL. The separation unit is a small round oven attached on the cooling column. A single capillary column (OV-1, 30 m × 0.32 mm I.D.) was used to separate the hydrocarbons. An optimal program temperature (-60 ∼ 170 °C) of the oven was achieved to efficiently separate C2-C12 hydrocarbons. There were good linear correlations (R(2)=0.993-0.999) between the signals of the hydrocarbons and the enrichment amount of hydrocarbons, and the relative standard deviation (RSD) was less than 5%, and the method detection limits (MDLs) for the hydrocarbons were in the range of 0.02-0.10 ppbv for sampling volume of 400 mL. Field measurements were also conducted and more than 50 hydrocarbons from C2 to C12 were detected in Beijing city. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Automatic on-line monitoring of atmospheric volatile organic compounds: Gas chromatography-mass spectrometry and gas chromatography-flame ionization detection as complementary systems

    Blas, Maite de; Navazo, Marino; Alonso, Lucio; Durana, Nieves; Iza, Jon

    2011-01-01

    Traditionally air quality networks have been carrying out the continuous, on-line measurement of volatile organic compounds (VOC) in ambient air with GC-FID. In this paper some identification and coelution problems observed while using this technique in long-term measurement campaigns are described. In order to solve these problems a GC-MS was set up and operated simultaneously with a GC-FID for C 2 -C 11 VOCs measurement. There are few on-line, unattended, long term measurements of atmospheric VOCs performed with GC-MS. In this work such a system has been optimized for that purpose, achieving good repeatability, linearity, and detection limits of the order of the GC-FID ones, even smaller in some cases. VOC quantification has been made by using response factors, which is not frequent in on-line GC-MS. That way, the identification and coelution problems detected in the GC-FID, which may led to reporting erroneous data, could be corrected. The combination of GC-FID and GC-MS as complementary techniques for the measurement of speciated VOCs in ambient air at sub-ppbv levels is proposed. Some results of the measurements are presented, including concentration values for some compounds not found until now on public ambient air VOC databases, which were identified and quantified combining both techniques. Results may also help to correct previously published VOC data with wrongly identified compounds by reprocessing raw chromatographic data.

  11. Two suicidal fatalities due to the ingestion of chlorfenvinphos formulations: simultaneous determination of the pesticide and the petroleum distillates in tissues by gas chromatography-flame-ionization detection and gas chromatography-mass spectrometry.

    Martínez, María A; Ballesteros, Salomé

    2012-01-01

    Chlorfenvinphos (CFVP) is an organophosporus insecticide designated as a threat agent by the National Institutes of Health (NIH). However, there are very few reported cases of poisonings in humans and none with postmortem toxicological analysis. We report the first two fatalities due to suicidal massive ingestion of a veterinary formulation containing CFVP and petroleum distillates. Case 1: A 24-year-old woman was found dead by her mother. According to the police records, the room was filled with an odor of solvents or pesticides and feces. There was an empty bottle of Supona(®) near the body and a suicide note on a Bible on a table. The only relevant postmortem finding was that the lungs appeared congested and edematous. Case 2: A 60-year-old man committed in his van by ingesting an unknown product. The vehicle was locked and had an odor that resembled an acid, sulfate, or solvent according to different witnesses. There was a suicide note as well as multiple containers containing automobile products nearby. The stomach of the victim was filled with abundant pale greenish fluid with a similar odor to that presented in the vehicle. The simultaneous toxicological screening and quantitation of CFVP and petroleum distillates [a mixture of trimethylbenzene isomers (TMBs)] was performed by means of gas chromatography with flame-ionization detection (GC-FID) and confirmation was performed using gas chromatography-mass spectrometry (GC-MS). Disposition of CFVP and TMBs in different tissues were, respectively, as follows: Case 1: heart blood, 8.6 and 3.7 mg/L; liver, 60.0 and 33.4 mg/kg; and stomach contents, 1132 mg/L (792.4 mg total) and 377.0 mg/L (263.9 mg total). Case 2: heart blood, 4.4 and 6.5 mg/L; urine, 1.4 and detected (distillates suitable for toxicological investigation in forensic and clinical cases. This is crucial to solving poisoning cases in which the poisoning source is uncertain.

  12. Mechanism of the flame ionization detector. II. Isotope effects and heteroatom effects

    Holm, Torkil

    1997-01-01

    The relative molar flame ionization detecton (FID) response (RMR) for a hydrocarbon does not change when deuterium is substituted for hydrogen. The exception is methane for which an inverse deuterium effect of 3..5% is observed for tetradeuteriomethane. [13C]Methane shows an inverse isotope effect...... of 2%. The reason for the small or non-existent isotope effects is that H/2H exchange takes place in the pre-combustion hydrogenolysis in the flame. This was shown by taking samples from the lower part of the flame by means of a fused silica capillary probe. By the same technique the hydrogenolytic...

  13. Ionizing radiations, detection, dosimetry, spectrometry

    Blanc, D.

    1997-10-01

    A few works in French language are devoted to the detection of radiations. The purpose of this book is to fill a gap.The five first chapters are devoted to the properties of ionizing radiations (x rays, gamma rays, leptons, hadrons, nuclei) and to their interactions with matter. The way of classification of detectors is delicate and is studied in the chapter six. In the chapter seven are studied the statistics laws for counting and the spectrometry of particles is treated. The chapters eight to thirteen study the problems of ionization: charges transport in a gas, ionization chambers (theory of Boag), counters and proportional chambers, counters with 'streamers', chambers with derive, spark detectors, ionization chambers in liquid medium, Geiger-Mueller counters. The use of a luminous signal is the object of the chapters 14 to 16: conversion of a luminous signal in an electric signal, scintillators, use of the Cerenkov radiation. Then, we find the neutron detection with the chapter seventeen and the dosimetry of particles in the chapter eighteen. This book does not pretend to answer to specialists questions but can be useful to physicians, engineers or physics teachers. (N.C.)

  14. 40 CFR 1065.260 - Flame-ionization detector.

    2010-07-01

    .... For compression-ignition engines, two-stroke spark-ignition engines, and four-stroke spark-ignition... CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.260 Flame... that has compensation algorithms that are functions of other gaseous measurements and the engine's...

  15. DC field response of one-dimensional flames using an ionized layer model

    Xiong, Yuan

    2015-11-18

    We develop a simplified model to better explain electric current response when direct current (DC) is applied to a flame. In particular, different current responses have been observed by changing the polarity of the DC in a sub-saturated current regime that results from the presence of ions and electrons in the flame zone. A flame zone was modeled as a thin, ionized layer located in one-dimensional DC electric fields. We derived simplified model-governing equations from species equations by implementing mobility differences dependent on the type of charged particle, particularly between ions and electrons; we performed experiments to substantiate the model. Results showed that the sub-saturated current and local field intensity were significantly influenced by the polarity of the DC because of the combined effect of unequal mobility of charged particles and the position of the ionized layer in the gap relative to two electrodes. When an energized electrode is close to the ionized layer, applying a negative DC causes a more rapid increase in current than by applying a positive DC to the same electrode. Results from our experimental measurement of current using counterflow diffusion flames agreed qualitatively well with the model predictions. A sensitivity analysis using dimensional and non-dimensional parameters also supported the importance of the mobility difference and the relative location of the ionized layer on the electric current response.

  16. Determination of polycyclic aromatic hydrocarbons in palm oil mill effluent by soxhlet extraction and gas chromatography-flame ionization detector

    Nor Fairolzukry Ahmad Rasdy; Mohd Marsin Sanagi; Wan Aini Wan Ibrahim; Ahmedy Abu Naim

    2008-01-01

    A method has been developed for the determination of polycyclic aromatic hydrocarbons (PAHs) from palm oil mill effluent based on gas chromatography-flame ionization detection. Extraction of spiked PAHs (napthalene, fluorene phenanthrene, fluoranthene and pyrene) in palm oil waste was carried out by Soxhlet extraction using hexane-dichloromethane (60:40 v/v) as the solvent. Excellent separations were achieved using temperature programmed GC on Ultra-1 fused-silica capillary column (30 m x 250 μm ID), carrier gas helium at a flow rate of 1 mL/ min. (author)

  17. Automatic, non-intrusive, flame detection in pipelines

    Morgan, M.D.; Mehta, S.A.; Moore, R.G. [Calgary Univ., AB (Canada). Dept. of Chemical and Petroleum Engineering; Al-Himyary, T.J. [Al-Himyary Consulting Inc., Calgary, AB (Canada)

    2004-07-01

    Flames have been known to occur within small diameter pipes operating under conditions of high turbulent flow. Although there are several methods of flame detection, few offer remote, non-line-of-site detection. In particular, combustion cannot be detected in cases where flammable mixtures are carried in flare lines, storage tank vents, air drilling or improperly designed purging operations. Combustion noise is being examined as a means to address this problem. A study was conducted in which flames within a small diameter tube were automatically detected using high speed pressure measurements and a newly developed algorithm. Commercially available, high-pressure, dynamic-pressure transducers were used for the measurements. The results of an experimental study showed that combustion noise can be distinguished from other sources of noise by its inverse power law relationship with frequency. This paper presented a newly developed algorithm which provides early detection of flames when combined with high-speed pressure measurements. The algorithm can also separate combustion noise automatically from other sources of noise when combined with other filters. In this study, the noise generated by a fluttering check valve was attenuated using a stop band filter. This detection method was found to be very reliable under the conditions tests, as long as there was no flow restriction between the sensor and the flame. A flow restriction would have resulted in the detection of only the strongest flame noise. It was shown that acoustic flame detection can be applied successfully in flare stacks, industrial burners and turbine combustors. It can be 15 times more sensitive than optical or electrical methods in diagnosing combustion problems with lean burning combustors. It may also be the only method available in applications that require remote, non-line-of-sight detection. 11 refs., 3 tabs., 15 figs.

  18. Methane Formation by Flame-Generated Hydrogen Atoms in the Flame Ionization Detector

    Holm, Torkil; Madsen, Jørgen Øgaard

    1996-01-01

    , and conceivably all hydrocarbons are quantitatively converted into methane at temperatures below 600 C, that is, before the proper combustion has started. The splitting of the C-C bonds is preceded by hydrogenation of double and triple bonds and aromatic rings. The reactions, no doubt, are caused by hydrogen...... atoms, which are formed in the burning hydrogen and which diffuse into the inner core of the flame. The quantitative formation of methane appears to explain the "equal per carbon" rule for the detector response of hydrocarbons, since all carbons are "exchanged" for methane molecules....

  19. Selective detection of isomers with photoionization mass spectrometry for studies of hydrocarbon flame chemistry

    Cool, Terrill A.; Nakajima, Koichi; Mostefaoui, Toufik A.; Qi, Fei; McIlroy, Andrew; Westmoreland, Phillip R.; Law, Matthew E.; Poisson, Lionel; Peterka, Darcy S.; Ahmed, Musahid

    2003-01-01

    We report the first use of synchrotron radiation, continuously tunable from 8 to 15 eV, for flame-sampling photoionization mass spectrometry (PIMS). Synchrotron radiation offers important advantages over the use of pulsed vacuum ultraviolet lasers for PIMS; these include superior signal-to-noise, soft ionization, and access to photon energies outside the limited tuning ranges of current VUV laser sources. Near-threshold photoionization efficiency measurements were used to determine the absolute concentrations of the allene and propyne isomers of C 3 H 4 in low-pressure laminar ethylene-oxygen and benzene-oxygen flames. Similar measurements of the isomeric composition of C 2 H 4 O species in a fuel-rich ethylene-oxygen flame revealed the presence of substantial concentrations of ethenol (vinyl alcohol) and acetaldehyde. Ethenol has not been previously detected in hydrocarbon flames. Absolute photoionization cross sections were measured for ethylene, allene, propyne, and acetaldehyde, using propene as a calibration standard. PIE curves are presented for several additional reaction intermediates prominent in hydrocarbon flames

  20. A planar micro-flame ionization detector with an integrated guard electrode

    Kuipers, W J; Müller, J

    2008-01-01

    The flame ionization detector (FID) quantifies small concentrations of organic compounds by flame ionization of hydrocarbons and measurement of the resulting ion current. The ion current represents the number of carbon atoms in the sample gas. The miniaturization of the FID by MEMS technology (µFID) is expected to increase its use, because of reduced oxyhydrogen consumption. This loosens safety precautions and makes portable applications possible. In contrast to a former µFID design, the current planar µFID is designed to prevent environmental air from entering the system and deteriorating the measurement signal. The oxyhydrogen flame burns in the silicon plane of an almost completely encapsulating glass–silicon–glass sandwich. Only a small opening remains for removal of the exhaust gas from the system. In between the detector electrodes, a guard electrode is integrated to intercept and by-pass leak currents past the picoammeter, which then only measures the ion current. Due to the design of the guard electrode, small leak currents are still measured by the picoammeter. Yet, these leak currents can be corrected for to obtain the ion current. Measurements of the ion current as a function of the applied voltage and the sample gas flow show expected FID behaviour

  1. Detection of atomic oxygen in flames by absorption spectroscopy

    Cheskis, S.; Kovalenko, S.A.

    1994-01-01

    The absolute concentration of atomic oxygen in an atmospheric pressure hydrogen/air flame has been measured using Intracavity Laser Spectroscopy (ICLS) based on a dye laser pumped by an argon-ion laser. Absorptions at the highly forbidden transitions at 630.030 nm and 636.380 nm were observed at an equivalent optical length of up to 10 km. The relatively low intensity of the dye laser avoids photochemical interferences that are inherent to some other methods for detecting atomic oxygen. The detection sensitivity is about 6x10 14 atom/cm 3 and can be improved with better flame and laser stabilization. (orig.)

  2. Device for detecting ionizing radiation

    Anatychuk, L.I.; Kharitonov, J.P.; Kusniruk, V.F.; Meir, V.A.; Melnik, A.P.; Ponomarev, V.S.; Skakodub, V.A.; Sokolov, A.D.; Subbotin, V.G.; Zhukovsky, A.N.

    1980-01-01

    The present invention relates to ionizing radiation sensors, and , more particularly, to semiconductor spectrometers with thermoelectric cooling, and can most advantageously be used in mineral raw material exploration and evaluation under field conditions. The spectrometer comprises a vacuum chamber with an entrance window for passing the radiation therethrough. The vacuum chamber accommodates a thermoelectric cooler formed by a set of peltier elements. A heat conducting plate is mounted on the cold side of the thermoelectric cooler, and its hot side is provided with a radiator. Mounted on the heat conducting plate are sets of peltier elements, integral with the thermoelectric cooler and independent of one another. The peltier elements of these sets are stacked so as to develop the minimum temperature conditions on one set carrying a semiconductor detector and to provide the maximum refrigeration capacity conditions on the other set provided with the field-effect transistor mounted thereon

  3. Flame Front Detection Using Formaldehyde Laser Induced Fluorescence In Turbulent Lean Premixed Flames

    Schenker, S.; Tylli, N.; Bombach, R.

    2005-03-01

    The present work aims at suggesting the excitation-detection scheme best suited for laser-induced fluorescence measurements of formaldehyde in turbulent lean premixed flames. In the literature, three different excitation schemes within the A{sup 1} X{sup 1} electronic transition have been suggested, with excitation into the 2{sup 1}{sub 0} 4{sup 1}{sub 0} , 4{sup 1}{sub 0} , and 4{sup 0}{sub 1} vibratoric bands, respectively. These excitation schemes were tested systematically and both advantages and disadvantages for each scheme are discussed. (author)

  4. Performance appraisal studies of laser-enhanced ionization in flames - the determination of nickel in petroleum products

    Turk, G.C.; Harvilla, G.J.; Webb, J.D.; Forster, A.R.; Shell Development Co., Houston, TX; The Standard Oil Co., Cleveland, OH)

    1984-01-01

    Laser-enhanced ionization (LEI) in flames is an ultrasensitive atomic flame spectrometric technique based on the efficient thermal ionization of atomic species which have been selectively excited by tunable laser radiation. The performance of LEI for real sample analysis is presently being evaluated. A successful determination of trace Ni concentrations in heavy oil flash distillate and Standard Reference Material Fuel Oil has been performed. One gram samples were diluted into 100 to 700 mL volumes of a xylene/n-butanol solvent mixture and aspirated directly into an air-acetylene flame. Stepwise laser excitation of Ni was performed using a Nd:YAG pumped dual-dye laser system. Accurate and reproducible results were obtained. 17 refs., 1 fig., 1 tab

  5. Composite scintillators for detection of ionizing radiation

    Dai, Sheng [Knoxville, TN; Stephan, Andrew Curtis [Knoxville, TN; Brown, Suree S [Knoxville, TN; Wallace, Steven A [Knoxville, TN; Rondinone, Adam J [Knoxville, TN

    2010-12-28

    Applicant's present invention is a composite scintillator having enhanced transparency for detecting ionizing radiation comprising a material having optical transparency wherein said material comprises nano-sized objects having a size in at least one dimension that is less than the wavelength of light emitted by the composite scintillator wherein the composite scintillator is designed to have selected properties suitable for a particular application.

  6. Atmospheric Pressure Chemical Ionization Gas Chromatography Mass Spectrometry for the Analysis of Selected Emerging Brominated Flame Retardants in Foods

    Lv, Surong; Niu, Yumin; Zhang, Jing; Shao, Bing; Du, Zhenxia

    2017-03-01

    Emerging brominated flame retardants (eBFRs) other than polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and their derivatives in foods have been in focus in recent years due to their increasing production volumes, indefinite information on toxicities and the lack of data on occurrence in environments, foods as well as humans. In this study, gas chromatography was coupled to an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS) for the analysis of six eBFRs in pork, chicken, egg, milk and fish. A short section of unpacked capillary column coupled to the end of the analytical column was applied to improve the chromatographic behaviors of high boiling point compounds. The method was comprehensively validated with method limit of quantification (mLOQ) lower than 8 pg/g wet weight (w.w.). Samples from Chinese Total Diet study were quantified following the validated APGC-MS/MS method. 2,3,4,5-pentabromo-6-ethylbenzene (PBEB), hexabromobenzene (HBB), pentabromotoluene (PBT) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were most frequently detected in samples. The highest concentration was found in fish with 351.9 pg/g w.w. of PBT. This is the first report on the presence of PBT in food samples with non-ignorable concentrations and detection rate.

  7. Atmospheric Pressure Chemical Ionization Gas Chromatography Mass Spectrometry for the Analysis of Selected Emerging Brominated Flame Retardants in Foods.

    Lv, Surong; Niu, Yumin; Zhang, Jing; Shao, Bing; Du, Zhenxia

    2017-03-10

    Emerging brominated flame retardants (eBFRs) other than polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and their derivatives in foods have been in focus in recent years due to their increasing production volumes, indefinite information on toxicities and the lack of data on occurrence in environments, foods as well as humans. In this study, gas chromatography was coupled to an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS) for the analysis of six eBFRs in pork, chicken, egg, milk and fish. A short section of unpacked capillary column coupled to the end of the analytical column was applied to improve the chromatographic behaviors of high boiling point compounds. The method was comprehensively validated with method limit of quantification (mLOQ) lower than 8 pg/g wet weight (w.w.). Samples from Chinese Total Diet study were quantified following the validated APGC-MS/MS method. 2,3,4,5-pentabromo-6-ethylbenzene (PBEB), hexabromobenzene (HBB), pentabromotoluene (PBT) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were most frequently detected in samples. The highest concentration was found in fish with 351.9 pg/g w.w. of PBT. This is the first report on the presence of PBT in food samples with non-ignorable concentrations and detection rate.

  8. Nonproliferation and safeguarding via ionization detection

    Koster, J.E.; Johnson, J.P.; Steadman, P.

    1995-01-01

    A significant signature of the presence of special nuclear material (SNM) is ionizing radiation. SNM naturally decays with the emission of alpha particles, gamma rays, and neutrons. Detecting and monitoring these emissions is an important capability for international safeguards. A new detection method collects the ions produced by such radiation in ambient air. Alpha particles in particular are specific to heavy nuclei but have very short range. The ions produced by an alpha, however, can be transported tens of meters to an ion detector. These new monitors are rugged, very sensitive, respond in real time, and in most cases are quite portable

  9. Detection of food treated with ionizing radiation

    Delincee, H.

    1998-01-01

    Treatment of food with ionizing energy-'food irradiation'- is finally becoming reality in many countries. The benefits include an improvement in food hygiene, spoilage reduction and extension of shelf-life. Although properly irradiated food is safe and wholesome, consumers should be able to make their own free choice between irradiated and non-irradiated food. For this purpose labelling is indispensable. In order to check compliance with existing regulations, detection of radiation treatment by analysing the food itself is highly desirable. Significant progress has been made in recent years in developing analytical detection methods utilizing changes in food originating from the radiation treatment

  10. Radiation, ionization, and detection in nuclear medicine

    Gupta, Tapan K.

    2013-01-01

    Up-to-date information on a wide range of topics relating to radiation, ionization, and detection in nuclear medicine. In-depth coverage of basic radiophysics relating to diagnosis and therapy. Extensive discussion of instrumentation and radiation detectors. Detailed information on mathematical modelling of radiation detectors. Although our understanding of cancer has improved, the disease continues to be a leading cause of death across the world. The good news is that the recent technological developments in radiotherapy, radionuclide diagnostics and therapy, digital imaging systems, and detection technology have raised hope that cancer will in the future be combatted more efficiently and effectively. For this goal to be achieved, however, safe use of radionuclides and detailed knowledge of radiation sources are essential. Radiation, Ionization, and Detection in Nuclear Medicine addresses these subjects and related issues very clearly and elaborately and will serve as the definitive source of detailed information in the field. Individual chapters cover fundamental aspects of nuclear radiation, including dose and energy, sources, and shielding; the detection and measurement of radiation exposure, with detailed information on mathematical modelling; medical imaging; the different types of radiation detector and their working principles; basic principles of and experimental techniques for deposition of scintillating materials; device fabrication; the optical and electrical behaviors of radiation detectors; and the instrumentation used in nuclear medicine and its application. The book will be an invaluable source of information for academia, industry, practitioners, and researchers.

  11. Radiation, ionization, and detection in nuclear medicine

    Gupta, Tapan K. [Radiation Monitoring Devices Research, Nuclear Medicine, Watertown, MA (United States)

    2013-08-01

    Up-to-date information on a wide range of topics relating to radiation, ionization, and detection in nuclear medicine. In-depth coverage of basic radiophysics relating to diagnosis and therapy. Extensive discussion of instrumentation and radiation detectors. Detailed information on mathematical modelling of radiation detectors. Although our understanding of cancer has improved, the disease continues to be a leading cause of death across the world. The good news is that the recent technological developments in radiotherapy, radionuclide diagnostics and therapy, digital imaging systems, and detection technology have raised hope that cancer will in the future be combatted more efficiently and effectively. For this goal to be achieved, however, safe use of radionuclides and detailed knowledge of radiation sources are essential. Radiation, Ionization, and Detection in Nuclear Medicine addresses these subjects and related issues very clearly and elaborately and will serve as the definitive source of detailed information in the field. Individual chapters cover fundamental aspects of nuclear radiation, including dose and energy, sources, and shielding; the detection and measurement of radiation exposure, with detailed information on mathematical modelling; medical imaging; the different types of radiation detector and their working principles; basic principles of and experimental techniques for deposition of scintillating materials; device fabrication; the optical and electrical behaviors of radiation detectors; and the instrumentation used in nuclear medicine and its application. The book will be an invaluable source of information for academia, industry, practitioners, and researchers.

  12. Determination of mineral oil aromatic hydrocarbons in edible oils and fats by online liquid chromatography-gas chromatography-flame ionization detection - Evaluation of automated removal strategies for biogenic olefins.

    Nestola, Marco; Schmidt, Torsten C

    2017-07-07

    The determination of mineral oil aromatic hydrocarbons (MOAH) in foodstuffs gained in importance over the last years as carcinogenicity cannot be excluded for certain MOAH. The existence of olefins in foodstuffs, such as edible oils and fats, can be problematic for the determination of MOAH by LC-GC-FID. Removal of these interfering substances by HPLC based on polarity differences is not possible. During gas chromatographic separation heavily overloaded peaks are observed rendering the detection of small mineral oil contaminations almost impossible. Therefore, removal of these olefins is necessary before subjection of the sample to LC-GC-FID. Epoxidation of olefins to increase their polarity proved to be a valuable tool in the past. Precision and trueness of the results as shown in a collaborative trial, however, are relying on exact reaction conditions. Additionally, it is known that certain MOAH are oxidized during epoxidation and therefore get lost. In the scope of this work, hydroboration, bromohydrin reaction, and epoxidation were examined for their potential for derivatization of unsaturated hydrocarbons with increased robustness and higher recovery of MOAH. Epoxidation by meta-chloroperoxybenzoic acid (mCPBA) delivered the best removal of olefins. Factors influencing this reaction were enlightened. Adaption of the reaction conditions and time-controlled automation increased the recovery of polycyclic MOAH. Good precision (RSD r oils spiked with a lubricating mineral oil (at 24.5mg/kg of MOAH). The trueness of the method was verified by analyzing collaborative trial samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Calcium Alginate-Caged Multiwalled Carbon Nanotubes Dispersive Microsolid Phase Extraction Combined With Gas Chromatography-Flame Ionization Detection for the Determination of Polycyclic Aromatic Hydrocarbons in Water Samples.

    Abboud, Ayad Sami; Sanagi, Mohd Marsin; Ibrahim, Wan Aini Wan; Keyon, Aemi S Abdul; Aboul-Enein, Hassan Y

    2018-02-01

    In this study, caged calcium alginate-caged multiwalled carbon nanotubes dispersive microsolid phase extraction was described for the first time for the extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples prior to gas chromatographic analysis. Fluorene, phenanthrene and fluoranthene were selected as model compounds. The caged calcium alginate-caged multiwalled carbon nanotubes was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and thermal gravimetry analyses. The effective parameters namely desorption solvent, solvent volume, extraction time, desorption time, the mass of adsorbent and sample volume were optimized. Under the optimum extraction conditions, the developed method showed good linearity in the range of 0.5-50 ng mL-1 (R2 ≥ 0.996), low limits of detection and quantification (0.42-0.22 ng mL-1) (0.73-1.38 ng mL-1) respectively, good relative recoveries (71.2-104.2%) and reproducibility (RSD 1.8-12.4%, n = 3) for the studied PAHs in water sample. With high enrichment factor (1,000), short extraction time (<30 min), low amounts of adsorbent (100 mg) and low amounts of solvent (0.1 mol) have proven that the microsolid phase extraction method based on calcium alginate-caged multiwalled carbon nanotubes are environmentally friendly and convenient extraction method to use as an alternative adsorbent in the simultaneous preconcentration of PAHs from environmental water samples. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  14. Detection and measurement of ionizing radiation

    Anon.

    1990-01-01

    All detection or measurement of radiation rests in the possibility of recognizing the interactions of radiation with matter. When radiation passes through any kind of material medium, all or a portion of its energy is transferred to this medium. This transferred energy produces an effect in the medium. In principle, the detection of radiation is based on the appearance and the observation of this effect. In theory, all of the effects produced by radiation may be used in detecting it: in practice, the effects most commonly employed are: (1) ionization of gases (gas detectors), or of some chemical substance which is transformed by radiation (photographic or chemical dosimeters); (2) excitations in scintillators or semiconductors (scintillation counters, semiconductor counters); (3) creation of structural defects through the passage of radiation (transparent thermoluminescent and radioluminescent detectors); and (4) raising of the temperature (calorimeters). This study evaluates in detail, instruments based on the ionization of gases and the production of luminescence. In addition, the authors summarize instruments which depend on other forms of interaction, used in radiation medicine and hygiene (radiology, nuclear medicine)

  15. Pencil-shaped radiation detection ionization chamber

    Suzuki, A.

    1979-01-01

    A radiation detection ionization chamber is described. It consists of an elongated cylindrical pencil-shaped tubing forming an outer wall of the chamber and a center electrode disposed along the major axis of the tubing. The length of the chamber is substantially greater than the diameter. A cable connecting portion at one end of the chamber is provided for connecting the chamber to a triaxial cable. An end support portion is connected at the other end of the chamber for supporting and tensioning the center electrode. 17 claims

  16. Waveshifters and Scintillators for Ionizing Radiation Detection

    Baumgaugh, B.; Bishop, J.; Karmgard, D.; Marchant, J.; McKenna, M.; Ruchti, R.; Vigneault, M.; Hernandez, L.; Hurlbut, C.

    2007-01-01

    Scintillation and waveshifter materials have been developed for the detection of ionizing radiation in an STTR program between Ludlum Measurements, Inc. and the University of Notre Dame. Several new waveshifter materials have been developed which are comparable in efficiency and faster in fluorescence decay than the standard material Y11 (K27) used in particle physics for several decades. Additionally, new scintillation materials useful for fiber tracking have been developed which have been compared to 3HF. Lastly, work was done on developing liquid scintillators and paint-on scintillators and waveshifters for high radiation environments

  17. Application of gas chromatography/flame ionization detector-based metabolite fingerprinting for authentication of Asian palm civet coffee (Kopi Luwak).

    Jumhawan, Udi; Putri, Sastia Prama; Yusianto; Bamba, Takeshi; Fukusaki, Eiichiro

    2015-11-01

    Development of authenticity screening for Asian palm civet coffee, the world-renowned priciest coffee, was previously reported using metabolite profiling through gas chromatography/mass spectrometry (GC/MS). However, a major drawback of this approach is the high cost of the instrument and maintenance. Therefore, an alternative method is needed for quality and authenticity evaluation of civet coffee. A rapid, reliable and cost-effective analysis employing a universal detector, GC coupled with flame ionization detector (FID), and metabolite fingerprinting has been established for discrimination analysis of 37 commercial and non-commercial coffee beans extracts. gas chromatography/flame ionization detector (GC/FID) provided higher sensitivity over a similar range of detected compounds than GC/MS. In combination with multivariate analysis, GC/FID could successfully reproduce quality prediction from GC/MS for differentiation of commercial civet coffee, regular coffee and coffee blend with 50 wt % civet coffee content without prior metabolite details. Our study demonstrated that GC/FID-based metabolite fingerprinting can be effectively actualized as an alternative method for coffee authenticity screening in industries. Copyright © 2015. Published by Elsevier B.V.

  18. Determination of 2-Octanone in Biological Samples Using Liquid–Liquid Microextractions Followed by Gas Chromatography–Flame Ionization Detectio

    Abolghasem Jouyban, Maryam Abbaspour, Mir Ali Farajzadeh, Maryam Khoubnasabjafari

    2017-06-01

    Full Text Available Background: Analysis of chemicals in biological fluids is required in many areas of medical sciences. Rapid, highly efficient, and reliable dispersive and air assisted liquid–liquid microextraction methods followed by gas chromatography-flame ionization detection were developed for the extraction, preconcentration, and determination of 2-octanone in human plasma and urine samples. Methods: Proteins of plasma samples are precipitated by adding methanol and urine sample is diluted with water prior to performing the microextraction procedure. Fine organic solvent droplets are formed by repeated suction and injection of the mixture of sample solution and extraction solvent into a test tube with a glass syringe. After extraction, phase separation is performed by centrifuging and the enriched analyte in the sedimented organic phase is determined by the separation system. The main factors influencing the extraction efficiency including extraction solvent type and volume, salt addition, pH, and extraction times are investigated. Results: Under the optimized conditions, the proposed method showed good precision (relative standard deviation less than 7%. Limit of detection and lower limit of quantification for 2-octanone were obtained in the range of 0.1–0.5 µg mL−1. The linear ranges were 0.5-500 and 0.5-200 µg mL−1 in plasma and urine, respectively (r2 ≥ 0.9995. Enrichment factors were in the range of 13-37. Good recoveries (55–86% were obtained for the spiked samples. Conclusion: Preconcentration methods coupled with GC analysis were developed and could be used to monitor 2-octanone in biological samples.

  19. Ionizing particle detection based on phononic crystals

    Aly, Arafa H., E-mail: arafa16@yahoo.com, E-mail: arafa.hussien@science.bsu.edu.eg; Mehaney, Ahmed; Eissa, Mostafa F. [Physics Department, Faculty of Science, Beni-Suef University, Beni-Suef (Egypt)

    2015-08-14

    Most conventional radiation detectors are based on electronic or photon collections. In this work, we introduce a new and novel type of ionizing particle detector based on phonon collection. Helium ion radiation treats tumors with better precision. There are nine known isotopes of helium, but only helium-3 and helium-4 are stable. Helium-4 is formed in fusion reactor technology and in enormous quantities during Big Bang nucleo-synthesis. In this study, we introduce a technique for helium-4 ion detection (sensing) based on the innovative properties of the new composite materials known as phononic crystals (PnCs). PnCs can provide an easy and cheap technique for ion detection compared with conventional methods. PnC structures commonly consist of a periodic array of two or more materials with different elastic properties. The two materials are polymethyl-methacrylate and polyethylene polymers. The calculations showed that the energies lost to target phonons are maximized at 1 keV helium-4 ion energy. There is a correlation between the total phonon energies and the transmittance of PnC structures. The maximum transmission for phonons due to the passage of helium-4 ions was found in the case of making polyethylene as a first layer in the PnC structure. Therefore, the concept of ion detection based on PnC structure is achievable.

  20. Whole body personnel monitoring via ionization detection

    Koster, J.E.; Bounds, K.A.; Kerr, P.L.; Steadman, P.A.; Whitley, C.R.

    1998-02-01

    A project between Fernald EMP and LANL is to field a monitor for the detection of alpha-emitting contamination on a human body. Traditional personnel monitoring for alpha emitters involves either frisking with a probe or pressing against large detectors in order to overcome the short range of alpha particles. These methods have a low alpha collection efficiency, and can miss contamination on less accessible surfaces. The authors have investigated the sensitivity and practicality of measuring the entire subject simultaneously using the technique of ionization monitoring. The goal is to create a booth that personnel step into quickly during egress from radiological facilities. The detection technique relies on a breeze of air passing over the subject. Alpha emission produces copious ions in the ambient air which are transported by the air current to an ion collector, resulting in a small electrical current proportional to the amount of contamination. Results indicate a conservative sensitivity of 3,000 disintegrations per minute localized to one of five areas of the body in a measurement lasting less than 2 minutes

  1. Detection of halogenated flame retardants in polyurethane foam by particle induced X-ray emission

    Maley, Adam M.; Falk, Kyle A.; Hoover, Luke; Earlywine, Elly B.; Seymour, Michael D.; DeYoung, Paul A.; Blum, Arlene; Stapleton, Heather M.; Peaslee, Graham F.

    2015-01-01

    A novel application of particle-induced X-ray emission (PIXE) has been developed to detect the presence of chlorinated and brominated flame retardant chemicals in polyurethane foams. Traditional Gas Chromatography–Mass Spectrometry (GC–MS) methods for the detection and identification of halogenated flame retardants in foams require extensive sample preparation and data acquisition time. The elemental analysis of the halogens in polyurethane foam performed by PIXE offers the opportunity to identify the presence of halogenated flame retardants in a fraction of the time and sample preparation cost. Through comparative GC–MS and PIXE analysis of 215 foam samples, excellent agreement between the two methods was obtained. These results suggest that PIXE could be an ideal rapid screening method for the presence of chlorinated and brominated flame retardants in polyurethane foams

  2. Detection of halogenated flame retardants in polyurethane foam by particle induced X-ray emission

    Maley, Adam M.; Falk, Kyle A.; Hoover, Luke; Earlywine, Elly B.; Seymour, Michael D. [Department of Chemistry, Hope College, 35 E. 12th Street, Holland, MI 49423 (United States); DeYoung, Paul A. [Department of Physics, Hope College, 27 Graves Place, Holland, MI 49423 (United States); Blum, Arlene [Green Science Policy Institute, Box 5455, Berkeley, CA 94705 (United States); Stapleton, Heather M. [Nicholas School of the Environment, Duke University, LSRC Box 90328, Durham, NC 27708 (United States); Peaslee, Graham F., E-mail: peaslee@hope.edu [Department of Chemistry, Hope College, 35 E. 12th Street, Holland, MI 49423 (United States)

    2015-09-01

    A novel application of particle-induced X-ray emission (PIXE) has been developed to detect the presence of chlorinated and brominated flame retardant chemicals in polyurethane foams. Traditional Gas Chromatography–Mass Spectrometry (GC–MS) methods for the detection and identification of halogenated flame retardants in foams require extensive sample preparation and data acquisition time. The elemental analysis of the halogens in polyurethane foam performed by PIXE offers the opportunity to identify the presence of halogenated flame retardants in a fraction of the time and sample preparation cost. Through comparative GC–MS and PIXE analysis of 215 foam samples, excellent agreement between the two methods was obtained. These results suggest that PIXE could be an ideal rapid screening method for the presence of chlorinated and brominated flame retardants in polyurethane foams.

  3. Mechanism of the flame ionization detector. II. Isotope effects and heteroatom effects

    Holm, Torkil

    1997-01-01

    reactions in the hydrogen flame of compounds added to the hydrogen gas in low concentrations were followed. Alcohols, ethers, ketones, and esters all produced methane and carbon monoxide, while amines produced methane and hydrogen cyanide, halogen compounds methane and hydrogen halide, etc. The FID response...

  4. Analysis of benzene, toluene, ethylbenzene and xylenes in soils by headspace and gas chromatography/flame ionization detector

    Jurandir Pereira Pinto

    2006-02-01

    Full Text Available The constituents of gasoline: benzene, toluene, ethylbenzene and xylenes (BTEX are frequently found in soils due to leaks in fuel storage tanks and they present chronic toxicity. In this work it was developed and validated a methodology of BTEX analysis in soil by gas chromatography/ flame ionization detector and static headspace. The recovery of BTEX in soil samples was evaluated using soils with different textures (sandy and loamy. The analysis method showed good resolution, in a low time of analysis (less than 30 minutes. Limits of quantification of 0.05 mg Kg¯¹ soil for benzene, toluene, ethylbenzene and xylenes are below the guiding values that range from 0.15 to 95 mg Kg¯¹ soil, established to determine soil quality. It was verified that the methodology enables the use of this method for BTEX analysis of soil samples for passive environmental identification of gas stations.

  5. Preliminary evaluation of a method using an FID (flame ionization detector) for measurement of methanol in auto emissions. Final report

    Gabele, P.A.; Ray, W.D.; Duncan, J.; Burton, C.

    1987-09-01

    This report evaluates a simplified technique for estimating methanol emission rates in auto exhaust. The technique, referred to as the FID Bubbled Method or FBM, is based in principle on the fact that, while hydrocarbons are not readily absorbed in water, methanol is. Hence, by using a heated flame ionization detector to measure the organic mass in samples before and after bubbling them in water, the quantity of methanol originally present can be estimated by taking the difference between the measurements. Evaluation of the method was done by comparing methanol measurements using the FBM with measurements made using an established reference method. Results showed poor to fair agreement between the two methods. The FBM appeared better at estimating methanol emission rates from evaporative tests than from exhaust tests and also exhibited better accuracy for samples containing higher levels of methanol

  6. Food ionization: principles, nutritional aspects and detection

    Raffi, J.

    1992-01-01

    This document reviews the possible applications of ionizing radiations in the food industry, pointing out the principles of the treatment and its consequences on the nutritionnal value of the product. The last part gives the present status of the researches about the identification of irradiated foodstuffs and of the concerted action sponsored by the Community Bureau of Reference from the Commission of the European Communities

  7. Detection of carbon monoxide (CO) in sooting hydrocarbon flames using femtosecond two-photon laser-induced fluorescence (fs-TPLIF)

    Wang, Yejun; Kulatilaka, Waruna D.

    2018-01-01

    Ultrashort-pulse, femtosecond (fs)-duration, two-photon laser-induced fluorescence (fs-TPLIF) measurements of carbon monoxide (CO) are reported in rich, sooting hydrocarbon flames. CO-TPLIF detection using conventional nanosecond or picosecond lasers are often plagued by photochemical interferences, specifically under fuel-rich flames conditions. In the current study, we investigate the commonly used CO two-photon excitation scheme of the B1Σ+ ← X1Σ+ electronic transition, using approximately 100-fs-duration excitation pulses. Fluorescence emission was observed in the Ångström band originating from directly populated B1Σ+ upper state, as well as, in the third positive band from collisionally populated b3Σ+ upper state. The current work was focused on the Ångström band emission. Interference from nascent C2 emissions originating from hot soot particles in the flame could be reduced to a negligible level using a narrower detection gate width. In contrast, avoiding interferences from laser-generated C2 Swan-band emissions required specific narrowband spectral filtering in sooting flame conditions. The observed less than quadratic laser pulse energy dependence of the TPLIF signal suggests the presence of strong three-photon ionization and stimulated emission processes. In a range of CH4/air and C2H4/air premixed flames investigated, the measured CO fluorescence signals agree well with the calculated equilibrium CO number densities. Reduced-interference CO-TPLIF imaging in premixed C2H4/O2/N2 jet flames is also reported.

  8. Ethanol concentration in 56 refillable electronic cigarettes liquid formulations determined by headspace gas chromatography with flame ionization detector (HS-GC-FID).

    Poklis, Justin L; Wolf, Carl E; Peace, Michelle R

    2017-10-01

    Personal battery-powered vaporizers or electronic cigarettes were developed as an alternative to traditional cigarettes. The modern electronic cigarettes were patented in 2004 by Hon Lik in China. In May 2016, the US Food and Drug Administration (FDA) imposed regulatory statutes on e-cigarettes and their liquid formulations (e-liquids); prior to that, they were unregulated. E-liquids are typically composed of propylene glycol and/or glycerin, flavouring component(s), and active ingredient(s), such as nicotine. Fifty-six commercially available e-liquids, purchased from various sources, contained a variety of flavours and active ingredients. A headspace gas chromatography with flame ionization detector (HS-GC-FID) method was used to analyze these e-liquids for volatiles content. Only one of the e-liquids listed ethanol as a component. The chromatographic separation of volatiles was performed on a Restek BAC-1 column. A linear calibration was generated for ethanol with limits of detection and quantification (LOD/LOQ) of 0.05 mg/mL. Ethanol concentrations in the 56 e-liquids ranged from none detected to 206 mg/mL. The ethanol determined in these products may have been used in flavourants or a solvent; the reason for inclusion cannot be fully ascertained. The implications of vaporizing ethanol as an e-liquid component are unknown. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  9. Quantification of Biogenic Volatile Organic Compounds with a Flame Ionization Detector Using the Effective Carbon Number Concept

    Faiola, C. L.; Erickson, M. H.; Fricaud, V. L.; Wallace, H. W.; Jobson, B. T.; VanReken, T. M.

    2011-12-01

    Biogenic volatile organic compounds (BVOCs) are emitted into the atmosphere by plants and include structurally complex organic molecules such as monoterpenes, sesquiterpenes, and their oxygenated derivatives. These BVOCs are among the principle factors influencing the oxidative capacity of the atmosphere in forested regions. BVOC emission rates are often measured by collecting samples onto adsorptive cartridges in the field and then transporting these samples to the laboratory for chromatographic analysis. One of the most commonly used detectors in gas chromatography is the flame ionization detector (FID) due to its broad linear range, high sensitivity, and predictable response to many compounds. The FID response to saturated aliphatic molecules is proportional to carbon number. However, deviations occur as the complexity of the molecular structure increases. To account for these deviations, Sternberg et al. (1962) developed the effective carbon number (ECN) concept, which describes the number of carbons the FID "effectively" responds to. The ECN of a complex molecule can be estimated from the number and type of functional groups present, allowing an estimate of relative response factors for quantification. This approach is particularly useful for applications where samples contain a mixture of organic compounds and standards are not realistically accessible- a common predicament for environmental measurements. ECNs for a limited number of compounds with varying functional groups have been quantified in previous studies. However, there remain large gaps in the variety of compounds for which published data are available. This results in higher than necessary uncertainties when quantifying compounds that are structurally dissimilar to those that have been reported in the literature. The purpose of this study was to determine the ECN for a variety of terpenoid compounds to enable improved quantification of BVOC measurements. A dynamic dilution system was developed to

  10. A New Supersensitive Flame Detector and its Use for Early Forest Fire Detection

    Peskov, Vladimir

    2007-01-01

    A new flame detector, three orders of magnitude more powerful than the existing ones, is presented. This detector needs to be mass-produced for its use in order to be incorporated in an early forest fire detection system. A project able to implement its use to overcome the forest fire emergency is described.

  11. Ionizing radiation source detection by personal TLD

    Marinkovic, O.; Mirkov, Z.

    2002-01-01

    The Laboratory for personal dosimetry has about 3000 workers under control. The most of them work in medicine. Some institutions, as big health centers, have different ionizing radiation sources. It is usefull to analyze what has been the source of irradiation, special when appears a dosimeter with high dose. Personal dosimetry equipment is Harshaw TLD Reader Model 6600 and dosimeters consist of two chips LiF TLD-100 assembled in bar-coded cards which are wearing in holders with one tissue-equivalent filter (to determine H(10)) and skin-equivalent the other (to determine H(0.07)). The calibration dosimeters have been irradiated in holders by different sources: x-ray (for 80keV and 100keV), 6 0C o, 9 0S r (for different distances from beta source) and foton beem (at radiotherapy accelerator by 6MeV, 10MeV and 18MeV). The dose ratio for two LiF cristals was calculated and represented with graphs. So, it is possible to calculate the ratio H(10)/H(0.07) for a personal TLD and analyze what has been the source of irradiation. Also, there is the calibration for determination the time of irradiation, according to glow curve deconvolution

  12. Dark Matter Detection Using Helium Evaporation and Field Ionization.

    Maris, Humphrey J; Seidel, George M; Stein, Derek

    2017-11-03

    We describe a method for dark matter detection based on the evaporation of helium atoms from a cold surface and their subsequent detection using field ionization. When a dark matter particle scatters off a nucleus of the target material, elementary excitations (phonons or rotons) are produced. Excitations which have an energy greater than the binding energy of helium to the surface can result in the evaporation of helium atoms. We propose to detect these atoms by ionizing them in a strong electric field. Because the binding energy of helium to surfaces can be below 1 meV, this detection scheme opens up new possibilities for the detection of dark matter particles in a mass range down to 1  MeV/c^{2}.

  13. Dark Matter Detection Using Helium Evaporation and Field Ionization

    Maris, Humphrey J.; Seidel, George M.; Stein, Derek

    2017-11-01

    We describe a method for dark matter detection based on the evaporation of helium atoms from a cold surface and their subsequent detection using field ionization. When a dark matter particle scatters off a nucleus of the target material, elementary excitations (phonons or rotons) are produced. Excitations which have an energy greater than the binding energy of helium to the surface can result in the evaporation of helium atoms. We propose to detect these atoms by ionizing them in a strong electric field. Because the binding energy of helium to surfaces can be below 1 meV, this detection scheme opens up new possibilities for the detection of dark matter particles in a mass range down to 1 MeV /c2 .

  14. Investigation of the profile of phenolic compounds in the leaves and stems of Pandiaka heudelotii using gas chromatography coupled with flame ionization detector.

    Ifeanacho, Mercy O; Ikewuchi, Catherine C; Ikewuchi, Jude C

    2017-05-01

    The profile of phenolic compounds in the leaves and stems of Pandiaka heudelotii was investigated using gas chromatography coupled with flame ionization detector. The leaves and stems had high flavonoids and benzoic acid derivatives content, and moderate levels of lignans and hydroxycinnamates. Twenty-eight known flavonoids were detected, which consisted mainly of kaempferol (41.93% in leaves and 47.97% in stems), (+)-catechin (17.12% in leaves and 16.11% in stems), quercetin (13.83% in leaves and 9.39% in stems), luteolin (7.34% in leaves and 7.71% in stems), and artemetin (6.53% in leaves and 4.83% in stems). Of the six known hydroxycinnamates detected, chlorogenic acid (80.79% in leaves and 87.56% in stems) and caffeic acid (18.98% in leaves and 12.30% in stems) were the most abundant, while arctigenin (77.81% in leaves and 83.40% in stems) and retusin (13.82% in leaves and 10.59% in stems) were the most abundant of the nine known lignans detected. Twelve known benzoic acid derivatives were detected, consisting mainly of ellagic acid (65.44% in leaves and 72.89% in stems), p-hydroxybenzoic acid (25.10% in leaves and 18.95% in stems), and vanillic acid (8.80% in leaves and 7.30% in stems). The rich phytochemical profile of the leaves and stems is an indication of their ability to serve as sources of nutraceuticals.

  15. Fire-detection device with an ionization chamber

    Conforti, F J; Ogden, W L

    1974-10-14

    The invention fire-detector in which a detecting circuit of adjustable sensitivity is connected to an ionization chamber sensitive to combustion products. An appropriate circuit is adapted to check the operation and to determine if: the apparatus is duly fed with power; the detector is working; and the apparatus is working at the appropriate sensitivity.

  16. Detection of single atoms by resonance ionization spectroscopy

    Hurst, G.S.

    1986-01-01

    Rutherford's idea for counting individual atoms can, in principle, be implemented for nearly any type of atom, whether stable or radioactive, by using methods of resonance ionization. With the RIS technique, a laser is tuned to a wavelength which will promote a valence electron in a Z-selected atom to an excited level. Additional resonance or nonresonance photoabsorption steps are used to achieve nearly 100% ionization efficiencies. Hence, the RIS process can be saturated for the Z-selected atoms; and since detectors are available for counting either single electrons or positive ions, one-atom detection is possible. Some examples are given of one-atom detection, including that of the noble gases, in order to show complementarity with AMS methods. For instance, the detection of 81 Kr using RIS has interesting applications for solar neutrino research, ice-cap dating, and groundwater dating. 39 refs., 7 figs., 2 tabs

  17. Minimum ionizing particle detection using amorphous silicon diodes

    Xi, J.; Hollingsworth, R.E.; Buitrago, R.H. (Glasstech Solar, Inc., Wheat Ridge, CO (USA)); Oakley, D.; Cumalat, J.P.; Nauenberg, U. (Colorado Univ., Boulder (USA). Dept. of Physics); McNeil, J.A. (Colorado School of Mines, Golden (USA). Dept. of Physics); Anderson, D.F. (Fermi National Accelerator Lab., Batavia, IL (USA)); Perez-Mendez, V. (Lawrence Berkeley Lab., CA (USA))

    1991-03-01

    Hydrogenated amorphous silicon pin diodes have been used to detect minimum ionizing electrons with a pulse height signal-to-noise ratio exceeding 3. A distinct signal was seen for shaping times from 100 to 3000 ns. The devices used had a 54 {mu}m thick intrinsic layer and an active area of 0.1 cm{sup 2}. The maximum signal was 3200 electrons with a noise width of 950 electrons for a shaping time of 250 ns. (orig.).

  18. Fast combustion waves and chemi-ionization processes in a flame initiated by a powerful local plasma source in a closed reactor

    Artem'ev, K. V.; Berezhetskaya, N. K.; Kazantsev, S. Yu.; Kononov, N. G.; Kossyi, I. A.; Popov, N. A.; Tarasova, N. M.; Filimonova, E. A.; Firsov, K. N.

    2015-01-01

    Results are presented from experimental studies of the initiation of combustion in a stoichiometric methane–oxygen mixture by a freely localized laser spark and by a high-current multispark discharge in a closed chamber. It is shown that, preceding the stage of ‘explosive’ inflammation of a gas mixture, there appear two luminous objects moving away from the initiator along an axis: a relatively fast and uniform wave of ‘incomplete combustion’ under laser spark ignition and a wave with a brightly glowing plasmoid behind under ignition from high-current slipping surface discharge. The gas mixtures in both the ‘preflame’ and developed-flame states are characterized by a high degree of ionization as the result of chemical ionization (plasma density ne≈1012 cm−3) and a high frequency of electron–neutral collisions (νen≈1012 s−1). The role of chemical ionization in constructing an adequate theory for the ignition of a gas mixture is discussed. The feasibility of the microwave heating of both the preflame and developed-flame plasma, supplementary to a chemical energy source, is also discussed. PMID:26170426

  19. Efficient Flame Detection and Early Warning Sensors on Combustible Materials Using Hierarchical Graphene Oxide/Silicone Coatings.

    Wu, Qian; Gong, Li-Xiu; Li, Yang; Cao, Cheng-Fei; Tang, Long-Cheng; Wu, Lianbin; Zhao, Li; Zhang, Guo-Dong; Li, Shi-Neng; Gao, Jiefeng; Li, Yongjin; Mai, Yiu-Wing

    2018-01-23

    Design and development of smart sensors for rapid flame detection in postcombustion and early fire warning in precombustion situations are critically needed to improve the fire safety of combustible materials in many applications. Herein, we describe the fabrication of hierarchical coatings created by assembling a multilayered graphene oxide (GO)/silicone structure onto different combustible substrate materials. The resulting coatings exhibit distinct temperature-responsive electrical resistance change as efficient early warning sensors for detecting abnormal high environmental temperature, thus enabling fire prevention below the ignition temperature of combustible materials. After encountering a flame attack, we demonstrate extremely rapid flame detection response in 2-3 s and excellent flame self-extinguishing retardancy for the multilayered GO/silicone structure that can be synergistically transformed to a multiscale graphene/nanosilica protection layer. The hierarchical coatings developed are promising for fire prevention and protection applications in various critical fire risk and related perilous circumstances.

  20. Detection of minimum-ionizing particles in hydrogenated amorphous silicon

    Kaplan, S.N.; Fujieda, I.; Perez-Mendez, V.; Qureshi, S.; Ward, W.; Street, R.A.

    1987-09-01

    Based on previously-reported results of the successful detection of alpha particles and 1- and 2-MeV protons with hydrogenated amorphous silicon (a-Si : H) diodes, detection of a single minimum-ionizing particle will require a total sensitive thickness of approximately 100 to 150 μm, either in the form of a single thick diode, or as a stack of several thinner diodes. Signal saturation at high dE/dx makes it necessary to simulate minimum ionization in order to evaluate present detectors. Two techniques, using pulsed infrared light, and pulsed x-rays, give single-pulse signals large enough for direct measurements. A third, using beta rays, requires multiple-transit signal averaging to produce signals measurable above noise. Signal amplitudes from the a-Si : H limit at 60% of the signal size from Si crystals extrapolated to the same thickness. This is consistent with an a-Si : H radiation ionization energy, W = 6 eV/electron-hole pair. Beta-ray signals are observed at the expected amplitude

  1. Monitoring of monooctanoyl phosphatidylcholine synthesis by enzymatic acidolysis between soybean phosphatidylcholine and caprylic acid by thin-layer chromatography with a flame ionization detector

    Vikbjerg, Anders Falk; Mu, Huiling; Xu, Xuebing

    2005-01-01

    Thin-layer chromatography with flame ionization detector (TLC-FID) method was used for monitoring the production of structured phospholipids (ML-type: L-long chain fatty acids; M-medium chain fatty acids) by enzyme-catalyzed acidolysis between soybean phosphatidylcholine (PC) and caprylic acid....... It was found that the structured PC fractionated into 2-3 distinct bands on both plate thin layer chromatography (TLC) and Chromarod TLC. These 3 bands represented PC of LL-type, ML-type and MM-type, respectively. The TLC-FID method was applied in the present study to examine the influence of enzyme dosage...

  2. Analysis of monomeric and oligomeric organophosphorus flame retardants in fish muscle tissues using liquid chromatography–electrospray ionization tandem mass spectrometry: Application to Nile tilapia (Oreochromis niloticus) from an e-waste processing area in northern Vietnam

    Matsukami, Hidenori; Suzuki, Go; Tue, Nguyen Minh; Tuyen, Le Huu; Viet, Pham Hung; Takahashi, Shin; Tanabe, Shinsuke; Takigami, Hidetaka

    2016-01-01

    Using electrospray ionization tandem mass spectrometry combined with liquid chromatography (LC), a novel analytical method was developed to quantify eight monomeric organophosphorus flame retardants (m-PFRs) and three oligomeric organophosphorus flame retardants (o-PFRs) in fish muscle samples. The optimization and validation experiments indicate that the developed method can determine accurately the concentrations of analytes in fish muscle samples. The recoveries of analytes in fish muscle ...

  3. Organic materials and devices for detecting ionizing radiation

    Doty, F Patrick [Livermore, CA; Chinn, Douglas A [Livermore, CA

    2007-03-06

    A .pi.-conjugated organic material for detecting ionizing radiation, and particularly for detecting low energy fission neutrons. The .pi.-conjugated materials comprise a class of organic materials whose members are intrinsic semiconducting materials. Included in this class are .pi.-conjugated polymers, polyaromatic hydrocarbon molecules, and quinolates. Because of their high resistivities (.gtoreq.10.sup.9 ohmcm), these .pi.-conjugated organic materials exhibit very low leakage currents. A device for detecting and measuring ionizing radiation can be made by applying an electric field to a layer of the .pi.-conjugated polymer material to measure electron/hole pair formation. A layer of the .pi.-conjugated polymer material can be made by conventional polymer fabrication methods and can be cast into sheets capable of covering large areas. These sheets of polymer radiation detector material can be deposited between flexible electrodes and rolled up to form a radiation detector occupying a small volume but having a large surface area. The semiconducting polymer material can be easily fabricated in layers about 10 .mu.m to 100 .mu.m thick. These thin polymer layers and their associated electrodes can be stacked to form unique multi-layer detector arrangements that occupy small volume.

  4. EPR detection of foods preserved with ionizing radiation

    Stachowicz, W.; Burlinska, G.; Michalik, J.

    1998-06-01

    The applicability of the epr technique for the detection of dried vegetables, mushrooms, some spices, flavour additives and some condiments preserved with ionizing radiation is discussed. The epr signals recorded after exposure to gamma rays and to beams of 10 MeV electrons from linac are stable, intense and specific enough as compared with those observed with nonirradiated samples and could be used for the detection of irradiation. However, stability of radiation induced epr signals produced in these foods depends on storage condition. No differences in shapes (spectral parameters) and intensities of the epr spectra recorded with samples exposed to the same doses of gamma rays ( 60Co) and 10 MeV electrons were observed

  5. EPR detection of foods preserved with ionizing radiation

    Stachowicz, W.; Burlinska, G.; Michalik, J.

    1998-01-01

    The applicability of the epr technique for the detection of dried vegetables, mushrooms, some spices, flavour additives and some condiments preserved with ionizing radiation is discussed. The epr signals recorded after exposure to gamma rays and to the beams of 10 MeV electrons from linac are stable, intense and specific enough as compared with those observed with nonirradiated samples and could be used for the detection of irradiation. However, stability of radiation induced epr signals produced in these foods depends on storage condition. No differences in shapes (spectral parameters) and intensities of the epr spectra recorded with samples exposed to the same doses of gamma rays ( 60 Co) and 10 MeV electrons were observed

  6. Discrimination capability of avalanche counters detecting different ionizing particles

    Prete, G.; Viesti, G.; Padua Univ.

    1985-01-01

    The discrimination capability of avalanche counters to detect different ionizing particles has been studied using a 252 Cf source. Pulse height, pulse-height resolution and timing properties have been measured as a function of the reduced applied voltage for parallel-plate and parallel-grid avalanche counters. At the highest applied voltages, space charge effects shift the pulse-height signal of the avalanche counter away from being linearly proportional to the stopping power of the detected particles and cause the pulse-height resolution to deteriorate. To optimize the avalanche counter capability, without loss of time resolution, it appears better to operate the detector at voltages well below the breakdown threshold. Measurements with 32 S ions are also reported. (orig.)

  7. EPR detection of foods preserved with ionizing radiation

    Stachowicz, W.; Burlinska, G.; Michalik, J

    1998-06-01

    The applicability of the epr technique for the detection of dried vegetables, mushrooms, some spices, flavour additives and some condiments preserved with ionizing radiation is discussed. The epr signals recorded after exposure to gamma rays and to the beams of 10 MeV electrons from linac are stable, intense and specific enough as compared with those observed with nonirradiated samples and could be used for the detection of irradiation. However, stability of radiation induced epr signals produced in these foods depends on storage condition. No differences in shapes (spectral parameters) and intensities of the epr spectra recorded with samples exposed to the same doses of gamma rays ({sup 60}Co) and 10 MeV electrons were observed.

  8. Ionization

    2002-01-01

    This document reprints the text of the French by-law from January 8, 2002 relative to the approval and to the controls and verifications of facilities devoted to the ionizing of food products for human beings and animals. The by-law imposes the operators of such facilities to perform measurements and dosimetric verifications all along the ionization process. (J.S.)

  9. Multiphoton Ionization Detection in Collinear Laser Spectroscopy of Isolde Beams

    2002-01-01

    The experiments using the multiphoton ionization technique have been continued in the beginning of 1990 with stable beam tests on the modified apparatus and with another radioactive beam time on Yb. Higher laser power and an increased vacuum in the ionization region (see figure) yielded a further gain in sensitivity, mainly due to the better suppression of the background ions produced in rest gas collisions. For even Yb isotopes we have now reached a detection efficiency of $\\epsilon$~=~1~x~10$^{-5}$ ions per incoming atom at a background count rate of 30~ions from a beam of 5~x~10$^9$. This sensitivity was high enough for spectroscopy on $^{157}$Yb, where the typical ISOLDE yield of 5~x~10$^7$Yb ions is covered by an isobaric contamination of more than 10$^{10}$ ions. Measurements have also been performed on $^{175}$Yb. These give the first precise value for the magnetic moment of this isotope, $\\mu$~=~0.766(8)$ mu _{N} $, which agrees rather well with the magnetic moment of the isotone $^{177}$Hf. The isoto...

  10. Laser-enhanced ionization spectroscopy around the ionization limit

    Axner, O.; Berglind, T.; Sjoestroem, S.

    1986-01-01

    Laser-induced photoionization and Laser-Enhanced collision Ionization (LEI) of Na, Tl, and Li in flames are detected by measuring the production of charges following a laser excitation. The ionization signal is investigated for excitations of the atoms from lower lying states both to Rydberg states close to the ionization limit, as well as to continuum states, i.e. the process of collision ionization is compared with that of photoionization. The qualitative behaviour of the ionization signal when scanning across the ionization limit is studied. It is shown that the ionization signal has a smooth behaviour when passing from bound states into continuum states. The laser-induced photoionization signal strength of atoms in flames is both calculated and measured and a good agreement is obtained. A calculation of wavelength dependent photoionization signal strengths for a number of elements is also presented. Photoionization is used to determine flame- and geometry-dependent parameters. An implication of photoionization in connection with LEI spectrometry for trace element analysis is that there will be a significant increase in background noise if the sample contains high concentrations of easily photoionizing elements and short wavelength light is used. (orig.)

  11. Ionization detector, electrode configuration and single polarity charge detection method

    He, Z.

    1998-07-07

    An ionization detector, an electrode configuration and a single polarity charge detection method each utilize a boundary electrode which symmetrically surrounds first and second central interlaced and symmetrical electrodes. All of the electrodes are held at a voltage potential of a first polarity type. The first central electrode is held at a higher potential than the second central or boundary electrodes. By forming the first and second central electrodes in a substantially interlaced and symmetrical pattern and forming the boundary electrode symmetrically about the first and second central electrodes, signals generated by charge carriers are substantially of equal strength with respect to both of the central electrodes. The only significant difference in measured signal strength occurs when the charge carriers move to within close proximity of the first central electrode and are received at the first central electrode. The measured signals are then subtracted and compared to quantitatively measure the magnitude of the charge. 10 figs.

  12. A Laboratory Experiment To Measure Henry's Law Constants of Volatile Organic Compounds with a Bubble Column and a Gas Chromatography Flame Ionization Detector (GC-FID)

    Lee, Shan-Hu; Mukherjee, Souptik; Brewer, Brittany; Ryan, Raphael; Yu, Huan; Gangoda, Mahinda

    2013-01-01

    An undergraduate laboratory experiment is described to measure Henry's law constants of organic compounds using a bubble column and gas chromatography flame ionization detector (GC-FID). This experiment is designed for upper-division undergraduate laboratory courses and can be implemented in conjunction with physical chemistry, analytical…

  13. Knock investigation by flame and radical species detection in spark ignition engine for different fuels

    Merola, Simona S.; Vaglieco, Bianca M.

    2007-01-01

    The present paper aims to evaluate the phenomena of normal combustion and knocking in a single cylinder, ported fuel injection, four-stroke spark-ignition engine with a four-valve production head. All the measurements were realized in an optically accessible engine equipped with a wide quartz window in the bottom of the chamber. The study was carried out using optical techniques based on flame natural emission imaging and spectroscopy from UV to visible. Radical species such as OH and HCO were detected and correlated to the onset and the duration of knock and presence of hot-spots in end-gas. Measurements were carried out at 1000 rpm with wide-open throttle and stoichiometric mixture. Pure iso-octane, suitable mixtures of iso-octane and n-heptane and commercial gasoline were used

  14. Detection of novel brominated flame retardants (NBFRs in the urban soils of Melbourne, Australia

    Thomas J. McGrath

    2017-03-01

    Full Text Available A range of brominated flame retardants (BFRs have been incorporated into polymeric materials like plastics, electronic equipment, foams and textiles to prevent fires. The most common of these, polybrominated diphenyl ethers (PBDEs, have been subject to legislated bans and voluntary withdrawal by manufacturers in North America, Europe and Australia over the past decade due to long-range atmospheric transport, persistence in the environment, and toxicity. Evidence has shown that replacement novel brominated flame retardants (NBFRs are released to the environment by the same mechanisms as PBDEs and share similar hazardous properties. The objective of the current research was to characterize soil contamination by NBFRs in the urban soils of Melbourne, Australia. A variety of industrial and non-industrial land-uses were investigated with the secondary objective of determining likely point sources of pollution. Six NBFRs; pentabromotoluene (PBT, pentabromoethylbenzene (PBEB, hexabromobenzene (HBB, 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB, 1,2-bis(2,4,6-tribromophenoxyethane (BTBPE and decabromodiphenyl ethane (DBDPE were measured in 30 soil samples using selective pressurized liquid extraction (S-PLE and gas chromatography coupled to triple quadrupole mass spectrometry (GC-MS/MS. NBFRs were detected in 24/30 soil samples with Σ5NBFR concentrations ranging from nd-385 ng/g dw. HBB was the most frequently detected compound (14/30, while the highest concentrations were observed for DBDPE, followed by BTBPE. Electronic waste recycling and polymer manufacturing appear to be key contributors to NBFR soil contamination in the city of Melbourne. A significant positive correlation between Σ8PBDEs and Σ5NBFR soil concentrations was observed at waste disposal sites to suggest that both BFR classes are present in Melbourne's waste streams, while no association was determined among manufacturing sites. This research provides the first account of NBFRs

  15. Simultaneous determination of organophosphorous insecticides in bean samples by gas chromatography - flame photometric detection

    Keyller Bastos Borges

    2014-02-01

    Full Text Available The indiscriminate use of organophosphorous pesticides (OPPs in crops may leave residues in food and may cause poisoning in the applicators. A method was developed for the determination of five OPPs in bean samples by Gas Chromatography-Flame Photometric Detection (GC-FPD. Validation parameters comprised linearity between 0.24 and 8.56 μg g-1 (r = 0.9985 for diazinon; 0.23 and 8.14 μg g-1 (r = 0.9959 for methyl parathion; 0.28 and 10.25 μg g-1 (r = 0.9987 for methyl pirimiphos; 0.52 and 18.87 μg g-1 (r = 0.9955 for malathion; 0.86 and 13.67 μg g-1 (r = 0.9919 for ethion. The limits of quantification (equal to those of detection were the lowest rates of ranges mentioned above for each compound. The extraction method showed approximately 95% recovery, with CV% < 15%. Although twenty-eight bean samples obtained in the southern region of the state of Minas Gerais,Brazil, were analyzed, they failed to match any of the OPPs under analysis. The absence of OPPs in the samples could be due to the degradation that occurred between the use of OPPs and bean commercialization, levels below the detection /quantification limits and the non-use of OPPs in bean cultivation.

  16. Gas chromatography with flame photometric detection of 31 organophosphorus pesticide residues in Alpinia oxyphylla dried fruits.

    Zhao, Xiangsheng; Kong, Weijun; Wei, Jianhe; Yang, Meihua

    2014-11-01

    A simple, rapid and effective gas chromatography-flame photometric detection method was established for simultaneous multi-component determination of 31 organophosphorus pesticides (OPPs) residues in Alpinia oxyphylla, which is widely consumed as a traditional medicine and food in China. Sample preparation was completed in a single step without any clean-up procedure. All pesticides expressed good linear relationships between 0.004 and 1.0 μg/mL with correlation coefficients higher than 0.9973. The method gave satisfactory recoveries for most pesticides. The limits of detection varied from 1 to 10 ng/mL, and the limits of quantification (LOQs) were between 4 and 30 ng/mL. The proposed method was successfully applied to 55 commercial samples purchased from five different areas. Five pesticide residues were detected in four (7.27%) samples. The positive samples were confirmed by gas chromatography with tandem mass spectrometry (GC-MS/MS). Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Organotin analysis by gas chromatography-pulsed flame-photometric detection (GC-PFPD)

    Leermakers, M.; Nuyttens, J.; Baeyens, W. [Vrije Universiteit Brussel, Analytical and Environmental Chemistry (ANCH), Brussel (Belgium)

    2005-03-01

    Monobutyltin (MBuT), dibutyltin (DBuT), and tributyltin (TBuT) mixtures have been separated and quantified by gas chromatography with pulsed flame-photometric detection (GC-PFPD). The compounds were first derivatized with NaBEt{sub 4}, then extracted with hexane and injected into the GC in splitless mode. Optimum GC and detector conditions were established. For GC, various injector temperatures and oven temperature programs were tested. For the PFPD detector, gate settings (gate delay and gate width) and detector temperature were optimized. A very good linearity was obtained up to 100-150 ppb for all organotin compounds. The detection limits obtained were: MBuT (0.7 ppb), DBuT (0.8 ppb), and TBuT (0.6 ppb). RSD for repeatability and reproducibility were well below 20% when the instrument was in routine operation. A biological sample (CRM 477) was also analyzed for organotins. Extraction from the biological matrix was performed with TMAH. Besides the increased risk of contamination, the derivatization step seemed to be critical. pH and amount of derivatizing agent were tested. When using an internal standard (TPrT) between 90% and 110% of the certified amounts of organotin were recovered. (orig.)

  18. The Determination of Pesticidal and Non-Pesticidal Organotin Compounds by in situ Ethylation and Capillary Gas Chromatography with Pulsed Flame Photometric Detection

    The concurrent determination of pesticidal and non-pesticidal organotin compounds in several water matrices, using a simultaneous in situ ethylation and liquid-liquid extraction followed by splitless injection mode capillary gas chromatography with pulsed flame photometric detect...

  19. The Determination of Pesticidal and Non-Pesticidal Organotin Compounds in Water Matrices by in situ Ethylation and Gas Chromatography with Pulsed Flame Photometric Detection

    The concurrent determination of pesticidal and non-pesticidal organotin compounds in several water matrices, using a simultaneous in situ ethylation and liquid-liquid extraction followed by splitless injection mode capillary gas chromatography with pulsed flame photometric detect...

  20. Electret ionization chamber: a new method for detection and dosimetry of thermal neutrons

    Ghilardi, A.J.P.

    1988-01-01

    An electret ionization chamber with boron coated walls is presented as a new method for detecting thermal neutrons. The efficiency of electret ionization chambers with different wall materials for the external electrode was inferred from the results. Detection of slow neutrons with discrimination against the detection of γ-rays and energetic neutrons was shown to depend on the selection of these materials. The charge stability over a long period of time and the charge decay owing to natural radiation were also studied. Numerical analysis was developed by the use of a micro-computer PC-XT. Both the experimental and numerical results show that the sensitivity of the electret ionization chamber for detection of thermal neutrons is comparable with that of the BF 3 ionization chamber and that new technologies for deposition of the boron layer will produce higher efficiency detectors. (author). 102 refs, 32 fig, 10 tabs

  1. Detection systems for high energy particle producing gaseous ionization

    Martinez, L.; Duran, I.

    1985-01-01

    This report contains a review on the most used detectors based on the collection of the ionization produced by high energy particles: proportional counters, multiwire proportional chambers, Geiger-Muller counters and drift chambers. In six sections, the fundamental principles, the field configuration and useful gas mixtures, are discussed, most relevant devices are reported along 90 pages with 98 references. (Author) 98 refs

  2. Detection systems for high energy particle producing gaseous ionization

    Duran, I.; Martinez, L.

    1985-01-01

    This report contains a review on the most used detectors based on the collection of the ionization produced by high energy particles: proportional counters, multiwire proportional chambers, Geiger-Mueller counters and drift chambers. In six sections, the fundamental principles, the field configuration and useful gas mixtures are discussed, most relevant devices are reported. (author)

  3. Lipids and Fatty Acids in Algae: Extraction, Fractionation into Lipid Classes, and Analysis by Gas Chromatography Coupled with Flame Ionization Detector (GC-FID).

    Guihéneuf, Freddy; Schmid, Matthias; Stengel, Dagmar B

    2015-01-01

    Despite the number of biochemical studies exploring algal lipids and fatty acid biosynthesis pathways and profiles, analytical methods used by phycologists for this purpose are often diverse and incompletely described. Potential confusion and potential variability of the results between studies can therefore occur due to change of protocols for lipid extraction and fractionation, as well as fatty acid methyl esters (FAME) preparation before gas chromatography (GC) analyses. Here, we describe a step-by-step procedure for the profiling of neutral and polar lipids using techniques such as solid-liquid extraction (SLE), thin-layer chromatography (TLC), and gas chromatography coupled with flame ionization detector (GC-FID). As an example, in this protocol chapter, analyses of neutral and polar lipids from the marine microalga Pavlova lutheri (an EPA/DHA-rich haptophyte) will be outlined to describe the distribution of fatty acid residues within its major lipid classes. This method has been proven to be a reliable technique to assess changes in lipid and fatty acid profiles in several other microalgal species and seaweeds.

  4. Ionizing radiation detection meter systems usability evaluation. Technical memorandum

    Severs, Y.; Hughes, R.; Tack, D.; Bossi, L.L.M.

    2002-12-01

    In support of the Canadian Forces Nuclear Detection, Identification and Dosimetry project a usability trial of three Ionizing Radiation Detection Meter Systems (IRDMS) was conducted 18-22 June 2001 at Connaught Ranges. The systems evaluated: System 1: ANPDR 77 Operational System with PDR 77 Alpha/Beta probes and GPS (Global Positioning System) Training System; System 2: ADM 300C Operational System with ABP 100 Alpha/Beta probes and GPS Training System, and System 3: RAM R200 Operational System with PA 100M and RG12 Alpha/Beta probes and GPS Training System. Twelve military personnel (Private to Captain) determined compliance with the bid evaluation criteria. The counter-balanced study, based on a Latin square design, was divided into two assessment phases, an operational phase and a training system phase, which rotated three groups (of four participants each) concurrently through each IRDMS. Groups were trained in set-up, maintenance and operation of each bid IRDMS prior to evaluation. The operational evaluation consisted of a test/maintenance stand, an indoor/outdoor operational stand, and an indoor,/outdoor training system stand. Participants rated the utility and usability of each system, by measuring case of use/maintenance under a range of relevant operational and clothing conditions, compatibility with soldier tasks, compatibility with clothing, compatibility with equipment and operational environments, and case of learning (including an assessment of initial and refresher training implications). A 7-point Likert-like acceptability rating scale, which covered a range from completely unacceptable (1) to completely acceptable (7), was used to evaluate the measures. The combined weighted mean scores were 584.3 for System 1 (70 o /b), 682.0 for System 2 (81 %) and 756.9 for System 3 (90%) out of a total possible score of 840. Participants reported mean scores for System 1 between barely unacceptable and borderline for both indoor and outdoor operations. System 2

  5. Emission flame spectrophotometry of chromium, cobalt, nickel trace amounts

    Prudnikov, Y.D.; Shapkina, Y.S.

    1976-01-01

    Chromium, cobalt, and nickel were determined in a flame spectrophotometer with a dual diffraction monochromator, DFS-12, in a high-temperature nitrogen-acetylene flame. The effect of ionization and the elements in the oxidizing flame was small. The lower limit of detection for the three elements is 1x10 -2 to 1 x10 -3 μg/ml, and the high selectivity of the analysis permits determining down to 10 -4 % Cr and Ni and to 10 -3 % Co. These elements may be determined in rocks and minerals from solutions prepared for analysis for alkali and alkali-earth elements. The possibilities of emission flame spectrophotometry are as great as those of atomic-absorption analysis, and it may be used for determining Cr, Co, and Ni in rocks and minerals, especially pure substances, metals, and other materials

  6. Separation of paralytic shellfish poisoning toxins on Chromarods-SIII by thin-layer chromatography with the Iatroscan (mark 5) and flame thermionic detection.

    Indrasena, W M; Ackman, R G; Gill, T A

    1999-09-10

    Thin-layer chromatography (TLC) on Chromarods-SIII with the Iatroscan (Mark-5) and a flame thermionic detector (FTID) was used to develop a rapid method for the detection of paralytic shellfish poisoning (PSP) toxins. The effect of variation in hydrogen (H2) flow, air flow, scan time and detector current on the FTID peak response for both phosphatidylcholine (PC) and PSP were studied in order to define optimum detection conditions. A combination of hydrogen and air flow-rates of 50 ml/min and 1.5-2.0 l/min respectively, along with a scan time of 40 s/rod and detector current of 3.0 A (ampere) or above were found to yield the best results for the detection of PSP compounds. Increasing the detector current level to as high as 3.3 A gave about 130 times more FTID response than did flame ionization detection (FID), for PSP components. Quantities of standards as small as 1 ng neosaxitoxin (NEO), 5 ng saxitoxin (STX), 5 ng B1-toxins (B1), 2 ng gonyautoxin (GTX) 2/3, 6 ng GTX 1/4 and 6 ng C-toxins (C1/C2) could be detected with the FTID. The method detection limits for toxic shellfish tissues using the FTID were 0.4, 2.1, 0.8 and 2.5 micrograms per g tissue for GTX 2/3, STX, NEO and C toxins, respectively. The FTID response increased with increasing detector current and with increasing the scan time. Increasing hydrogen and air flow-rates resulted in decreasing sensitivity within defined limits. Numerous solvent systems were tested, and, solvent consisting of chloroform: methanol-water-acetic acid (30:50:8:2) could separate C toxins from GTX, which eluted ahead of NEO and STX. Accordingly, TLC/FTID with the Iatroscan (Mark-5) seems to be a promising, relatively inexpensive and rapid method of screening plant and animal tissues for PSP toxins.

  7. Large single-crystal diamond substrates for ionizing radiation detection

    Girolami, Marco; Bellucci, Alessandro; Calvani, Paolo; Trucchi, Daniele M. [Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), Sede Secondaria di Montelibretti, Monterotondo Stazione, Roma (Italy)

    2016-10-15

    The need for large active volume detectors for ionizing radiations and particles, with both large area and thickness, is becoming more and more compelling in a wide range of applications, spanning from X-ray dosimetry to neutron spectroscopy. Recently, 8.0 x 8.0 mm{sup 2} wide and 1.2 mm thick single-crystal diamond plates have been put on the market, representing a first step to the fabrication of large area monolithic diamond detectors with optimized charge transport properties, obtainable up to now only with smaller samples. The more-than-double thickness, if compared to standard plates (typically 500 μm thick), demonstrated to be effective in improving the detector response to highly penetrating ionizing radiations, such as γ-rays. Here we report on the first measurements performed on large active volume single-crystal diamond plates, both in the dark and under irradiation with optical wavelengths (190-1100 nm), X-rays, and radioactive γ-emitting sources ({sup 57}Co and {sup 22}Na). (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Development of Multiple-Element Flame Emission Spectrometer Using CCD Detection

    Seney, Caryn S.; Sinclair, Karen V.; Bright, Robin M.; Momoh, Paul O.; Bozeman, Amelia D.

    2005-01-01

    The full wavelength coverage of charge coupled device (CCD) detector when coupled with an echelle spectrography, the system allows for simultaneously multiple element spectroscopy to be performed. The multiple-element flame spectrometer was built and characterized through the analysis of environmentally significant elements such as Ca, K, Na, Cu,…

  9. Electron cascades in sensors for optical detection of ionizing radiation

    London, Richard A.; Lowry, Mark E.; Vernon, Stephen P.; Stewart, Richard E.

    2013-01-01

    A new class of high-speed detectors, called RadOptic detectors, measures ionizing radiation incident on a transparent semiconductor by sensing changes in the refractive index with an optical probe beam. We describe the role of radiation-initiated electron cascades in setting the sensitivity and the spatial and temporal resolution of RadOptic detectors. We model electron cascades with both analytical and Monte Carlo computational methods. We find that the timescale for the development of an electron cascade is less than of order 100 fs and is not expected to affect the time response of a detector. The characteristic size of the electron cloud is typically less than 2 μm, enabling high spatial resolution in imaging systems. The electron-hole pair density created by single x-rays is much smaller than the saturation density and, therefore, single events should not saturate the detector

  10. Atmospheric Pressure Chemical Ionization Sources Used in The Detection of Explosives by Ion Mobility Spectrometry

    Waltman, Melanie J. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

    2010-05-01

    Explosives detection is a necessary and wide spread field of research. From large shipping containers to airline luggage, numerous items are tested for explosives every day. In the area of trace explosives detection, ion mobility spectrometry (IMS) is the technique employed most often because it is a quick, simple, and accurate way to test many items in a short amount of time. Detection by IMS is based on the difference in drift times of product ions through the drift region of an IMS instrument. The product ions are created when the explosive compounds, introduced to the instrument, are chemically ionized through interactions with the reactant ions. The identity of the reactant ions determines the outcomes of the ionization process. This research investigated the reactant ions created by various ionization sources and looked into ways to manipulate the chemistry occurring in the sources.

  11. Technical specifications manual for the MARK-1 pulsed ionizing radiation detection system

    Lawrence, R.S.; Harker, Y.D.; Jones, J.L.; Hoggan, J.M.

    1993-03-01

    The MARK-1 detection system was developed by the Idaho National Engineering Laboratory for the US Department of Energy Office of Arms Control and Nonproliferation. The completely portable system was designed for the detection and analysis of intense photon emissions from pulsed ionizing radiation sources. This manual presents the technical design specifications for the MARK-1 detection system and was written primarily to assist the support or service technician in the service, calibration, and repair of the system. The manual presents the general detection system theory, the MARK-1 component design specifications, the acquisition and control software, the data processing sequence, and the system calibration procedure. A second manual entitled: Volume 2: Operations Manual for the MARK-1 Pulsed Ionizing Radiation Detection System (USDOE Report WINCO-1108, September 1992) provides a general operational description of the MARK-1 detection system. The Operations Manual was written primarily to assist the field operator in system operations and analysis of the data

  12. Technical specifications manual for the MARK-1 pulsed ionizing radiation detection system. Volume 1

    Lawrence, R.S.; Harker, Y.D.; Jones, J.L.; Hoggan, J.M.

    1993-03-01

    The MARK-1 detection system was developed by the Idaho National Engineering Laboratory for the US Department of Energy Office of Arms Control and Nonproliferation. The completely portable system was designed for the detection and analysis of intense photon emissions from pulsed ionizing radiation sources. This manual presents the technical design specifications for the MARK-1 detection system and was written primarily to assist the support or service technician in the service, calibration, and repair of the system. The manual presents the general detection system theory, the MARK-1 component design specifications, the acquisition and control software, the data processing sequence, and the system calibration procedure. A second manual entitled: Volume 2: Operations Manual for the MARK-1 Pulsed Ionizing Radiation Detection System (USDOE Report WINCO-1108, September 1992) provides a general operational description of the MARK-1 detection system. The Operations Manual was written primarily to assist the field operator in system operations and analysis of the data.

  13. Gas chromatography-flame ionization determination of benzaldehyde in non-steroidal anti-inflammatory drug injectable formulations using new ultrasound-assisted dispersive liquid-liquid micro extraction

    Mashayekhi, H.A.; Pourshamsian, K.

    2012-01-01

    Summary: In this study, simple and efficient ultrasound-assisted dispersive liquid-liquid micro extraction combined with gas chromatography (GC) was developed for the preconcentration and determination of benzaldehyde in injectable formulations of the non-steroidal anti-inflammatory drugs, diclofenac, Vitamin B-complex and Voltaren injection solutions. Fourteen microliters of toluene was injected slowly into 10 mL home-designed centrifuge glass vial containing an aqueous sample without salt addition that was located inside the ultrasonic water bath. The formed emulsion was centrifuged and 2 macro L of separated toluene was injected into a gas chromatographic system equipped with a flame ionization detector (GC-FID) for analysis. Several factors influencing the extraction efficiency as the nature and volume of organic solvent, extraction temperature, ionic strength and centrifugation time were investigated and optimized. Using optimum extraction conditions a detection limit of 0.3 macro g L/sup -1/ and a good linearity in a calibration range of 2.0-1000 macro g L/sup -1/ were achieved for analyte. This proposed method was successfully applied to the analysis of benzaldehyde in three injection formulations and relative standard deviation (RSD) of analysis (n=3), before spiking with standard benzaldehyde were 3.3, 2.0 and 1.3% for Na-diclofenac, vitamin B-complex and voltaren, respectively and after spiking of standard benzaldehyde (0.3 mg L/sup -1/), the RSD were 6.5, 3.6 and 2.8% for Na-diclofenac, vitamin B-complex and voltaren, respectively. (author)

  14. Effectiveness in detecting fission fragments with ionization chambers

    Manrique Garcia, J.; Monne, G.

    1991-01-01

    Detection of fission fragments is important in nuclear measurements. When a high detection accuracy is required it is necessary to take in account the detection losses due to the absorption of fragments in the fissionable material. The losses corrections might change the final results in 2-3%. The traditional expression used in the calculation of the detection efficiency does not consider neither the density variation of the fissionable substance with its width, because it depends on the target material. That's why actually in many labs it is being searched new methods that allow to find the efficiency for each target. In this work a new method for determination of absorption efficiency is presented. The obtained results are analyzed

  15. Method for the depth corrected detection of ionizing events from a co-planar grids sensor

    De Geronimo, Gianluigi [Syosset, NY; Bolotnikov, Aleksey E [South Setauket, NY; Carini, Gabriella [Port Jefferson, NY

    2009-05-12

    A method for the detection of ionizing events utilizing a co-planar grids sensor comprising a semiconductor substrate, cathode electrode, collecting grid and non-collecting grid. The semiconductor substrate is sensitive to ionizing radiation. A voltage less than 0 Volts is applied to the cathode electrode. A voltage greater than the voltage applied to the cathode is applied to the non-collecting grid. A voltage greater than the voltage applied to the non-collecting grid is applied to the collecting grid. The collecting grid and the non-collecting grid are summed and subtracted creating a sum and difference respectively. The difference and sum are divided creating a ratio. A gain coefficient factor for each depth (distance between the ionizing event and the collecting grid) is determined, whereby the difference between the collecting electrode and the non-collecting electrode multiplied by the corresponding gain coefficient is the depth corrected energy of an ionizing event. Therefore, the energy of each ionizing event is the difference between the collecting grid and the non-collecting grid multiplied by the corresponding gain coefficient. The depth of the ionizing event can also be determined from the ratio.

  16. Development, optimization, validation and application of faster gas chromatography - flame ionization detector method for the analysis of total petroleum hydrocarbons in contaminated soils.

    Zubair, Abdulrazaq; Pappoe, Michael; James, Lesley A; Hawboldt, Kelly

    2015-12-18

    This paper presents an important new approach to improving the timeliness of Total Petroleum Hydrocarbon (TPH) analysis in the soil by Gas Chromatography - Flame Ionization Detector (GC-FID) using the CCME Canada-Wide Standard reference method. The Canada-Wide Standard (CWS) method is used for the analysis of petroleum hydrocarbon compounds across Canada. However, inter-laboratory application of this method for the analysis of TPH in the soil has often shown considerable variability in the results. This could be due, in part, to the different gas chromatography (GC) conditions, other steps involved in the method, as well as the soil properties. In addition, there are differences in the interpretation of the GC results, which impacts the determination of the effectiveness of remediation at hydrocarbon-contaminated sites. In this work, multivariate experimental design approach was used to develop and validate the analytical method for a faster quantitative analysis of TPH in (contaminated) soil. A fractional factorial design (fFD) was used to screen six factors to identify the most significant factors impacting the analysis. These factors included: injection volume (μL), injection temperature (°C), oven program (°C/min), detector temperature (°C), carrier gas flow rate (mL/min) and solvent ratio (v/v hexane/dichloromethane). The most important factors (carrier gas flow rate and oven program) were then optimized using a central composite response surface design. Robustness testing and validation of model compares favourably with the experimental results with percentage difference of 2.78% for the analysis time. This research successfully reduced the method's standard analytical time from 20 to 8min with all the carbon fractions eluting. The method was successfully applied for fast TPH analysis of Bunker C oil contaminated soil. A reduced analytical time would offer many benefits including an improved laboratory reporting times, and overall improved clean up

  17. Detection of methyl-, dimethyl- and diethylamine using a nitrate-based chemical ionization mass spectrometer

    Jokinen, T.; Smith, J. N.

    2016-12-01

    New particle formation is one of the main sources of cloud condensation nuclei (CCN) contributing approximately half of the global CCN budget. The initial steps of nucleation have been studied for decades and it is widely accepted that in most places nucleation requires presence of sulphuric acid (SA) and cluster-stabilizing vapours. Recent results from the CLOUD chamber show that only a few pptv levels of dimethylamine (DMA) with SA forms stable clusters at boundary layer conditions. Ambient sulphuric acid is typically measured using nitrate-based chemical ionization mass spectrometers. Unfortunately, because of higher volatilities and stickiness of amines to surfaces, amine measurement techniques suffer from memory effects and high detection limits. Recently it was discovered that DMA can be detected by utilizing nitrate ionization, simultaneously with sulphuric acid measurements. Here we present results of detecting methylamine, dimethylamine and diethylamine using nitrate-based chemical ionization. We conducted a series of measurements with a home-built transverse chemical ionization inlet and a high resolution time-of-flight mass spectrometer (CI-HToF). Amine vapour was produced using permeation tubes. Three stages of dilution were applied at roughly one order-of-magnitude dilution per stage. The diluted flow of selected amine was then introduced to a sample flow rate of 7 slpm, thus achieving a final amine concentration of 10 pptv. All selected amines were detected as clusters with HNO3NO3- and showed linear response with increasing concentrations (0.5-minute integration time). Zero measurements were performed using clean nitrogen gas right after injection of a selected amine. Memory effects were only observed when using high amine concentrations (ppbv levels). Our results indicate that a variety of amines can be detected using nitrate-based chemical ionization mass spectrometers. However, more experiments are required to see if this presented method will be

  18. Results from the development of ionization detection systems for the DRAGON facility

    Chen, A A

    2003-01-01

    We discuss the implementation of an ionization detection system for the focal plane of the DRAGON recoil mass separator. We report recent tests performed with stable beams to test the feasibility of such a system for use in measurements of radiative capture reactions in inverse kinematics with radioactive beams.

  19. Results from the development of ionization detection systems for the DRAGON facility

    Chen, Alan A.

    2003-01-01

    We discuss the implementation of an ionization detection system for the focal plane of the DRAGON recoil mass separator. We report recent tests performed with stable beams to test the feasibility of such a system for use in measurements of radiative capture reactions in inverse kinematics with radioactive beams

  20. Speciation of four selenium compounds using high performance liquid chromatography with on-line detection by inductively coupled plasma mass spectrometry or flame atomic absorption spectrometry

    Pedersen, Gitte Alsing; Larsen, Erik Huusfeldt

    1997-01-01

    An analytical method for the speciation of selenomethionine, selenocystine, selenite and selenate by high performance liquid chromatography (HPLC) with atomic spectrometric detection is presented. An organic polymeric strong anion exchange column was used as the stationary phase in combination...... spectrometry (ICP-MS). The signal-to-noise ratio of the FAAS detector was optimized using a hydrogen-argon entrained-air flame and a slotted-tube atom trap (STAT) in the flame. The limit of detection (3 sigma) achieved by the HPLC-FAAS system was 1 mg L-1 of selenium (100 mu L injections) for each of the four...

  1. Power supply connection for ionizing radiation detection probes

    Zajic, J.

    1990-01-01

    One wire of the supply line is connected, through a diode in the forward direction, to the input terminal of the voltage stabilizer, and through the first resistor to the current limiter terminal of the voltage stabilizer, and also directly to the pulse separator terminal. The current limiter terminal of the voltage stabilizer is connected, through the second resistor, to the output terminal of the voltage stabilizer, and through the first capacitor to the voltage stabilizer earthing terminal, the earthing terminal of the pulse separator and through the other wire of the supply line to the earthing terminal of the detection probe. Furthermore, the input terminal of the voltage stabilizer is connected to a parallel combination of the third resistor with the second capacitor, whose other end is connected to the earthing terminal of the voltage stabilizer. The main asset of this connection consists in the high-frequency matching of the supply line being accomplished by a suitable choice of the resistor value without affecting the voltage for the detection probe. (M.D.)

  2. Detection limits by EPR spectroscopy of cumulated doses ionizing radiations in molluscs shells

    Ostrowski, K.; Burlinska, G.; Dziedzic-Goclawska, A.; Stachowicz, W.; Michalik, J.; Sadlo, J.

    1997-01-01

    The exposure of waters to ionizing radiation from radionuclides stored in concrete containers or freed in nuclear accidents or underwater eruption might be difficult to be proved, when currents, rains, exchange of water displace sand soils or rocks in the bottom. Ionizing radiation evokes stable paramagnetic centers in the crystalline lattice of mineral components in bones as well as in exoskeletons of most molluscs, which are detected by the EPR spectroscopy and could be used as an indicator of the exposure to the action of radiation during prolonged period of time. (authors)

  3. First Results of Using a UVTron Flame Sensor to Detect Alpha-Induced Air Fluorescence in the UVC Wavelength Range

    Anita J. Crompton

    2017-11-01

    Full Text Available In this work, a robust stand-off alpha detection method using the secondary effects of alpha radiation has been sought. Alpha particles ionise the surrounding atmosphere as they travel. Fluorescence photons produced as a consequence of this can be used to detect the source of the alpha emissions. This paper details experiments carried out to detect this fluorescence, with the focus on photons in the ultraviolet C (UVC wavelength range (180–280 nm. A detector, UVTron R9533 (Hamamatsu, 325-6, Sunayama-cho, Naka-ku, Hamamatsu City, Shizuoka Pref., 430-8587, Japan, designed to detect the UVC emissions from flames for fire alarm purposes, was tested in various gas atmospheres with a 210Po alpha source to determine if this could provide an avenue for stand-off alpha detection. The results of the experiments show that this detector is capable of detecting alpha-induced air fluorescence in normal indoor lighting conditions, as the interference from daylight and artificial lighting is less influential on this detection system which operates below the UVA and UVB wavelength ranges (280–315 nm and 315–380 nm respectively. Assuming a standard 1 r 2 drop off in signal, the limit of detection in this configuration can be calculated to be approximately 240 mm, well beyond the range of alpha-particles in air, which indicates that this approach could have potential for stand-off alpha detection. The gas atmospheres tested produced an increase in the detector count, with xenon having the greatest effect with a measured 52% increase in the detector response in comparison to the detector response in an air atmosphere. This type of alpha detection system could be operated at a distance, where it would potentially provide a more cost effective, safer, and faster solution in comparison with traditional alpha detection methods to detect and characterise alpha contamination in nuclear decommissioning and security applications.

  4. Methods for Creation and Detection of Ultra-Strong Artificial Ionization in the Upper Atmosphere (Invited)

    Bernhardt, P. A.; Siefring, C. L.; Briczinski, S. J.; Kendall, E. A.; Watkins, B. J.; Bristow, W. A.; Michell, R.

    2013-12-01

    The High Frequency Active Auroral Research Program (HAARP) transmitter in Alaska has been used to produce localized regions of artificial ionization at altitudes between 150 and 250 km. High power radio waves tuned near harmonics of the electron gyro frequency were discovered by Todd Pederson of the Air Force Research Laboratory to produce ionosonde traces that looked like artificial ionization layers below the natural F-region. The initial regions of artificial ionization (AI) were not stable but had moved down in altitude over a period of 15 minutes. Recently, artificial ionization has been produced by the 2nd, 3rd, 4th and 6th harmonics transmissions by the HAARP. In march 2013, the artificial ionization clouds were sustained for more the 5 hours using HAARP tuned to the 4 fce at the full power of 3.6 Mega-Watts with a twisted-beam antenna pattern. Frequency selection with narrow-band sweeps and antenna pattern shaping has been employed for optimal generation of AI. Recent research at HAARP has produced the longest lived and denser artificial ionization clouds using HF transmissions at the harmonics of the electron cyclotron frequency and ring-shaped radio beams tailored to prevent the descent of the clouds. Detection of artificial ionization employs (1) ionosonde echoes, (2) coherent backscatter from the Kodiak SuperDARN radar, (3) enhanced ion and plasma line echoes from the HAARP MUIR radar at 400 MHz, (4) high resolution optical image from ground sites, and (5) unique stimulated electromagnetic emissions, and (6) strong UHF and L-Band scintillation induced into trans-ionospheric signals from satellite radio beacons. Future HAARP experiments will determine the uses of long-sustained AI for enhanced HF communications.

  5. Characterization of ionization chambers in double face for X-ray detection systems

    Costa, Alessandro M. da; Caldas, Linda V.O.

    2000-01-01

    Two identical parallel-plate ionization chambers with collecting electrodes of different materials (in order to obtain different energy dependences), developed at Instituto de Pesquisas Energeticas e Nucleares, were tested in low energy X-radiation beams, simulating a special ionization chamber, of double face, in a Tandem system. The purpose of this work is to justify a project of a double face detection system utilizing ionization chambers in Tandem. In relation to conventional methods, this kind of system will provide more efficient and precise absorbed dose in air measurements and radiation effective energy determinations. The results obtained in relation to characteristics of short- and long-term stabilities and angular and energy dependence show that the project is feasible and very appropriate. (author)

  6. Ionization Chambers for the LHC Beam Loss Detection

    Assmann, R W; Ferioli, G; Gschwendtner, E; Kain, V

    2003-01-01

    At the Large Hadron Collider (LHC) a beam loss system will be used to prevent and protect superconducting magnets against coil quenches and coil damages. Ionisation chambers will be mounted outside the cryostat to measure the secondary shower particles caused by lost beam particles. Since the stored particle beam intensity is eight orders of magnitude larger than the lowest quench level and the losses should be detected with a relative error of two, the design and the location of the detectors have to be optimised. For that purpose a two-fold simulation was carried out. The longitudinal loss locations of the tertiary halo is investigated by tracking the halo through several magnet elements. These loss distributions are combined with simulations of the particle fluence outside the cryostat, which is induced by lost protons at the vacuum pipe. The base-line ionisation chamber has been tested at the PS Booster in order to determine the detector response at the high end of the dynamic range.

  7. Graphene Field Effect Transistor-Based Detectors for Detection of Ionizing Radiation

    Jovanovic, Igor; Cazalas, Edward; Childres, I.; Patil, A.; Koybasi, O.; Chen, Y-P.

    2013-06-01

    We present the results of our recent efforts to develop novel ionizing radiation sensors based on the nano-material graphene. Graphene used in the field effect transistor architecture could be employed to detect the radiation-induced charge carriers produced in undoped semiconductor absorber substrates, even without the need for charge collection. The detection principle is based on the high sensitivity of graphene to ionization-induced local electric field perturbations in the electrically biased substrate. We experimentally demonstrated promising performance of graphene field effect transistors for detection of visible light, X-rays, gamma-rays, and alpha particles. We propose improved detector architectures which could result in a significant improvement of speed necessary for pulsed mode operation. (authors)

  8. Flame photometric detection of sodium leaks: Tests on a fullscale model for the control gear sodium rig

    Grundy, B.R.; Knowles, P.

    1971-01-01

    The proposed arrangement for detecting sodium leaks from the large flanges of the Control Gear Sodium Rig (Test Section No. 8, MCTR) at REML is to jacket then in a secondary containment from which air samples will be continuously pumped. Pipework feeds the air to a flame photometer which responds if soditun is present. To prove that sodium smoke could be transferred through the system, tests were performed on a fullscale model by burning small amounts of sodium in different jackets. Large signals free from fluctuations were obtained in all tests, peak response occurring in 2 1/4 minutes or less. The signal quickly cleared after isolating the appropriate vessel. A waiting period of several hours was sufficient to reduce the signal to zero, no cleaning of pipework, etc being necessary. In contrast, samples of two lagging materials heated to 400 °C gave no response with the photometer at maximum sensitivity. (author)

  9. Possible standoff detection of ionizing radiation using high-power THz electromagnetic waves

    Nusinovich, Gregory S.; Sprangle, Phillip; Romero-Talamas, Carlos A.; Rodgers, John; Pu, Ruifeng; Kashyn, Dmytro G.; Antonsen, Thomas M., Jr.; Granatstein, Victor L.

    2012-06-01

    Recently, a new method of remote detection of concealed radioactive materials was proposed. This method is based on focusing high-power short wavelength electromagnetic radiation in a small volume where the wave electric field exceeds the breakdown threshold. In the presence of free electrons caused by ionizing radiation, in this volume an avalanche discharge can then be initiated. When the wavelength is short enough, the probability of having even one free electron in this small volume in the absence of additional sources of ionization is low. Hence, a high breakdown rate will indicate that in the vicinity of this volume there are some materials causing ionization of air. To prove this concept a 0.67 THz gyrotron delivering 200-300 kW power in 10 microsecond pulses is under development. This method of standoff detection of concealed sources of ionizing radiation requires a wide range of studies, viz., evaluation of possible range, THz power and pulse duration, production of free electrons in air by gamma rays penetrating through container walls, statistical delay time in initiation of the breakdown in the case of low electron density, temporal evolution of plasma structure in the breakdown and scattering of THz radiation from small plasma objects. Most of these issues are discussed in the paper.

  10. Apparatus and method for the simultaneous detection of neutrons and ionizing electromagnetic radiation

    Bell, Zane W.

    2000-01-01

    A sensor for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising: a sensor for the detection of gamma radiation, the sensor defining a sensing head; the sensor further defining an output end in communication with the sensing head; and an exterior neutron-sensitive material configured to form around the sensing head; wherein the neutron-sensitive material, subsequent to the capture of the neutron, fissions into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the first excited state decaying via the emission of a single gamma ray at 478 keV which can in turn be detected by the sensing head; and wherein the sensing head can also detect the ionizing electromagnetic radiation from an incident radiation field without significant interference from the neutron-sensitive material. A method for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising the steps of: providing a gamma ray sensitive detector comprising a sensing head and an output end; conforming an exterior neutron-sensitive material configured to form around the sensing head of the detector; capturing neutrons by the sensing head causing the neutron-sensitive material to fission into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the state decaying via the emission of a single gamma ray at 478 keV; sensing gamma rays entering the detector through the neutron-sensitive material; and producing an output through a readout device coupled to the output end; wherein the detector provides an output which is proportional to the energy of the absorbed ionizing electromagnetic radiation.

  11. [Determination of 44 organophosphorus pesticides in food by SPE disk extraction-capillary gas chromatography with pulsed flame photometric detection].

    Luo, Xiao-Fei; Yang, Yuan; Sun, Cheng-Jun

    2012-01-01

    To develop a method for the simultaneous determination of 44 organophosphorus pesticides in food by SPE disk extraction-capillary gas chromatography with pulsed flame photometric detection. Organophosphorus pesticides in food were extracted ultrasonically with water. Then the extract was cleaned-up with SPE disk and eluted with ethyl acetate. Finally the eluent was condensed to 1mL under N2 at 55 degrees C. Gas chromatography was applied for quantitative detection of the organophosphorus pesticides in the sample. The linear range of the method for all the pesticides were in the range of 0.01-0.5 mg/kg with correlation coefficients of 0.992-1.000. The detection limits of the method were in the range of 0.0005-0.01 mg/kg. The recoveries for most pesticides were 60%-120% with relative standard deviations of less than 15%. The method is simple, sensitive, environmentally friendly and suitable for the determination of organophosphorous pesticides in food.

  12. A tripolar-electrode ionization gas sensor using a carbon nanotube cathode for NO detection

    Song, Hui; Li, Kun; Li, Quanfu

    2018-06-01

    Nitric oxide accounts for more than 95% of the total NO X emission from power plants, which is a major air pollutant. Therefore, it is imperative to accurately detect NO for environmental protection. A tripolar-electrode ionization sensor with a carbon nanotube (CNT) cathode is proposed for NO detection. The non-self-sustaining discharge state and the tripolar-electrode configuration ensures a long nanotube life, which ensures a good stability and fast response of the sensor. Experimental results demonstrate that the tripolar-electrode ionization sensor with 120 µm separations has an intrinsic monotonously decreasing response to NO and exhibits a fast response time of 7 s and recovery time of 8 s. More consumption of the two metastable states N2(A3  ∑  u +) and N2(aʹ1  ∑  u +) of N2 with the increasing of NO concentration is responsible for this. The tripolar-electrode ionization sensor also shows excellent long-term stability of at least one month due to the long CNT life. In addition, the weak effect of SO2 introduction on NO response indicates a good selectivity of the sensor to NO.

  13. Analysis of monomeric and oligomeric organophosphorus flame retardants in fish muscle tissues using liquid chromatography–electrospray ionization tandem mass spectrometry: Application to Nile tilapia (Oreochromis niloticus from an e-waste processing area in northern Vietnam

    Hidenori Matsukami

    2016-06-01

    Full Text Available Using electrospray ionization tandem mass spectrometry combined with liquid chromatography (LC, a novel analytical method was developed to quantify eight monomeric organophosphorus flame retardants (m-PFRs and three oligomeric organophosphorus flame retardants (o-PFRs in fish muscle samples. The optimization and validation experiments indicate that the developed method can determine accurately the concentrations of analytes in fish muscle samples. The recoveries of analytes in fish muscle samples were in the range of 74–105%. The coefficients of variation of the concentrations of analytes in fish muscle samples were 0.6–8.9%. The concentrations of analytes in procedural blanks were below the limit of quantification (LOQ values. Furthermore, the developed method was applied to the analysis of m-PFRs and o-PFRs in the muscle samples of tilapias collected from an electronic waste (e-waste processing area in northern Vietnam. The concentrations of m-PFRs such as tris(2-chloroethyl phosphate (TCEP, tris(2-chloroisopropyl phosphate (TCIPP, and triphenyl phosphate (TPHP were dominant among the investigated m-PFRs. The respective concentrations of TCEP, TCIPP, and TPHP were up to 160, 300, and 230 ng g−1 lipid weight, respectively, whereas those of o-PFRs were up to 10 ng g−1 lipid weight. The results of this study indicate lower accumulation potential of o-PFRs compared with m-PFRs for the first time.

  14. Rapid in situ detection of alkaloids in plant tissue under ambient conditions using desorption electrospray ionization.

    Talaty, Nari; Takáts, Zoltán; Cooks, R Graham

    2005-12-01

    Desorption electrospray ionization (DESI) mass spectrometry is applied to the in situ detection of alkaloids in the tissue of poison hemlock (Conium maculatum), jimsonweed (Datura stramonium) and deadly nightshade (Atropa belladonna). The experiment is carried out by electrospraying micro-droplets of solvent onto native or freshly-cut plant tissue surfaces. No sample preparation is required and the mass spectra are recorded under ambient conditions, in times of a few seconds. The impact of the sprayed droplets on the surface produces gaseous ions from organic compounds originally present in the plant tissue. The effects of operating parameters, including the electrospray high voltage, heated capillary temperature, the solvent infusion rate and the carrier gas pressure on analytical performance are evaluated and optimized. Different types of plant material are analyzed including seeds, stems, leaves, roots and flowers. All the previously reported alkaloids have been detected in C. maculatum, while fifteen out of nineteen known alkaloids for D. stramonium and the principal alkaloids of A. belladonna were also identified. All identifications were confirmed by tandem mass spectrometry. Results obtained show similar mass spectra, number of alkaloids, and signal intensities to those obtained when extraction and separation processes are performed prior to mass spectrometric analysis. Evidence is provided that DESI ionization occurs by both a gas-phase ionization process and by a droplet pick-up mechanism. Quantitative precision of DESI is compared with conventional electrospray ionization mass spectrometry (after sample workup) and the RSD values for the same set of 25 dicotyledonous C. maculatum seeds (one half of each seed analyzed by ESI and the other by DESI) are 9.8% and 5.2%, respectively.

  15. Cross validation of gas chromatography-flame photometric detection and gas chromatography-mass spectrometry methods for measuring dialkylphosphate metabolites of organophosphate pesticides in human urine.

    Prapamontol, Tippawan; Sutan, Kunrunya; Laoyang, Sompong; Hongsibsong, Surat; Lee, Grace; Yano, Yukiko; Hunter, Ronald Elton; Ryan, P Barry; Barr, Dana Boyd; Panuwet, Parinya

    2014-01-01

    We report two analytical methods for the measurement of dialkylphosphate (DAP) metabolites of organophosphate pesticides in human urine. These methods were independently developed/modified and implemented in two separate laboratories and cross validated. The aim was to develop simple, cost effective, and reliable methods that could use available resources and sample matrices in Thailand and the United States. While several methods already exist, we found that direct application of these methods required modification of sample preparation and chromatographic conditions to render accurate, reliable data. The problems encountered with existing methods were attributable to urinary matrix interferences, and differences in the pH of urine samples and reagents used during the extraction and derivatization processes. Thus, we provide information on key parameters that require attention during method modification and execution that affect the ruggedness of the methods. The methods presented here employ gas chromatography (GC) coupled with either flame photometric detection (FPD) or electron impact ionization-mass spectrometry (EI-MS) with isotopic dilution quantification. The limits of detection were reported from 0.10ng/mL urine to 2.5ng/mL urine (for GC-FPD), while the limits of quantification were reported from 0.25ng/mL urine to 2.5ng/mL urine (for GC-MS), for all six common DAP metabolites (i.e., dimethylphosphate, dimethylthiophosphate, dimethyldithiophosphate, diethylphosphate, diethylthiophosphate, and diethyldithiophosphate). Each method showed a relative recovery range of 94-119% (for GC-FPD) and 92-103% (for GC-MS), and relative standard deviations (RSD) of less than 20%. Cross-validation was performed on the same set of urine samples (n=46) collected from pregnant women residing in the agricultural areas of northern Thailand. The results from split sample analysis from both laboratories agreed well for each metabolite, suggesting that each method can produce

  16. Highly sensitive detection of ionizing radiations by a photoluminescent uranyl organic framework

    Xie, Jian; Wang, Yaxing; Liu, Wei; Yin, Xuemiao; Chen, Lanhua; Diwu, Juan; Chai, Zhifang; Wang, Shuao [School for Radiological and interdisciplinary Sciences (RAD-X) and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou (China); Zou, Youming [High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui (China); Albrecht-Schmitt, Thomas E. [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL (United States); Liu, Guokui [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL (United States)

    2017-06-19

    Precise detection of low-dose X- and γ-radiations remains a challenge and is particularly important for studying biological effects under low-dose ionizing radiation, safety control in medical radiation treatment, survey of environmental radiation background, and monitoring cosmic radiations. We report here a photoluminescent uranium organic framework, whose photoluminescence intensity can be accurately correlated with the exposure dose of X- or γ-radiations. This allows for precise and instant detection of ionizing radiations down to the level of 10{sup -4} Gy, representing a significant improvement on the detection limit of approximately two orders of magnitude, compared to other chemical dosimeters reported up to now. The electron paramagnetic resonance analysis suggests that with the exposure to radiations, the carbonyl double bonds break affording oxo-radicals that can be stabilized within the conjugated uranium oxalate-carboxylate sheet. This gives rise to a substantially enhanced equatorial bonding of the uranyl(VI) ions as elucidated by the single-crystal structure of the γ-ray irradiated material, and subsequently leads to a very effective photoluminescence quenching through phonon-assisted relaxation. The quenched sample can be easily recovered by heating, enabling recycled detection for multiple runs. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Organophosphorus pesticide and ester analysis by using comprehensive two-dimensional gas chromatography with flame photometric detection.

    Liu, Xiangping; Li, Dengkun; Li, Jiequan; Rose, Gavin; Marriott, Philip J

    2013-12-15

    Thirty-seven phosphorus (P)-containing compounds comprising organophosphorus pesticides and organophosphate esters were analyzed by using comprehensive two-dimensional gas chromatography with flame photometric detection in P mode (GC × GC-FPD(P)), with a non-polar/moderately polar column set. A suitable modulation temperature and period was chosen based on experimental observation. A number of co-eluting peak pairs on the (1)D column were well separated in 2D space. Excellent FPD(P) detection selectivity, responding to compounds containing the P atom, produces clear 2D GC × GC plots with little interference from complex hydrocarbon matrices. Limits of detection (LOD) were within the range of 0.0021-0.048 μmol L(-1), and linear calibration correlation coefficients (R(2)) for all 37 P-compounds were at least 0.998. The P-compounds were spiked in 2% diesel and good reproducibility for their response areas and retention times was obtained. Spiked recoveries were 88%-157% for 5 μg L(-1) and 80%-138% for 10 μg L(-1) spiked levels. Both (1)tR and (2)tR shifts were noted when the content of diesel was in excess of 5% in the matrix. Soil samples were analyzed by using the developed method; some P-compounds were positively detected. In general, this study shows that GC × GC-FPD(P) is an accurate, sensitive and simple method for P-compound analysis in complicated environmental samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Fast quantitative detection of cocaine in beverages using nanoextractive electrospray ionization tandem mass spectrometry.

    Hu, Bin; Peng, Xuejiao; Yang, Shuiping; Gu, Haiwei; Chen, Huanwen; Huan, Yanfu; Zhang, Tingting; Qiao, Xiaolin

    2010-02-01

    Without any sample pretreatment, effervescent beverage fluids were manually sprayed into the primary ion plume created by using a nanoelectrospray ionization source for direct ionization, and the analyte ions of interest were guided into an ion trap mass spectrometer for tandem mass analysis. Functional ingredients (e.g., vitamins, taurine, and caffeine, etc.) and spiked impurity (e.g., cocaine) in various beverages, such as Red Bull energy drink, Coco-cola, and Pepsi samples were rapidly identified within 1.5 s. The limit of detection was found to be 7-15 fg (S/N = 3) for cocaine in different samples using the characteristic fragment (m/z 150) observed in the MS(3) experiments. Typical relative standard deviation and recovery of this method were 6.9%-8.6% and 104%-108% for direct analysis of three actual samples, showing that nanoextractive electrospray ionization tandem mass spectrometry is a useful technique for fast screening cocaine presence in beverages. 2010. Published by Elsevier Inc.

  19. Early Detection of Biofouling on Water Purification Membranes by Ambient Ionization Mass Spectrometry Imaging.

    Jakka Ravindran, Swathy; Kumar, Ramesh; Srimany, Amitava; Philip, Ligy; Pradeep, Thalappil

    2018-01-02

    By direct analysis of water purification membranes using ambient ionization mass spectrometry, an attempt has been made to understand the molecular signatures of bacterial fouling. Membrane based purification methods are used extensively in water treatment, and a major challenge for them is biofouling. The buildup of microbes and their extracellular polymeric matrix clog the purification membranes and reduce their efficiency. To understand the early stages of bacterial fouling on water purification membranes, we have used desorption electrospray ionization mass spectrometry (DESI MS), where ion formation occurs in ambient conditions and the ionization event is surface sensitive. Biosurfactants at the air-water interface generated by microorganisms as a result of quorum sensing, influence the water-membrane interface and are important for the bacterial attachment. We show that these biosurfactants produced by bacteria can be indicator molecular species signifying initiation of biofilms on membrane surfaces, demonstrated by specific DESI MS signatures. In Pseudomonas aeruginosa, one of the best studied models for biofilm formation, this process is mediated by rhamnolipids forewarning bacterial fouling. Species dependent variation of such molecules can be used for the precise identification of the microorganisms, as revealed by studies on P. aeroginosa (ATCC 25619). The production of biosurfactants is tightly regulated at the transcriptional level by the quorum-sensing (QS) response. Thus, secretion of these extracellular molecules across the membrane surface allows rapid screening of the biofilm community. We show that, the ambient ionization mass spectrometry can detect certain toxic heavy metals present in water, using surfactant-metal complexes as analytes. We believe that such studies conducted on membranes in various input water streams will help design suitable membrane processes specific to the input streams.

  20. Method of shaping of direction-characterization of sensitivity of ionizing radiation detection probe

    Czarnecki, J.; Jaszczuk, J.; Kruczyk, M.; Slapa, M.; Wroblewski, T.

    1986-01-01

    A method of shaping of direction-characterization of sensitivity of the ionizing radiation detection probe, especially equipped with small gamma detectors is described. Two detectors are placed coaxially in the bases of the cylindrical shield. One of them is uncovered in the highest degree and the second is not covered to a maximum. The signals from them are processed on the standarized sequences of electrical impulses (taking into account the heights and the widths of the amplitude). 2 figs., 1 tab. (A.S.)

  1. Flame Length

    Earth Data Analysis Center, University of New Mexico — Flame length was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The tool...

  2. Organophosphorus pesticide and ester analysis by using comprehensive two-dimensional gas chromatography with flame photometric detection

    Liu, Xiangping; Li, Dengkun; Li, Jiequan [Nanjing Centre for Disease Control and Prevention, Zizhulin Street, Gulou 210003, Nanjing (China); Rose, Gavin [Department of Environment and Primary Industries, Macleod Centre, Ernest Jones Drive, Macleod, Vic 3085 (Australia); Marriott, Philip J., E-mail: philip.marriott@monash.edu [Australian Centre for Research on Separation Science, School of Chemistry, Monash University, Wellington Road, Clayton 3800 (Australia)

    2013-12-15

    Highlights: • GC × GC-FPD(P-mode) was applied to detection of 37 phosphorus (P)-containing compounds. • The method improves resolution of P-compounds that coelute in the first dimension. • P-compounds are analyzed with excellent sensitivity supported by cryogenic modulation. • The FPD(P-mode) selectivity allows analysis in high hydrocarbon (H/C) matrix. • Soil samples and spiked chemical weapon compounds in H/C matrix are readily screened. -- Abstract: Thirty-seven phosphorus (P)-containing compounds comprising organophosphorus pesticides and organophosphate esters were analyzed by using comprehensive two-dimensional gas chromatography with flame photometric detection in P mode (GC × GC-FPD(P)), with a non-polar/moderately polar column set. A suitable modulation temperature and period was chosen based on experimental observation. A number of co-eluting peak pairs on the {sup 1}D column were well separated in 2D space. Excellent FPD(P) detection selectivity, responding to compounds containing the P atom, produces clear 2D GC × GC plots with little interference from complex hydrocarbon matrices. Limits of detection (LOD) were within the range of 0.0021–0.048 μmol L{sup −1}, and linear calibration correlation coefficients (R{sup 2}) for all 37 P-compounds were at least 0.998. The P-compounds were spiked in 2% diesel and good reproducibility for their response areas and retention times was obtained. Spiked recoveries were 88%–157% for 5 μg L{sup −1} and 80%–138% for 10 μg L{sup −1} spiked levels. Both {sup 1}t{sub R} and {sup 2}t{sub R} shifts were noted when the content of diesel was in excess of 5% in the matrix. Soil samples were analyzed by using the developed method; some P-compounds were positively detected. In general, this study shows that GC × GC-FPD(P) is an accurate, sensitive and simple method for P-compound analysis in complicated environmental samples.

  3. Thermal ionization mass spectrometry (TIMS) of actinides: Pushing the limits of accuracy and detection

    Buerger, Stefan; Boulyga, Sergei; Cunningham, Alan; Klose, Dilani; Koepf, Andreas; Poths, Jane [Safeguards Analytical Laboratory, International Atomic Energy Agency, Vienna (Austria); Richter, Stephan [Institute for Reference Materials and Measurements, JRC-EU, Geel (Belgium)

    2010-07-01

    New method developments in multi-collector thermal ionization mass spectrometry (MC-TIMS) for actinide isotope ratio analysis to improve accuracy and limits of detection will be presented. With respect to limits of detection, results on improving work function using various carbon additives will be reviewed and presented as well as developments in cavity ion source (as compared to standard flat ribbon filament ion source) for femto- and attogram levels of uranium, plutonium, and americium. With respect to accuracy, results on isotope ratio measurements of isotopes of uranium (relative accuracy of 0.3% to 0.01%) are presented with an example being U-234-Th-230 age-dating (NBL CRM 112-A). In this context, the importance of traceability (to the S.I. units) and the use of (certified) reference materials are emphasized. The focus of this presentation is on applications to nuclear safeguards / forensics.

  4. SU-F-T-310: Does a Head-Mounted Ionization Chamber Detect IMRT Errors?

    Wegener, S; Herzog, B; Sauer, O

    2016-01-01

    Purpose: The conventional plan verification strategy is delivering a plan to a QA-phantom before the first treatment. Monitoring each fraction of the patient treatment in real-time would improve patient safety. We evaluated how well a new detector, the IQM (iRT Systems, Germany), is capable of detecting errors we induced into IMRT plans of three different treatment regions. Results were compared to an established phantom. Methods: Clinical plans of a brain, prostate and head-and-neck patient were modified in the Pinnacle planning system, such that they resulted in either several percent lower prescribed doses to the target volume or several percent higher doses to relevant organs at risk. Unaltered plans were measured on three days, modified plans once, each with the IQM at an Elekta Synergy with an Agility MLC. All plans were also measured with the ArcCHECK with the cavity plug and a PTW semiflex 31010 ionization chamber inserted. Measurements were evaluated with SNC patient software. Results: Repeated IQM measurements of the original plans were reproducible, such that a 1% deviation from the mean as warning and 3% as action level as suggested by the manufacturer seemed reasonable. The IQM detected most of the simulated errors including wrong energy, a faulty leaf, wrong trial exported and a 2 mm shift of one leaf bank. Detection limits were reached for two plans - a 2 mm field position error and a leaf bank offset combined with an MU change. ArcCHECK evaluation according to our current standards also left undetected errors. Ionization chamber evaluation alone would leave most errors undetected. Conclusion: The IQM detected most errors and performed as well as currently established phantoms with the advantage that it can be used throughout the whole treatment. Drawback is that it does not indicate the source of the error.

  5. SU-F-T-310: Does a Head-Mounted Ionization Chamber Detect IMRT Errors?

    Wegener, S; Herzog, B; Sauer, O [University of Wuerzburg, Wuerzburg (Germany)

    2016-06-15

    Purpose: The conventional plan verification strategy is delivering a plan to a QA-phantom before the first treatment. Monitoring each fraction of the patient treatment in real-time would improve patient safety. We evaluated how well a new detector, the IQM (iRT Systems, Germany), is capable of detecting errors we induced into IMRT plans of three different treatment regions. Results were compared to an established phantom. Methods: Clinical plans of a brain, prostate and head-and-neck patient were modified in the Pinnacle planning system, such that they resulted in either several percent lower prescribed doses to the target volume or several percent higher doses to relevant organs at risk. Unaltered plans were measured on three days, modified plans once, each with the IQM at an Elekta Synergy with an Agility MLC. All plans were also measured with the ArcCHECK with the cavity plug and a PTW semiflex 31010 ionization chamber inserted. Measurements were evaluated with SNC patient software. Results: Repeated IQM measurements of the original plans were reproducible, such that a 1% deviation from the mean as warning and 3% as action level as suggested by the manufacturer seemed reasonable. The IQM detected most of the simulated errors including wrong energy, a faulty leaf, wrong trial exported and a 2 mm shift of one leaf bank. Detection limits were reached for two plans - a 2 mm field position error and a leaf bank offset combined with an MU change. ArcCHECK evaluation according to our current standards also left undetected errors. Ionization chamber evaluation alone would leave most errors undetected. Conclusion: The IQM detected most errors and performed as well as currently established phantoms with the advantage that it can be used throughout the whole treatment. Drawback is that it does not indicate the source of the error.

  6. Determinação de metil-etil-cetona em amostras de urina com amostragem por micro extração em fase sólida (MEFS em headspace associada à cromatografia gasosa com detector de ionização de chama (CG-DIC Determination of methyl ethyl ketone in urine samples by headspace solid phase micro extraction (SPME sampling associated to gas chromatography with flame-ionization detectoR (GC-FID

    Marina Venzon Antunes

    2008-01-01

    Full Text Available Methyl ethyl ketone (MEK is a solvent commonly used in chemical, paint and shoe industry. The aim of this study was to develop and validate a method for urinary quantification of MEK, employing headspace solid phase micro extraction sampling (SPME coupled to gas chromatography with flame ionization detection (GC-FID. The calibration curve (y=4.6851x-0.0011 presented good linearity with r²=0.9993. Accuracy (94-109%, intra-assay precision (4.07-5.91% and inter-assay precision (3.03-5.62% were acceptable. The quantification limit was 0.19 mg/L. This low cost method can be used routinely in the biological monitoring of occupational exposure to MEK, according to the requirements of the Brazilian legislation.

  7. Ionizing radiation

    Kruger, J.

    1989-01-01

    Ionizing radiation results in biological damage that differs from other hazardous substances and is highly dangerous to man. Ionizing radiation cannot be perceived by man's sense organs and the biological damage cannot be detected immediately afterwards (except in very high doses). Every human being is exposed to low doses of radiation. The structure of the atom; sources of ionizing radiation; radiation units; biological effects; norms for radiation protection; and the national control in South Africa are discussed. 1 fig., 5 refs

  8. Detection of mitochondrial DNA deletions in human cells induced by ionizing radiation

    Liu, Qing-Jie; Feng, Jiang-Bin; Lu, Xue; Li, Yu-Wen; Chen, De-Qing

    2008-01-01

    Full text: Purpose: To screen the novel mitochondrial DNA (mt DNA) deletions induced by ionizing radiation, and analyze the several kinds of mt DNA deletions, known as 3895 bp, 889 bp, 7436 bp or 4934 bp deletions. Methods: Long-range PCR with two pairs of primers, which could amplify the whole human mitochondrial genome, was used to analyze the lymphoblastoid cell line before and after exposed to 10 Gy 60 Co γ-rays. The limited condition PCR was used to certify the possible mt DNA deletion showed by long-range PCR. The PCR products were purified, cloned, sequenced and the sequence result were BLASTed. Regular PCR or nest-PCR were used to analyze the 3895 bp, 889 bp, 7436 bp or 4934 bp deletions before and after radiation exposure. The final PCR products were purified, sequenced and BALSTed on standard human mitochondrial genome sequence database. Results: (1) The predicted bands of mt DNA were observed on the control cell lines, and the possible mt DNA deletions were also detected on the irradiated cell lines. The deletions were certified by the limited condition PCR. The sequence BLAST results of the cloned PCR products showed that two kinds of deletions, 7455 bp deletion (nt 475-7929 in heavy strand) and 9225 bp deletion (nt 7714-369 in heavy strand), which were between two 8 bp direct repeats. Further bioinformatics analysis showed that the two deletions were novel deletions. (2) The 889 bp and 3895 bp deletion were not detected for the cell line samples not exposed to 60 Co γ-rays. The 889 bp and 3895 bp deletions were detected on samples exposed to 10 Gy 60 Co γ-rays. The BALST results showed that the 889 bp and 3895 deletions flanked nt 11688 bp-12576, nt 548 bp-4443, respectively. The 7436 bp deletion levels were not changed much before and after irradiation. (3) The 4934 bp deletions had the same pattern as 7436 bp deletion, but it could induced by radiation. Conclusions: Ionizing radiation could induce the human lymphoblastoid two novel mt DNA

  9. HgI2 nanostructures obtained hydrothermally for application in ionizing radiation detection

    Pérez Barthaburu, María; Bentos Pereira, Heinkel; Fornaro, Laura; Galain, Isabel; Aguiar, Ivana

    2016-01-01

    The compound semiconductor HgI 2 has been widely studied and employed as a material for ionizing radiation detection. Monocrystal growth is an intricate method for obtaining materials for this application. With the aim of finding a simpler and more effective way to develop ionizing radiation detectors, we employed HgI 2 nanostructures subjected to a hydrothermal treatment and then pressed for this purpose. In the synthesis procedure, aqueous solutions of Hg(NO 3 ) 2 and NaI were mixed until their reaction completed and the suspension obtained was then placed in a homemade autoclave and heated at 120 °C for 2, 10 or 24 h. We confirmed the HgI 2 tetragonal phase by powder XRD in all cases, independently of the synthesis conditions employed. Nanoparticles were characterized by their size and morphology by TEM. We used the HgI 2 nanostructures to obtain a pellet by applying 0.7 GPa of pressure at room temperature. The pellet was then used to construct the detector, and we studied the electrical properties of the detector and its response to 241 Am sources of different exposure rates. The resistivity and signal-to-noise ratio obtained are of the order of those reported for HgI 2 detectors assembled with monocrystals. The results obtained in this work encourage us to work further on this topic, improving the method, scaling the detector’s size and studying its spectrometric grade. (paper)

  10. Quantum dots assisted laser desorption/ionization mass spectrometric detection of carbohydrates: qualitative and quantitative analysis.

    Bibi, Aisha; Ju, Huangxian

    2016-04-01

    A quantum dots (QDs) assisted laser desorption/ionization mass spectrometric (QDA-LDI-MS) strategy was proposed for qualitative and quantitative analysis of a series of carbohydrates. The adsorption of carbohydrates on the modified surface of different QDs as the matrices depended mainly on the formation of hydrogen bonding, which led to higher MS intensity than those with conventional organic matrix. The effects of QDs concentration and sample preparation method were explored for improving the selective ionization process and the detection sensitivity. The proposed approach offered a new dimension to the application of QDs as matrices for MALDI-MS research of carbohydrates. It could be used for quantitative measurement of glucose concentration in human serum with good performance. The QDs served as a matrix showed the advantages of low background, higher sensitivity, convenient sample preparation and excellent stability under vacuum. The QDs assisted LDI-MS approach has promising application to the analysis of carbohydrates in complex biological samples. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Detection of polychlorinated biphenyls in transformer oils in Vietnam by multiphoton ionization mass spectrometry using a far-ultraviolet femtosecond laser as an ionization source.

    Duong, Vu Thi Thuy; Duong, Vu; Lien, Nghiem Thi Ha; Imasaka, Tomoko; Tang, Yuanyuan; Shibuta, Shinpei; Hamachi, Akifumi; Hoa, Do Quang; Imasaka, Totaro

    2016-03-01

    Polychlorinated biphenyls (PCBs) in transformer and food oils were measured using gas chromatography combined with multiphoton ionization mass spectroscopy. An ultrashort laser pulse emitting in the far-ultraviolet region was utilized for efficient ionization of the analytes. Numerous signal peaks were clearly observed for a standard sample mixture of PCBs when the third and fourth harmonic emissions (267 and 200nm) of a femtosecond Ti:sapphire laser (800nm) were employed. The signal intensities were found to be greater when measured at 200nm compared with those measured at 267nm, providing lower detection limits especially for highly chlorinated PCBs at shorter wavelengths. After simple pretreatment using disposable columns, PCB congeners were measured and found to be present in the transformer oils used in Vietnam. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Comparison of Cocaine Detections in Corona Discharge Ionization-Ion Mobility Spectrometry and in Atmospheric Pressure Chemical Ionization-Mass Spectrometry

    Choi, Sung Seen; Kim, Yun Ki; Kim, Ok Bae; An, Seung Geon; Shin, Myung Won; Maeng, Seug Jin; Choi, Gyu Seop

    2010-01-01

    In this study, we determined the detection limit and reproducibility of the new IMS equipped with corona discharge ionization source using cocaine. The sample was injected with liquid solution to compare the results of APCI-MS. Ion mobility spectrometry (IMS) was a technique originally applied for the detection of trace compounds. IMS has been widely used to detect chemical warfare agents, explosives, and illegal drugs since it combines both high sensitivity (detection limits down to the ng/L range to pg/L range, ppb range and ppt range) and relatively low technical expenditure with high-speed data acquisition. The time required to acquire a single spectrum is in the range of several tens ms. The working principle is based on the drift of ions at ambient pressure under the influence of an external electric field

  13. Comparison of Cocaine Detections in Corona Discharge Ionization-Ion Mobility Spectrometry and in Atmospheric Pressure Chemical Ionization-Mass Spectrometry

    Choi, Sung Seen; Kim, Yun Ki; Kim, Ok Bae [Sejong University, Seoul (Korea, Republic of); An, Seung Geon; Shin, Myung Won; Maeng, Seug Jin; Choi, Gyu Seop [Wooju Communication and Technology Co., Seoul (Korea, Republic of)

    2010-08-15

    In this study, we determined the detection limit and reproducibility of the new IMS equipped with corona discharge ionization source using cocaine. The sample was injected with liquid solution to compare the results of APCI-MS. Ion mobility spectrometry (IMS) was a technique originally applied for the detection of trace compounds. IMS has been widely used to detect chemical warfare agents, explosives, and illegal drugs since it combines both high sensitivity (detection limits down to the ng/L range to pg/L range, ppb range and ppt range) and relatively low technical expenditure with high-speed data acquisition. The time required to acquire a single spectrum is in the range of several tens ms. The working principle is based on the drift of ions at ambient pressure under the influence of an external electric field.

  14. Development of laser excited atomic fluorescence and ionization methods

    Winefordner, J.D.

    1991-01-01

    Progress report: May 1, 1988 to December 31, 1991. The research supported by DE-FG05-88ER13881 during the past (nearly) 3 years can be divided into the following four categories: (1) theoretical considerations of the ultimate detection powers of laser fluorescence and laser ionization methods; (2) experimental evaluation of laser excited atomic fluorescence; (3) fundamental studies of atomic and molecular parameters in flames and plasmas; (4) other studies

  15. Use of resonance ionization spectroscopy to detect DNA bands on ultrathin spin-coated gels.

    Doktycz, M J; Gibson, W A; Arlinghaus, H F; Allen, R C; Jacobson, K B

    1993-01-01

    Development of alternative electrophoresis procedures are necessary for large volume sequencing and mapping studies. The use of stable isotopes as DNA labels and ultrathin gels promises to greatly increase the rate of sequencing. Spin coating is presented as an alternative method for producing ultrathin polyacrylamide gels. The technique has the potential of producing gels of micron to submicron thicknesses by varying the viscosity of the acrylamide solution and the spinning speed. Thirty micron thick 6% (weight %) gels were produced in this manner. Tin-labeled DNA oligomers were electrophoresed and detected using sputter-initiated resonance ionization spectroscopy (SIRIS). The usefulness of SIRIS and laser atomization RIS (LARIS) to sample the surface and deeper layers of 240 microns thick gels was investigated. With LARIS, whole cross-sections of the gel can be atomized, possibly allowing complete sampling of labels.

  16. Studies of ground-state dynamics in isolated species by ionization-detected stimulated Raman techniques

    Felker, P.M. [Univ. of California, Los Angeles (United States)

    1993-12-01

    First, the author aims to develop methods of nonlinear Raman spectroscopy for application in studies of sparse samples. Second, the author wishes to apply such methods to structural and dynamical studies of species (molecules, complexes, and clusters) in supersonic molecular beams. In the past year, the author has made progress in several areas. The first pertains to the application of mass-selective ionization-detected stimulated Raman spectroscopies (IDSRS) to the size-specific vibrational spectroscopy of solute-solvent{sub n} clusters. The second involves the application of IDSRS methods to studies of jet-cooled benzene clusters. The third pertains to the use of IDSRS methods in the study of intermolecular vibrational transitions in van der Waals complexes.

  17. Widespread detection of a brominated flame retardant, hexabromocyclododecane, in expanded polystyrene marine debris and microplastics from South Korea and the Asia-Pacific coastal region

    Jang, Mi; Shim, Won Joon; Han, Gi Myung; Rani, Manviri; Song, Young Kyoung; Hong, Sang Hee

    2017-01-01

    The role of marine plastic debris and microplastics as a carrier of hazardous chemicals in the marine environment is an emerging issue. This study investigated expanded polystyrene (EPS, commonly known as styrofoam) debris, which is a common marine debris item worldwide, and its additive chemical, hexabromocyclododecane (HBCD). To obtain a better understanding of chemical dispersion via EPS pollution in the marine environment, intensive monitoring of HBCD levels in EPS debris and microplastics was conducted in South Korea, where EPS is the predominant marine debris originate mainly from fishing and aquaculture buoys. At the same time, EPS debris were collected from 12 other countries in the Asia-Pacific region, and HBCD concentrations were measured. HBCD was detected extensively in EPS buoy debris and EPS microplastics stranded along the Korean coasts, which might be related to the detection of a quantity of HBCD in non-flame-retardant EPS bead (raw material). The wide detection of the flame retardant in sea-floating buoys, and the recycling of high-HBCD-containing EPS waste inside large buoys highlight the need for proper guidelines for the production and use of EPS raw materials, and the recycling of EPS waste. HBCD was also abundantly detected in EPS debris collected from the Asia-Pacific coastal region, indicating that HBCD contamination via EPS debris is a common environmental issue worldwide. Suspected tsunami debris from Alaskan beaches indicated that EPS debris has the potential for long-range transport in the ocean, accompanying the movement of hazardous chemicals. The results of this study indicate that EPS debris can be a source of HBCD in marine environments and marine food web. - Highlights: • A brominated flame retardant, HBCD, was assessed in EPS debris and microplastics. • HBCD was widely detected in EPS debris from the Asia-Pacific coastal region. • Additive HBCD are dispersed via EPS pollution in marine environments. • EPS debris can be a

  18. Detection of reciprocal chromosome translocations as an indicator of organism exposure to ionizing radiation by FISH-WCP method

    Holeckova, B.; Sivikova, K.; Dianovsky, J.; Piesova, E.; Lakatosova, M.

    2006-01-01

    Chromosome translocations are considered to be the gold standard for assessing ionizing radiation exposure. Because translocations are inherently more stable through cell division than dicentrics, translocations have become the aberration of choice for evaluating many types of exposure. Fluorescence in situ hybridization with whole chromosome painting probes (FISH-WCP) has been shown to be a rapid method of detecting chromosomal rearrangements, and appears to be especially useful for analysis of induced translocations. The present paper shortly describes FISH-WCP method for detection of reciprocal translocations as indicators of exposure to ionizing radiation. (authors)

  19. Detection of Bacteriocins by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

    Rose, Natisha L.; Sporns, Peter; McMullen, Lynn M.

    1999-01-01

    The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the detection of bacteriocins was investigated. A 30-s water wash of the sample on the MALDI-TOF MS probe was effective in removing contaminants of the analyte. This method was used for rapid detection of nisin, pediocin, brochocin A and B, and enterocin A and B from culture supernatants and for detection of enterocin B throughout its purification.

  20. A promising new mechanism of ionizing radiation detection for positron emission tomography: modulation of optical properties

    Tao, Li; Daghighian, Henry M.; Levin, Craig S.

    2016-11-01

    Using conventional scintillation detection, the fundamental limit in positron emission tomography (PET) time resolution is strongly dependent on the inherent temporal variances generated during the scintillation process, yielding an intrinsic physical limit for the coincidence time resolution of around 100 ps. On the other hand, modulation mechanisms of the optical properties of a material exploited in the optical telecommunications industry can be orders of magnitude faster. In this paper we borrow from the concept of optics pump-probe measurement to for the first time study whether ionizing radiation can produce modulations of optical properties, which can be utilized as a novel method for radiation detection. We show that a refractive index modulation of approximately 5× {{10}-6} is induced by interactions in a cadmium telluride (CdTe) crystal from a 511 keV photon source. Furthermore, using additional radionuclide sources, we show that the amplitude of the optical modulation signal varies linearly with both the detected event rate and average photon energy of the radiation source.

  1. Detection of Biosignatures by Geomatrix-Assisted Laser Desorption/Ionization (GALDI) Mass Spectrometry

    Jill R. Scott; Beizhan Yan; Daphne L. Stoner; J. Michelle Kotler; Nancy W. Hinman

    2007-04-01

    Identification of mineral-associated biosignatures is of significance for retrieving biochemical information from geological records here on Earth and detecting signs of life on other planets, such as Mars. The importance of the geomatrix for identifying amino acids (e.g., histidine, threonine, and cysteine) and small proteins (e.g., gramicidin S) was investigated by laser desorption Fourier transform mass spectrometry. The investigated geomatrices include analogues of Fe-bearing minerals such as hematite and Na-bearing evaporites (e.g., halite). Samples were prepared by two methods: 1) application of analyte to the geomatrix surface and 2) production of homogenous analyte:geomatrix mixtures. Comparison of the two sample preparation methods revealed that the mixing method produces a better signal/noise ratio than surface application for the analyses of amino acids. The composition of the geomatrix has a profound influence on the detection of biomolecules. Peaks corresponding to the cation-attached biomolecular ions were observed for the Na-bearing evaporite analogue. No detectable peaks for the biomolecular ion species were observed when the biomolecules were associated with Fe-bearing minerals. Instead, only minor peaks were observed that may correspond to ions from fragments of the biomolecules. Depending on the underlying mineral composition, geomatrix-assisted laser desorption/ionization shows promise for directly identifying biosignatures associated with minerals.

  2. Selective and sensitive detection of chromium(VI) in waters using electrospray ionization mass spectrometry.

    Weldy, Effie; Wolff, Chloe; Miao, Zhixin; Chen, Hao

    2013-09-01

    From 2000 through 2011, there were 14 criminal cases of violations of the Clean Water Act involving the discharge of chromium, a toxic heavy metal, into drinking and surface water sources. As chromium(VI), a potential carcinogen present in the environment, represents a significant safety concern, it is currently the subject of an EPA health risk assessment. Therefore, sensitive and selective detection of this species is highly desired. This study reports the analysis of chromium(VI) in water samples by electrospray ionization mass spectrometry (ESI-MS) following its reduction and complexation with ammonium pyrrolidinedithiocarbamate (APDC). The reduction and subsequent complexation produce a characteristic [Cr(III)O]-PDC complex which can be detected as a protonated ion of m/z 507 in the positive ion mode. The detection is selective to chromium(VI) under acidic pH, even in the presence of chromium(III) and other metal ions, providing high specificity. Different water samples were examined, including deionized, tap, and river waters, and sensitive detection was achieved. In the case of deionized water, quantification over the concentration range of 3.7 to 148ppb gave an excellent correlation coefficient of 0.9904 using the enhanced MS mode scan. Using the single-reaction monitoring (SRM) mode (monitoring the characteristic fragmentation of m/z 507 to m/z 360), the limit of detection (LOD) was found to be 0.25ppb. The LOD of chromium(VI) for both tap and river water samples was determined to be 2.0ppb. A preconcentration strategy using simple vacuum evaporation of the aqueous sample was shown to further improve the ESI signal by 15 fold. This method, with high sensitivity and selectivity, should provide a timely solution for the real-world analysis of toxic chromium(VI). Copyright © 2012 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

  3. Detection limits of absorbed dose of ionizing radiation in molluscan shells as determined by e.p.r. spectroscopy

    Stachowicz, W.; Michalik, J.; Burlinska, G.; Sadlo, J.; Dziedzic-Goclawska, A.; Ostrowski, K.

    1995-01-01

    The exposure of waters to ionizing radiation from radionuclides imprisoned in dumped nuclear waste containers, freed in nuclear submarine accidents or released in underwater magma eruptions are difficult to be evaluated by conventional radiometric methods. Ionizing radiation evokes stable paramagnetic centers in crystalline lattice of mineral components in bone skeletons of mammals and fishes as well as in exoskeletons of mollusca. They give rise in e.p.r. to specific, extremely stable signals which are proposed to be applied as indicators of radiation exposure levels. In the present study the e.p.r. detection limits of the dose of ionizing radiation absorbed in shells of fresh water and marine mollusca (selected species) have been estimated. It has been found that with fresh water mollusca the dose of 1-2 Gy can be detected, while the sea water mollusca by one order of magnitude lower, i.e. about 0.1 Gy. (author)

  4. Flames in vortices & tulip-flame inversion

    Dold, J. W.

    This article summarises two areas of research regarding the propagation of flames in flows which involve significant fluid-dynamical motion [1]-[3]. The major difference between the two is that in the first study the fluid motion is present before the arrival of any flame and remains unaffected by the flame [1, 2] while, in the second study it is the flame that is responsible for all of the fluid dynamical effects [3]. It is currently very difficult to study flame-motion in which the medium is both highly disturbed before the arrival of a flame and is further influenced by the passage of the flame.

  5. On-Chip Spyhole Nanoelectrospray Ionization Mass Spectrometry for Sensitive Biomarker Detection in Small Volumes

    Zhong, Xiaoqin; Qiao, Liang; Stauffer, Géraldine; Liu, Baohong; Girault, Hubert H.

    2018-03-01

    A polyimide microfluidic chip with a microhole emitter (Ø 10-12 μm) created on top of a microchannel by scanning laser ablation has been designed for nanoelectrospray ionization (spyhole-nanoESI) to couple microfluidics with mass spectrometry. The spyhole-nanoESI showed higher sensitivity compared to standard ESI and microESI from the end of the microchannel. The limits of detection (LOD) for peptide with the spyhole-nanoESI MS reached 50 pM, which was 600 times lower than that with standard ESI. The present microchip emitter allows the analysis of small volumes of samples. As an example, a small cell lung cancer biomarker, neuron-specific enolase (NSE), was detected by monitoring the transition of its unique peptide with the spyhole-nanoESI MS/MS. NSE at 0.2 nM could be well identified with a signal to noise ratio (S/N) of 50, and thereby its LOD was estimated to be 12 pM. The potential application of the spyhole-nanoESI MS/MS in cancer diagnosis was further demonstrated with the successful detection of 2 nM NSE from 1 μL of human serum. Before the detection, the serum sample spiked with NSE was first depleted with immune spin column, then desalted by centrifugal filter device, and finally digested by trypsin, without any other complicated preparation steps. The concentration matched the real condition of clinical samples. In addition, the microchips can be disposable to avoid any cross contamination. The present technique provides a highly efficient way to couple microfluidics with MS, which brings additional values to various microfluidics and MS-based analysis.

  6. A new mechanism of ionizing radiation detection for positron emission tomography: modulation of optical properties

    Tao, Li; Daghighian, Henry M.; Levin, Craig S.

    2016-10-01

    Using conventional scintillation detection, the fundamental limit in positron emission tomography (PET) annihilation photon pair coincidence time resolution is strongly dependent on the inherent temporal variances generated during the scintillation process, yielding an intrinsic physical limit of around 100 ps. On the other hand, modulation mechanisms of a material's optical properties as exploited in the optical telecommunications industry can be orders of magnitude faster. In this paper we borrow from the concept of optics pump-probe measurement to study whether ionizing radiation can also produce fast modulations of optical properties, which can be utilized as a novel method for radiation detection. We show that a refractive index modulation of approximately 5x10-6 is induced by interactions in a cadmium telluride (CdTe) crystal from a 511 keV photon source. Furthermore, using additional radionuclide sources, we show that the amplitude of the optical modulation signal varies linearly with both the radiation source flux rate and average photon energy.

  7. Laser ionization time of flight mass spectrometer for isotope mass detection and elemental analysis of materials

    Ahmed, Nasar; Ahmed, Rizwan; Umar, Z. A.; Aslam Baig, M.

    2017-08-01

    In this paper we present the construction and modification of a linear time-of-flight mass spectrometer to improve its mass resolution. This system consists of a laser ablation/ionization section based on a Q-switched Nd:YAG laser (532 nm, 500 mJ, 5 ns pulse duration) integrated with a one meter linear time-of-flight mass spectrometer coupled with an electric sector and a magnetic lens and outfitted with a channeltron electron multiplier for ion detection. The resolution of the system has been improved by optimizing the accelerating potential and inserting a magnetic lens after the extraction region. The isotopes of lithium, lead and cadmium samples have been resolved and detected in accordance with their natural abundance. The capability of the system has been further exploited to determine the elemental composition of a brass alloy, having a certified composition of zinc and copper. Our results are in excellent agreement with its certified composition. This setup is found to be extremely efficient and convenient for fast analyses of any solid sample.

  8. Effects of Ionizing Radiation on Biological Molecules—Mechanisms of Damage and Emerging Methods of Detection

    Reisz, Julie A.; Bansal, Nidhi; Qian, Jiang; Zhao, Weiling

    2014-01-01

    Abstract Significance: The detrimental effects of ionizing radiation (IR) involve a highly orchestrated series of events that are amplified by endogenous signaling and culminating in oxidative damage to DNA, lipids, proteins, and many metabolites. Despite the global impact of IR, the molecular mechanisms underlying tissue damage reveal that many biomolecules are chemoselectively modified by IR. Recent Advances: The development of high-throughput “omics” technologies for mapping DNA and protein modifications have revolutionized the study of IR effects on biological systems. Studies in cells, tissues, and biological fluids are used to identify molecular features or biomarkers of IR exposure and response and the molecular mechanisms that regulate their expression or synthesis. Critical Issues: In this review, chemical mechanisms are described for IR-induced modifications of biomolecules along with methods for their detection. Included with the detection methods are crucial experimental considerations and caveats for their use. Additional factors critical to the cellular response to radiation, including alterations in protein expression, metabolomics, and epigenetic factors, are also discussed. Future Directions: Throughout the review, the synergy of combined “omics” technologies such as genomics and epigenomics, proteomics, and metabolomics is highlighted. These are anticipated to lead to new hypotheses to understand IR effects on biological systems and improve IR-based therapies. Antioxid. Redox Signal. 21: 260–292. PMID:24382094

  9. OBSERVATIONAL DETECTION OF DRIFT VELOCITY BETWEEN IONIZED AND NEUTRAL SPECIES IN SOLAR PROMINENCES

    Khomenko, Elena; Collados, Manuel [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Díaz, Antonio J., E-mail: khomenko@iac.es, E-mail: mcv@iac.es, E-mail: aj.diaz@uib.es [Universitat de les Illes Balears, 07122, Crta Valldemossa, km 7.5, Palma de Mallorca (Spain)

    2016-06-01

    We report the detection of differences in the ion and neutral velocities in prominences using high-resolution spectral data obtained in 2012 September at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife). A time series of scans of a small portion of a solar prominence was obtained simultaneously with high cadence using the lines of two elements with different ionization states, namely, Ca ii 8542 Å and He i 10830 Å. The displacements, widths, and amplitudes of both lines were carefully compared to extract dynamical information about the plasma. Many dynamical features are detected, such as counterstreaming flows, jets, and propagating waves. In all of the cases, we find a very strong correlation between the parameters extracted from the lines of both elements, confirming that both lines trace the same plasma. Nevertheless, we also find short-lived transients where this correlation is lost. These transients are associated with ion-neutral drift velocities of the order of several hundred m s{sup −1}. The patches of non-zero drift velocity show coherence in time–distance diagrams.

  10. Ionizing radiation-induced DNA injury and damage detection in patients with breast cancer

    Borrego-Soto, Gissela; Ortiz-Lopez, Rocio; Rojas-Martinez, Augusto, E-mail: arojasmtz@gmail.com, E-mail: augusto.rojasm@uanl.mx [Departamento de Bioquímica y Medicina Molecular, Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León (Mexico)

    2015-10-15

    Breast cancer is the most common malignancy in women. Radiotherapy is frequently used in patients with breast cancer, but some patients may be more susceptible to ionizing radiation, and increased exposure to radiation sources may be associated to radiation adverse events. This susceptibility may be related to deficiencies in DNA repair mechanisms that are activated after cell-radiation, which causes DNA damage, particularly DNA double strand breaks. Some of these genetic susceptibilities in DNA-repair mechanisms are implicated in the etiology of hereditary breast/ovarian cancer (pathologic mutations in the BRCA 1 and 2 genes), but other less penetrant variants in genes involved in sporadic breast cancer have been described. These same genetic susceptibilities may be involved in negative radiotherapeutic outcomes. For these reasons, it is necessary to implement methods for detecting patients who are susceptible to radiotherapy-related adverse events. This review discusses mechanisms of DNA damage and repair, genes related to these functions, and the diagnosis methods designed and under research for detection of breast cancer patients with increased radiosensitivity. (author)

  11. Comet assay as a procedure for detecting possible genotoxicity induced by non-ionizing radiation

    Zsuzsanna Nemeth

    2015-01-01

    Non-ionizing radiation (NIR) is the term given to radiation in the part of the electromagnetic spectrum that does not have enough energy to ionize atoms or molecules directly. The NIR includes electric and magnetic fields up to 300 GHz, infrared, visible, and ultraviolet radiation (UV). People are exposed to non-ionizing radiation by several man-made sources every day. From highest to lowest energy, this includes for example microwave ovens, cell phones, baby monitors, cordless phones, ga...

  12. Coupling continuous ultrasound-assisted extraction, preconcentration and flame atomic absorption spectrometric detection for the determination of cadmium and lead in mussel samples

    Yebra-Biurrun, M.C.; Cancela-Perez, S.; Moreno-Cid-Barinaga, A.

    2005-01-01

    Continuous ultrasound-assisted extraction has been coupled with preconcentration and flame atomic absorption spectrometry for the determination of cadmium and lead in mussel samples. Experimental designs were used for the optimisation of the leaching and preconcentration steps. The use of diluted nitric acid as extractant in the continuous mode at a flow rate of 3.5 ml min -1 and room temperature was sufficient for quantitative extraction of these trace metals. A minicolumn containing a chelating resin (Chelite P, with aminomethylphosphoric acid groups) was proved as an excellent material for the quantitative preconcentration of cadmium and lead prior to their flame atomic absorption detection. A flow injection manifold was used as interface for coupling the three analytical steps, which allowed the automation of the whole analytical process. A good precision of the whole procedure (2.0 and 2.3%), high enrichment factors (20.5 and 11.8) and a detection limit of 0.011 and 0.25 μg g -1 for cadmium and lead, respectively, were obtained for 80 mg of sample. The sample throughputs were ca. 16 and 14 samples h -1 for cadmium and lead, respectively. The accuracy of the analytical procedures was verified by using a standard reference material (BCR 278-R, mussel tissue) and the results were in good agreement with the certified values. The method was successfully applied to the determination of trace amounts of cadmium and lead in mussel samples from the coast of Galicia (NW, Spain)

  13. Quantitative detection of nitric oxide in exhaled human breath by extractive electrospray ionization mass spectrometry

    Pan, Susu; Tian, Yong; Li, Ming; Zhao, Jiuyan; Zhu, Lanlan; Zhang, Wei; Gu, Haiwei; Wang, Haidong; Shi, Jianbo; Fang, Xiang; Li, Penghui; Chen, Huanwen

    2015-03-01

    Exhaled nitric oxide (eNO) is a useful biomarker of various physiological conditions, including asthma and other pulmonary diseases. Herein a fast and sensitive analytical method has been developed for the quantitative detection of eNO based on extractive electrospray ionization mass spectrometry (EESI-MS). Exhaled NO molecules selectively reacted with 2-phenyl-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) reagent, and eNO concentration was derived based on the EESI-MS response of 1-oxyl-2-phenyl-4, 4, 5, 5-tetramethylimidazoline (PTI) product. The method allowed quantification of eNO below ppb level (~0.02 ppbv) with a relative standard deviation (RSD) of 11.6%. In addition, eNO levels of 20 volunteers were monitored by EESI-MS over the time period of 10 hrs. Long-term eNO response to smoking a cigarette was recorded, and the observed time-dependent profile was discussed. This work extends the application of EESI-MS to small molecules (mass spectrometers. Long-term quantitative profiling of eNO by EESI-MS opens new possibilities for the research of human metabolism and clinical diagnosis.

  14. Detection of the Level of Reactive Oxygen Species Induced by Ionizing Radiation in Cells

    Kim, Jin Kyu; Chung, Dong Min; Kim, Jin-Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    By definition, the direct effect is referred to interaction between photon and DNA molecule, whereas the indirect effect is mediated by the reactive oxygen species (ROS) generated by radiolysis and subsequent reaction. It has been reported that ROS produced after exposure to IR can react with cellular materials such as DNA, proteins, carbohydrates and lipids. ROS is free radicals such as the superoxide anion, hydroxyl radicals and the non-radical hydrogen peroxide. Cells generate ROS during aerobic metabolism. Excessive production of ROS can lead to oxidative stress, genetic alteration and even cell death. It has been reported that ROS plays a critical role in radiation-induced cell injury. Thus, it is of great interest to determine the radiation-induced ROS level. Many kinds of methods to detect the level of ROS have been developed so far. There were random changes of fluorescence intensity in the treatment after irradiation. This result meant that this protocol was not appropriate for determination of radiation-induced ROS. On the other hand, the fluorescence intensity was increased in a dose-dependent manner when the cells were treated with the DCFH-DA solution before irradiation. Conclusions can be drawn from the experimental results of this study. In order to properly measure the ROS level in the cells exposed to ionizing radiation, the cells should be treated with the DCFH-DA solution before irradiation.

  15. Towards radiation detected resonance ionization spectroscopy on transfermium elements in a buffer gas cell

    Lautenschlaeger, Felix; Walther, Thomas [Institut fuer Angewandte Physik, TU Darmstadt, 64289 Darmstadt (Germany); Laatiaoui, Mustapha; Block, Michael [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Helmholtz-Institut Mainz, 55128 Mainz (Germany); Lauth, Werner; Backe, Hartmut [Institut fuer Kernphysik, JGU Mainz, 55128 Mainz (Germany); Hessberger, Fritz-Peter [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, 64291 Darmstadt (Germany)

    2013-07-01

    The study of the atomic structure of transfermium elements like nobelium (No) and lawrencium (Lr) via Radiation Detected Resonance Ionization Spectroscopy (RADRIS) is one of the most fascinating disciplines of modern atomic physics. It allows the determination of relativistic effects at the heaviest elements and provides a critical test of theoretical predictions. For these transfermium elements no experimental data on atomic level schemes are available at present. First experiments on {sup 254}No were performed in 2007, in which a buffer gas cell with an overall efficiency of 1%. In this experiment the evaporation temperature of nobelium was determined for the first time. To increase the efficiency of the buffer gas cell, off-line measurements have been performed with nat. ytterbium, the chemical homologue of nobelium. Also on-line experiments during a parasitic beam-time in 2012 provided an insight into the critical parameters of our setup. The results of the off-line and on-line measurements are briefly summarized in this talk.

  16. Temporal trends of hexabromocyclododecanes (HBCDs) and polybrominated diphenyl ethers (PBDEs) and detection of two novel flame retardants in marine mammals from Hong Kong, South China.

    Lam, James C W; Lau, Ridge K F; Murphy, Margaret B; Lam, Paul K S

    2009-09-15

    Concentrations of hexabromocyclododecanes (HBCDs), polybrominated diphenyl ethers (PBDEs), and three novel flame retardants, namely2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB), bis-(2-ethylhexyl)-tetrabromophthalate (TBPH), and hexachlorocyclopentadienyldibromocyclooctane (HCDBCO), were determined in blubber samples of Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides). The levels of HBCDs and PBDEs in cetacean samples ranged from 4.1 to 519 and 103 to 51,100 ng/g lw, respectively. A significant increasing trend of SigmaHBCDs was observed in dolphin samples from 1997 to 2007 with an estimated annual rate of 5%, whereas no significant temporal trends of SigmaPBDEs appeared over the sampling period. This pattern may be attributed to the increasing usage of HBCDs following the restriction/voluntary withdrawal of the production and use of PBDE commercial mixtures in several countries. HCDBCO was not found in the blubber samples. This is the first report of the presence of TBB and TBPH, two new flame retardants that have previously been identified in house dust from the U.S., in marine mammals; concentrations of these compounds in dolphins and porpoises ranged from the instrumental detection limit (IDL) (<0.04) to 70 and IDL (<0.04) to 3859 ng/g lw, respectively. Levels of TBPH were comparable to SigmaHBCDs in porpoise samples. The presence of these novel flame retardants in top-trophic-level marine organisms raises concern about their release into the environment and indicates the need for further monitoring of these compounds in other environmental matrices.

  17. Quantitative Detection of Trace Malachite Green in Aquiculture Water Samples by Extractive Electrospray Ionization Mass Spectrometry.

    Fang, Xiaowei; Yang, Shuiping; Chingin, Konstantin; Zhu, Liang; Zhang, Xinglei; Zhou, Zhiquan; Zhao, Zhanfeng

    2016-08-11

    Exposure to malachite green (MG) may pose great health risks to humans; thus, it is of prime importance to develop fast and robust methods to quantitatively screen the presence of malachite green in water. Herein the application of extractive electrospray ionization mass spectrometry (EESI-MS) has been extended to the trace detection of MG within lake water and aquiculture water, due to the intensive use of MG as a biocide in fisheries. This method has the advantage of obviating offline liquid-liquid extraction or tedious matrix separation prior to the measurement of malachite green in native aqueous medium. The experimental results indicate that the extrapolated detection limit for MG was ~3.8 μg·L(-1) (S/N = 3) in lake water samples and ~0.5 μg·L(-1) in ultrapure water under optimized experimental conditions. The signal intensity of MG showed good linearity over the concentration range of 10-1000 μg·L(-1). Measurement of practical water samples fortified with MG at 0.01, 0.1 and 1.0 mg·L(-1) gave a good validation of the established calibration curve. The average recoveries and relative standard deviation (RSD) of malachite green in lake water and Carassius carassius fish farm effluent water were 115% (6.64% RSD), 85.4% (9.17% RSD) and 96.0% (7.44% RSD), respectively. Overall, the established EESI-MS/MS method has been demonstrated suitable for sensitive and rapid (malachite green in various aqueous media, indicating its potential for online real-time monitoring of real life samples.

  18. The DNA comet assay and the germination test in detection of food treated by ionizing radiation

    Huachaca, Nelida Simona Marin

    2002-01-01

    Two methods of irradiated food detection, one biochemical, the comet assay and, other biological, the germination test, were applied in bovine meat and fruit samples. The comet assay detects the damage on DNA caused by ionizing radiation. The germination test evaluates the sensitivity to radiation of seeds as for germination ability, shooting and, rooting. The samples were irradiated in gamma font and electron accelerator. For bovine meat samples, the doses were 0.0; 2.5; 4.5 e 7.0 kGy at chilled condition and, 0.0; 2.5; 4.5; 7.0 e 8.5 kGy at frozen conditions. For fruit samples such as melon, watermelon, apple, orange, papaya and, tomato, the doses were: 0.0; 0.5; 0.75; 1.0; 2.0 e 4.0 kGy. The differences between the gamma rays and the electron beam effects on extent of DNA migration and, on shooting and rooting, showed to be similar. The comet assay, under neutral conditions, permitted to discriminate between irradiated and unirradiated bovine meat samples, until one month of storage. Also, it was possible to distinguish, by the comet assay, the control sample with regard to irradiated fruit, at doses as low as 0,5 kGy. In the germination test, the root length was the best parameter to discriminate irradiated and unirradiated samples of melon, watermelon and tomato, while the germination percent was the best parameter for apple and orange. (author)

  19. Ionization detector

    Solomon, E.E.

    1980-01-01

    A safe and reliable apparatus for detecting products of combustion and aerosols in the atmosphere was developed which uses a beta source. It is easy to adjust for optimum performance. The ionization detector comprises a double chamber; one of the chambers is the basic sensing chamber. The sensing chamber is ported to both the secondary chambers to account for slow ambient changes in the atmosphere outside of the chamber. The voltages from the ionization chamber are adjusted with electrodes in each chamber. The ionization chamber contains baffles to direct the air to be sensed as well as an electrostatic screen. A unique electronic circuit provides an inexpensive and reliable means for detecting the signal change which occurs in the ionization chamber. The decision level of the alarm circuit can be adjusted to allow for any desired sensitivity. (D.N.)

  20. Ionization detector for aerosol air pollution detection and ventilation control in the metal processing industry

    Kovacs, Istvan

    1989-01-01

    An indicator and measuring instrument was developed for the continuous monitoring, recording and indicating aerosol mass concentrations in mechanical workshops, like in metal cutting, welding or forming industries, for air pollution control and ventilation of the atmosphere in the workshops. An ionization chamber containing alpha radiation source was modified for this purpose, and a suitable electronic circuit was built for the measurement of ionization current. The calibration of the ionization aerosol detectors was performed for welding smoke and oil mist. They were suitable for continuous monitoring of workshop atmospheres and controlling ventilation equipment, or as portable instruments, for the rapid inspection of air pollution. (R.P.) 4 refs.; 3 figs

  1. Development of sodium leak detection technology using laser resonance ionization mass spectrometry. Design and functional test using prototype sodium detection system

    Aoyama, Takafumi; Ito, Chikara; Harano, Hideki; Okazaki, Koki; Watanabe, Kenichi; Iguchi, Tetsuo

    2009-01-01

    In a sodium-cooled fast reactor, highly sensitive technology is required to detect small amounts of sodium leaking from the cooling system piping or components. The conventional sodium leak detectors have a fundamental difficulty in improving the detection sensitivity for a sodium leak because of the presence of salinity ( 23 NaCl) in the atmosphere around the components and piping of cooling systems. In order to overcome this problem, an innovative technology has been developed to selectively detect the radioactive sodium ( 22 Na) produced by a neutron reaction in the primary cooling system using Laser Resonance Ionization Mass Spectrometry (RIMS). In this method, sodium ions produced with the two processes of (1) atomization of sodium aerosols and (2) resonance ionization of sodium atom, are detected selectively using a time-of-flight mass spectrometer. The 22 Na can be distinguished from the stable isotope ( 23 Na) by mass spectrometry, which is the advantage of RIMS comparing to the other methods. The design and the construction of the prototype system based on fundamental experiments are shown in the paper. The aerodynamic lens was newly introduced, which can transfer aerosols at atmospheric pressure into a vacuum chamber while increasing the aerosol density at the same time. Furthermore, the ionization process was applied by using the external electric field after resonance exciting from the ground level to the Rydberg level in order to increase the ionization efficiency. The preliminary test results using the stable isotope ( 23 Na) showed that prototype system could easily detect sodium aerosol of 100 ppb, equivalent to the sensitivity of the conventional detectors. (author)

  2. Signalling detection of DNA damage induced by low doses of ionizing radiation in human lymphocytes

    Valente, M.

    2011-01-01

    Individuals spontaneously present different sensitivities to ionizing radiation, measured by the severity of their post-radiotherapy side-effects. Cells from some patients with extreme clinical radiosensitivity have shown altered cellular radiosensitivity measured by different endpoints as apoptosis or DNA damage. Linking clinical and cellular sensitivity is of fundamental importance to establish a clinical test capable of predicting a person's radiosensitivity from a sample. Easily sampled, peripheral blood lymphocytes (PBL) are an appealing cellular model to study individual radiosensitivity as they have been shown to be the most radiosensitive hematopoietic cells. DNA damages and repair can be visualized by observing the kinetics of appearance and disappearance of gamma-H2AX foci on DNA double-strand breaks through immunofluorescence microscopy. The experimental strategy chosen here was to follow lymphocyte gamma-H2AX foci kinetics in response to different levels of irradiation as delayed gamma-H2AX foci disappearance has been observed in cells of individuals with high clinical radiosensitivity. For our initial study we irradiated in vitro samples of radiotherapy patients with different clinical radiosensitivities. The groups of distinct clinical sensitivities showed no corresponding differences in their cellular gamma-H2AX response. In addition, several samples were lost, mainly due to the long transportation period before being treated in our lab. To render this method usable for clinical applications, several changes were made: after improving sample viability, speed was increased by automation of image acquisition (Metasystem) and gamma-H2AX focus scoring (freeware CellProfiler). This technique was able to detect doses as low as 0.005 Gy and gave similar results to manual focus scoring. The possibility of discriminating different lymphocyte subsets (CD4, CD8 and CD19) during analysis was added to identify among the lymphocyte subsets the one producing more

  3. Comet assay as a procedure for detecting possible genotoxicity induced by non-ionizing radiation

    Zsuzsanna Nemeth

    2015-05-01

    In our laboratory we use comet assay for testing genotoxicity of non-ionizing radiation for more than ten years. In the experiments we use whole blood samples (human or dog, cell lines (e.g. H295R cell line or 3 dimensional in vitro skin tissue (epidermis models. In our protocol a slightly modified alkaline Comet assay method of Singh et al. (1988 is used. On our poster there will be presented a brief summary of our experiments with exposure to different types of radiation (ELF, RF, and intermediate frequency. In our protocols the non-ionizing radiation was often combined with ionizing radiation to see whether the non-ionizing radiation can influence the repair of the DNA damage induced by ionizing radiation. For the evaluation of the slides mainly Komet 4.0 image analysis system software (Kinetic Imaging, Liverpool, UK was used, but as we got familiarized with other methods for slide evaluation like grading the comets by visual scoring into 5 categories or the CaspLab software, the comparison of these three methods will be also presented.

  4. Novel charge plasma based dielectric modulated impact ionization MOSFET as a biosensor for label-free detection

    Chanda, Manash; Dey, Prithu; De, Swapnadip; Sarkar, Chandan Kumar

    2015-10-01

    In this paper a charge plasma based dielectric modulated impact ionization MOSFET (CP-DIMOSFET) has been proposed for the first time to ease the label free detection of biomolecules. The concept of CP-DIMOSFET is proposed and analyzed on basis of simulated data using SILVACO ATLAS. Low thermal budgeting and thin silicon layer without any dopant implantations make the proposed structure advantageous compared to the existing MOSFET based biosensors. The results show that the proposed device is capable to detect the presence of biomolecules. Simple fabrication schemes, miniaturization, high sensitivity, dominance of dielectric modulation make the proposed biosensor a promising one that could one day revolutionize the healthcare industry.

  5. Study and optimization of bolometers designed to measure both ionization and heat in order to detect black matter

    Navick, X.F.

    1997-01-01

    The detection of black matter in the form of wimp (weakly interactive massive particle) requires the identification of the incident particle so that events due to wimp interactions can be set apart from events due to surrounding radioactivity. Bolometers allow to measure both the energy deposited and the ionization made by a particle. The amount of energy is determined by calorimetry. Wimp detection implies bolometers to run at very low temperature. After a presentation of particle interactions with matter, this thesis describes the physical phenomena involved in heat and ionization measurements. The behaviour of semiconductors at low temperature is investigated and qualitative expectations are drawn about the working of metal-semiconductor interface and the pin diode. An experimental setting is presented. The operating voltage needs to be very low in order to be the least disturbing possible. At so low voltage, a decrease of the ionization signal in terms of time appears. It is shown that this phenomenon is linked to the level density in the forbidden band of the semiconductor and to the intensity of infrared radiation reaching the detector. (A.C.)

  6. Electret ionization chamber: a new method for detection and dosimetry of thermal neutrons; Camara de ionizacao de eletretos: um novo metodo para deteccao e dosimetria de neutrons termicos

    Ghilardi, A J.P.

    1988-12-31

    An electret ionization chamber with boron coated walls is presented as a new method for detecting thermal neutrons. The efficiency of electret ionization chambers with different wall materials for the external electrode was inferred from the results. Detection of slow neutrons with discrimination against the detection of {gamma}-rays and energetic neutrons was shown to depend on the selection of these materials. The charge stability over a long period of time and the charge decay owing to natural radiation were also studied. Numerical analysis was developed by the use of a micro-computer PC-XT. Both the experimental and numerical results show that the sensitivity of the electret ionization chamber for detection of thermal neutrons is comparable with that of the BF{sub 3} ionization chamber and that new technologies for deposition of the boron layer will produce higher efficiency detectors. (author). 102 refs, 32 fig, 10 tabs.

  7. Non-Linear Optical Phenomena in Detecting Materials as a Possibility for Fast Timing in Detectors of Ionizing Radiation

    Korjik, M. V.; Buganov, O.; Fedorov, A. A.; Emelianchik, I.; Griesmayer, E.; Mechinsky, V.; Nargelas, S.; Sidletskiy, O.; Tamulaitis, G.; Tikhomirov, S. N.; Vaitkevicius, A.

    2016-01-01

    The time resolution of the detectors currently in use is limited by 50-70 ps due to the spontaneous processes involved in the development of the response signal, which forms after the relaxation of carriers generated during the interaction. In this study, we investigate the feasibility of exploiting sub-picosecond phenomena occurring after the interaction of scintillator material with ionizing radiation by probing the material with ultra-short laser pulses. One of the phenomena is the elastic polarization due to the local lattice distortion caused by the displacement of electrons and holes generated by ionization. The key feature of the elastic polarization is its short response time, which makes it prospective for using as an optically detectable time mark. The nonlinear optical absorption of femtosecond light pulses of appropriate wavelength is demonstrated to be a prospective tool to form the mark. This study was aimed at searching for inorganic crystalline media combining scintillation properties and non-...

  8. Luminescence as a new detection method for non-relativistic highly ionizing particles in water/ice neutrino telescopes

    Pollmann, Anna [Bergische Universitaet Wuppertal (Germany); Collaboration: IceCube-Collaboration

    2016-07-01

    Cosmic ray detectors use air as a radiator for luminescence. In water and ice detectors Cherenkov light is the dominant light producing mechanism when the particle velocity exceeds the Cherenkov threshold, approximately three quarters of the speed of light. Luminescence is produced by highly ionizing particles passing through matter due to the excitation of the surrounding atoms. The observables of luminescence, such as the wavelength spectrum and decay times, are highly dependent on the properties of the medium. Therefore, the results of measurements, in which luminescence was produced by particles passing through water or ice, vary by two orders of magnitude in intensity. It is shown that, even for the most conservative intensity value, luminescence can be used as a detection method for highly ionizing particles with velocities below the Cherenkov threshold. These could be magnetic monopoles or other massive and highly penetrating exotic particles. In the most optimistic case, luminescence contributes even to the light output of standard model particles.

  9. Recent measurements of flame acceleration in semiconfined geometries

    Abou-Arab, T.W. (King Fahd Univ. of Petroleum and Minerals, Dhahran (SA). Mechanical Engineering Dept.); Enayet, M.M.; Kamel, M.M. (Cairo Univ., Giza (EG). Mechanical Power Engineering Dept.)

    1991-04-01

    Turbulent premixed combustion under certain conditions may lead to large flame speeds sufficient to cause significant damage to nearby structures. Experiments, both large and small scale, have confirmed that obstructions cause severe flame acceleration to occur. In these cases, flame speeds as high as 800 ms{sup -1} may be achieved. In this work experimental investigation of some factors affecting flame acceleration in a semiconfined channel has been carried out. The experimental facility and the developed ionization gap measuring technique are also described. It has been found that the presence of obstacles, degree of confinement, height of fuel-air cloud (FAC), as well as fuel concentration gradient in the FAC have profound effects on the rate at which the flame accelerates. Finally, consideration of the flame acceleration as a possible mechanism for the transition to detonation will be discussed. (author).

  10. Improved detection limits for electrospray ionization on a magnetic sector mass spectrometer by using an array detector.

    Cody, R B; Tamura, J; Finch, J W; Musselman, B D

    1994-03-01

    Array detection was compared with point detection for solutions of hen egg-white lysozyme, equine myoglobin, and ubiquitin analyzed by electrospray ionization with a magnetic sector mass spectrometer. The detection limits for samples analyzed by using the array detector system were at least 10 times lower than could be achieved by using a point detector on the same mass spectrometer. The minimum detectable quantity of protein corresponded to a signal-to-background ratio of approximately 2∶1 for a 500 amol/μL solution of hen egg-white lysozyme. However, the ultimate practical sample concentrations appeared to be in the 10-100 fmol/μL range for the analysis of dilute solutions of relatively pure proteins or simple mixtures.

  11. Aerosol ionization gas analyzer for continious detection of toxic compounds in industrial gaseous effluents

    Groze, Kh.; Dering, Kh.; Gleizberg, F.

    1979-01-01

    In is noted that the problem of the environment protection as well as protection of the personnel at their working places against influence of harmful substances in air, demands continious measuring of an increasing number of harmful substances with provision of high sensitivity and accuracy of measurements. The demands are listed to the gas analyzers developed for these purposes: flexibility towards solution of different problems of measurement; great number of the substances to be measured; acceptable threshold of determination of different substances concentration in air and small measurement error; simplicity of maintanance and technical service and high reliability in exploitation; economy of fabrication and application. The data are given for the aerosol ionization gas analyzer which, in many cases, met the requirements listed. In the gas analyzer described, the analysed substance is converted for measuring its concentration into an aerosol by means of the aerosol generator, especially designed for this substance or group of substances. The produced aerosol is introduced into an ionization chamber with build-in radiation source and caused decrease of the ionization current in it. According to the decrease of the ionization current, concentration of the harmful substance in air is determined. Characteristics and possibilities of the gas analyzer exploitation are given and discussed on the base of the results of determination of some harmful substances concentrations in air in the laboratory conditions and in the real conditions of industrial production and in the health protection system [ru

  12. Solid-state device for detecting and locating the points of impact of ionizing radiation

    Rougeot, H.; Roziere, G.

    1979-01-01

    A semiconductor body contains microscopic passages in which multiplication of the free electrons appearing at the entrances to said passages, under the effect of the incident ionizing radiation, takes place. A conductive film forms a surface barrier in conjunction with the semiconductor body which is endowed with the property of secondary emission with an emission coefficient better than unity

  13. Determination of propineb and its metabolites propylenethiourea and propylenediamine in banana and soil using gas chromatography with flame photometric detection and LC-MS/MS analysis.

    Song, Shiming; Wei, Jie; Chen, Zhaojie; Lei, Yuhao; Zhang, Yan; Deng, Cheng; Tan, Huihua; Li, Xuesheng

    2018-03-04

    A sensitive and specific method for the determination of propineb and its metabolites, propylenethiourea (PTU) and propylenediamine (PDA), using gas chromatography with flame photometric detection (GC-FPD) and LC-MS/MS was developed and validated. Propineb and its metabolite residue dynamics in supervised field trials under Good Agricultural Practice (GAP) conditions in banana and soil were studied. Recovery of propineb (as CS 2 ), PDA and PTU ranged from 75.3 to 115.4% with RSD (n = 5) of 1.3-11.1%. The limit of quantification (LOQ) of CS 2 , PDA and PTU ranged from 0.005 to 0.01 mg kg -1 , and the limit of detection (LOD) ranged from 0.0015 to 0.0033 mg kg -1 . Dissipation experiments showed that the half-life of propineb in banana and soil ranged from 4.4 to 13.3 days. PTU was found in banana with a half-life of 31.5-69.3 days, while levels of PDA were less than 0.01 mg kg -1 in banana and soil. It has been suggested that PTU is the major metabolite of propineb in banana. The method was demonstrated to be reliable and sensitive for the routine monitoring of propineb and its metabolites in banana and soil. It also serves as a reference for the detection and monitoring of dithiocarbamates (DTCs) residues and the evaluation of their metabolic pathway.

  14. [High throuput analysis of organophosphorus pesticide residues and their metabolites in animal original foods by dual gas chromatography-dual pulse flame photometric detection].

    Yang, Lixin; Li, Heli; Miao, Hong; Zeng, Fangang; Li, Ruifeng; Chen, Huijing; Zhao, Yunfeng; Wu, Yongning

    2011-10-01

    A method was established for the quantitative determination of 54 organophosphorus pesticide residues and their metabolites in foods of animal origin by dual gas chromatography-dual pulse flame photometric detection. Homogenized samples were extracted with acetone and methylene chloride, and cleaned-up by gel permeation chromatography (GPC). The response of each analyte showed a good linearity with a correlation coefficient not less than 0. 99. The recovery experiments were performed by a blank sample spiked at low, medium and high fortification levels. The recoveries for beef, mutton, pork, chicken were in the range of 50. 5% -128. 1% with the relative standard deviations (n = 6) of 1. 1% -25. 5%, which demonstrated the good precision and accuracy of the present method. The limits of detection for the analytes were in the range of 0. 001 -0. 170 mg/kg, and the limits of quantification were in the range of 0. 002 -0. 455 mg/kg. Animal food samples collected from markets such as meat, liver and kidney were analyzed, and the residues of dichlorovos and disulfoton-sulfoxide were found in the some samples. The established method is sensitive and selective enough to detect organophosphorus pesticide residues in animal foods.

  15. An investigation of the matrix sensitivity of refinery gas analysis using gas chromatography with flame ionisation detection.

    Ferracci, Valerio; Brown, Andrew S; Harris, Peter M; Brown, Richard J C

    2015-02-27

    The response of a flame ionisation detector (FID) on a gas chromatograph to methane, ethane, propane, i-butane and n-butane in a series of multi-component refinery gas standards was investigated to assess the matrix sensitivity of the instrument. High-accuracy synthetic gas standards, traceable to the International System of Units, were used to minimise uncertainties. The instrument response exhibited a small dependence on the component amount fraction: this behaviour, consistent with that of another FID, was thoroughly characterised over a wide range of component amount fractions and was shown to introduce a negligible bias in the analysis of refinery gas samples, provided a suitable reference standard is employed. No significant effects of the molar volume, density and viscosity of the gas mixtures on the instrument response were observed, indicating that the FID is suitable for the analysis of refinery gas mixtures over a wide range of component amount fractions provided that appropriate drift-correction procedures are employed. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Systems and methods for controlling flame instability

    Cha, Min Suk

    2016-07-21

    A system (62) for controlling flame instability comprising: a nozzle (66) coupled to a fuel supply line (70), an insulation housing (74) coupled to the nozzle, a combustor (78) coupled to the nozzle via the insulation housing, where the combustor is grounded (80), a pressure sensor (82) coupled to the combustor and configured to detect pressure in the combustor, and an instability controlling assembly coupled to the pressure sensor and to an alternating current power supply (86), where, the instability controlling assembly can control flame instability of a flame in the system based on pressure detected by the pressure sensor.

  17. Detection of Metastatic Breast and Thyroid Cancer in Lymph Nodes by Desorption Electrospray Ionization Mass Spectrometry Imaging

    Zhang, Jialing; Feider, Clara L.; Nagi, Chandandeep; Yu, Wendong; Carter, Stacey A.; Suliburk, James; Cao, Hop S. Tran; Eberlin, Livia S.

    2017-06-01

    Ambient ionization mass spectrometry has been widely applied to image lipids and metabolites in primary cancer tissues with the purpose of detecting and understanding metabolic changes associated with cancer development and progression. Here, we report the use of desorption electrospray ionization mass spectrometry (DESI-MS) to image metastatic breast and thyroid cancer in human lymph node tissues. Our results show clear alterations in lipid and metabolite distributions detected in the mass spectra profiles from 42 samples of metastatic thyroid tumors, metastatic breast tumors, and normal lymph node tissues. 2D DESI-MS ion images of selected molecular species allowed discrimination and visualization of specific histologic features within tissue sections, including regions of metastatic cancer, adjacent normal lymph node, and fibrosis or adipose tissues, which strongly correlated with pathologic findings. In thyroid cancer metastasis, increased relative abundances of ceramides and glycerophosphoinisitols were observed. In breast cancer metastasis, increased relative abundances of various fatty acids and specific glycerophospholipids were seen. Trends in the alterations in fatty acyl chain composition of lipid species were also observed through detailed mass spectra evaluation and chemical identification of molecular species. The results obtained demonstrate DESI-MSI as a potential clinical tool for the detection of breast and thyroid cancer metastasis in lymph nodes, although further validation is needed. [Figure not available: see fulltext.

  18. Rapid gas chromatography with flame photometric detection of multiple organophosphorus pesticides in Salvia miltiorrhizae after ultrasonication assisted one-step extraction.

    Zhang, Shanshan; Liu, Xiaofei; Qin, Jia'an; Yang, Meihua; Zhao, Hongzheng; Wang, Yong; Guo, Weiying; Ma, Zhijie; Kong, Weijun

    2017-11-15

    A simple and rapid gas chromatography-flame photometric detection (GC-FPD) method was developed for the determination of 12 organophosphorus pesticides (OPPs) in Salvia miltiorrhizae by using ultrasonication assisted one-step extraction (USAE) without any clean-up steps. Some crucial parameters such as type of extraction solvent were optimized to improve the method performance for trace analysis. Any clean-up steps were negligent as no interferences were detected in the GC-FPD chromatograms for sensitive detection. Under the optimized conditions, limits of detection (LODs) and quantitation (LOQs) for all pesticides were in the range of 0.001-0.002mg/kg and 0.002-0.01mg/kg and 0.002-0.01mg/kg, respectively, which were all below the regulatory maximum residue limits suggested. RSDs for method precision (intra- and inter-day variations) were lower than 6.8% in approval with international regulations. Average recovery rates for all pesticides at three fortification levels (0.5, 1.0 and 5.0mg/kg) were in the range of 71.2-101.0% with relative standard deviations (RSDs) pesticide (dimethoate) out of the 12 targets was simultaneously detected in four samples at concentrations of 0.016-0.02mg/kg. Dichlorvos and omethoate were found in the same sample from Sichuan province at 0.004 and 0.027mg/kg, respectively. Malathion and monocrotophos were determined in the other two samples at 0.014 and 0.028mg/kg, respectively. All the positive samples were confirmed by LC-MS/MS. The simple, reliable and rapid USAE-GC-FPD method with many advantages over traditional techniques would be preferred for trace analysis of multiple pesticides in more complex matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Determination of organotin compounds by headspace solid-phase microextraction-gas chromatography-pulsed flame-photometric detection (HS-SPME-GC-PFPD)

    Bravo, Manuel [Universite de Pau et des Pays de L' Adour, Laboratoire de Chimie Analytique, LCABIE, UMR CNRS 5034, Pau (France); Pontificia Universidad Catolica de Valparaiso, Laboratorio de Quimica Analitica y Ambiental, Instituto de Quimica, Valparaiso (Chile); Lespes, Gaetane; Gautier, Martine Potin [Pontificia Universidad Catolica de Valparaiso, Laboratorio de Quimica Analitica y Ambiental, Instituto de Quimica, Valparaiso (Chile); Gregori, Ida de; Pinochet, Hugo [Universite de Pau et des Pays de L' Adour, Laboratoire de Chimie Analytique, LCABIE, UMR CNRS 5034, Pau (France)

    2005-12-01

    A method based on Headspace solid-phase microextraction (HS-SPME, with a 100 {mu}m PDMS-fiber) in combination with gas-chromatography and pulsed flame-photometric detection (GC-PFPD) has been investigated for simultaneous determination of eight organotin compounds. Monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPhT), and the semi-volatile diphenyltin (DPhT), triphenyltin (TPhT), monooctyltin (MOcT), and dioctyltin (DOcT) were determined after derivatization with sodium tetraethylborate. The conditions used for the extraction and preconcentration step were optimised by experimental design methodology. Tripropyltin (TPrT) and diheptyltin (DHepT) were used as internal standards for quantification of volatile and semi-volatile organotin compounds, respectively. The analytical precision (RSD) for ten successive injections of a standard mixture containing all the organic tin compounds ranged between 2 and 11%. The limits of detection for all the organotin compounds were sub ng (Sn) L{sup -1} in water and close to ng (Sn) kg{sup -1} in sediments. The accuracy of the method was evaluated by analysis of two certified reference material (CRM) sediment samples. The HS-SPME-GC-PFPD was then applied to the analysis of three harbour sediment samples. The results showed that headspace SPME is an attractive tool for analysis of organotin compounds in solid environmental matrices. (orig.)

  20. Speciation analysis of organotin compounds in human urine by headspace solid-phase micro-extraction and gas chromatography with pulsed flame photometric detection.

    Valenzuela, Aníbal; Lespes, Gaëtane; Quiroz, Waldo; Aguilar, Luis F; Bravo, Manuel A

    2014-07-01

    A new headspace solid-phase micro-extraction (HS-SPME) method followed by gas chromatography with pulsed flame photometric detection (GC-PFPD) analysis has been developed for the simultaneous determination of 11 organotin compounds, including methyl-, butyl-, phenyl- and octyltin derivates, in human urine. The methodology has been validated by the analysis of urine samples fortified with all analytes at different concentration levels, and recovery rates above 87% and relative precisions between 2% and 7% were obtained. Additionally, an experimental-design approach has been used to model the storage stability of organotin compounds in human urine, demonstrating that organotins are highly degraded in this medium, although their stability is satisfactory during the first 4 days of storage at 4 °C and pH=4. Finally, this methodology was applied to urine samples collected from harbor workers exposed to antifouling paints; methyl- and butyltins were detected, confirming human exposure in this type of work environment. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Experimental applications for the MARK-1 and MARK-1A pulsed ionizing radiation detection systems. Volume 3

    Harker, Y.D.; Lawrence, R.S.; Yoon, W.Y.; Lones, J.L.

    1993-12-01

    This report is the third volume in a three volume set describing the MARK series of pulsed ionizing radiation detection systems. This volume describes the MARK-1A detection system, compares it with the MARK-1 system, and describes the experimental testing of the detection systems. Volume 1 of this set presents the technical specifications for the MARK-1 detection system. Volume 2 is an operations manual specifically for the MARK-1 system, but it generally applies to the MARK-1A system as well. These detection systems operate remotely and detect photon radiation from a single or a multiple pulsed source. They contain multiple detector (eight in the MARK-1 and ten in the MARK-1A) for determination of does and incident photon effective energy. The multiple detector arrangement, having different detector sizes and shield thicknesses, provides the capability of determining the effective photon energy of the radiation spectrum. Dose measurements using these units are consistent with TLD measurements. The detection range is from 3 nanorads to 90 microrads per source burst; the response is linear over that range. Three units were built and are ready for field deployment

  2. Detecting Biosignatures Associated with Minerals by Geomatrix-Assisted Laser Desorption/Ionization Fourier Transorm Mass Spectromety (GALDI-FTMS)

    C. Doc Richardson; J. Michelle Kotler; Nancy W. Hinman; Timothy R. McJunkin; Jill R. Scott

    2008-07-01

    The ability to detect carbon signatures that can be linked to complex, possibly biogenic, organic molecules is imperative in research into the origin and distribution of life in our solar system particularly when used in conjunction with inorganic, mineralogical, and isotopic signatures that provide strong evidence for geochemical influences of living organisms on their environment. Ideally, the method used to detect these signatures must (i) accurately and automatically translate the organic and other information into usable forms, (ii) precisely distinguish such information from alternative compositions, (iii) operate with high spatial resolution coupled with precise location abilities, and (iv) require little to no sample preparation because of the potential for contamination. Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform mass spectrometer (FTMS) has been used to determine the presence of bio/organic molecules (BOM) associated with different minerals and mineraloids including oxide, sulfate, carbonate, chloride, and silicate minerals. BOM is defined as an organic structure that can be produced by living organisms or derived from another organic compound made by living organisms (i.e., degradation product). GALDI requires no sample preparation because the mineral matrix assists desorption. Ultimately, however, the detectability of BOM is controlled by the desorption efficiency, ionization efficiency, and the specific experimental conditions. Results from experiments with combinations of known BOM and mineral standards indicated that the detectability of BOM increased with decreasing concentration, contrary to most analytical procedures. Results suggest that BOM when combined with certain minerals is more easily detected than when combined with other minerals. Such conclusions can guide selection of appropriate samples for sample return missions.

  3. Ionization of food products

    Vasseur, J.P.

    1991-01-01

    After general remarks on foods preservation, on international works and on ionization future prospects, main irradiation sources are described. Recalls on radioactivity, on radiation-matter interaction, on toxicology of ionized foods and on ionized foods detection are given. Ionization applications to various products are reviewed, especially in: - Poultry meat - Fishing products - Fresh fruits and vegetables - Dry fruits and vegetables - spices, tea, infusion - prepacked products... An evaluation of economics and sociocultural impacts is presented in connection with recent experiments [fr

  4. Flame structure of methane inverse diffusion flame

    Elbaz, Ayman M.

    2014-07-01

    This paper presents high speed images of OH-PLIF at 10. kHz simultaneously with 2D PIV (particle image velocimetry) measurements collected along the entire length of an inverse diffusion flame with circumferentially arranged methane fuel jets. For a fixed fuel flow rate, the central air jet Re was varied, leading to four air to fuel velocity ratios, namely Vr = 20.7, 29, 37.4 and 49.8. A double flame structure could be observed composed of a lower fuel entrainment region and an upper mixing and intense combustion region. The entrainment region was enveloped by an early OH layer, and then merged through a very thin OH neck to an annular OH layer located at the shear layer of the air jet. The two branches of this annular OH layer broaden as they moved downstream and eventfully merged together. Three types of events were observed common to all flames: breaks, closures and growing kernels. In upstream regions of the flames, the breaks were counterbalanced by flame closures. These breaks in OH signal were found to occur at locations where locally high velocity flows were impinging on the flame. As the Vr increased to 37.4, the OH layers became discontinuous over the downstream region of the flame, and these regions of low or no OH moved upstream. With further increases in Vr, these OH pockets act as flame kernels, growing as they moved downstream, and became the main mechanism for flame re-ignition. Along the flame length, the direction of the two dimensional principle compressive strain rate axis exhibited a preferred orientation of approximately 45° with respect to the flow direction. Moreover, the OH zones were associated with elongated regions of high vorticity. © 2013 Elsevier Inc.

  5. Detection of creatinine in exhaled breath of humans with chronic kidney disease by extractive electrospray ionization mass spectrometry.

    Zeng, Qian; Li, Penghui; Cai, Yunfeng; Zhou, Wei; Wang, Haidong; Luo, Jiao; Ding, Jianhua; Chen, Huanwen

    2016-02-09

    Exhaled breath contains chemicals that have a diagnostic value in human pathologies. Here in vivo breath analysis of creatinine has been demonstrated by constructing a novel platform based on extractive electrospray ionization mass spectrometry (EESI-MS) without sample pretreatment. Under optimized experimental conditions, the limit of creatinine detection in breath was 30.57 ng L(-1), and the linear range of detection was from 0.3 μg L(-1) to 100 μg L(-1). The concentration range of creatinine in the exhaled breath of 50 volunteers with chronic kidney disease was from 42 pptv to 924 pptv, and the range of the relative standard deviations was from 9.3% to 19.2%. The method provides high sensitivity, high specificity and high speed for semi-quantitative analysis of creatinine in exhaled human breath.

  6. Photometric and fluorometric detection of radiolytic changes to selected animal foods as a result of treatment with ionizing rays

    Chory, C.

    1993-01-01

    The methods specified in the heading were tested for their suitability to detect any previous irradiation treatment of shrimps, chickens or mock salmon. Shrimps and chickens are among those foods that are already routinely irradiated for commercial reasons and have therefore been included in the most recent version of the provisional guidelines of the EC commission on the irradiation of foodstuffs. Parameters like radiation-induced formation of carbonyl compounds, changes to radiation-responsive sulfhydryl groups of proteins and DNA strand breaks caused by ionizing radiation offered useful approaches to the detection of any such irradiation. One decisive factor for the choice of the chemical methods of analysis to be used was their straightforwardness. (orig./HP) [de

  7. Rapid detection of undesired cosmetic ingredients by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

    Ouyang, Jie; An, Dongli; Chen, Tengteng; Lin, Zhiwei

    2017-10-01

    In recent years, cosmetic industry profits soared due to the widespread use of cosmetics, which resulted in illicit manufacturers and products of poor quality. Therefore, the rapid and accurate detection of the composition of cosmetics has become crucial. At present, numerous methods, such as gas chromatography and liquid chromatography-mass spectrometry, were available for the analysis of cosmetic ingredients. However, these methods present several limitations, such as failure to perform comprehensive and rapid analysis of the samples. Compared with other techniques, matrix-assisted laser desorption ionization time-of-flight mass spectrometry offered the advantages of wide detection range, fast speed and high accuracy. In this article, we briefly summarized how to select a suitable matrix and adjust the appropriate laser energy. We also discussed the rapid identification of undesired ingredients, focusing on antibiotics and hormones in cosmetics.

  8. On the Flame Height Definition for Upward Flame Spread

    Consalvi, Jean L; Pizzo, Yannick; Porterie, Bernard; Torero, Jose L

    2007-01-01

    Flame height is defined by the experimentalists as the average position of the luminous flame and, consequently is not directly linked with a quantitative value of a physical parameter. To determine flame heights from both numerical and theoretical results, a more quantifiable criterion is needed to define flame heights and must be in agreement with the experiments to allow comparisons. For wall flames, steady wall flame experiments revealed that flame height may be define...

  9. Direct detection of illicit drugs from biological fluids by desorption/ionization mass spectrometry with nanoporous silicon microparticles.

    Guinan, T M; Kirkbride, P; Della Vedova, C B; Kershaw, S G; Kobus, H; Voelcker, N H

    2015-12-07

    Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is a high throughput analytical technique capable of detecting low molecular weight analytes, including illicit drugs, and with potential applications in forensic toxicology as well as athlete and workplace testing, particularly for biological fluids (oral fluids, urine and blood). However, successful detection of illicit drugs using SALDI-MS often requires extraction steps to reduce the inherent complexity of biological fluids. Here, we demonstrate an all-in-one extraction and analytical system consisting of hydrophobically functionalized porous silicon microparticles (pSi-MPs) for affinity SALDI-MS of prescription and illicit drugs. This novel approach allows for the analysis of drugs from multiple biological fluids without sample preparation protocols. The effect of pSi-MP size, pore diameter, pore depth and functionalization on analytical performance is investigated. pSi-MPs were optimized for the rapid and high sensitivity detection of methadone, cocaine and 3,4-methylenedioxymethamphetamine (MDMA). This optimized system allowed extraction and detection of methadone from spiked saliva and clinical urine samples. Furthermore, by detecting oxycodone in additional clinical saliva and plasma samples, we were able to demonstrate the versatility of the pSi-MP SALDI-MS technique.

  10. Ionizing radiation as optimization method for aluminum detection from drinking water samples

    Bazante-Yamguish, Renata; Geraldo, Aurea Beatriz C.; Moura, Eduardo; Manzoli, Jose Eduardo

    2013-01-01

    The presence of organic compounds in water samples is often responsible for metal complexation; depending on the analytic method, the organic fraction may dissemble the evaluation of the real values of metal concentration. Pre-treatment of the samples is advised when organic compounds are interfering agents, and thus sample mineralization may be accomplished by several chemical and/or physical methods. Here, the ionizing radiation was used as an advanced oxidation process (AOP), for sample pre-treatment before the analytic determination of total and dissolved aluminum by ICP-OES in drinking water samples from wells and spring source located at Billings dam region. Before irradiation, the spring source and wells' samples showed aluminum levels of 0.020 mg/l and 0.2 mg/l respectively; after irradiation, both samples showed a 8-fold increase of aluminum concentration. These results are discussed considering other physical and chemical parameters and peculiarities of sample sources. (author)

  11. Application of cholesterol determination method to indirectly detect meat and bone meals in ruminant feeds

    Cecília M. Bandeira

    2013-01-01

    Full Text Available The aim of this study was to verify the presence of meat and bone meal (MBM in ruminant feed, by identifying the cholesterol using gas chromatography with a flame ionization detector. The proposed method demonstrated precision, trueness, and capability to detect MBM in the ruminant feed.

  12. A combined segmented anode gas ionization chamber and time-of-flight detector for heavy ion elastic recoil detection analysis

    Ström, Petter; Petersson, Per; Rubel, Marek; Possnert, Göran

    2016-10-01

    A dedicated detector system for heavy ion elastic recoil detection analysis at the Tandem Laboratory of Uppsala University is presented. Benefits of combining a time-of-flight measurement with a segmented anode gas ionization chamber are demonstrated. The capability of ion species identification is improved with the present system, compared to that obtained when using a single solid state silicon detector for the full ion energy signal. The system enables separation of light elements, up to Neon, based on atomic number while signals from heavy elements such as molybdenum and tungsten are separated based on mass, to a sample depth on the order of 1 μm. The performance of the system is discussed and a selection of material analysis applications is given. Plasma-facing materials from fusion experiments, in particular metal mirrors, are used as a main example for the discussion. Marker experiments using nitrogen-15 or oxygen-18 are specific cases for which the described improved species separation and sensitivity are required. Resilience to radiation damage and significantly improved energy resolution for heavy elements at low energies are additional benefits of the gas ionization chamber over a solid state detector based system.

  13. Rapid analysis of ethanol and water in commercial products using ionic liquid capillary gas chromatography with thermal conductivity detection and/or barrier discharge ionization detection.

    Weatherly, Choyce A; Woods, Ross M; Armstrong, Daniel W

    2014-02-26

    Analysis of ethanol and water in consumer products is important in a variety of processes and often is mandated by regulating agencies. A method for the simultaneous quantitation of ethanol and water that is simple, accurate, precise, rapid, and cost-effective is demonstrated. This approach requires no internal standard for the quantitation of both ethanol and water at any/all levels in commercial products. Ionic liquid based gas chromatography (GC) capillary columns are used to obtain a fast analysis with high selectivity and resolution of water and ethanol. Typical run times are just over 3 min. Examination of the response range of water and ethanol with GC, thermal conductivity detection (TCD), and barrier ionization detection (BID) is performed. Quantitation of both ethanol and water in consumer products is accomplished with both TCD and BID GC detectors using a nonlinear calibration. Validation of method accuracy is accomplished by using standard reference materials.

  14. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : determination of organophosphate pesticides in bottom sediment by gas chromatography with flame photometric detection

    Jha, Virendra Kumar; Wydoski, Duane S.

    2003-01-01

    A method for the isolation of 20 parent organophosphate pesticides and 5 pesticide degradates from bottom-sediment samples is described. The compound O-ethyl-O-methyl-S-proplyphosphorothioate is reported as an estimated concentration because of variable performance. In this method, the sediment samples are centrifuged to remove excess waster mixed with anhydrous sodium sulfate and Soxhlet extracted overnight with dichloromethane (93 percent) and methanol (7 percent). The extract is concentrated and then filtered through a 0.2-micrometer polytetrafluoroethylene membrane syringe filter. An aliquot of the sample extract is quantitatively injected onto two polystyrene-divinylbenzene gel-permeation chromatographic columns connected in series. The compounds are eluted with dichloromethane and a fraction is collected for analysis, with some coextracted interferences, including elemental sulfur, separated and discarded. The aliquot is concentrated and solvent exchanged to ethyl acetate. The extract is analyzed by dual capillary-column gas chromatography with flame photometric detection. Single-operator method detection limits in sodium sulfate matrix samples ranged from 0.81 to 2 micrograms per kilogram. Method performance was validated by spiking all compounds into three different solid matrices (sodium sulfate, bed sediment from Clear Creek, and bed sediment from Evergreen Lake) at three different concentrations. Eight replicates were analyzed at each concentration in each matrix. Mean recoveries of method compounds spiked in Clear Creek samples ranged from 43 to 110 percent, and those in Evergreen Lake samples ranged from 62 to 118 percent for all pesticides. Mean recoveries of method compounds spiked in reagent sodium sulfate samples ranged from 41 to 101 percent for all pesticides. The only exception was O-ethyl-O-methyl-S-propylphosphorothioate, which had an average recovery of 35 percent, and, thus, sample concentration is reported as estimated ('E' remark code).

  15. [Magnetic solid phase extraction combined with gas chromatography-flame photometric detection for the determination of organophosphorus pesticides in juice samples].

    Huang, Qian; He, Man; Chen, Beibei; Hu, Bin

    2014-10-01

    A novel method for the determination of organophosphorous pesticides (OPPs) in fresh juice samples was developed. Fe3O4 @ P (St-co-MAA) magnetic microparticles were synthesized and modified with styrene (St) and methacrylic acid (MAA) by coating St and MAA on magnetic particles and characterized by a series of techniques. The results indicated that Fe3 O4 magnetic nanoparticles (MNPs) have been successfully modified with St and MAA. Based on the prepared FeO4 @ P (St-co-MAA) magnetic microparticles, a novel method of magnetic solid phase extraction (MSPE)-gas chromatography (GC)-flame photometric detection (FPD) was developed for the determination of OPPs. The extraction/desorption conditions of MSPE were optimized, and the analytical performance was evaluated under the optimal conditions. The limits of detection (LODs, S/N = 3) for target OPPs were in the range of 0.013-0.305 μg/L with the RSDs (n = 7) ranging from 3.1% to 8.8%. The enrichment factors varied from 406 to 951. The linear ranges were over three orders of magnitudes (R2 > 0.99) and the reproducibilities were 7.4%-14.5% (n = 5). Finally, the proposed MSPE-GC-FPD method was successfully applied to the analysis of the five OPPs in fresh tomato and strawberry juice samples, with the recoveries of target OPPs in the range of 85.4%-118.9% for the spiked samples. The proposed MSPE-GC-FPD method is featured with low cost, fast separation and high enrichment factor.

  16. Flame-in-gas-shield and miniature diffusion flame hydride atomizers for atomic fluorescence spectrometry: optimization and comparison

    Marschner, Karel; Musil, Stanislav; Dědina, Jiří

    2015-01-01

    A detailed optimization of relevant experimental parameters of two hydride atomizers for atomic fluorescence spectrometry: flame-in-gas-shield atomizer with a two-channel shielding unit and a standard atomizer for atomic fluorescence spectrometry, miniature diffusion flame, was performed. Arsine, generated by the reaction with NaBH 4 in a flow injection arrangement, was chosen as the model hydride. Analytical characteristics of both the atomizers (sensitivity, noise, limits of detection) were compared. Under optimum conditions sensitivity obtained with flame-in-gas-shield atomizer was approximately twice higher than with miniature diffusion flame. The additional advantage of flame-in-gas-shield atomizer is significantly lower flame emission resulting in a better signal to noise ratio. The resulting arsenic limits of detection for miniature diffusion flame and flame-in-gas-shield atomizer were 3.8 ng l −1 and 1.0 ng l −1 , respectively. - Highlights: • We optimized and compared two hydride atomizers for atomic fluorescence spectrometry. • Miniature diffusion flame and flame-in-gas-shield atomizer were optimized. • The limit of detection for arsenic was 1.0 ng l −1

  17. Flame-in-gas-shield and miniature diffusion flame hydride atomizers for atomic fluorescence spectrometry: optimization and comparison

    Marschner, Karel, E-mail: karel.marschner@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Charles University in Prague, Faculty of Science, Department of Analytical Chemistry, Albertov 8, 128 43 Prague (Czech Republic); Musil, Stanislav; Dědina, Jiří [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

    2015-07-01

    A detailed optimization of relevant experimental parameters of two hydride atomizers for atomic fluorescence spectrometry: flame-in-gas-shield atomizer with a two-channel shielding unit and a standard atomizer for atomic fluorescence spectrometry, miniature diffusion flame, was performed. Arsine, generated by the reaction with NaBH{sub 4} in a flow injection arrangement, was chosen as the model hydride. Analytical characteristics of both the atomizers (sensitivity, noise, limits of detection) were compared. Under optimum conditions sensitivity obtained with flame-in-gas-shield atomizer was approximately twice higher than with miniature diffusion flame. The additional advantage of flame-in-gas-shield atomizer is significantly lower flame emission resulting in a better signal to noise ratio. The resulting arsenic limits of detection for miniature diffusion flame and flame-in-gas-shield atomizer were 3.8 ng l{sup −1} and 1.0 ng l{sup −1}, respectively. - Highlights: • We optimized and compared two hydride atomizers for atomic fluorescence spectrometry. • Miniature diffusion flame and flame-in-gas-shield atomizer were optimized. • The limit of detection for arsenic was 1.0 ng l{sup −1}.

  18. Direct Detection of Pharmaceuticals and Personal Care Products from Aqueous Samples with Thermally-Assisted Desorption Electrospray Ionization Mass Spectrometry

    Campbell, Ian S.; Ton, Alain T.; Mulligan, Christopher C.

    2011-07-01

    An ambient mass spectrometric method based on desorption electrospray ionization (DESI) has been developed to allow rapid, direct analysis of contaminated water samples, and the technique was evaluated through analysis of a wide array of pharmaceutical and personal care product (PPCP) contaminants. Incorporating direct infusion of aqueous sample and thermal assistance into the source design has allowed low ppt detection limits for the target analytes in drinking water matrices. With this methodology, mass spectral information can be collected in less than 1 min, consuming ~100 μL of total sample. Quantitative ability was also demonstrated without the use of an internal standard, yielding decent linearity and reproducibility. Initial results suggest that this source configuration is resistant to carryover effects and robust towards multi-component samples. The rapid, continuous analysis afforded by this method offers advantages in terms of sample analysis time and throughput over traditional hyphenated mass spectrometric techniques.

  19. Perfume fingerprinting by easy ambient sonic-spray ionization mass spectrometry: nearly instantaneous typification and counterfeit detection.

    Haddad, Renato; Catharino, Rodrigo Ramos; Marques, Lygia Azevedo; Eberlin, Marcos Nogueira

    2008-11-01

    Perfume counterfeiting is an illegal worldwide practice that involves huge economic losses and potential consumer risk. EASI is a simple, easily performed and rapidly implemented desorption/ionization technique for ambient mass spectrometry (MS). Herein we demonstrate that EASI-MS allows nearly instantaneous perfume typification and counterfeit detection. Samples are simply sprayed onto a glass rod or paper surface and, after a few seconds of ambient drying, a profile of the most polar components of the perfume is acquired. These components provide unique and reproducible chemical signatures for authentic perfume samples. Counterfeiting is readily recognized since the exact set and relative proportions of the more polar chemicals, sometimes at low concentrations, are unknown or hard to reproduce by the counterfeiters and hence very distinct and variable EASI-MS profiles are observed for the counterfeit samples.

  20. Non-ionizing radiofrequency electromagnetic waves traversing the head can be used to detect cerebrovascular autoregulation responses

    Oziel, M.; Hjouj, M.; Gonzalez, C. A.; Lavee, J.; Rubinsky, B.

    2016-02-01

    Monitoring changes in non-ionizing radiofrequency electromagnetic waves as they traverse the brain can detect the effects of stimuli employed in cerebrovascular autoregulation (CVA) tests on the brain, without contact and in real time. CVA is a physiological phenomenon of importance to health, used for diagnosis of a number of diseases of the brain with a vascular component. The technology described here is being developed for use in diagnosis of injuries and diseases of the brain in rural and economically underdeveloped parts of the world. A group of nine subjects participated in this pilot clinical evaluation of the technology. Substantial research remains to be done on correlating the measurements with physiology and anatomy.

  1. A study for the detection of ionizing particles with phototransistors on thick high-resistivity silicon substrates

    Batignani, G.; Angelini, C.; Bisogni, M.G.; Boscardin, M.; Bettarini, S.; Bondioli, M.; Bosisio, L.; Bucci, F.; Calderini, G.; Carpinelli, M.; Ciacchi, M.; Dalla Betta, G.F.; Dittongo, S.; Forti, F.; Giorgi, M.A.; Gregori, P.; Han, D.J.; Manfredi, P.F.; Manghisoni, M.; Marchiori, G.; Neri, N.; Novelli, M.; Paoloni, E.; Piemonte, C.; Rachevskaia, I.; Rama, M.; Ratti, L.; Re, V.; Rizzo, G.; Ronchin, S.; Rosso, V.; Simi, G.; Speziali, V.; Stefanini, A.; Zorzi, N.

    2004-01-01

    We report on bipolar NPN phototransistors fabricated at ITC-IRST on thick high-resistivity silicon substrates. The phototransistor emitter is composed of a phosphorus n+ implant, the base is a diffused high-energy boron implant, and the collector is the 600-800 μm thick silicon bulk, contacted on the backplane. We have studied the current amplification for two different doping profiles of the emitter, obtaining values of β ranging from 60 to 3000. For various emitter and base configurations, we measured the static device characteristics and extracted the leakage currents and the base resistance, verifying the fundamental relationship between them and the total base capacitances. The use of such phototransistors to detect ionizing particles is exploited and discussed

  2. A study for the detection of ionizing particles with phototransistors on thick high-resistivity silicon substrates

    Batignani, G. E-mail: giovanni.batignani@pi.infn.it; Angelini, C.; Bisogni, M.G.; Boscardin, M.; Bettarini, S.; Bondioli, M.; Bosisio, L.; Bucci, F.; Calderini, G.; Carpinelli, M.; Ciacchi, M.; Dalla Betta, G.F.; Dittongo, S.; Forti, F.; Giorgi, M.A.; Gregori, P.; Han, D.J.; Manfredi, P.F.; Manghisoni, M.; Marchiori, G.; Neri, N.; Novelli, M.; Paoloni, E.; Piemonte, C.; Rachevskaia, I.; Rama, M.; Ratti, L.; Re, V.; Rizzo, G.; Ronchin, S.; Rosso, V.; Simi, G.; Speziali, V.; Stefanini, A.; Zorzi, N

    2004-09-01

    We report on bipolar NPN phototransistors fabricated at ITC-IRST on thick high-resistivity silicon substrates. The phototransistor emitter is composed of a phosphorus n+ implant, the base is a diffused high-energy boron implant, and the collector is the 600-800 {mu}m thick silicon bulk, contacted on the backplane. We have studied the current amplification for two different doping profiles of the emitter, obtaining values of {beta} ranging from 60 to 3000. For various emitter and base configurations, we measured the static device characteristics and extracted the leakage currents and the base resistance, verifying the fundamental relationship between them and the total base capacitances. The use of such phototransistors to detect ionizing particles is exploited and discussed.

  3. Detection of protonated non-Watson-Crick base pairs using electrospray ionization mass spectrometry.

    Ishida, Riyoko; Iwahashi, Hideo

    2018-03-01

    Many studies have shown that protonated nucleic acid base pairs are involved in a wide variety of nucleic acid structures. However, little information is available on relative stability of hemiprotonated self- and non-self-dimers at monomer level. We used electrospray ionization mass spectrometry (ESI-MS) to evaluate the relative stability under various concentrations of hydrogen ion. These enable conjecture of the formation of protonated non-Watson-Crick base pairs based on DNA and RNA base sequence. In the present study, we observed that ESI-MS peaks corresponded to respective self-dimers for all examined nucleosides except for adenosine. Peak heights depended on the concentration of hydrogen ion. The ESI-MS peak heights of the hemiprotonated cytidine dimers and the hemiprotonated thymidine dimer sharply increased with increased concentration of hydrogen ion, suggesting direct participation of hydrogen ion in dimer formations. In ESI-MS measurements of the solutions containing adenosine, cytidine, thymidine and guanosine, we observed protonated cytidine-guanosine dimer (CH+-G) and protonated cytidine-thymidine dimer (CH+-T) in addition to hemiprotonated cytidine-cytidine dimer (CH+-C) with following relative peak height, (CH+-C) > (CH+-G) ≈ (CH+-T) > (CH+-A). Additionally, in the ESI-MS measurements of solutions containing adenosine, thymidine and guanosine, we observed a considerable amount of protonated adenosine-guanosine (AH+-G) and protonated adenosine-thymidine (AH+-T).

  4. Ammonium Bicarbonate Addition Improves the Detection of Proteins by Desorption Electrospray Ionization Mass Spectrometry

    Honarvar, Elahe; Venter, Andre R.

    2017-06-01

    The analysis of protein by desorption electrospray ionization mass spectrometry (DESI-MS) is considered impractical due to a mass-dependent loss in sensitivity with increase in protein molecular weights. With the addition of ammonium bicarbonate to the DESI-MS analysis the sensitivity towards proteins by DESI was improved. The signal to noise ratio (S/N) improvement for a variety of proteins increased between 2- to 3-fold relative to solvent systems containing formic acid and more than seven times relative to aqueous methanol spray solvents. Three methods for ammonium bicarbonate addition during DESI-MS were investigated. The additive delivered improvements in S/N whether it was mixed with the analyte prior to sample deposition, applied over pre-prepared samples, or simply added to the desorption spray solvent. The improvement correlated well with protein pI but not with protein size. Other ammonium or bicarbonate salts did not produce similar improvements in S/N, nor was this improvement in S/N observed for ESI of the same samples. As was previously described for ESI, DESI also caused extensive protein unfolding upon the addition of ammonium bicarbonate. [Figure not available: see fulltext.

  5. Development of novel semiconductor detectors for the detection of ionizing radiation

    Strueder, L.

    1989-08-01

    The present thesis treats the development of novel energy- and position-resolving semiconductor detectors: Fully depletable pn CCD's. In experiments of high-energy physics they are suited as highly resolving position-sensitive detectors for minimally ionizing particles. In nuclear and atomic physics they can be applied as position-resolving energy spectrometers. Increasing interest detectors of this type find also at synchrotron-radiation sources with photon energies from 20 eV to 50 keV. As focal instruments of X-ray telescopes they are in astrophysical measurements in an energy range from 100 eV to 15 keV of use. The required accuracy in the energy measurement amounts to 100 eV (FWHM) at an X-ray energy of 1 keV, at a simultaneous precision of the position determination of 50 μm. The measurement results which are here presented on the first fully depletable CCD's show that the components posses the potential to fulfill these requirements. (orig.) [de

  6. Separation of seven arsenic compounds by high performance liquid chromatography with on-line detection by hydrogen-argon flame atomic absorption spectrometry and inductively coupled plasma mass spectrometry

    Hansen, S. H.; Larsen, Erik Huusfeldt; Pritzl, G.

    1992-01-01

    -to-noise ratio of the on-line AAS detector was optimized. This involved the use of the hydrogen-argon-entrained air flame, a slotted tube atom trap in the flame for signal enhancement, electronic noise damping and a high-intensity light source. The detection limits in mu-g cm-3, using 100 mm3 injections...... of mixtures of arsenic standards into the HPLC system were: arsenite, As(III) 1.1; arsenate, As(V) 1.4; MMA 1.4; DMA 0.7; AsB 0.3; AsC 0.5; and the TMAs 0.4. The HPLC-AAS system was used for the analysis of arsenic species in aqueous extracts of soil samples from a polluted land site. Only arsenate was found...

  7. Flame emission spectrometry using atomic absorption apparatus. I. Determination of Sr in sea water

    Aizawa, S.; Yoshimura, E.; Hamachi, M.; Haraguchi, H.; Dokiya, Y.; Fuwa, K.

    1976-01-01

    Flame emission determination of Sr in seawater was studied using an ordinary atomic absorption apparatus. The analytical line 4607 A was used with a background correction at 4616 A. The ionization was negligible in an air acetylene flame with seawater, and the interference of H 2 SO 4 was eliminated using the higher part of the flame. Sr concentration of seawater of Tokyo Bay and Sagami Bay has been determined

  8. Rapid detection of illegal colorants on traditional Chinese pastries through mass spectrometry with an interchangeable thermal desorption electrospray ionization source.

    Chao, Yu-Ying; Chen, Yen-Ling; Chen, Wei-Chu; Chen, Bai-Hsiun; Huang, Yeou-Lih

    2018-06-30

    Ambient mass spectrometry using an interchangeable thermal desorption/electrospray ionization source (TD-ESI) is a relatively new technique that has had only a limited number of applications to date. Nevertheless, this direct-analysis technique has potential for wider use in analytical chemistry (e.g., in the rapid direct detection of contaminants, residues, and adulterants on and in food) when operated in dual-working mode (pretreatment-free qualitative screening and conventional quantitative confirmation) after switching to a TD-ESI source from a conventional ESI source. Herein, we describe the benefits and challenges associated with the use of a TD-ESI source to detect adulterants on traditional Chinese pastries (TCPs), as a proof-of-concept for the detection of illegal colorants. While TD-ESI can offer direct (i.e., without any sample preparation) qualitative screening analyses for TCPs with adequate sensitivity within 30 s, the use of TD-ESI for semi-quantification is applicable only for homogeneous matrices (e.g., tang yuan). Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Detection of Amyloid Beta (Aβ) Oligomeric Composition Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI MS)

    Wang, Jasmine S.-H.; Whitehead, Shawn N.; Yeung, Ken K.-C.

    2018-02-01

    The use of MALDI MS as a fast and direct method to detect the Aβ oligomers of different masses is examined in this paper. Experimental results suggest that Aβ oligomers are ionized and detected as singly charged ions, and thus, the resulting mass spectrum directly reports the oligomer size distribution. Validation experiments were performed to verify the MS data against artifacts. Mass spectra collected from modified Aβ peptides with different propensities for aggregation were compared. Generally, the relative intensities of multimers were higher from samples where oligomerization was expected to be more favorable, and vice versa. MALDI MS was also able to detect the differences in oligomeric composition before and after the incubation/oligomerization step. Such differences in sample composition were also independently confirmed with an in vitro Aβ toxicity study on primary rat cortical neurons. An additional validation was accomplished through removal of oligomers from the sample using molecular weight cutoff filters; the resulting MS data correctly reflected the removal at the expected cutoff points. The results collectively validated the ability of MALDI MS to assess the monomeric/multimeric composition of Aβ samples. [Figure not available: see fulltext.

  10. Detection of trace organics in Mars analog samples containing perchlorate by laser desorption/ionization mass spectrometry.

    Li, Xiang; Danell, Ryan M; Brinckerhoff, William B; Pinnick, Veronica T; van Amerom, Friso; Arevalo, Ricardo D; Getty, Stephanie A; Mahaffy, Paul R; Steininger, Harald; Goesmann, Fred

    2015-02-01

    Evidence from recent Mars missions indicates the presence of perchlorate salts up to 1 wt % level in the near-surface materials. Mixed perchlorates and other oxychlorine species may complicate the detection of organic molecules in bulk martian samples when using pyrolysis techniques. To address this analytical challenge, we report here results of laboratory measurements with laser desorption mass spectrometry, including analyses performed on both commercial and Mars Organic Molecule Analyzer (MOMA) breadboard instruments. We demonstrate that the detection of nonvolatile organics in selected spiked mineral-matrix materials by laser desorption/ionization (LDI) mass spectrometry is not inhibited by the presence of up to 1 wt % perchlorate salt. The organics in the sample are not significantly degraded or combusted in the LDI process, and the parent molecular ion is retained in the mass spectrum. The LDI technique provides distinct potential benefits for the detection of organics in situ on the martian surface and has the potential to aid in the search for signs of life on Mars.

  11. Trace detection of organic compounds in complex sample matrixes by single photon ionization ion trap mass spectrometry: real-time detection of security-relevant compounds and online analysis of the coffee-roasting process.

    Schramm, Elisabeth; Kürten, Andreas; Hölzer, Jasper; Mitschke, Stefan; Mühlberger, Fabian; Sklorz, Martin; Wieser, Jochen; Ulrich, Andreas; Pütz, Michael; Schulte-Ladbeck, Rasmus; Schultze, Rainer; Curtius, Joachim; Borrmann, Stephan; Zimmermann, Ralf

    2009-06-01

    An in-house-built ion trap mass spectrometer combined with a soft ionization source has been set up and tested. As ionization source, an electron beam pumped vacuum UV (VUV) excimer lamp (EBEL) was used for single-photon ionization. It was shown that soft ionization allows the reduction of fragmentation of the target analytes and the suppression of most matrix components. Therefore, the combination of photon ionization with the tandem mass spectrometry (MS/MS) capability of an ion trap yields a powerful tool for molecular ion peak detection and identification of organic trace compounds in complex matrixes. This setup was successfully tested for two different applications. The first one is the detection of security-relevant substances like explosives, narcotics, and chemical warfare agents. One test substance from each of these groups was chosen and detected successfully with single photon ionization ion trap mass spectrometry (SPI-ITMS) MS/MS measurements. Additionally, first tests were performed, demonstrating that this method is not influenced by matrix compounds. The second field of application is the detection of process gases. Here, exhaust gas from coffee roasting was analyzed in real time, and some of its compounds were identified using MS/MS studies.

  12. Lifted Turbulent Jet Flames

    1993-04-14

    flame length L simultaneously with h, and measuring the visible radiation I simultaneously with h. L(t) was found to be nearly uncorrelated with h(t...variation of 7i/2 /76 with ýh. These experiments included measuring the flame length L simultaneously with h, and measuring the visible radiation I...Measurements of Liftoff Height and Flame Length ... 66 4.5 Simultaneous Measurements of Liftoff Height and Radiation ....... 71 4.6 D scussion

  13. Radiation transmission type pipe wall thinning detection device and measuring instruments utilizing ionizing radiation

    Higashi, Yasuhiko

    2009-01-01

    We developed the device to detect thinning of pipe thorough heat insulation in Power Plant, etc, even while the plant is under operation. It is necessary to test many parts of many pipes for pipe wall thinning management, but it is difficult within a limited time of the routine test. This device consists of detector and radiation source, which can detect the pipe (less than 500 mm in external diameter, less than 50 mm in thickness) with 1.6%-reproducibility (in a few-minutes measurement), based on the attenuation rate. Operation is easy and effective without removing the heat insulation. We will expand this thinning detection system, and contribute the safety of the Plant. (author)

  14. Detection and measurement of ionizing radiation by the Radioactive Waste Management Centre

    Mudra, Josef

    2013-01-01

    The following topics are dealt with: Basic properties of radionuclides and selection of suitable detectors; radiation characteristics of sealed sources (radiation detection, dose rate measurement, surface contamination measurement, gamma spectroscopy); non-destructive analysis (segment gamma scanner, digital radiography); destructive analysis; radiation monitoring of humans and workplaces; and dosimetric monitoring of workplace surroundings and discharges. (orig.)

  15. Aerosol quantification with the Aerodyne Aerosol Mass Spectrometer: detection limits and ionizer background effects

    S. Borrmann

    2009-02-01

    Full Text Available Systematic laboratory experiments were performed to investigate quantification of various species with two versions of the Aerodyne Aerosol Mass Spectrometer, a Quadrupole Aerosol Mass Spectrometer (Q-AMS and a compact Time-of-Flight Aerosol Mass Spectrometer (c-ToF-AMS. Here we present a new method to continuously determine the detection limits of the AMS analyzers during regular measurements, yielding detection limit (DL information under various measurement conditions. Minimum detection limits range from 0.03 μg m−3 (nitrate, sulfate, and chloride up to 0.5 μg m−3 (organics for the Q-AMS. Those of the c-ToF-AMS are found between 0.003 μg m−3 (nitrate, sulfate and 0.03 μg m−3 (ammonium, organics. The DL values found for the c-ToF-AMS were ~10 times lower than those of the Q-AMS, mainly due to differences in ion duty cycle. Effects causing an increase of the detection limits include long-term instrument contamination, measurement of high aerosol mass concentrations and short-term instrument history. The self-cleaning processes which reduce the instrument background after measurement of large aerosol concentrations as well as the influences of increased instrument background on mass concentration measurements are discussed. Finally, improvement of detection limits by extension of averaging time intervals, selected or reduced ion monitoring, and variation of particle-to-background measurement ratio are investigated.

  16. The EPR detection of foods preserved with the use of ionizing radiation

    Stachowicz, W.; Burlińska, G.; Michalik, J.; Dziedzic-Gocławska, A.; Ostrowski, K.

    1995-02-01

    Solid constituents extracted from irradiated foods have been examined by the epr (esr) spectroscopy. It has been proved that some epr active species produced by radiation in foods are specific and stable enough to be used for the detection of irradiation treatment. The most promising results have been obtained with bones extracted from frozen raw meat (beef, pork, poultry and fish), with seeds of fruits (dates and figs), with dried mushrooms, gelatin and macaroni.

  17. A promising new mechanism of ionizing radiation detection for positron emission tomography: Modulation of optical properties

    Tao, Li; Daghighian, Henry M.; Levin, Craig S.

    2016-01-01

    Using conventional scintillation detection, the fundamental limit in positron emission tomography (PET) time resolution is strongly dependent on the inherent temporal variances generated during the scintillation process, yielding an intrinsic physical limit for the coincidence time resolution of around 100 ps. On the other hand, modulation mechanisms of the optical properties of a material exploited in the optical telecommunications industry can be orders of magnitude faster. In this paper we...

  18. Detection of Staphylococcus aureus by functional gold nanoparticle-based affinity surface-assisted laser desorption/ionization mass spectrometry.

    Lai, Hong-Zheng; Wang, Sin-Ge; Wu, Ching-Yi; Chen, Yu-Chie

    2015-02-17

    Staphylococcus aureus is one of the common pathogenic bacteria responsible for bacterial infectious diseases and food poisoning. This study presents an analytical method based on the affinity nanoprobe-based mass spectrometry that enables detection of S. aureus in aqueous samples. A peptide aptamer DVFLGDVFLGDEC (DD) that can recognize S. aureus and methicillin-resistant S. aureus (MRSA) was used as the reducing agent and protective group to generate DD-immobilized gold nanoparticles (AuNPs@DD) from one-pot reactions. The thiol group from cysteine in the peptide aptamer, i.e., DD, can interact with gold ions to generate DD-immobilized AuNPs in an alkaline solution. The generated AuNPs@DD has an absorption maximum at ∼518 nm. The average particle size is 7.6 ± 1.2 nm. Furthermore, the generated AuNPs@DD can selectively bind with S. aureus and MRSA. The conjugates of the target bacteria with AuNPs were directly analyzed by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The gold ions generated from the AuNPs@DD anchored on the target bacteria were monitored. Gold ions (m/z 197 and 394) were only generated from the conjugates of the target bacterium-AuNP@DD in the SALDI process. Thus, the gold ions could be used as the indicators for the presence of the target bacteria. The detection limit of S. aureus using this method is in the order of a few tens of cells. The low detection limit is due to the ease of generation of gold cluster ion derived from AuNPs under irradiation with a 355 nm laser beam. Apple juice mixed with S. aureus was used as the sample to demonstrate the suitability of the method for real-world application. Because of its low detection limit, this approach can potentially be used to screen the presence of S. aureus in complex samples.

  19. Ambient Pressure Laser Desorption—Chemical Ionization Mass Spectrometry for Fast and Reliable Detection of Explosives, Drugs, and Their Precursors

    René Reiss

    2018-06-01

    Full Text Available Fast and reliable information is crucial for first responders to draw correct conclusions at crime scenes. An ambient pressure laser desorption (APLD mass spectrometer is introduced for this scenario, which enables detecting substances on surfaces without sample pretreatment. It is especially useful for substances with low vapor pressure and thermolabile ones. The APLD allows for the separation of desorption and ionization into two steps and, therefore, both can be optimized separately. Within this work, an improved version of the developed system is shown that achieves limits of detection (LOD down to 500 pg while remaining fast and flexible. Furthermore, realistic scenarios are applied to prove the usability of this system in real-world issues. For this purpose, post-blast residues of a bomb from the Second World War were analyzed, and the presence of PETN was proven without sample pretreatment. In addition, the analyzable substance range could be expanded by various drugs and drug precursors. Thus, the presented instrumentation can be utilized for an increased number of forensically important compound classes without changing the setup. Drug precursors revealed a LOD ranging from 6 to 100 ng. Drugs such as cocaine hydrochloride, heroin, (3,4-methylendioxy-methamphetamine hydrochloride (MDMA hydrochloride, and others exhibit a LOD between 10 to 200 ng.

  20. Detection of lung cancer using plasma protein profiling by matrix-assisted laser desorption/ionization mass spectrometry.

    Shevchenko, Valeriy E; Arnotskaya, Natalia E; Zaridze, David G

    2010-01-01

    There are no satisfactory plasma biomarkers which are available for the early detection and monitoring of lung cancer, one of the most frequent cancers worldwide. The aim of this study is to explore the application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) to plasma proteomic patterns to distinguish lung cancer patients from healthy individuals. The EDTA plasma samples have been pre-fractionated using magnetic bead kits functionalized with weak cation exchange coatings. We compiled MS protein profiles for 90 patients with squamous cell carcinomas (SCC) and compared them with profiles from 187 healthy controls. The MALDI-ToF spectra were analyzed statistically using ClinProTools bioinformatics software. Depending on the sample used, up to 441 peaks/spectrum could be detected in a mass range of 1000-20,000 Da; 33 of these proteins had statistically differential expression levels between SCC and control plasma (P 90%) in external validation test. These results suggest that plasma MALDI-ToF MS protein profiling can distinguish patients with SCC and also from healthy individuals with relatively high sensitivity and specificity and that MALDI- ToF MS is a potential tool for the screening of lung cancer.

  1. Effect of ionizing radiation on the quantitative detection of Salmonella using real-time PCR

    Lim, Sangyong; Jung, Jinwoo [Radiation Research Center for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Kim, Minjeong; Ryu, Sangryeol [Department of Food and Animal Biotechnology, School of Agricultural Biotechnology, Center for Agricultural Biomaterials, Seoul National University, Seoul 151-921 (Korea, Republic of); Kim, Dongho [Radiation Research Center for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)], E-mail: fungikim@kaeri.re.kr

    2008-09-15

    Food irradiation is an economically viable technology for inactivating foodborne pathogens, but irradiation can mask pathogens in unhygienically prepared food. The aim of this study was to investigate the effect of irradiation treatment on the detection of Salmonella using real-time PCR. Three commercially available kits were tested, of which the InstaGene Matrix procedure was most effective in preparing template DNA from Salmonella exposed to radiation in broth culture. The minimum level of detection by real-time PCR combined with InstaGene Matrix was 3 log units of Salmonella per milliliter. However, when pure cultures of Salmonella were irradiated at 3 and 5 kGy, the cycle threshold (C{sub T}) increased 1-1.5-fold compared to irradiation at 0 and 1 kGy. This indicated that irradiation treatment may result in an underestimation of bacterial counts due to radiation-induced DNA lesions. We also compared C{sub T} values in inoculated chicken homogenates before and after irradiation, which in this model caused a 1.3-3.3-fold underestimation of bacterial counts with respect to irradiation dose.

  2. Influence of Culture Media on Detection of Carbapenem Hydrolysis by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

    Ramos, Ana Carolina; Carvalhaes, Cecília Godoy; Cordeiro-Moura, Jhonatha Rodrigo; Rockstroh, Anna Carolina; Machado, Antonia Maria Oliveira; Gales, Ana Cristina

    2016-07-01

    In this study, we evaluated the influence of distinct bacterial growth media on detection of carbapenemase hydrolysis by matrix-assisted laser desorption ionization-time of flight mass spectrometry. False-negative results were observed for OXA-25-, OXA-26-, and OXA-72-producing Acinetobacter baumannii isolates grown on MacConkey agar medium. The other culture media showed 100% sensitivity and 100% specificity for detecting carbapenemase. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  3. Detection and quantification of neurotensin in human brain tissue by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    Gobom, J; Kraeuter, K O; Persson, R

    2000-01-01

    A method was developed for mass spectrometric detection of neurotensin (NT)-like immunoreactivity and quantification of NT in human brain tissue. The method is based on immunoprecipitation followed by analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF......-MS). The identity of the major component of the immunoprecipitates as neurotensin was confirmed by fragment ion analysis on an electrospray ionization quadrupole time-of-flight instrument. MALDI-TOF-MS quantification of NT was achieved using stable-isotope-labeled NT as the internal standard, yielding an error...

  4. Study and characterization of III-V semiconductor materials for applications in ionizing radiation detection

    Moulin, H.

    1989-11-01

    The photoconduction in the bulk of the gallium arsenide (GaAs) and of the indium phosphide doped with iron (InP:Fe) is investigated. These semiconductor materials are to be applied in X rays detection. The photoconduction theory and the physical characteristics of those materials are reviewed. The computer simulation models for studying the photoconductor responses to the radiation pulses are described. The experimental results are discussed. They include the following aspects: the characterization of the GaAs and InP:Fe, in the obscurity, as a function of the polarized electric field and of the neutrons dose; the characterization under X ray. Continuous X rays and pulsed synchrotron radiation are applied [fr

  5. Unsteady Flame Embedding

    El-Asrag, Hossam A.

    2011-01-01

    Direct simulation of all the length and time scales relevant to practical combustion processes is computationally prohibitive. When combustion processes are driven by reaction and transport phenomena occurring at the unresolved scales of a numerical simulation, one must introduce a dynamic subgrid model that accounts for the multiscale nature of the problem using information available on a resolvable grid. Here, we discuss a model that captures unsteady flow-flame interactions- including extinction, re-ignition, and history effects-via embedded simulations at the subgrid level. The model efficiently accounts for subgrid flame structure and incorporates detailed chemistry and transport, allowing more accurate prediction of the stretch effect and the heat release. In this chapter we first review the work done in the past thirty years to develop the flame embedding concept. Next we present a formulation for the same concept that is compatible with Large Eddy Simulation in the flamelet regimes. The unsteady flame embedding approach (UFE) treats the flame as an ensemble of locally one-dimensional flames, similar to the flamelet approach. However, a set of elemental one-dimensional flames is used to describe the turbulent flame structure directly at the subgrid level. The calculations employ a one-dimensional unsteady flame model that incorporates unsteady strain rate, curvature, and mixture boundary conditions imposed by the resolved scales. The model is used for closure of the subgrid terms in the context of large eddy simulation. Direct numerical simulation (DNS) data from a flame-vortex interaction problem is used for comparison. © Springer Science+Business Media B.V. 2011.

  6. NO concentration imaging in turbulent nonpremixed flames

    Schefer, R.W. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The importance of NO as a pollutant species is well known. An understanding of the formation characteristics of NO in turbulent hydrocarbon flames is important to both the desired reduction of pollutant emissions and the validation of proposed models for turbulent reacting flows. Of particular interest is the relationship between NO formation and the local flame zone, in which the fuel is oxidized and primary heat release occurs. Planar imaging of NO provides the multipoint statistics needed to relate NO formation to the both the flame zone and the local turbulence characteristics. Planar imaging of NO has been demonstrated in turbulent flames where NO was seeded into the flow at high concentrations (2000 ppm) to determine the gas temperature distribution. The NO concentrations in these experiments were significantly higher than those expected in typical hydrocarbon-air flames, which require a much lower detectability limit for NO measurements. An imaging technique based on laser-induced fluorescence with sufficient sensitivity to study the NO formation mechanism in the stabilization region of turbulent lifted-jet methane flames.

  7. Determination of plant stanols and plant sterols in phytosterol enriched foods with a gas chromatographic-flame ionization detection method: NMKL collaborative study.

    Laakso, Päivi H

    2014-01-01

    This collaborative study with nine participating laboratories was conducted to determine the total plant sterol and/or plant stanol contents in phytosterol fortified foods with a gas chromatographic method. Four practice and 12 test samples representing mainly commercially available foodstuffs were analyzed as known replicates. Twelve samples were enriched with phytosterols, whereas four samples contained only natural contents of phytosterols. The analytical procedure consisted of two alternative approaches: hot saponification method, and acid hydrolysis treatment prior to hot saponification. As a result, sterol/stanol compositions and contents in the samples were measured. The amounts of total plant sterols and total plant stanols varying from 0.005 to 8.04 g/100 g product were statistically evaluated after outliers were eliminated. The repeatability RSD (RSDr) varied from 1.34 to 17.13%. The reproducibility RSD (RSDR) ranged from 3.03 to 17.70%, with HorRat values ranging from 0.8 to 2.1. When only phytosterol enriched food test samples are considered, the RSDr ranged from 1.48 to 6.13%, the RSD, ranged from 3.03 to 7.74%, and HorRat values ranged from 0.8 to 2.1. Based on the results of this collaborative study, the study coordinator concludes the method is fit for its purpose.

  8. One-step extraction and quantitation of toxic alcohols and ethylene glycol in plasma by capillary gas chromatography (GC) with flame ionization detection (FID).

    Orton, Dennis J; Boyd, Jessica M; Affleck, Darlene; Duce, Donna; Walsh, Warren; Seiden-Long, Isolde

    2016-01-01

    Clinical analysis of volatile alcohols (i.e. methanol, ethanol, isopropanol, and metabolite acetone) and ethylene glycol (EG) generally employs separate gas chromatography (GC) methods for analysis. Here, a method for combined analysis of volatile alcohols and EG is described. Volatile alcohols and EG were extracted with 2:1 (v:v) acetonitrile containing internal standards (IS) 1,2 butanediol (for EG) and n-propanol (for alcohols). Samples were analyzed on an Agilent 6890 GC FID. The method was evaluated for precision, accuracy, reproducibility, linearity, selectivity and limit of quantitation (LOQ), followed by correlation to existing GC methods using patient samples, Bio-Rad QC, and in-house prepared QC material. Inter-day precision was from 6.5-11.3% CV, and linearity was verified from down to 0.6mmol/L up to 150mmol/L for each analyte. The method showed good recovery (~100%) and the LOQ was calculated to be between 0.25 and 0.44mmol/L. Patient correlation against current GC methods showed good agreement (slopes from 1.03-1.12, and y-intercepts from 0 to 0.85mmol/L; R(2)>0.98; N=35). Carryover was negligible for volatile alcohols in the measuring range, and of the potential interferences tested, only toluene and 1,3 propanediol interfered. The method was able to resolve 2,3 butanediol, diethylene glycol, and propylene glycol in addition to the peaks quantified. Here we describe a simple procedure for simultaneous analysis of EG and volatile alcohols that comes at low cost and with a simple liquid-liquid extraction requiring no derivitization to obtain adequate sensitivity for clinical specimens. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  9. Multi-channel integrated circuits for the detection and measurement of ionizing radiation

    Engel, G.L.; Duggireddi, N.; Vangapally, V.; Elson, J.M.; Sobotka, L.G.; Charity, R.J.

    2011-01-01

    The Integrated Circuits (IC) Design Research Laboratory at Southern Illinois University Edwardsville (SIUE) has collaborated with the Nuclear Reactions Group at Washington University (WU) to develop a family of multi-channel integrated circuits. To date, the collaboration has successfully produced two micro-chips. The first was an analog shaped and peak sensing chip with on-board constant-fraction discriminators and sparsified readout. This chip is known as Heavy-Ion Nuclear Physics-16 Channel (HINP16C). The second chip, christened PSD8C, was designed to logically complement (in terms of detector types) the HINP16C chip. Pulse Shape Discrimination-8 Channel (PSD8C), featuring three settable charge integration windows per channel, performs pulse shape discrimination (PSD). This paper summarizes the design, capabilities, and features of the HINP16C and PSD8C ICs. It proceeds to discuss the modifications, made to the ICs and their associated systems, which have attempted to improve ease of use, increase performance, and extend capabilities. The paper concludes with a brief discussion of what may be the next chip (employing a multi-sampling scheme) to be added to our CMOS ASIC 'tool box' for radiation detection instrumentation.

  10. A novel lead imprinted polymer as the selective solid phase for extraction and trace detection of lead ions by flame atomic absorption spectrophotometry: Synthesis, characterization and analytical application

    Homeira Ebrahimzadeh

    2017-05-01

    Full Text Available A novel ion imprinted polymer as the selective solid phase combined with flame atomic absorption spectrometry (FAAS was applied for preconcentration and determination of lead in real samples. In the first step, Pb(II-IIP was synthesized by copolymerization of 2-vinyl pyridine as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, 2,2-azobisisobutyronitrile as the initiator that imprinted with Pb(II as the template ion, 2-amino pyridine as the ligand. Subsequently, the imprinted Pb(II was completely removed by leaching the dried and powdered imprinted polymer with HCl (2 mol L−1. This polymer was characterized by Fourier Transform Infrared (FT-IR spectrometer. The effect of different variables on the extraction efficiency such as type and volume of eluent for extraction, solution’s pH for adsorption, sorption and desorption times was evaluated. Under the optimum conditions: type of eluent, HCl (2 mol L−1; volume of eluent, 5 mL; solution’s pH for sorption, 5; sorption time, 90 min; desorption time, 125 min and breakthrough volume of 750 mL were obtained. Preconcentration factor of the method was about 150. The limit of detection was obtained 0.75 μg L−1 and a dynamic linear range (DLR of 3–150 μg L−1 was found. The maximum sorption retention capacity of Pb(II ions on the imprinted polymer was 85.6 mg g−1. The prepared ion-imprinted polymer particles have an increased selectivity toward Pb(II ions over a range of competing metal ions with the same charge and similar ionic radius. Performance of the present method was evaluated for extraction and determination of Pb(II in water samples at microgram per liter concentration and satisfactory results were obtained (RSD = 2.7%.

  11. Hydrogen-enriched non-premixed jet flames : analysis of the flame surface, flame normal, flame index and Wobbe index

    Ranga Dinesh, K.K.J.; Jiang, X.; Oijen, van J.A.

    2014-01-01

    A non-premixed impinging jet flame is studied using three-dimensional direct numerical simulation with detailed chemical kinetics in order to investigate the influence of fuel variability on flame surface, flame normal, flame index and Wobbe index for hydrogen-enriched combustion. Analyses indicate

  12. On the origin of highly ionized X-ray absorbers detected in the galactic X-ray binaries

    Luo, Yang; Fang, Taotao

    2014-01-01

    X-ray observations of the Galactic X-ray binaries (XRBs) revealed numerous highly ionized metal absorption lines. However, it is unclear whether such lines are produced by the hot interstellar medium (ISM) or the circumstellar medium intrinsic to the binaries. Here we present a Chandra X-ray absorption line study of 28 observations of 12 XRBs, with a focus on the Ne IX and Fe XVII lines. We report the first detections of these lines in a significant amount of observations. We do not find a significant dependence of the line equivalent width on the distance of the XRBs, but we do see a weak dependence on the source X-ray luminosity. We also find 2 out of 12 selected targets show strong temporal variation of the Ne IX absorbers. While the line ratio between the two ion species suggests a temperature consistent with the previous predictions of the ISM, comparing with two theoretical models of the ISM shows the observed column densities are significantly higher than predictions. On the other hand, photoionization by the XRBs provides a reasonably good fit to the data. Our findings suggest that a significant fraction of these X-ray absorbers may originate in the hot gas intrinsic to the XRBs, and that the ISM makes small, if not negligible, contribution. We briefly discuss the implications to the study of the Milky Way hot gas content.

  13. Flame structure of methane inverse diffusion flame

    Elbaz, Ayman M.; Roberts, William L.

    2014-01-01

    This paper presents high speed images of OH-PLIF at 10. kHz simultaneously with 2D PIV (particle image velocimetry) measurements collected along the entire length of an inverse diffusion flame with circumferentially arranged methane fuel jets. For a

  14. Detection of DNA damage in cells exposed to ionizing radiation by use of antisingle-stranded-DNA monoclonal antibody

    Schans, G.P. van der; Loon, A.A.W.M. van; Groenendijk, R.H.; Baan, R.A.

    1989-03-01

    An immunochemical method has been developed for quantitative detection of DNA damage in mammalian cells. The method is based on the binding of a monoclonal antibody to single-stranded DNA. The clone producing this antibody, D1B, was obtained as a by-product from fusion of mouse myeloma cells with spleen cells isolated from a mouse immunized with chemically modified DNA. The technique is based upon the determination of the percentage single-strandedness resulting from the partial umwinding of cellular DNA under alkaline conditions, a time-dependent process. Single-strand and double-strand DNA breaks, or lesions converted into such breaks in alkaline medium, form initiation points for the unwinding. The extent of unwinding under controlled conditions is a measure, therefore, of the amount of such sites. The method is rapid, does not require radioactive labelling of DNA or physical separation of single- from double-stranded molecules, is sufficiently sensitive to detect damage induced by 1 Gu of ionizing radiation and needs only small amounts of cells. The usefulness of the technique was demonstrated in a study on the induction of damage and its repair in unlabelled cultured Chinese hamster cells and in DNA-containing cells of human blood, both after exposure to 60 Co-γ-rays, and in white blood cells and bone marrow cells of X-irradiated mice. A dose-related degree of unwinding was observed and repair could be observed up to 60 min after irradiation. (author). 19 refs.; 3 figs.; 1 tab

  15. Ionizing radiation in environment

    Jandl, J.; Petr, I.

    1988-01-01

    The basic terms are explained such as the atom, radioactivity, nuclear reaction, interaction of ionizing radiation with matter, etc. The basic dosimetric variables and units and properties of radionuclides and ionizing radiation are given. Natural and artificial sources of ionizing radiation are discussed with regard to the environment and the propagation and migration of radionuclides is described in the environment to man. The impact is explained of ionizing radiation on the cell and the somatic and genetic effects of radiation on man are outlined. Attention is devoted to protection against ionizing radiation and to radiation limits, also to the detection, dosimetry and monitoring of ionizing radiation in the environment. (M.D.). 92 figs., 40 tabs. 74 refs

  16. Speciation analysis of arsenic by selective hydride generation- cryotrapping-atomic fluorescence spectrometry with flame-in-gas- shield atomizer: Achieving extremely low detection limits with inexpensive instrumentation

    Musil, Stanislav; Matoušek, Tomáš; Currier, J. M.; Stýblo, M.; Dědina, Jiří

    2014-01-01

    Roč. 86, č. 20 (2014), s. 10422-10428 ISSN 0003-2700 R&D Projects: GA ČR GA14-23532S; GA MŠk LH12040 Institutional support: RVO:68081715 Keywords : speciation analysis of arsenic * selective hydride generation * flame-in-gas-shield atomizer * cryotrapping-atomic fluorescence spectrometry Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 5.636, year: 2014

  17. Unsteady Flame Embedding

    El-Asrag, Hossam A.; Ghoniem, Ahmed F.

    2011-01-01

    simulation, one must introduce a dynamic subgrid model that accounts for the multiscale nature of the problem using information available on a resolvable grid. Here, we discuss a model that captures unsteady flow-flame interactions- including extinction, re

  18. Direct detection of fungal siderophores on bats with white-nose syndrome via fluorescence microscopy-guided ambient ionization mass spectrometry.

    Mascuch, Samantha J; Moree, Wilna J; Hsu, Cheng-Chih; Turner, Gregory G; Cheng, Tina L; Blehert, David S; Kilpatrick, A Marm; Frick, Winifred F; Meehan, Michael J; Dorrestein, Pieter C; Gerwick, Lena

    2015-01-01

    White-nose syndrome (WNS) caused by the pathogenic fungus Pseudogymnoascus destructans is decimating the populations of several hibernating North American bat species. Little is known about the molecular interplay between pathogen and host in this disease. Fluorescence microscopy ambient ionization mass spectrometry was used to generate metabolic profiles from the wings of both healthy and diseased bats of the genus Myotis. Fungal siderophores, molecules that scavenge iron from the environment, were detected on the wings of bats with WNS, but not on healthy bats. This work is among the first examples in which microbial molecules are directly detected from an infected host and highlights the ability of atmospheric ionization methodologies to provide direct molecular insight into infection.

  19. Direct detection of fungal siderophores on bats with white-nose syndrome via fluorescence microscopy-guided ambient ionization mass spectrometry

    Mascuch, Samantha J.; Moree, Wilna J.; Cheng-Chih Hsu, Cheng-Chih; Turner, Gregory G.; Cheng, Tina L.; Blehert, David S.; Kilpatrick, A. Marm; Frick, Winifred F.; Meehan, Michael J.; Dorrestein, Pieter C.; Gerwick, Lena

    2015-01-01

    White-nose syndrome (WNS) caused by the pathogenic fungus Pseudogymnoascus destructans is decimating the populations of several hibernating North American bat species. Little is known about the molecular interplay between pathogen and host in this disease. Fluorescence microscopy ambient ionization mass spectrometry was used to generate metabolic profiles from the wings of both healthy and diseased bats of the genus Myotis. Fungal siderophores, molecules that scavenge iron from the environment, were detected on the wings of bats with WNS, but not on healthy bats. This work is among the first examples in which microbial molecules are directly detected from an infected host and highlights the ability of atmospheric ionization methodologies to provide direct molecular insight into infection.

  20. Direct detection of fungal siderophores on bats with white-nose syndrome via fluorescence microscopy-guided ambient ionization mass spectrometry.

    Samantha J Mascuch

    Full Text Available White-nose syndrome (WNS caused by the pathogenic fungus Pseudogymnoascus destructans is decimating the populations of several hibernating North American bat species. Little is known about the molecular interplay between pathogen and host in this disease. Fluorescence microscopy ambient ionization mass spectrometry was used to generate metabolic profiles from the wings of both healthy and diseased bats of the genus Myotis. Fungal siderophores, molecules that scavenge iron from the environment, were detected on the wings of bats with WNS, but not on healthy bats. This work is among the first examples in which microbial molecules are directly detected from an infected host and highlights the ability of atmospheric ionization methodologies to provide direct molecular insight into infection.

  1. First Limit on the Direct Detection of Lightly Ionizing Particles for Electric Charge as Low as e /1000 with the Majorana Demonstrator

    Alvis, S. I.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Barton, C. J.; Bertrand, F. E.; Brudanin, V.; Busch, M.; Buuck, M.; Caldwell, T. S.; Chan, Y.-D.; Christofferson, C. D.; Chu, P.-H.; Cuesta, C.; Detwiler, J. A.; Dunagan, C.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Gilliss, T.; Giovanetti, G. K.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Haufe, C. R.; Hehn, L.; Henning, R.; Hoppe, E. W.; Howe, M. A.; Konovalov, S. I.; Kouzes, R. T.; Lopez, A. M.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Myslik, J.; O'Shaughnessy, C.; Othman, G.; Pettus, W.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Reine, A. L.; Rielage, K.; Robertson, R. G. H.; Ruof, N. W.; Shanks, B.; Shirchenko, M.; Suriano, A. M.; Tedeschi, D.; Varner, R. L.; Vasilyev, S.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C.-H.; Yumatov, V.; Zhitnikov, I.; Zhu, B. X.; Majorana Collaboration

    2018-05-01

    The Majorana Demonstrator is an ultralow-background experiment searching for neutrinoless double-beta decay in 76Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. Free, relativistic, lightly ionizing particles with an electrical charge less than e are forbidden by the standard model but predicted by some of its extensions. If such particles exist, they might be detected in the Majorana Demonstrator by searching for multiple-detector events with individual-detector energy depositions down to 1 keV. This search is background-free, and no candidate events have been found in 285 days of data taking. New direct-detection limits are set for the flux of lightly ionizing particles for charges as low as e /1000 .

  2. The ionizing treatment of food

    1998-01-01

    This book of proceedings contains the talks given by the members of the Society of chemical experts of France (SECF) and by various specialists of the ionizing treatment during the scientific days of September 25-26, 1997. The aim of this meeting was to reconsider the effects of ionization from a scientific point of view and apart from the polemics generated by this domain. The following topics were discussed successively: source and characterization of a ionizing treatment, biological effects of ionization on food and the expected consequences, the ionizing treatment and the reduction of the vitamin C content of fruits and vegetables, is it safe to eat irradiated food?, the organoleptic modifications of food after ionization, quality assurance of dosimetry measurements in an industrial installation of food ionization, the French and European regulations in food ionization, the detection of irradiated foodstuffs, processed food and complex lipid matrices, sterilization of dishes for immuno-depressed patients using ionization. (J.S.)

  3. Degradation of chlorpyrifos by ionizing radiation

    Mori, M.N.; Oikawa, H.; Sampa, M.H.O.; Duarte, C.L.

    2006-01-01

    Chlorpyrifos is an organophosphate pesticide commercialized since 1965 and it is now one of the top five commercial insecticides. It is registered for use in over 900 different pesticide formulations in the world. Chlorpyrifos poisoning usually affects many organs of the body, such as the central and peripheral nervous system, eyes, respiratory system, and the digestive tract. Depending on the pesticide formulation and type of application, chlorpyrifos residues may be detectable in water, soil, and on the surfaces from months to years. This paper presents preliminary studies of the removal of chlorpyrifos by exposition to ionizing radiation, to be applied in pesticide container decontamination. Samples containing various concentrations of chlorpyrifos in acetonitrile were irradiated with absorbed doses varying from 5 to 50 kGy, using a 60 Co gamma-source with 5,000 Ci activity (Gamma cell type). The chemical analysis of the chlorpyrifos and the by-products resulted from the radiolytic degradation were made using a gas chromatography associated to mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GCFID). (author)

  4. Organophosphorous flame retardants in biota from Svalbard, Norway

    Hallanger, I.G.; Sagerup, K.; Evenset, A.; Kovacs, K.M.; Leonards, P.E.G.; Fuglei, E.; Routti, H.; Aars, J.; Strom, H.; Lydersen, C.; Gabrielsen, G. W.

    2015-01-01

    Eight arctic species, including fish, birds and mammals, from diverse habitats (marine and terrestrial) within the Svalbard Archipelago, Norway, were screened for 14 organophosphorus flame retardant (PFR) compounds. Ten PFRs were detected: tris(2-chloroethyl)phosphate (TCEP),

  5. Ion measurements in premixed methane-oxygen flames

    Alquaity, Awad

    2014-07-25

    Ions are formed as a result of chemi-ionization processes in combustion systems. Recently, there has been an increasing interest in understanding flame ion chemistry due to the possible application of external electric fields to reduce emissions and improve combustion efficiency by active control of combustion process. In order to predict the effect of external electric fields on combustion plasma, it is critical to gain a good understanding of the flame ion chemistry. In this work, a Molecular Beam Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry on equivalence ratio of premixed flames. The relative ion concentration profiles are compared qualitatively with previous methane-oxygen studies and show good agreement. The relative ion concentration data obtained in the present study can be used to validate and improve ion chemistry models for methane-oxygen flames.

  6. Strained flamelets for turbulent premixed flames II: Laboratory flame results

    Kolla, H.; Swaminathan, N. [Department of Engineering, Cambridge University, Cambridge CB2 1PZ (United Kingdom)

    2010-07-15

    The predictive ability of strained flamelets model for turbulent premixed flames is assessed using Reynolds Averaged Navier Stokes (RANS) calculations of laboratory flames covering a wide range of conditions. Reactant-to-product (RtP) opposed flow laminar flames parametrised using the scalar dissipation rate of reaction progress variable are used as strained flamelets. Two turbulent flames: a rod stabilised V-flame studied by Robin et al. [Combust. Flame 153 (2008) 288-315] and a set of pilot stabilised Bunsen flames studied by Chen et al. [Combust. Flame 107 (1996) 223-244] are calculated using a single set of model parameters. The V-flame corresponds to the corrugated flamelets regime. The strained flamelet model and an unstrained flamelet model yield similar predictions which are in good agreement with experimental measurements for this flame. On the other hand, for the Bunsen flames which are in the thin reaction zones regime, the unstrained flamelet model predicts a smaller flame brush compared to experiment. The predictions of the strained flamelets model allowing for fluid-dynamics stretch induced attenuation of the chemical reaction are in good agreement with the experimental data. This model predictions of major and minor species are also in good agreement with experimental data. The results demonstrate that the strained flamelets model using the scalar dissipation rate can be used across the combustion regimes. (author)

  7. Study on the detection of three-dimensional soot temperature and volume fraction fields of a laminar flame by multispectral imaging system

    Ni, Mingjiang; Zhang, Haidan; Wang, Fei; Xie, Zhengchao; Huang, Qunxing; Yan, Jianhua; Cen, Kefa

    2016-01-01

    Highlights: • Multispectral flame images were used to reconstruct the soot temperature and volume fraction. • The proposed multi-wavelength method and the original two-color method were compared. • The effect of signal to noise ratio (SNR) was discussed. • The best number of selected wavelengths was determined to be 6–11. - Abstract: Charge-coupled device (CCD) cameras with liquid crystal tunable filters (LCTF) were introduced to capture the multispectral flame images for obtaining the line-of-sight radiation intensities. A least square QR decomposition method was applied to solve the reconstruction matrix equation and obtain the multi-wavelength local emission distributions from which temperature and volume fraction profiles can be retrieved. Compared with the original two-color method, the use of a wide range of spectral data was proved to be capable of reducing the reconstruction error. Reconstruction results of the two methods with different signal to noise ratio (SNR) were discussed. The effect of selected wavelength number is analyzed and the best number is determined to be in the range of 6–11. The proposed multispectral imaging system was verified to be feasible for the reconstruction of temperature and soot volume fraction distributions according to the experimental measurement results.

  8. High-performance ion mobility spectrometry with direct electrospray ionization (ESI-HPIMS) for the detection of additives and contaminants in food

    Midey, Anthony J., E-mail: anthony.midey@excellims.com; Camacho, Amanda; Sampathkumaran, Jayanthi; Krueger, Clinton A.; Osgood, Mark A.; Wu, Ching

    2013-12-04

    Graphical abstract: -- Highlights: •A new ESI source was built for direct ionization from syringe. •Phthalates, food dyes, and sweeteners detected with high-performance IMS. •Phthalates directly detected in cola, soy bubble tea matrices with simple treatment. -- Abstract: High-performance ion mobility spectrometry (HPIMS) with an electrospray ionization (ESI) source detected a series of food contaminants and additive compounds identified as critical to monitoring the safety of food samples. These compounds included twelve phthalate plasticizers, legal and illegal food and cosmetic dyes, and artificial sweeteners that were all denoted as detection priorities. HPIMS separated and detected the range of compounds with a resolving power better than 60 in both positive and negative ion modes, comparable to the commonly used high-performance liquid chromatography (HPLC) methods, but with most acquisition times under a minute. The reduced mobilities, K{sub 0}, have been determined, as have the linear response ranges for ESI-HPIMS, which are 1.5–2 orders of magnitude for concentrations down to sub-ng μL{sup −1} levels. At least one unique mobility peak was seen for two subsets of the phthalates grouped by the country where they were banned. Furthermore, ESI-HPIMS successfully detected low nanogram levels of a phthalate at up to 30 times lower concentration than international detection levels in both a cola matrix and a soy-based bubble tea beverage using only a simplified sample treatment. A newly developed direct ESI source (Directspray) was combined with HPIMS to detect food-grade dyes and industrial dye adulterants, as well as the sweeteners sodium saccharin and sodium cyclamate, with the same good performance as with the phthalates. However, the Directspray method eliminated sources of carryover and decreased the time between sample runs. Limits-of-detection (LOD) for the analyte standards were estimated to be sub-ng μL{sup −1} levels without extensive

  9. High-performance ion mobility spectrometry with direct electrospray ionization (ESI-HPIMS) for the detection of additives and contaminants in food

    Midey, Anthony J.; Camacho, Amanda; Sampathkumaran, Jayanthi; Krueger, Clinton A.; Osgood, Mark A.; Wu, Ching

    2013-01-01

    Graphical abstract: -- Highlights: •A new ESI source was built for direct ionization from syringe. •Phthalates, food dyes, and sweeteners detected with high-performance IMS. •Phthalates directly detected in cola, soy bubble tea matrices with simple treatment. -- Abstract: High-performance ion mobility spectrometry (HPIMS) with an electrospray ionization (ESI) source detected a series of food contaminants and additive compounds identified as critical to monitoring the safety of food samples. These compounds included twelve phthalate plasticizers, legal and illegal food and cosmetic dyes, and artificial sweeteners that were all denoted as detection priorities. HPIMS separated and detected the range of compounds with a resolving power better than 60 in both positive and negative ion modes, comparable to the commonly used high-performance liquid chromatography (HPLC) methods, but with most acquisition times under a minute. The reduced mobilities, K 0 , have been determined, as have the linear response ranges for ESI-HPIMS, which are 1.5–2 orders of magnitude for concentrations down to sub-ng μL −1 levels. At least one unique mobility peak was seen for two subsets of the phthalates grouped by the country where they were banned. Furthermore, ESI-HPIMS successfully detected low nanogram levels of a phthalate at up to 30 times lower concentration than international detection levels in both a cola matrix and a soy-based bubble tea beverage using only a simplified sample treatment. A newly developed direct ESI source (Directspray) was combined with HPIMS to detect food-grade dyes and industrial dye adulterants, as well as the sweeteners sodium saccharin and sodium cyclamate, with the same good performance as with the phthalates. However, the Directspray method eliminated sources of carryover and decreased the time between sample runs. Limits-of-detection (LOD) for the analyte standards were estimated to be sub-ng μL −1 levels without extensive sample handling

  10. Method for detecting and distinguishing between specific types of environmental radiation using a high pressure ionization chamber with pulse-mode readout

    Degtiarenko, Pavel V.

    2017-12-19

    An environmental radiation detector for detecting and distinguishing between all types of environmental radiation, including photons, charged particles, and neutrons. A large volume high pressure ionization chamber (HPIC) includes BF.sub.3 gas at a specific concentration to render the radiation detector sensitive to the reactions of neutron capture in Boron-10 isotope. A pulse-mode readout is connected to the ionization chamber capable of measuring both the height and the width of the pulse. The heavy charged products of the neutron capture reaction deposit significant characteristic energy of the reaction in the immediate vicinity of the reaction in the gas, producing a signal with a pulse height proportional to the reaction energy, and a narrow pulse width corresponding to the essentially pointlike energy deposition in the gas. Readout of the pulse height and the pulse width parameters of the signals enables distinguishing between the different types of environmental radiation, such as gamma (x-rays), cosmic muons, and neutrons.

  11. The Simulation of Energy Distribution of Electrons Detected by Segmental Ionization Detector in High Pressure Conditions of ESEM

    Neděla, Vilém; Konvalina, Ivo; Oral, Martin; Hudec, Jiří

    2015-01-01

    Roč. 21, S4 (2015), s. 264-269 ISSN 1431-9276 R&D Projects: GA ČR(CZ) GA14-22777S Institutional support: RVO:68081731 Keywords : electron-gas interactions * Monte Carlo simulation * signal amplification * segmented ionization detector Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

  12. Detection systems for high energy particle producing gaseous ionization; Sistemas de deteccion de particulas de alta energia mediante ionizacion gaseosa

    Martinez, L; Duran, I

    1985-07-01

    This report contains a review on the most used detectors based on the collection of the ionization produced by high energy particles: proportional counters, multiwire proportional chambers, Geiger-Muller counters and drift chambers. In six sections, the fundamental principles, the field configuration and useful gas mixtures, are discussed, most relevant devices are reported along 90 pages with 98 references. (Author) 98 refs.

  13. Flaming on YouTube

    Moor, Peter J.; Heuvelman, A.; Verleur, R.

    2010-01-01

    In this explorative study, flaming on YouTube was studied using surveys of YouTube users. Flaming is defined as displaying hostility by insulting, swearing or using otherwise offensive language. Three general conclusions were drawn. First, although many users said that they themselves do not flame,

  14. High-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry and gas chromatography-flame ionization detection chracterization of delta 5-polyenoic fatty acids in triacylglycerols from conifer seed oils

    Lísa, M.; Holčapek, M.; Řezanka, Tomáš; Kabátová, N.

    2007-01-01

    Roč. 1146, - (2007), s. 67-77 ISSN 0021-9673 R&D Projects: GA ČR GA203/06/0219 Grant - others:GA ČR(CZ) GA203/05/2106 Program:GA Institutional research plan: CEZ:AV0Z50200510 Keywords : conifer seed oil * triacylglycerol * triglyceride Subject RIV: EE - Microbiology, Virology Impact factor: 3.641, year: 2007

  15. Ionizing and non-ionizing radiations

    1994-01-01

    The monograph is a small manual to get a knowledge of ionizing and non-ionizing radiations. The main chapters are: - Electromagnetic radiations - Ionizing and non-ionizing radiations - Non-ionizing electromagnetic radiations - Ionizing electromagnetic radiation - Other ionizing radiations - Ionizing radiation effects - The Nuclear Safety Conseil

  16. COMPLETE IONIZATION OF THE NEUTRAL GAS: WHY THERE ARE SO FEW DETECTIONS OF 21 cm HYDROGEN IN HIGH-REDSHIFT RADIO GALAXIES AND QUASARS

    Curran, S. J. [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Whiting, M. T., E-mail: sjc@physics.usyd.edu.au [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia)

    2012-11-10

    From the first published z {approx}> 3 survey of 21 cm absorption within the hosts of radio galaxies and quasars, Curran et al. found an apparent dearth of cool neutral gas at high redshift. From a detailed analysis of the photometry, each object is found to have a {lambda} = 1216 A continuum luminosity in excess of L {sub 1216} {approx} 10{sup 23} W Hz{sup -1}, a critical value above which 21 cm has never been detected at any redshift. At these wavelengths, and below, hydrogen is excited above the ground state so that it cannot absorb in 21 cm. In order to apply the equation of photoionization equilibrium, we demonstrate that this critical value also applies to the ionizing ({lambda} {<=} 912 A) radiation. We use this to show, for a variety of gas density distributions, that upon placing a quasar within a galaxy of gas, there is always an ultraviolet luminosity above which all of the large-scale atomic gas is ionized. While in this state, the hydrogen cannot be detected or engage in star formation. Applying the mean ionizing photon rate of all of the sources searched, we find, using canonical values for the gas density and recombination rate coefficient, that the observed critical luminosity gives a scale length (3 kpc) similar that of the neutral hydrogen (H I) in the Milky Way, a large spiral galaxy. Thus, this simple yet physically motivated model can explain the critical luminosity (L {sub 912} {approx} L {sub 1216} {approx} 10{sup 23} W Hz{sup -1}), above which neutral gas is not detected. This indicates that the non-detection of 21 cm absorption is not due to the sensitivity limits of current radio telescopes, but rather that the lines of sight to the quasars, and probably the bulk of the host galaxies, are devoid of neutral gas.

  17. Ionization particle detector

    Ried, L.

    1982-01-01

    A new device is claimed for detecting particles in a gas. The invention comprises a low cost, easy to assemble, and highly accurate particle detector using a single ionization chamber to contain a reference region and a sensing region. The chamber is designed with the radioactive source near one electrode and the second electrode located at a distance less than the distance of maximum ionization from the radioactive source

  18. Stratified turbulent Bunsen flames : flame surface analysis and flame surface density modelling

    Ramaekers, W.J.S.; Oijen, van J.A.; Goey, de L.P.H.

    2012-01-01

    In this paper it is investigated whether the Flame Surface Density (FSD) model, developed for turbulent premixed combustion, is also applicable to stratified flames. Direct Numerical Simulations (DNS) of turbulent stratified Bunsen flames have been carried out, using the Flamelet Generated Manifold

  19. Supplementary Material for: Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    Alquaity, Awad B. S.

    2017-01-01

    Cations and anions are formed as a result of chemi-ionization processes in combustion systems. Electric fields can be applied to reduce emissions and improve combustion efficiency by active control of the combustion process. Detailed flame ion chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon burner-stabilized atmospheric flames. Lean and stoichiometric flames are considered to assess the dependence of ion chemistry on flame stoichiometry. Relative ion concentration profiles are compared with numerical simulations using various temperature profiles, and good qualitative agreement was observed for the stoichiometric flame. However, for the lean flame, numerical simulations misrepresent the spatial distribution of selected ions greatly. Three modifications are suggested to enhance the ion mechanism and improve the agreement between experiments and simulations. The first two modifications comprise the addition of anion detachment reactions to increase anion recombination at low temperatures. The third modification involves restoring a detachment reaction to its original irreversible form. To our knowledge, this work presents the first detailed measurements of cations and flame temperature in canonical methane–oxygen-argon atmospheric flat flames. The positive ion profiles reported here may be useful to validate and improve ion chemistry models for methane-oxygen flames.

  20. Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames

    Alquaity, Awad

    2016-08-22

    Cations and anions are formed as a result of chemi-ionization processes in combustion systems. Electric fields can be applied to reduce emissions and improve combustion efficiency by active control of the combustion process. Detailed flame ion chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon burner-stabilized atmospheric flames. Lean and stoichiometric flames are considered to assess the dependence of ion chemistry on flame stoichiometry. Relative ion concentration profiles are compared with numerical simulations using various temperature profiles, and good qualitative agreement was observed for the stoichiometric flame. However, for the lean flame, numerical simulations misrepresent the spatial distribution of selected ions greatly. Three modifications are suggested to enhance the ion mechanism and improve the agreement between experiments and simulations. The first two modifications comprise the addition of anion detachment reactions to increase anion recombination at low temperatures. The third modification involves restoring a detachment reaction to its original irreversible form. To our knowledge, this work presents the first detailed measurements of cations and flame temperature in canonical methane–oxygen-argon atmospheric flat flames. The positive ion profiles reported here may be useful to validate and improve ion chemistry models for methane-oxygen flames.

  1. Direct Flame Impingement

    None

    2005-09-01

    During the DFI process, high velocity flame jets impinge upon the material being heated, creating a high heat transfer rate. As a result, refractory walls and exhaust gases are cooler, which increases thermal efficiency and lowers NOx emissions. Because the jet nozzles are located a few inches from the load, furnace size can be reduced significantly.

  2. Inkjet-printed gold nanoparticle surfaces for the detection of low molecular weight biomolecules by laser desorption/ionization mass spectrometry.

    Marsico, Alyssa L M; Creran, Brian; Duncan, Bradley; Elci, S Gokhan; Jiang, Ying; Onasch, Timothy B; Wormhoudt, Joda; Rotello, Vincent M; Vachet, Richard W

    2015-11-01

    Effective detection of low molecular weight compounds in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is often hindered by matrix interferences in the low m/z region of the mass spectrum. Here, we show that monolayer-protected gold nanoparticles (AuNPs) can serve as alternate matrices for the very sensitive detection of low molecular weight compounds such as amino acids. Amino acids can be detected at low fmol levels with minimal interferences by properly choosing the AuNP deposition method, density, size, and monolayer surface chemistry. By inkjet-printing AuNPs at various densities, we find that AuNP clusters are essential for obtaining the greatest sensitivity. Graphical Abstract ᅟ.

  3. Flame visualization in power stations

    Hulshof, H J.M.; Thus, A W; Verhage, A J.L. [KEMA - Fossil Power Plants, Arnhem (Netherlands)

    1993-01-01

    The shapes and temperature of flames in power stations, fired with powder coal and gas, have been measured optically. Spectral information in the visible and near infrared is used. Coal flames are visualized in the blue part of the spectrum, natural gas flames are viewed in the light of CH-emission. Temperatures of flames are derived from the best fit of the Planck-curve to the thermal radiation spectrum of coal and char, or to that of soot in the case of gas flames. A measuring method for the velocity distribution inside a gas flame is presented, employing pulsed alkali salt injection. It has been tested on a 100 kW natural gas flame. 3 refs., 9 figs.

  4. Sensitive and comprehensive detection of chemical warfare agents in air by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow introduction.

    Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Yamashiro, Shigeharu; Sano, Yasuhiro; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Sekiguchi, Hiroyuki; Iura, Kazumitsu; Nagashima, Hisayuki; Nagoya, Tomoki; Tsuge, Kouichiro; Ohsawa, Isaac; Okumura, Akihiko; Takada, Yasuaki; Ezawa, Naoya; Watanabe, Susumu; Hashimoto, Hiroaki

    2014-05-06

    A highly sensitive and specific real-time field-deployable detection technology, based on counterflow air introduction atmospheric pressure chemical ionization, has been developed for a wide range of chemical warfare agents (CWAs) comprising gaseous (two blood agents, three choking agents), volatile (six nerve gases and one precursor agent, five blister agents), and nonvolatile (three lachrymators, three vomiting agents) agents in air. The approach can afford effective chemical ionization, in both positive and negative ion modes, for ion trap multiple-stage mass spectrometry (MS(n)). The volatile and nonvolatile CWAs tested provided characteristic ions, which were fragmented into MS(3) product ions in positive and negative ion modes. Portions of the fragment ions were assigned by laboratory hybrid mass spectrometry (MS) composed of linear ion trap and high-resolution mass spectrometers. Gaseous agents were detected by MS or MS(2) in negative ion mode. The limits of detection for a 1 s measurement were typically at or below the microgram per cubic meter level except for chloropicrin (submilligram per cubic meter). Matrix effects by gasoline vapor resulted in minimal false-positive signals for all the CWAs and some signal suppression in the case of mustard gas. The moisture level did influence the measurement of the CWAs.

  5. Comparative study of fourteen alkaloids from Uncaria rhynchophylla hooks and leaves using HPLC-diode array detection-atmospheric pressure chemical ionization/MS method.

    Qu, Jialin; Gong, Tianxing; Ma, Bin; Zhang, Lin; Kano, Yoshihiro; Yuan, Dan

    2012-01-01

    The purpose of the study is to compare alkaloid profile of Uncaria rhynchophylla hooks and leaves. Ten oxindole alkaloids and four glycosidic indole alkaloids were identified using HPLC-diode array detection (DAD) or LC-atmospheric pressure chemical ionization (APCI)-MS method, and a HPLC-UV method for simultaneous quantification of major alkaloids was validated. The hooks are characterized by high levels of four oxindole alkaloids rhynchophylline (R), isorhynchophylline (IR), corynoxeine (C) and isocorynoxeine (IC), while the leaves contained high level of two glycosidic indole alkaloids vincoside lactam (VL) and strictosidine (S). The presented methods have proven its usefulness in chemical characterization of U. rhynchophylla hooks and leaves.

  6. High-resolution ion pulse ionization chamber with air filling for the {sup 222}Rn decays detection

    Gavrilyuk, Yu.M.; Gangapshev, A.M.; Gezhaev, A.M.; Etezov, R.A.; Kazalov, V.V.; Kuzminov, V.V. [Baksan Neutrino Observatory,Institute for Nuclear Research RAS, 361609 Neutrino (Russian Federation); Panasenko, S.I. [V.N.Karazin Kharkiv National University, 61022 Kharkiv (Ukraine); Ratkevich, S.S., E-mail: ssratk@gmail.com [V.N.Karazin Kharkiv National University, 61022 Kharkiv (Ukraine); Tekueva, D.A.; Yakimenko, S.P. [Baksan Neutrino Observatory,Institute for Nuclear Research RAS, 361609 Neutrino (Russian Federation)

    2015-11-21

    The construction and characteristics of the cylindrical ion pulse ionization chamber (CIPIC) with a working volume of 3.2 L are described. The chamber is intended to register α-particles from the {sup 222}Rn and its daughter's decays in the filled air sample. The detector is less sensitive to electromagnetic pick-ups and mechanical noises. The digital pulse processing method is proposed to improve the energy resolution of the ion pulse ionization chamber. An energy resolution of 1.6% has been achieved for the 5.49 MeV α-line. The dependence of the energy resolution on high voltage and working media pressure has been investigated and the results are presented. - Highlights: • The construction and characteristics of the cylindrical ion pulse ionization chamber (CIPIC) with a working volume of 3.2 L are described. • The chamber is intended to register alpha-particles from {sup 222}Rn and its daughter's decays in the filled air sample. • The detector is less sensitive to electromagnetic pick-ups and mechanical noises. • An energy resolution of 1.6% has been achieved for the 5.49 MeV alpha-line. The dependence of the energy resolution on high voltage and working media pressure have been investigated and the results are presented.

  7. Ion composition of a propane-butane-air flame at low pressure

    Fialkov, A.B.; Fialkov, B.S.

    1985-06-01

    Ion types and distributions are determined experimentally for propane-butane-air flames with excess oxidizer coefficients of 0.7-1.2 in the pressure range 4-65 KPa. It is shown that nonthermal ionization occurs not only in the known chemiionization zone (which practically coincides with the chemiluminescence zone) but also in the mixture preparation zone. A general mechanism for ion formation in the flame is proposed. 42 references.

  8. Ambient ionization mass spectrometry: A tutorial

    Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Shiea, Jentaie, E-mail: jetea@fac.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Cancer Center, Kaohsiung Medical University, Kaohsiung, Taiwan (China)

    2011-09-19

    Highlights: {yields} Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. {yields} We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. {yields} The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

  9. Ambient ionization mass spectrometry: A tutorial

    Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu; Shiea, Jentaie

    2011-01-01

    Highlights: → Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. → We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. → The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

  10. Recent contributions of flame-sampling molecular-beam mass spectrometry to a fundamental understanding of combustion chemistry

    Hansen, Nils [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551 (United States); Cool, Terrill A. [School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853 (United States); Westmoreland, Phillip R. [Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003 (United States); Kohse-Hoeinghaus, Katharina [Department of Chemistry, Bielefeld University, D-33615 Bielefeld (Germany)

    2009-04-15

    Flame-sampling molecular-beam mass spectrometry of premixed, laminar, low-pressure flat flames has been demonstrated to be an efficient tool to study combustion chemistry. In this technique, flame gases are sampled through a small opening in a quartz probe, and after formation of a molecular beam, all flame species are separated using mass spectrometry. The present review focuses on critical aspects of the experimental approach including probe sampling effects, different ionization processes, and mass separation procedures. The capability for isomer-resolved flame species measurements, achievable by employing tunable vacuum-ultraviolet radiation for single-photon ionization, has greatly benefited flame-sampling molecular-beam mass spectrometry. This review also offers an overview of recent combustion chemistry studies of flames fueled by hydrocarbons and oxygenates. The identity of a variety of intermediates in hydrocarbon flames, including resonantly stabilized radicals and closed-shell intermediates, is described, thus establishing a more detailed understanding of the fundamentals of molecular-weight growth processes. Finally, molecular-beam mass-spectrometric studies of reaction paths in flames of alcohols, ethers, and esters, which have been performed to support the development and validation of kinetic models for bio-derived alternative fuels, are reviewed. (author)

  11. Gaschromatographic proof of nitrous oxide concentrations in air by means of radiation ionization detectors

    Popp, P.; Schoentube, E.; Oppermann, G.

    1985-01-01

    For the analysis of nitrous oxide concentrations at workplaces in operating theatres, gaschromatography is a particularly suitable method if it is possible to measure nitrous oxide concentrations in the ppm to ppb region. For this, most frequently used gaschromatographic detectors (flame ionization detector, thermal conductivity detector) are unsuitable, whereas radiation ionization detectors can be used successfully. The investigations using detectors designed at the Central Institute for Isotopes and Radiation Research of the GDR Academy of Sciences showed that a high-temperature electron-capture detector (ECD), working at a temperatur of 250 0 C, enables the determination of traces of nitrous oxide with a detection limit of about 200 ppb, while the helium detector has a limit of 50 ppb of nitrous oxide in room air. Since the helium detector requires extremely pure carrier gas, the high-temperature ECD appears more suitable for analyzing nitrous oxide. (author)

  12. Ionizing radiations

    Anon.

    1999-01-01

    This is an update about the radiological monitoring in base nuclear installations. A departmental order of the 23. march 1999 (J.O.28. april, p.6309) determines the enabling rules by the Office of Protection against Ionizing Radiations of person having at one's disposal the results with names of individual exposure of workers put through ionizing radiations. (N.C.)

  13. Tracing organophosphorus and brominated flame retardants and plasticizers in an estuarine food web

    Brandsma, S.H.; Leonards, P.E.G.; Leslie, H.A.; de Boer, J.

    2015-01-01

    Nine organophosphorus flame retardants (PFRs) were detected in a pelagic and benthic food web of the Western Scheldt estuary, The Netherlands. Concentrations of several PFRs were an order of magnitude higher than those of the brominated flame retardants (BFRs). However, the detection frequency of

  14. Detection and Repair of Ionizing Radiation-Induced DNA Double Strand Breaks: New Developments in Nonhomologous End Joining

    Wang, Chen; Lees-Miller, Susan P.

    2013-01-01

    DNA damage can occur as a result of endogenous metabolic reactions and replication stress or from exogenous sources such as radiation therapy and chemotherapy. DNA double strand breaks are the most cytotoxic form of DNA damage, and defects in their repair can result in genome instability, a hallmark of cancer. The major pathway for the repair of ionizing radiation-induced DSBs in human cells is nonhomologous end joining. Here we review recent advances on the mechanism of nonhomologous end joining, as well as new findings on its component proteins and regulation

  15. Detection and Repair of Ionizing Radiation-Induced DNA Double Strand Breaks: New Developments in Nonhomologous End Joining

    Wang, Chen [Departments of Biochemistry and Molecular Biology and Oncology, and Southern Alberta Cancer Research Institute, University of Calgary, Calgary (Canada); Lees-Miller, Susan P., E-mail: leesmill@ucalgary.ca [Departments of Biochemistry and Molecular Biology and Oncology, and Southern Alberta Cancer Research Institute, University of Calgary, Calgary (Canada)

    2013-07-01

    DNA damage can occur as a result of endogenous metabolic reactions and replication stress or from exogenous sources such as radiation therapy and chemotherapy. DNA double strand breaks are the most cytotoxic form of DNA damage, and defects in their repair can result in genome instability, a hallmark of cancer. The major pathway for the repair of ionizing radiation-induced DSBs in human cells is nonhomologous end joining. Here we review recent advances on the mechanism of nonhomologous end joining, as well as new findings on its component proteins and regulation.

  16. Chemotaxonomic markers of organic, natural, and genetically modified soybeans detected by direct infusion electrospray ionization mass spectrometry

    Santos, L.S.; Catharino, R.R.; Eberlin, M.N.; Tsai, S.M.

    2006-01-01

    The crude methanolic extracts of a single bean from samples of organic, natural or genetically modified (GM) soybeans [Glycine max. (Merrill) L.] were analyzed by direct infusion electrospray ionization mass spectrometry (ESI-MS). These extracts, containing the most polar natural products of soybeans (free aglycones, monoglucosides, diglucosides and esters including isoflavones and flavones) provide characteristic fingerprinting mass spectra owing to different proportions or sets of components. Spectra distinctiveness is confirmed by chemometric multivariate analysis of the ESIMS data, which place the three-types of beans into well-defined groups. When ESI-MS is applied, these polar components constitute therefore unique chemotaxonomic markers able to provide fast soybean typification. (author)

  17. Chlorine activation by N2O5: simultaneous, in situ detection of ClNO2 and N2O5 by chemical ionization mass spectrometry

    J. A. Thornton

    2009-05-01

    Full Text Available We report a new method for the simultaneous in situ detection of nitryl chloride (ClNO2 and dinitrogen pentoxide (N2O5 using chemical ionization mass spectrometry (CIMS. The technique relies on the formation and detection of iodide ion-molecule clusters, I(ClNO2− and I(N2O5−. The novel N2O5 detection scheme is direct. It does not suffer from high and variable chemical interferences, which are associated with the typical method of nitrate anion detection. We address the role of water vapor, CDC electric field strength, and instrument zero determinations, which influence the overall sensitivity and detection limit of this method. For both species, the method demonstrates high sensitivity (>1 Hz/pptv, precision (~10% for 100 pptv in 1 s, and accuracy (~20%, the latter ultimately determined by the nitrogen dioxide (NO2 cylinder calibration standard and characterization of inlet effects. For the typically low background signals (S/N ratios of 2 for 1 pptv in 60 s averages, but uncertainty associated with the instrumental zero currently leads to an ultimate detection limit of ~5 pptv for both species. We validate our approach for the simultaneous in situ measurement of ClNO2 and N2O5 while on board the R/V Knorr as part of the ICEALOT 2008 Field Campaign.

  18. Antimony: a flame fighter

    Wintzer, Niki E.; Guberman, David E.

    2015-01-01

    Antimony is a brittle, silvery-white semimetal that conducts heat poorly. The chemical compound antimony trioxide (Sb2O3) is widely used in plastics, rubbers, paints, and textiles, including industrial safety suits and some children’s clothing, to make them resistant to the spread of flames. Also, sodium antimonate (NaSbO3) is used during manufacturing of high-quality glass, which is found in cellular phones.

  19. A method to detect metal–drug complexes and their interactions with pathogenic bacteria via graphene nanosheet assist laser desorption/ionization mass spectrometry and biosensors

    Abdelhamid, Hani Nasser; Wu, Hui-Fen

    2012-01-01

    Highlights: ► Probe transition metals-complexes based on noncovalent functionalized graphene for MALDI-MS. ► Study interaction of transition metals complexes with pathogenic bacteria. ► Propose a new biosensor for two pathogenic bacteria. - Abstract: A new method was proposed to probe the interactions between transition metals of Fe(II), Fe(III), Cu(II) with a non steroidal anti-inflammatory drug (NSAID), flufenamic acid (FF) using graphene as a matrix for Graphene assisted laser desorption ionization mass spectrometry (GALDI-MS). Metal–drug complexation was confirmed via UV absorption spectroscopy, fluorescence spectroscopy, pH meter, and change in solution conductivity. The optimal molar ratios for these complexation interactions are stoichiometry 1:2 in both Cu(II) and Fe(II) complexes, and 1:3 in Fe(III) complexes at physiological pH (7.4). Metal complexation of the drug could enhance fluorescence for 20 fold which is due to the charge transfer reaction or increase rigidity of the drug. The main interaction between graphene and flufenamic acid is the Π–Π interaction which allows us to probe the metal–drug complexation. The GALDI-MS could sensitively detect the drug at m/z 281.0 Da (protonated molecule) with detection limit 2.5 pmol (1.0 μM) and complexation at m/z 661.0, 654.0 and 933.0 Da corresponding to [Cu(II)(FF) 2 (H 2 O) 2 + H] + , [Fe(II)(FF) 2 (H 2 O) 2 + H] + and [Fe(III) (FF) 3 (H 2 O) 2 + H] + , respectively (with limit of detection (LOD) 2.0 pmol (10.0 μM). Matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) spectra show change in the protein profile of intact pathogenic bacteria (Pseudomonas aeroginosa, Staphylococcus aureus). The change in the ionization ability (mainly proton affinity) of pathogenic bacteria may be due to the interactions between the bacteria with the drug (or its complexes). Shielding carboxylic group by metals and increase the hydrophilicity could enhance the biocompatibility of complexes

  20. A method to detect metal-drug complexes and their interactions with pathogenic bacteria via graphene nanosheet assist laser desorption/ionization mass spectrometry and biosensors

    Abdelhamid, Hani Nasser [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan (China); Wu, Hui-Fen, E-mail: hwu@faculty.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan (China); School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, 800, Taiwan (China); Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan (China); Doctoral Degree Program in Marine Biotechnology, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan (China)

    2012-11-02

    Highlights: Black-Right-Pointing-Pointer Probe transition metals-complexes based on noncovalent functionalized graphene for MALDI-MS. Black-Right-Pointing-Pointer Study interaction of transition metals complexes with pathogenic bacteria. Black-Right-Pointing-Pointer Propose a new biosensor for two pathogenic bacteria. - Abstract: A new method was proposed to probe the interactions between transition metals of Fe(II), Fe(III), Cu(II) with a non steroidal anti-inflammatory drug (NSAID), flufenamic acid (FF) using graphene as a matrix for Graphene assisted laser desorption ionization mass spectrometry (GALDI-MS). Metal-drug complexation was confirmed via UV absorption spectroscopy, fluorescence spectroscopy, pH meter, and change in solution conductivity. The optimal molar ratios for these complexation interactions are stoichiometry 1:2 in both Cu(II) and Fe(II) complexes, and 1:3 in Fe(III) complexes at physiological pH (7.4). Metal complexation of the drug could enhance fluorescence for 20 fold which is due to the charge transfer reaction or increase rigidity of the drug. The main interaction between graphene and flufenamic acid is the {Pi}-{Pi} interaction which allows us to probe the metal-drug complexation. The GALDI-MS could sensitively detect the drug at m/z 281.0 Da (protonated molecule) with detection limit 2.5 pmol (1.0 {mu}M) and complexation at m/z 661.0, 654.0 and 933.0 Da corresponding to [Cu(II)(FF){sub 2}(H{sub 2}O){sub 2} + H]{sup +}, [Fe(II)(FF){sub 2}(H{sub 2}O){sub 2} + H]{sup +} and [Fe(III) (FF){sub 3}(H{sub 2}O){sub 2} + H]{sup +}, respectively (with limit of detection (LOD) 2.0 pmol (10.0 {mu}M). Matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) spectra show change in the protein profile of intact pathogenic bacteria (Pseudomonas aeroginosa, Staphylococcus aureus). The change in the ionization ability (mainly proton affinity) of pathogenic bacteria may be due to the interactions between the bacteria with the drug (or its

  1. Direct detection of benzene, toluene, and ethylbenzene at trace levels in ambient air by atmospheric pressure chemical ionization using a handheld mass spectrometer.

    Huang, Guangming; Gao, Liang; Duncan, Jason; Harper, Jason D; Sanders, Nathaniel L; Ouyang, Zheng; Cooks, R Graham

    2010-01-01

    The capabilities of a portable mass spectrometer for real-time monitoring of trace levels of benzene, toluene, and ethylbenzene in air are illustrated. An atmospheric pressure interface was built to implement atmospheric pressure chemical ionization for direct analysis of gas-phase samples on a previously described miniature mass spectrometer (Gao et al. Anal. Chem.2006, 78, 5994-6002). Linear dynamic ranges, limits of detection and other analytical figures of merit were evaluated: for benzene, a limit of detection of 0.2 parts-per-billion was achieved for air samples without any sample preconcentration. The corresponding limits of detection for toluene and ethylbenzene were 0.5 parts-per-billion and 0.7 parts-per-billion, respectively. These detection limits are well below the compounds' permissible exposure levels, even in the presence of added complex mixtures of organics at levels exceeding the parts-per-million level. The linear dynamic ranges of benzene, toluene, and ethylbenzene are limited to approximately two orders of magnitude by saturation of the detection electronics. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

  2. Effects of Palladium Loading on the Response of Thick Film Flame-made ZnO Gas Sensor for Detection of Ethanol Vapor

    Sukon Phanichphant

    2007-07-01

    Full Text Available ZnO nanoparticles doped with 0-5 mol% Pd were successfully produced in asingle step by flame spray pyrolysis (FSP using zinc naphthenate and palladium (IIacetylacetonate dissolved in toluene-acetonitrile (80:20 vol% as precursors. The effect ofPd loading on the ethanol gas sensing performance of the ZnO nanoparticles and thecrystalline sizes were investigated. The particle properties were analyzed by XRD, BET,AFM, SEM (EDS line scan mode, TEM, STEM, EDS, and CO-pulse chemisorptionmeasurements. A trend of an increase in specific surface area of samples and a decrease inthe dBET with increasing Pd concentrations was noted. ZnO nanoparticles were observed asparticles presenting clear spheroidal, hexagonal and rod-like morphologies. The sizes ofZnO spheroidal and hexagonal particle crystallites were in the 10-20 nm range. ZnOnanorods were in the range of 10-20 nm in width and 20-50 nm in length. The size of Pdnanoparticles increased and Pd-dispersion% decreased with increasing Pd concentrations.The sensing films were produced by mixing the particles into an organic paste composedof terpineol and ethyl cellulose as a vehicle binder. The paste was doctor-bladed ontoAl2O3 substrates interdigitated with Au electrodes. The film morphology was analyzed bySEM and EDS analyses. The gas sensing of ethanol (25-250 ppm was studied in dry air at400°C. The oxidation of ethanol on the sensing surface of the semiconductor wasconfirmed by MS. A well-dispersed of 1 mol%Pd/ZnO films showed the highest sensitivityand the fastest response time (within seconds.

  3. Subwoofer and nanotube butterfly acoustic flame extinction

    Aliev, Ali E.; Mayo, Nathanael K.; Baughman, Ray H.; Mills, Brent T.; Habtour, Ed

    2017-01-01

    Nonchemical flame control using acoustic waves from a subwoofer and a lightweight carbon nanotube thermoacoustic projector was demonstrated. The intent was to manipulate flame intensity, direction and propagation. The mechanisms of flame suppression using low frequency acoustic waves were discussed.

  4. Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

    Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

    1993-01-01

    A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

  5. On the theory of turbulent flame velocity

    Bychkov, Vitaly; Akkerman, Vyacheslav; Petchenko, Arkady

    2012-01-01

    The renormalization ideas of self-similar dynamics of a strongly turbulent flame front are applied to the case of a flame with realistically large thermal expansion of the burning matter. In that case a flame front is corrugated both by external turbulence and the intrinsic flame instability. The analytical formulas for the velocity of flame propagation are obtained. It is demonstrated that the flame instability is of principal importance when the integral turbulent length scale is much large...

  6. Ionization chambers

    Boag, J.W.

    1987-01-01

    Although a variety of solid-state and chemical methods for measuring radiation dose have been developed in recent decades and calorimetry can now provide an absolute standard of reference, ionization dosimetry retains its position as the most widely used, most convenient, and, in most situations, most accurate method of measuring either exposure or absorbed dose. The ionization chamber itself is the central element in this system of dosimetry. In this chapter the principles governing the construction and operation of ionization chambers of various types are examined. Since the ionization chambers now in general use are nearly all of commercial manufacture, the emphasis is on operating characteristics and interpretation of measurements rather than on details of construction, although some knowledge of the latter is often required when applying necessary corrections to the measured quantities. Examples are given of the construction of typical chambers designed for particular purposes, and the methods of calibrating them are discussed

  7. Calcium - ionized

    ... diuretics Thrombocytosis (high platelet count) Tumors Vitamin A excess Vitamin D excess Lower-than-normal levels may be due to: Hypoparathyroidism Malabsorption Osteomalacia Pancreatitis Renal failure Rickets Vitamin D deficiency Alternative Names Free calcium; Ionized calcium ...

  8. Investigation of a flame holder geometry effect on flame structure in non-premixed combustion

    Hashemi, S. A.; Hajialigol, N.; Fattahi, A.; Heydari, R.; Mazaheri, K.

    2013-01-01

    In this paper the effect of flame holder geometry on flame structure is studied. The obtained numerical results using realizable k-ε and β-PDF models show a good agreement with experimental data. The results show that increasing in flame holder length decreases flame length and increases flame temperature. Additionally, it is observed that flame lengths decrease by increasing in flame holder radius and increase for larger radii. Furthermore in various radii, the flame temperature is higher for smaller flame lengths. It was found that behavior of flame structure is mainly affected by the mass flow rate of hot gases that come near the reactant by the recirculation zone.

  9. Investigation of a flame holder geometry effect on flame structure in non-premixed combustion

    Hashemi, S. A.; Hajialigol, N.; Fattahi, A.; Heydari, R. [University of Kashan, Kashan (Iran, Islamic Republic of); Mazaheri, K. [University of Tarbiat Moddares, Tehran (Iran, Islamic Republic of)

    2013-11-15

    In this paper the effect of flame holder geometry on flame structure is studied. The obtained numerical results using realizable k-ε and β-PDF models show a good agreement with experimental data. The results show that increasing in flame holder length decreases flame length and increases flame temperature. Additionally, it is observed that flame lengths decrease by increasing in flame holder radius and increase for larger radii. Furthermore in various radii, the flame temperature is higher for smaller flame lengths. It was found that behavior of flame structure is mainly affected by the mass flow rate of hot gases that come near the reactant by the recirculation zone.

  10. Collisional ionization

    Arnaud, M.

    1985-07-01

    In low density, thin plasmas (such as stellar coronae, interstellar medium, intracluster medium) the ionization process is governed by collision between electrons and ions in their ground state. In view of the recent improvements we thought an updating of ionization rates was really needed. The work is based on both experimental data and theoretical works and give separate estimates for the direct and autoionization rates

  11. Ionization chamber

    Jilbert, P.H.

    1975-01-01

    The invention concerns ionization chambers with particular reference to air-equivalent ionization chambers. In order to ensure that similar chambers have similar sensitivities and responses the surface of the chamber bounding the active volume carries a conducting material, which may be a colloidal graphite, arranged in the form of lines so that the area of the conducting material occupies only a small proportion of the area of said surface. (U.S.)

  12. Amorphous silicon ionizing particle detectors

    Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  13. Determination of the detection limit and decision threshold for ionizing radiation measurements. Part 2: Fundamentals and application to counting measurements with the influence of sample treatment

    2000-01-01

    This part of ISO 11929 addresses the field of ionizing radiation measurements in which events (in particular pulses) on samples are counted after treating them (e.g. aliquotation, solution, enrichment, separation). It considers, besides the random character of radioactive decay and of pulse counting, all other influences arising from sample treatment, (e.g. weighing, enrichment, calibration or the instability of the test setup). ISO 11929 consists of the following parts, under the general title Determination of the detection limit and decision threshold for ionizing radiation measurements: Part 1: Fundamentals and application to counting measurements without the influence of sample treatment; Part 2: Fundamentals and application to counting measurements with the influence of sample treatment; Part 3: Fundamentals and application to counting measurements by high resolution gamma spectrometry, without the influence of sample treatment; Part 4: Fundamentals and application to measurements by use of linear scale analogue ratemeters, without the influence of sample treatment. This part of ISO 11929 was prepared in parallel with other International Standards prepared by WG 2 (now WG 17): ISO 11932:1996, Activity measurements of solid materials considered for recycling, re-use or disposal as non radioactive waste, and ISO 11929-1, ISO 11929-3 and ISO 11929-4 and is, consequently, complementary to these documents

  14. Polydisperse effects in jet spray flames

    Weinberg, Noam; Greenberg, J. Barry

    2018-01-01

    A laminar jet polydisperse spray diffusion flame is analysed mathematically for the first time using an extension of classical similarity solutions for gaseous jet flames. The analysis enables a comparison to be drawn between conditions for flame stability or flame blow-out for purely gaseous flames and for spray flames. It is found that, in contrast to the Schmidt number criteria relevant to gas flames, droplet size and initial spray polydispersity play a critical role in determining potential flame scenarios. Some qualitative agreement for lift-off height is found when comparing predictions of the theory and sparse independent experimental evidence from the literature.

  15. Computational Flame Diagnostics for Direct Numerical Simulations with Detailed Chemistry of Transportation Fuels

    Lu, Tianfeng [Univ. of Connecticut, Storrs, CT (United States)

    2017-02-16

    The goal of the proposed research is to create computational flame diagnostics (CFLD) that are rigorous numerical algorithms for systematic detection of critical flame features, such as ignition, extinction, and premixed and non-premixed flamelets, and to understand the underlying physicochemical processes controlling limit flame phenomena, flame stabilization, turbulence-chemistry interactions and pollutant emissions etc. The goal has been accomplished through an integrated effort on mechanism reduction, direct numerical simulations (DNS) of flames at engine conditions and a variety of turbulent flames with transport fuels, computational diagnostics, turbulence modeling, and DNS data mining and data reduction. The computational diagnostics are primarily based on the chemical explosive mode analysis (CEMA) and a recently developed bifurcation analysis using datasets from first-principle simulations of 0-D reactors, 1-D laminar flames, and 2-D and 3-D DNS (collaboration with J.H. Chen and S. Som at Argonne, and C.S. Yoo at UNIST). Non-stiff reduced mechanisms for transportation fuels amenable for 3-D DNS are developed through graph-based methods and timescale analysis. The flame structures, stabilization mechanisms, local ignition and extinction etc., and the rate controlling chemical processes are unambiguously identified through CFLD. CEMA is further employed to segment complex turbulent flames based on the critical flame features, such as premixed reaction fronts, and to enable zone-adaptive turbulent combustion modeling.

  16. Investigation of absolute and relative response for three different liquid chromatography/tandem mass spectrometry systems; the impact of ionization and detection saturation.

    Nilsson, Lars B; Skansen, Patrik

    2012-06-30

    The investigations in this article were triggered by two observations in the laboratory; for some liquid chromatography/tandem mass spectrometry (LC/MS/MS) systems it was possible to obtain linear calibration curves for extreme concentration ranges and for some systems seemingly linear calibration curves gave good accuracy at low concentrations only when using a quadratic regression function. The absolute and relative responses were tested for three different LC/MS/MS systems by injecting solutions of a model compound and a stable isotope labeled internal standard. The analyte concentration range for the solutions was 0.00391 to 500 μM (128,000×), giving overload of the chromatographic column at the highest concentrations. The stable isotope labeled internal standard concentration was 0.667 μM in all samples. The absolute response per concentration unit decreased rapidly as higher concentrations were injected. The relative response, the ratio for the analyte peak area to the internal standard peak area, per concentration unit was calculated. For system 1, the ionization process was found to limit the response and the relative response per concentration unit was constant. For systems 2 and 3, the ion detection process was the limiting factor resulting in decreasing relative response at increasing concentrations. For systems behaving like system 1, simple linear regression can be used for any concentration range while, for systems behaving like systems 2 and 3, non-linear regression is recommended for all concentration ranges. Another consequence is that the ionization capacity limited systems will be insensitive to matrix ion suppression when an ideal internal standard is used while the detection capacity limited systems are at risk of giving erroneous results at high concentrations if the matrix ion suppression varies for different samples in a run. Copyright © 2012 John Wiley & Sons, Ltd.

  17. Ions generated from uranyl nitrate solutions by electrospray ionization (ESI) and detected with Fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometry.

    Pasilis, Sofie; Somogyi, Arpád; Herrmann, Kristin; Pemberton, Jeanne E

    2006-02-01

    Electrospray ionization (ESI) of uranyl nitrate solutions generates a wide variety of positively and negatively charged ions, including complex adducts of uranyl ions with methoxy, hydroxy, and nitrate ligands. In the positive ion mode, ions detected by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry are sensitive to instrumental tuning parameters such as quadrupole operating frequency and trapping time. Positive ions correspond to oligomeric uranyl nitrate species that can be characterized as having a general formula of [(UO(2))(n)(A)(m)(CH(3)OH)(s)](+) or [(UO(2))(n)(O)(A)(m)(CH(3)OH)(s)](+) with n = 1-4, m = 1-7, s = 0 or 1, and A = OH, NO(3), CH(3)O or a combination of these, although the formation of NO(3)-containing species is preferred. In the negative ion mode, complexes of the form [(UO(2))(NO(3))(m)](-) (m = 1-3) are detected, although the formation of the oxo-containing ions [(UO(2))(O)(n)(NO(3))(m)](-) (n = 1-2, m = 1-2) and the hydroxy-containing ions [(UO(2))(OH)(n)(NO(3))(m)](-) (n = 1-2, m = 0-1) are also observed. The extent of coordinative unsaturation of both positive and negative ions can be determined by ligand association/exchange and H/D exchange experiments using D(2)O and CD(3)OD as neutral reaction partners in the gas-phase. Positive ions are of varying stability and reactivity and may fragment extensively upon collision with D(2)O, CD(3)OD and N(2) in sustained off-resonance irradiation/collision-induced dissociation (SORI-CID) experiments. Electron-transfer reactions, presumably occurring during electrospray ionization but also in SORI-CID, can result in reduction of U(VI) to U(V) and perhaps even U(IV).

  18. Evaluation of hyperpolarized [1-¹³C]-pyruvate by magnetic resonance to detect ionizing radiation effects in real time.

    Sandulache, Vlad C; Chen, Yunyun; Lee, Jaehyuk; Rubinstein, Ashley; Ramirez, Marc S; Skinner, Heath D; Walker, Christopher M; Williams, Michelle D; Tailor, Ramesh; Court, Laurence E; Bankson, James A; Lai, Stephen Y

    2014-01-01

    Ionizing radiation (IR) cytotoxicity is primarily mediated through reactive oxygen species (ROS). Since tumor cells neutralize ROS by utilizing reducing equivalents, we hypothesized that measurements of reducing potential using real-time hyperpolarized (HP) magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) can serve as a surrogate marker of IR induced ROS. This hypothesis was tested in a pre-clinical model of anaplastic thyroid carcinoma (ATC), an aggressive head and neck malignancy. Human ATC cell lines were utilized to test IR effects on ROS and reducing potential in vitro and [1-¹³C] pyruvate HP-MRS/MRSI imaging of ATC orthotopic xenografts was used to study in vivo effects of IR. IR increased ATC intra-cellular ROS levels resulting in a corresponding decrease in reducing equivalent levels. Exogenous manipulation of cellular ROS and reducing equivalent levels altered ATC radiosensitivity in a predictable manner. Irradiation of ATC xenografts resulted in an acute drop in reducing potential measured using HP-MRS, reflecting the shunting of reducing equivalents towards ROS neutralization. Residual tumor tissue post irradiation demonstrated heterogeneous viability. We have adapted HP-MRS/MRSI to non-invasively measure IR mediated changes in tumor reducing potential in real time. Continued development of this technology could facilitate the development of an adaptive clinical algorithm based on real-time adjustments in IR dose and dose mapping.

  19. Evaluation of hyperpolarized [1-¹³C]-pyruvate by magnetic resonance to detect ionizing radiation effects in real time.

    Vlad C Sandulache

    Full Text Available Ionizing radiation (IR cytotoxicity is primarily mediated through reactive oxygen species (ROS. Since tumor cells neutralize ROS by utilizing reducing equivalents, we hypothesized that measurements of reducing potential using real-time hyperpolarized (HP magnetic resonance spectroscopy (MRS and spectroscopic imaging (MRSI can serve as a surrogate marker of IR induced ROS. This hypothesis was tested in a pre-clinical model of anaplastic thyroid carcinoma (ATC, an aggressive head and neck malignancy. Human ATC cell lines were utilized to test IR effects on ROS and reducing potential in vitro and [1-¹³C] pyruvate HP-MRS/MRSI imaging of ATC orthotopic xenografts was used to study in vivo effects of IR. IR increased ATC intra-cellular ROS levels resulting in a corresponding decrease in reducing equivalent levels. Exogenous manipulation of cellular ROS and reducing equivalent levels altered ATC radiosensitivity in a predictable manner. Irradiation of ATC xenografts resulted in an acute drop in reducing potential measured using HP-MRS, reflecting the shunting of reducing equivalents towards ROS neutralization. Residual tumor tissue post irradiation demonstrated heterogeneous viability. We have adapted HP-MRS/MRSI to non-invasively measure IR mediated changes in tumor reducing potential in real time. Continued development of this technology could facilitate the development of an adaptive clinical algorithm based on real-time adjustments in IR dose and dose mapping.

  20. A Simple Analytical Model for Predicting the Detectable Ion Current in Ion Mobility Spectrometry Using Corona Discharge Ionization Sources

    Kirk, Ansgar Thomas; Kobelt, Tim; Spehlbrink, Hauke; Zimmermann, Stefan

    2018-05-01

    Corona discharge ionization sources are often used in ion mobility spectrometers (IMS) when a non-radioactive ion source with high ion currents is required. Typically, the corona discharge is followed by a reaction region where analyte ions are formed from the reactant ions. In this work, we present a simple yet sufficiently accurate model for predicting the ion current available at the end of this reaction region when operating at reduced pressure as in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) or most IMS-MS instruments. It yields excellent qualitative agreement with measurement results and is even able to calculate the ion current within an error of 15%. Additional interesting findings of this model are the ion current at the end of the reaction region being independent from the ion current generated by the corona discharge and the ion current in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) growing quadratically when scaling down the length of the reaction region. [Figure not available: see fulltext.

  1. Dynamics and structure of stretched flames

    Law, C.K. [Princeton Univ., NJ (United States)

    1993-12-01

    This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.

  2. Liquid ionizing radiaion detector

    deGaston, A.N.

    1979-01-01

    A normally nonconducting liquid such as liquid hydrocarbon is encased between a pair of electrodes in an enclosure so that when the liquid is subjected to ionizing radiation, the ion pairs so created measurably increase the conductivity of the fluid. The reduced impedance between the electrodes is detectable with a sensitive ohm-meter and indicates the amount of ionizing radiation. The enclosure, the electrodes and the fluid can be constructed of materials that make the response of the detector suitable for calibrating a large range of radiation energy levels. The detector is especially useful in medical applications where tissue equivalent X ray detectors are desired

  3. DMSO Assisted Electrospray Ionization for the Detection of Small Peptide Hormones in Urine by Dilute-and-Shoot-Liquid-Chromatography-High Resolution Mass Spectrometry

    Judák, Péter; Grainger, Janelle; Goebel, Catrin; Van Eenoo, Peter; Deventer, Koen

    2017-08-01

    The mobile phase additive (DMSO) has been described as a useful tool to enhance electrospray ionization (ESI) of peptides and proteins. So far, this technique has mainly been used in proteomic/peptide research, and its applicability in a routine clinical laboratory setting (i.e., doping control analysis) has not been described yet. This work provides a simple, easy to implement screening method for the detection of doping relevant small peptides (GHRPs, GnRHs, GHS, and vasopressin-analogues) with molecular weight less than 2 kDa applying DMSO in the mobile phase. The gain in sensitivity was sufficient to inject the urine samples after a 2-fold dilution step omitting a time consuming sample preparation. The employed analytical procedure was validated for the qualitative determination of 36 compounds, including 13 metabolites. The detection limits (LODs) ranged between 50 and 1000 pg/mL and were compliant with the 2 ng/mL minimum detection level required by the World Anti-Doping Agency (WADA) for all the target peptides. To demonstrate the feasibility of the work, urine samples obtained from patients who have been treated with desmopressin or leuprolide and urine samples that have been declared as adverse analytical findings were analyzed.

  4. Detection of chlorinated and brominated byproducts of drinking water disinfection using electrospray ionization-high-field asymmetric waveform ion mobility spectrometry-mass spectrometry.

    Ells, B; Barnett, D A; Froese, K; Purves, R W; Hrudey, S; Guevremont, R

    1999-10-15

    The lower limit of detection for low molecular weight polar and ionic analytes using electrospray ionization-mass spectrometry (ESI-MS) is often severely compromised by an intense background that obscures ions of trace components in solution. Recently, a new technique, referred to as high-field asymmetric waveform ion mobility spectrometry (FAIMS), has been shown to separate gas-phase ions at atmospheric pressure and room temperature. A FAIMS instrument is an ion filter that may be tuned, by control of electrical voltages, to continuously transmit selected ions from a complex mixture. This capability offers significant advantages when FAIMS is coupled with ESI, a source that generates a wide variety of ions, including solvent clusters and salt adducts. In this report, the tandem arrangement of ESI-FAIMS-MS is used for the analysis of haloacetic acids, a class of disinfection byproducts regulated by the US EPA. FAIMS is shown to effectively discriminate against background ions resulting from the electrospray of tap water solutions containing the haloacetic acids. Consequently, mass spectra are simplified, the selectivity of the method is improved, and the limits of detection are lowered compared with conventional ESI-MS. The detection limits of ESI-FAIMS-MS for six haloacetic acids ranged between 0.5 and 4 ng/mL in 9:1 methanol/tap water (5 and 40 ng/mL in the original tap water samples) with no preconcentration, derivatization, or chromatographic separation prior to analysis.

  5. Determination of Phenolic Content in Different Barley Varieties and Corresponding Malts by Liquid Chromatography-diode Array Detection-Electrospray Ionization Tandem Mass Spectrometry

    Daniel O. Carvalho

    2015-08-01

    Full Text Available A simple and reliable method for the simultaneous determination of nine phenolic compounds in barley and malted barley was established, using liquid chromatography-diode array detection-electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS/MS. The phenolic compounds can be easily detected with both systems, despite significant differences in sensitivity. Concentrations approximately 180-fold lower could be achieved by mass spectrometry analysis compared to diode array detection, especially for the flavan-3-ols (+-catechin and (−-epicatechin, which have poor absorptivity in the UV region. Malt samples were characterized by higher phenolic content comparing to corresponding barley varieties, revealing a significant increase of the levels of (+-catechin and (−-epicatechin during the malting process. Moreover, the industrial malting is responsible for modification on the phenolic profile from barley to malt, namely on the synthesis or release of sinapinic acid and epicatechin. Accordingly, the selection of the malting parameters, as well as the barley variety plays an important role when considering the quality and antioxidant stability of beer.

  6. Molecular formulae of marine and terrigenous dissolved organic matter detected by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

    Koch, Boris P.; Witt, Matthias; Engbrodt, Ralph; Dittmar, Thorsten; Kattner, Gerhard

    2005-07-01

    The chemical structure of refractory marine dissolved organic matter (DOM) is still largely unknown. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR-MS) was used to resolve the complex mixtures of DOM and provide valuable information on elemental compositions on a molecular scale. We characterized and compared DOM from two sharply contrasting aquatic environments, algal-derived DOM from the Weddell Sea (Antarctica) and terrigenous DOM from pore water of a tropical mangrove area in northern Brazil. Several thousand molecular formulas in the mass range of 300-600 Da were identified and reproduced in element ratio plots. On the basis of molecular elemental composition and double-bond equivalents (DBE) we calculated an average composition for marine DOM. O/C ratios in the marine samples were lower (0.36 ± 0.01) than in the mangrove pore-water sample (0.42). A small proportion of chemical formulas with higher molecular mass in the marine samples were characterized by very low O/C and H/C ratios probably reflecting amphiphilic properties. The average number of unsaturations in the marine samples was surprisingly high (DBE = 9.9; mangrove pore water: DBE = 9.4) most likely due to a significant contribution of carbonyl carbon. There was no significant difference in elemental composition between surface and deep-water DOM in the Weddell Sea. Although there were some molecules with unique marine elemental composition, there was a conspicuous degree of similarity between the terrigenous and algal-derived end members. Approximately one third of the molecular formulas were present in all marine as well as in the mangrove samples. We infer that different forms of microbial degradation ultimately lead to similar structural features that are intrinsically refractory, independent of the source of the organic matter and the environmental conditions where degradation took place.

  7. Ionizing radiations

    Newton, W.

    1984-01-01

    The purpose of this article is to simplify some of the relevant points of legislation, biological effects and protection for the benefit of the occupational health nurse not familiar with the nuclear industries. The subject is dealt with under the following headings; Understanding atoms. What is meant by ionizing radiation. Types of ionizing radiation. Effects of radiation: long and short term somatic effects, genetic effects. Control of radiation: occupational exposure, women of reproductive age, medical aspects, principles of control. The occupational health nurse's role. Emergency arrangements: national arrangements for incidents involving radiation, action to be taken by the nurse. Decontamination procedures: external and internal contamination. (U.K.)

  8. III. Penning ionization, associative ionization and chemi-ionization processes

    Cermak, V.

    1975-01-01

    Physical mechanisms of three important ionization processes in a cold plasma and the methods of their experimental study are discussed. An apparatus for the investigation of the Penning ionization using ionization processes of long lived metastable rare gas atoms is described. Methods of determining interaction energies and ionization rates from the measured energy spectra of the originating electrons are described and illustrated by several examples. Typical associative ionization processes are listed and the ionization rates are compared with those of the Penning ionization. Interactions with short-lived excited particles and the transfer of excitation without ionization are discussed. (J.U.)

  9. Photoionization mass spectrometer for studies of flame chemistry with a synchrotron light source

    Cool, Terrill A.; McIlroy, Andrew; Qi, Fei; Westmoreland, Phillip R.; Poisson, Lionel; Peterka, Darcy S.; Ahmed, Musahid

    2005-01-01

    A flame-sampling molecular-beam photoionization mass spectrometer, recently designed and constructed for use with a synchrotron-radiation light source, provides significant improvements over previous molecular-beam mass spectrometers that have employed either electron-impact ionization or vacuum ultraviolet laser photoionization. These include superior signal-to-noise ratio, soft ionization, and photon energies easily and precisely tunable [E/ΔE(FWHM)≅250-400] over the 7.8-17-eV range required for quantitative measurements of the concentrations and isomeric compositions of flame species. Mass resolution of the time-of-flight mass spectrometer is m/Δm=400 and sensitivity reaches ppm levels. The design of the instrument and its advantages for studies of flame chemistry are discussed

  10. Mechanistic aspects of ionic reactions in flames

    Egsgaard, H.; Carlsen, L.

    1993-01-01

    Some fundamentals of the ion chemistry of flames are summarized. Mechanistic aspects of ionic reactions in flames have been studied using a VG PlasmaQuad, the ICP-system being substituted by a simple quartz burner. Simple hydrocarbon flames as well as sulfur-containing flames have been investigated...

  11. Effects of AC Electric Field on Small Laminar Nonpremixed Flames

    Xiong, Yuan

    2015-04-01

    80 Hz and became saturated at over 80 Hz, which has been explained based on the interaction between the buoyancy and ionic wind. Electrical measurement showed the power consumed by the AC was smaller than 0.01% of the heat release rate from the flame. To improve the understanding on the electric current resulting from applying electric field on flames, a simplified one-dimensional model was developed in that the reaction zone was modeled as a thin ionized layer. Model governing equations were derived from species equations by implementing mobility differences depending on the type of charged particles, especially between ions and electrons. The result showed that the sub-saturated current along with field intensity was significantly influenced by the polarity of DC due to the combined effect of non-equal mobility of charged particles as well as the position of the ionized layer in a gap relative to two electrodes. Experiments with quasi-one-dimensional flames under DC were conducted to substantiate the model and measured currents agreed qualitatively well with the model predictions.

  12. Ionizing radiation

    Dennis, J.A.

    1982-01-01

    The subject is discussed under the headings: characteristics of ionizing radiations; biological effects; comparison of radiation and other industrial risks; principles of protection; cost-benefit analysis; dose limits; the control and monitoring of radiation; reference levels; emergency reference levels. (U.K.)

  13. Ionizing radiation

    Tobias, C. A.; Grigoryev, Y. G.

    1975-01-01

    The biological effects of ionizing radiation encountered in space are considered. Biological experiments conducted in space and some experiences of astronauts during space flight are described. The effects of various levels of radiation exposure and the determination of permissible dosages are discussed.

  14. Detection of base damage in DNA in human blood exposed to ionizing radiation at biologically relevant doses

    Loon, A.A.W.M. van; Lohman, P.H.M.; Groenendijk, R.H.; Schans, G.P. van der; Baan, R.A.

    1991-01-01

    The alkaline elution technique for the detection of DNA damage has been adapted to allow application on unlabelled blood cells. Both the induction and subsequent repair have been studied of two classes of DNA damage, viz. single-strand breaks and base damage recognized by the γ-endonuclease activity in a cell-free extract of Micrococcus luteus bacteria. The high sensitivity of the assay permitted the measurement of induction and repair of base damage after in vitro exposure of full blood under aerobic conditions to biologically relevant doses of γ-rays (1.5-4.5 Gy). After a radiation dose of 3 Gy about 50% of the base damage was removed within 1.5 h of repair. Base damage could still be detected at 24h after exposure to 15 Gy. (author)

  15. Trace analysis of tiamulin in honey by liquid chromatography-diode array-electrospray ionization mass spectrometry detection.

    Nozal, M J; Bernal, J L; Martín, M T; Jiménez, J J; Bernal, J; Higes, M

    2006-05-26

    A liquid chromatography with diode array or electrospray ionisation mass spectrometry detection (LC-DAD-ESI-MS) method for the determination of tiamulin residues in honey is presented. The procedure employs a solid-phase extraction (SPE) on polymeric cartridges for the isolation of tiamulin from honey samples diluted in aqueous solution of tartaric acid. Chromatographic separation of the tiamulin is performed, in isocratic mode, on a C18 column using methanol and ammonium carbonate 0.1% in water, in proportion (30:70, v/v). Average analyte recoveries were from 88 to 106% in replica sets of fortified honey samples. The LC-ESI-MS method detection limits differ from 0.5 microg kg(-1) for clear honeys to 1.2 microg kg(-1) for dark honeys. The developed method has been applied to the analysis of tiamulin residues in multifloral honey samples collected from veterinary treated beehives.

  16. Study and characterization of the III-V semiconductor materials for applications in the detection of ionizing radiation

    Moulin, H.

    1989-11-01

    The photoconduction in the bulk of the gallium arsenide (GaAs) and of the indium phosphide doped with iron (InP:Fe) is investigated. These compounds are to be applied in devices for X-ray detection. In such semiconductor materials the detection of X-rays occurs in the bulk. The photoconduction theory and the characteristics of the materials are reviewed. Two computerized simulation models for studying the response of the photoconductors to the radiation pulses are described. The results concerning the following measurements are presented: the characterization of GaAs and InP:Fe photoconductors, in obscurity, as a function of the electric field of polarization and of the neutrons dose; and their characterization under X-ray radiation [fr

  17. Role of the outer-edge flame on flame extinction in nitrogen-diluted non-premixed counterflow flames with finite burner diameters

    Chung, Yong Ho; Park, Daegeun; Park, Jeong; Kwon, Oh Boong; Yun, Jin Han; Keel, Sang In

    2013-01-01

    This study of nitrogen-diluted non-premixed counterflow flames with finite burner diameters investigates the important role of the outer-edge flame on flame extinction through experimental and numerical analyses. It explores flame stability diagrams

  18. Broad-Range PCR Coupled with Electrospray Ionization Time of Flight Mass Spectrometry for Detection of Bacteremia and Fungemia in Patients with Neutropenic Fever

    Maertens, J.; Bueselinck, K.; Lagrou, K.

    2016-01-01

    Infection is an important complication in patients with hematologic malignancies or solid tumors undergoing intensive cytotoxic chemotherapy. In only 20 to 30% of the febrile neutropenic episodes, an infectious agent is detected by conventional cultures. In this prospective study, the performance of broad-range PCR coupled with electrospray ionization time of flight mass spectrometry (PCR/ESI-MS) technology was compared to conventional blood cultures (BC) in a consecutive series of samples from high-risk hematology patients. In 74 patients, BC and a whole-blood sample for PCR/ESI-MS (Iridica BAC BSI; Abbott, Carlsbad, CA, USA) were collected at the start of each febrile neutropenic episode and, in case of persistent fever, also at day 5. During 100 different febrile episodes, 105 blood samples were collected and analyzed by PCR/ESI-MS. There was evidence of a bloodstream infection (BSI) in 36/105 cases (34%), based on 14 cases with both PCR/ESI-MS and BC positivity, 17 cases with BC positivity only, and 5 cases with PCR/ESI-MS positivity only. The sensitivity of PCR/ESI-MS was 45%, specificity was 93%, and the negative predictive value was 80% compared to blood culture. PCR/ESI-MS detected definite pathogens (Fusobacterium nucleatum and Streptococcus pneumoniae) missed by BC, whereas it missed both Gram-negative and Gram-positive organisms detected by BC. PCR/ESI-MS testing detected additional microorganisms but showed a low sensitivity (45%) compared to BC in neutropenic patients. Our results indicate a lower concordance between BC and PCR/ESI-MS in the neutropenic population than what has been previously reported in other patient groups with normal white blood cell distribution, and a lower sensitivity than other PCR-based methods. PMID:27440820

  19. Flame spraying of polymers

    Varacalle, D.J. Jr.; Zeek, D.P.; Couch, K.W.; Benson, D.M.; Kirk, S.M.

    1997-01-01

    Statistical design-of-experiment studies of the thermal spraying of polymer powders are presented. Studies of the subsonic combustion (i.e., Flame) process were conducted in order to determine the quality and economics of polyester and urethane coatings. Thermally sprayed polymer coatings are of interest to several industries for anticorrosion applications, including the chemical, automotive, and aircraft industries. In this study, the coating design has been optimized for a site-specific application using Taguchi-type fractional-factorial experiments. Optimized coating designs are presented for the two powder systems. A substantial range of thermal processing conditions and their effect on the resultant polymer coatings is presented. The coatings were characterized by optical metallography, hardness testing, tensile testing, and compositional analysis. Characterization of the coatings yielded the thickness, bond strength, Knoop microhardness, roughness, deposition efficiency, and porosity. Confirmation testing was accomplished to verify the coating designs

  20. Physical and Chemical Processes in Turbulent Flames

    2015-06-23

    equiangular sectors, defined as the ratio of the actual flame length to the length of a circular-arc of radius equal to the average flame radius. Assuming... flame length ratio obtained directly from the experiments, without any assumption. As explained earlier (Eq. 2.8) the length ratio, (LR=dl(G0)/dl0) is...spherically expanding flames, with the length ratio on the measurement plane, at predefined equiangular sectors, defined as the ratio of the actual flame length to

  1. Improved detection of drugs of abuse using high-performance ion mobility spectrometry with electrospray ionization (ESI-HPIMS) for urine matrices.

    Midey, Anthony J; Patel, Aesha; Moraff, Carol; Krueger, Clinton A; Wu, Ching

    2013-11-15

    High-performance ion mobility spectrometry (HPIMS) with electrospray ionization (ESI) has been used to separate drugs of abuse compounds as a function of drift time (ion mobility), which is based on their size, structural shape, and mass-to-charge. HPIMS has also been used to directly detect and identify a variety of the most commonly encountered illegal drugs, as well as a mixture of opiates in a urine matrix without extra sample pretreatment. HPIMS has shown resolving power greater than 65 comparable to that of high-performance liquid chromatography (HPLC) with only 1 mL of solvent and sample required using air as the IMS separation medium. The HPIMS method can achieve two-order of magnitude linear response, precise drift times, and high peak area precision with percent relative standard deviations (%RSD) less than 3% for sample quantitation. The reduced mobilities measured agree very well with other IMS measurements, allowing a simple "dilute-and-shoot" method to be used to detect a mixture of codeine and morphine in urine matrix. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Quantitative analysis of the eight major compounds in the Samsoeum using a high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometer

    Weon, Jin Bae; Yang, Hye Jin; Lee, Bohyoung; Ma, Jin Yeul; Ma, Choong Je

    2015-01-01

    Background: Samsoeum was traditionally used for treatment of a respiratory disease. Objective: The simultaneous determination of eight major compounds, ginsenoside Rg3, caffeic acid, puerarin, costunolide, hesperidin, naringin, glycyrrhizin, and 6-gingerol in the Samsoeum using a high-performance liquid chromatography (HPLC) coupled with diode array detection (DAD) and an electrospray ionization mass spectrometer was developed for an accurate and reliable quality assessment. Materials and Methods: Eight compounds were qualitative identified based on their mass spectra and by comparing with standard compounds and quantitative analyzed by HPLC-DAD. Separation of eight compounds was carried out on a LUNA C18 column (S-5 μm, 4.6 mm i.d. ×250 mm) with gradient elution composed of acetonitrile and 0.1% trifluoroacetic acid. Results: The data showed good linearity (R2 > 0.9996). The limits of detection and the limits of quantification were <0.53 μg and 1.62 μg, respectively. Inter- and Intra-day precisions (expressed as relative standard deviation values) were within 1.94% and 1.91%, respectively. The recovery of the method was in the range of 94.24–107.90%. Conclusion: The established method is effective and could be applied to quality control of Samsoeum. PMID:25829771

  3. An improved multiple flame photometric detector for gas chromatography.

    Clark, Adrian G; Thurbide, Kevin B

    2015-11-20

    An improved multiple flame photometric detector (mFPD) is introduced, based upon interconnecting fluidic channels within a planar stainless steel (SS) plate. Relative to the previous quartz tube mFPD prototype, the SS mFPD provides a 50% reduction in background emission levels, an orthogonal analytical flame, and easier more sensitive operation. As a result, sulfur response in the SS mFPD spans 4 orders of magnitude, yields a minimum detectable limit near 9×10(-12)gS/s, and has a selectivity approaching 10(4) over carbon. The device also exhibits exceptionally large resistance to hydrocarbon response quenching. Additionally, the SS mFPD uniquely allows analyte emission monitoring in the multiple worker flames for the first time. The findings suggest that this mode can potentially further improve upon the analytical flame response of sulfur (both linear HSO, and quadratic S2) and also phosphorus. Of note, the latter is nearly 20-fold stronger in S/N in the collective worker flames response and provides 6 orders of linearity with a detection limit of about 2.0×10(-13)gP/s. Overall, the results indicate that this new SS design notably improves the analytical performance of the mFPD and can provide a versatile and beneficial monitoring tool for gas chromatography. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. The coupling of supercritical fluid chromatography and field ionization time-of-flight high-resolution mass spectrometry for rapid and quantitative analysis of petroleum middle distillates.

    Qian, Kuangnan; Diehl, John W; Dechert, Gary J; DiSanzo, Frank P

    2004-01-01

    We report the first coupling of supercritical fluid chromatography (SFC) with field ionization time-of-flight high-resolution mass spectrometry (FI-ToF HRMS), in parallel with ultraviolet (UV) detection and flame ionization detection (FID), for rapid and quantitative analysis of petroleum middle distillates. SFC separates petroleum middle distillates into saturates and 1- to 3-ring aromatics. FI generates molecular ions for hydrocarbon species eluted from the SFC. The high resolution and exact mass measurements by ToF mass spectrometry provide elemental compositions of the molecules in the petroleum product. The amounts of saturates and aromatic ring types were quantified using the parallel SFC-FID assisted by SFC-UV. With a proper carbon-number calibration, the detailed composition of the petroleum middle distillate was rapidly determined.

  5. Trace determination of the flame retardant tetrabromobisphenol A in the atmosphere by gas chromatography-mass spectrometry

    Xie Zhiyong; Ebinghaus, Ralf; Lohmann, Rainer; Heemken, Olaf; Caba, Armando; Puettmann, Wilhelm

    2007-01-01

    A simple and effective method has been developed for analysis of the flame retardant tetrabromobisphenol A (TBBPA) in environmental samples by using modified soxhlet extraction in combination with silica gel clean-up, derivatization with silylation reagent and gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode (SIM). Satisfactory recoveries were achieved for the large volume sampling, soxhlet extraction and silica gel clean-up. The overall recovery is 79 ± 1%. The derivatization procedure is simple and fast, and produces stable TBBPA derivative. GC-MS with electronic impact (EI) ionization mode shows better detection power than using negative chemical ionization (NCI) mode. EI gives a method detection limit of 0.04 pg m -3 and enables to determine trace TBBPA in ambient air in remote area. The method was successfully applied to the determination of TBBPA in atmospheric samples collected over land and coastal regions. The concentrations of TBBPA ranged from below the method detection limit (0.04 pg m -3 ) to 0.85 pg m -3 . A declining trend with increasing latitude was present from the Wadden Sea to the Arctic. The atmospheric occurrence of TBBPA in the Arctic is significant and might imply that TBBPA has long-range transport potential

  6. Imaging live humans through smoke and flames using far-infrared digital holography.

    Locatelli, M; Pugliese, E; Paturzo, M; Bianco, V; Finizio, A; Pelagotti, A; Poggi, P; Miccio, L; Meucci, R; Ferraro, P

    2013-03-11

    The ability to see behind flames is a key challenge for the industrial field and particularly for the safety field. Development of new technologies to detect live people through smoke and flames in fire scenes is an extremely desirable goal since it can save human lives. The latest technologies, including equipment adopted by fire departments, use infrared bolometers for infrared digital cameras that allow users to see through smoke. However, such detectors are blinded by flame-emitted radiation. Here we show a completely different approach that makes use of lensless digital holography technology in the infrared range for successful imaging through smoke and flames. Notably, we demonstrate that digital holography with a cw laser allows the recording of dynamic human-size targets. In this work, easy detection of live, moving people is achieved through both smoke and flames, thus demonstrating the capability of digital holography at 10.6 μm.

  7. Neurotoxicity of brominated flame retardants

    Polybrominated diphenyl ethers (PBDEs) have been commonly used as commercial flame retardants in a variety of products including plastics and textiles. Despite their decreasing usage worldwide, congeners continue to accumulate in the environment, including soil, dust, food, anima...

  8. Extinction of laminar partially premixed flames

    Aggarwal, Suresh K. [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor Street, Room 2039, MC-251, Chicago, IL 60607-7022 (United States)

    2009-12-15

    Flame extinction represents one of the classical phenomena in combustion science. It is important to a variety of combustion systems in transportation and power generation applications. Flame extinguishment studies are also motivated from the consideration of fire safety and suppression. Such studies have generally considered non-premixed and premixed flames, although fires can often originate in a partially premixed mode, i.e., fuel and oxidizer are partially premixed as they are transported to the reaction zone. Several recent investigations have considered this scenario and focused on the extinction of partially premixed flames (PPFs). Such flames have been described as hybrid flames possessing characteristics of both premixed and non-premixed flames. This paper provides a review of studies dealing with the extinction of PPFs, which represent a broad family of flames, including double, triple (tribrachial), and edge flames. Theoretical, numerical and experimental studies dealing with the extinction of such flames in coflow and counterflow configurations are discussed. Since these flames contain both premixed and non-premixed burning zones, a brief review of the dilution-induced extinction of premixed and non-premixed flames is also provided. For the coflow configuration, processes associated with flame liftoff and blowout are described. Since lifted non-premixed jet flames often contain a partially premixed or an edge-flame structure prior to blowout, the review also considers such flames. While the perspective of this review is broad focusing on the fundamental aspects of flame extinction and blowout, results mostly consider flame extinction caused by the addition of a flame suppressant, with relevance to fire suppression on earth and in space environment. With respect to the latter, the effect of gravity on the extinction of PPFs is discussed. Future research needs are identified. (author)

  9. Development of a gas-cylinder-free plasma desorption/ionization system for on-site detection of chemical warfare agents.

    Iwai, Takahiro; Kakegawa, Ken; Aida, Mari; Nagashima, Hisayuki; Nagoya, Tomoki; Kanamori-Kataoka, Mieko; Miyahara, Hidekazu; Seto, Yasuo; Okino, Akitoshi

    2015-06-02

    A gas-cylinder-free plasma desorption/ionization system was developed to realize a mobile on-site analytical device for detection of chemical warfare agents (CWAs). In this system, the plasma source was directly connected to the inlet of a mass spectrometer. The plasma can be generated with ambient air, which is drawn into the discharge region by negative pressure in the mass spectrometer. High-power density pulsed plasma of 100 kW could be generated by using a microhollow cathode and a laboratory-built high-intensity pulsed power supply (pulse width: 10-20 μs; repetition frequency: 50 Hz). CWAs were desorbed and protonated in the enclosed space adjacent to the plasma source. Protonated sample molecules were introduced to the mass spectrometer by airflow through the discharge region. To evaluate the analytical performance of this device, helium and air plasma were directly irradiated to CWAs in the gas-cylinder-free plasma desorption/ionization system and the protonated molecules were analyzed by using an ion-trap mass spectrometer. A blister agent (nitrogen mustard 3) and nerve gases [cyclohexylsarin (GF), tabun (GA), and O-ethyl S-2-N,N-diisopropylaminoethyl methylphosphonothiolate (VX)] in solution in n-hexane were applied to the Teflon rod and used as test samples, after solvent evaporation. As a result, protonated molecules of CWAs were successfully observed as the characteristic ion peaks at m/z 204, 181, 163, and 268, respectively. In air plasma, the limits of detection were estimated to be 22, 20, 4.8, and 1.0 pmol, respectively, which were lower than those obtained with helium plasma. To achieve quantitative analysis, calibration curves were made by using CWA stimulant dipinacolyl methylphosphonate as an internal standard; straight correlation lines (R(2) = 0.9998) of the peak intensity ratios (target per internal standard) were obtained. Remarkably, GA and GF gave protonated dimer ions, and the ratios of the protonated dimer ions to the protonated

  10. Application of the microbiological method DEFT/APC and DNA comet assay to detect ionizing radiation processing of minimally processed vegetables

    Araujo, Michel Mozeika

    2008-01-01

    Marketing of minimally processed vegetables (MPV) are gaining impetus due to its convenience, freshness and apparent healthy. However, minimal processing does not reduce pathogenic microorganisms to safe levels. Food irradiation is used to extend the shelf life and inactivation of food-borne pathogens, Its combination with minimal processing could improve the safety and quality of MPV. Two different food irradiation detection methods, a biological, the DEFT/APC, and another biochemical, the DNA Comet Assay were applied to MPV in order to test its applicability to detect irradiation treatment. DEFT/APC is a microbiological screening method based on the use of the direct epi fluorescent filter technique (DEFT) and the aerobic plate count (APC). DNA Comet Assay detects DNA damage due to ionizing radiation. Samples of lettuce, chard, watercress, dandelion, kale, chicory, spinach, cabbage from retail market were irradiated O.5 kGy and 1.0 kGy using a 60 Co facility. Irradiation treatment guaranteed at least 2 log cycle reduction for aerobic and psychotropic microorganisms. In general, with increasing radiation doses, DEFT counts remained similar independent of irradiation processing while APC counts decreased gradually. The difference of the two counts gradually increased with dose increment in all samples. It could be suggested that a DEFT/APC difference over 2.0 log would be a criteria to judge if a MPV was treated by irradiation. DNA Comet Assay allowed distinguishing non-irradiated samples from irradiated ones, which showed different types of comets owing to DNA fragmentation. Both DEFT/APC method and DNA Comet Assay would be satisfactorily used as a screening method for indicating irradiation processing. (author)

  11. Ionization chamber

    1977-01-01

    An improved ionization chamber type X-ray detector comprises a heavy gas at high pressure disposed between an anode and a cathode. An open grid structure is placed next to the anode and is maintained at a voltage intermediate between the cathode and anode potentials. The electric field which is produced by positive ions drifting towards the cathode is thus shielded from the anode. Current measuring circuits connected to the anode are, therefore, responsive only to electron current flow within the chamber and the recovery time of the chamber is shortened. The grid structure also serves to shield the anode from electrical currents which might otherwise be induced by mechanical vibrations in the ionization chamber structure

  12. Study and characterization of semi-conductor materials III-V for their applications to the ionizing radiation detection

    Moulin, H.

    1989-01-01

    This work is the study of photoconduction in volume of gallium arsenide and of indium phosphide doped with iron for their applications to X-ray detection which is carried out directly in the material. After having recalled the physical characterization of materials and the principle of photoconduction, we describe two informatic simulations. The first supposes the spatial uniformity of the electric field on the semiconductor, the second takes the spatial and temporal variations of the field into consideration. Then we show the advantage of a first irradiation to neutrons of the photoconductors. With the gallium arsenide there is swiftness improvement of the detectors to the detriment of the sensitivity. The second part studies first the characterizations in the obscurity of the photoconductors according to the electric polarization field and to the neutron dose they received before and then their characterizations under X radiation. 77 refs., 221 figs., 33 tabs., 6 photos., 3 annexes

  13. Edge flame instability in low-strain-rate counterflow diffusion flames

    Park, June Sung; Hwang, Dong Jin; Park, Jeong; Kim, Jeong Soo; Kim, Sungcho [School of Mechanical and Aerospace Engineering, Sunchon National University, 315 Maegok-dong, Suncheon, Jeonnam 540-742 (Korea, Republic of); Keel, Sang In [Environment & amp; Energy Research Division, Korea Institute of Machinery and Materials, P.O. Box 101, Yusung-gu, Taejon 305-343 (Korea, Republic of); Kim, Tae Kwon [School of Mechanical & amp; Automotive Engineering, Keimyung University, 1000 Sindang-dong, Dalseo-gu, Daegu 704-701 (Korea, Republic of); Noh, Dong Soon [Energy System Research Department, Korea Institute of Energy Research, 71-2 Jang-dong, Yusung-gu, Taejon 305-343 (Korea, Republic of)

    2006-09-15

    Experiments in low-strain-rate methane-air counterflow diffusion flames diluted with nitrogen have been conducted to study flame extinction behavior and edge flame oscillation in which flame length is less than the burner diameter and thus lateral conductive heat loss, in addition to radiative loss, could be high at low global strain rates. The critical mole fraction at flame extinction is examined in terms of velocity ratio and global strain rate. Onset conditions of the edge flame oscillation and the relevant modes are also provided with global strain rate and nitrogen mole fraction in the fuel stream or in terms of fuel Lewis number. It is observed that flame length is intimately relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation considerably. Lateral heat loss causes flame oscillation even at fuel Lewis number less than unity. Edge flame oscillations, which result from the advancing and retreating edge flame motion of the outer flame edge of low-strain-rate flames, are categorized into three modes: a growing, a decaying, and a harmonic-oscillation mode. A flame stability map based on the flame oscillation modes is also provided for low-strain-rate flames. The important contribution of lateral heat loss even to edge flame oscillation is clarified finally. (author)

  14. Development and validation of a multiresidue method for the simultaneous determination of organophosphorus insecticides and their toxic metabolites in sugarcane juice and refined sugar by gas chromatography with flame photometric detection.

    Ramasubramanian, Thirumalaiandi; Paramasivam, Mariappan

    2016-06-01

    A multiresidue method has been developed and validated for the simultaneous determination of organophosphorus insecticides and their toxic metabolites in sugarcane juice and refined sugar by gas chromatography with flame photometric detection. Limits of quantification of the method varied between 0.007 and 0.01 μg/g. Ethyl acetate based extraction followed by dispersive solid-phase extraction cleanup with primary secondary amine yielded internationally acceptable recoveries of acephate, chlorpyrifos, dichlorvos, monocrotophos, malathion, malaoxon, phorate, phorate-sulfoxide, phorate-oxon, phorate-sulfone, and quinalphos from selected matrices. The recoveries of target analytes from cane juice were 75.55 ± 0.5-102.57 ± 4.2, 77.45 ± 4.7-103.33 ± 3.3, and 80.55 ± 6.6-105.82 ± 9.8% at 0.01, 0.02, and 0.1 μg/g levels of fortification, respectively. The recoveries from cane sugar were 73.24 ± 3.5-104.47 ± 1.9, 75.23 ± 1.5-116.10 ± 3.7, and 70.75 ± 5.7-110.15 ± 2.7%, respectively at 0.01, 0.02, and 0.1 μg/g levels of fortification. Matrix effect and measurement uncertainty were within the permissible limit (less than 20%) as prescribed for pesticide residue analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Sensor for ionizable elements

    Berkey, E.; Reed, W.A. III; Hickam, W.M.

    1977-01-01

    Sensor to detect thermally ionizable elements or molucules in air, water vapour or oxygen or to be used as alkali leak detector in vacuum systems, e.g. in the pipe system of a liquid-metal cooled FBR. The sensor consists of an filament made of thorium-containing iridium as cathode with a temperature upto 1000 0 C and an anode sheet of molybdenum, nickel or stainless steal. (ORU) [de

  16. Ionization probes of molecular structure and chemistry

    Johnson, P.M. [State Univ. of New York, Stony Brook (United States)

    1993-12-01

    Various photoionization processes provide very sensitive probes for the detection and understanding of the spectra of molecules relevant to combustion processes. The detection of ionization can be selective by using resonant multiphoton ionization or by exploiting the fact that different molecules have different sets of ionization potentials. Therefore, the structure and dynamics of individual molecules can be studied even in a mixed sample. The authors are continuing to develop methods for the selective spectroscopic detection of molecules by ionization, and to use these methods for the study of some molecules of combustion interest.

  17. Flame analysis using image processing techniques

    Her Jie, Albert Chang; Zamli, Ahmad Faizal Ahmad; Zulazlan Shah Zulkifli, Ahmad; Yee, Joanne Lim Mun; Lim, Mooktzeng

    2018-04-01

    This paper presents image processing techniques with the use of fuzzy logic and neural network approach to perform flame analysis. Flame diagnostic is important in the industry to extract relevant information from flame images. Experiment test is carried out in a model industrial burner with different flow rates. Flame features such as luminous and spectral parameters are extracted using image processing and Fast Fourier Transform (FFT). Flame images are acquired using FLIR infrared camera. Non-linearities such as thermal acoustic oscillations and background noise affect the stability of flame. Flame velocity is one of the important characteristics that determines stability of flame. In this paper, an image processing method is proposed to determine flame velocity. Power spectral density (PSD) graph is a good tool for vibration analysis where flame stability can be approximated. However, a more intelligent diagnostic system is needed to automatically determine flame stability. In this paper, flame features of different flow rates are compared and analyzed. The selected flame features are used as inputs to the proposed fuzzy inference system to determine flame stability. Neural network is used to test the performance of the fuzzy inference system.

  18. Stratified turbulent Bunsen flames: flame surface analysis and flame surface density modelling

    Ramaekers, W. J. S.; van Oijen, J. A.; de Goey, L. P. H.

    2012-12-01

    In this paper it is investigated whether the Flame Surface Density (FSD) model, developed for turbulent premixed combustion, is also applicable to stratified flames. Direct Numerical Simulations (DNS) of turbulent stratified Bunsen flames have been carried out, using the Flamelet Generated Manifold (FGM) reduction method for reaction kinetics. Before examining the suitability of the FSD model, flame surfaces are characterized in terms of thickness, curvature and stratification. All flames are in the Thin Reaction Zones regime, and the maximum equivalence ratio range covers 0.1⩽φ⩽1.3. For all flames, local flame thicknesses correspond very well to those observed in stretchless, steady premixed flamelets. Extracted curvature radii and mixing length scales are significantly larger than the flame thickness, implying that the stratified flames all burn in a premixed mode. The remaining challenge is accounting for the large variation in (subfilter) mass burning rate. In this contribution, the FSD model is proven to be applicable for Large Eddy Simulations (LES) of stratified flames for the equivalence ratio range 0.1⩽φ⩽1.3. Subfilter mass burning rate variations are taken into account by a subfilter Probability Density Function (PDF) for the mixture fraction, on which the mass burning rate directly depends. A priori analysis point out that for small stratifications (0.4⩽φ⩽1.0), the replacement of the subfilter PDF (obtained from DNS data) by the corresponding Dirac function is appropriate. Integration of the Dirac function with the mass burning rate m=m(φ), can then adequately model the filtered mass burning rate obtained from filtered DNS data. For a larger stratification (0.1⩽φ⩽1.3), and filter widths up to ten flame thicknesses, a β-function for the subfilter PDF yields substantially better predictions than a Dirac function. Finally, inclusion of a simple algebraic model for the FSD resulted only in small additional deviations from DNS data

  19. Direct detection of carbapenemase-associated proteins of Acinetobacter baumannii using nanodiamonds coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Chang, Kai-Chih; Chung, Chin-Yi; Yeh, Chen-Hsing; Hsu, Kuo-Hsiu; Chin, Ya-Ching; Huang, Sin-Siang; Liu, Bo-Rong; Chen, Hsi-An; Hu, Anren; Soo, Po-Chi; Peng, Wen-Ping

    2018-04-01

    The appearance and spread of carbapenem-resistant Acinetobacter baumannii (CRAB) pose a challenge for optimization of antibiotic therapies and outbreak preventions. The carbapenemase production can be detected through culture-based methods (e.g. Modified Hodge Test-MHT) and DNA based methods (e.g. Polymerase Chain Reaction-PCR). The culture-based methods are time-consuming, whereas those of PCR assays need only a few hours but due to its specificity, can only detect known genetic targets encoding carbapenem-resistance genes. Therefore, new approaches to detect carbapenemase-producing A. baumannii are of great importance. Here, we have developed a rapid and novel method using detonation nanodiamonds (DNDs) as a platform for concentration and extraction of A. baumannii carbapenemase-associated proteins prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS) analysis. To concentrate and extract the A. baumannii carbapenemase-associated proteins, we tested several protein precipitation conditions and found a 0.5% trifluoroacetic acid (TFA) solution within the bacterial suspension could result in strong ion signals with DNDs. A total of 66 A. baumannii clinical-isolates including 51 carbapenem-resistant strains and 15 carbapenem-susceptible strains were tested. Our result showed that among the 51 carbapenem-resistant strains 49 strains had a signal at m/z ~40,279 (±87); among the 15 carbapenem-susceptible strains, 4 strains showed a signal at m/z ~40,279. With on-diamond digestion, we confirmed that the captured protein at m/z ~40,279 was related to ADC family extended-spectrum class C beta-lactamase, from A. baumannii. Using this ADC family protein as a biomarker (m/z ~ 40,279) for carbapenem susceptibility testing of A. baumannii, the sensitivity and the specificity could reach 96% and 73% as compared to traditional imipenem susceptibility testing (MIC results). However, the sensitivity and specificity of this method

  20. Detection of gamma-rays with a 3.5 l liquid xenon ionization chamber triggered by the primary scintillation light

    Aprile, E; Chen Dan Li; Muhkerjee, R; Xu Fan

    2002-01-01

    A gridded ionization chamber with a drift length of 4.5 cm and a total volume of 3.5 l, was operated with high-purity liquid xenon and extensively tested with gamma-rays from sup 1 sup 3 sup 7 Cs, sup 2 sup 2 Na and sup 6 sup 0 Co radioactive sources. An electron lifetime in excess of 1 ms was inferred from two independent measurements. The electric field dependence of the collected charge and energy resolution was studied in the range 0.1-4 kV/cm, for different gamma-ray energies. With an electric field of 4 kV/cm, the spectral performance of the detector is consistent with an energy resolution of 5.9% at 1 MeV, scaling with energy as E sup - sup 0 sup . sup 5. The chamber was also used to detect the primary scintillation light produced by gamma-ray interactions in liquid xenon. The light signal was successfully used to trigger the acquisition of the charge signal with a FADC readout. A trigger efficiency of approx 85% was measured at 662 keV.

  1. Chemical analysis of raw and processed Fructus arctii by high-performance liquid chromatography/diode array detection-electrospray ionization-mass spectrometry

    Qin, Kunming; Liu, Qidi; Cai, Hao; Cao, Gang; Lu, Tulin; Shen, Baojia; Shu, Yachun; Cai, Baochang

    2014-01-01

    Background: In traditional Chinese medicine (TCM), raw and processed herbs are used to treat the different diseases. Fructus Arctii, the dried fruits of Arctium lappa l. (Compositae), is widely used in the TCM. Stir-frying is the most common processing method, which might modify the chemical compositions in Fructus Arctii. Materials and Methods: To test this hypothesis, we focused on analysis and identification of the main chemical constituents in raw and processed Fructus Arctii (PFA) by high-performance liquid chromatography/diode array detection-electrospray ionization-mass spectrometry. Results: The results indicated that there was less arctiin in stir-fried materials than in raw materials. however, there were higher levels of arctigenin in stir-fried materials than in raw materials. Conclusion: We suggest that arctiin reduced significantly following the thermal conversion of arctiin to arctigenin. In conclusion, this finding may shed some light on understanding the differences in the therapeutic values of raw versus PFA in TCM. PMID:25422559

  2. High performance liquid chromatography (HPLC fingerprints and primary structure identification of corn peptides by HPLC-diode array detection and HPLC-electrospray ionization tandem mass spectrometry

    Chi Wang

    2016-01-01

    Full Text Available Corn peptides (CPs are reported to have many biological functions, such as facilitating alcohol metabolism, antioxidation, antitumor, antihypertension, and hepatoprotection. To develop a method for quality control, the high-performance liquid chromatography (HPLC system was applied. Twenty-eight common peaks were found in all the CPs of corn samples from Enshi, China, based on which, a fingerprinting chromatogram was established for use in quality control in future research. Subsequently, the major chemical constituents of these common peaks were identified respectively using the HPLC-diode-array detection electrospray ionization tandem mass spectrometry (DAD-ESI-MS/MS system, and 48 peptide fractions were determined ultimately. This was the first time for the majority of these peptides to be reported, and many of them contained amino acids of glutamine (Q, L and A, which might play an important role in the exhibition of the bioactivities of CPs. Many peptides had a similar primary structure to the peptides which had been proven to be bioactive such as facilitating alcohol metabolism, scavenging free radicals, and inhibiting lipid peroxidation. This systematical analysis of the primary structure of CPs facilitated subsequent studies on the relationship between the structures and functions, and could accelerate holistic research on CPs.

  3. Ammonium Sulfate Improves Detection of Hydrophilic Quaternary Ammonium Compounds through Decreased Ion Suppression in Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry.

    Sugiyama, Eiji; Masaki, Noritaka; Matsushita, Shoko; Setou, Mitsutoshi

    2015-11-17

    Hydrophilic quaternary ammonium compounds (QACs) include derivatives of carnitine (Car) or choline, which are known to have essential bioactivities. Here we developed a technique for improving the detection of hydrophilic QACs using ammonium sulfate (AS) in matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS). In MALDI mass spectrometry for brain homogenates, the addition of AS greatly increased the signal intensities of Car, acetylcarnitine (AcCar), and glycerophosphocholine (GPC) by approximately 300-, 700-, and 2500-fold. The marked improvement required a higher AS concentration than that needed for suppressing the potassium adduction on phosphatidylcholine and 2,5-dihydroxybenzoic acid. Adding AS also increased the signal intensities of Car, AcCar, and GPC by approximately 10-, 20-, and 40-fold in MALDI-IMS. Consequently, the distributions of five hydrophilic QACs (Car, AcCar, GPC, choline, and phosphocholine) were simultaneously visualized by this technique. The distinct mechanism from other techniques such as improved matrix application, derivatization, or postionization suggests the great potential of AS addition to achieve higher sensitivity of MALDI-IMS for various analytes.

  4. Analysis of phenolic compounds from different morphological parts of Helichrysum devium by liquid chromatography with on-line UV and electrospray ionization mass spectrometric detection.

    Gouveia, Sandra C; Castilho, Paula C

    2009-12-01

    A simple and rapid method has been used for the screening and identification of the main phenolic compounds from Helichrysum devium using high-performance liquid chromatography with on-line UV and electrospray ionization mass spectrometric detection (LC-DAD/ESI-MS(n)). The total aerial parts and different morphological parts of the plant, namely leaves, flowers and stems, were analyzed separately. A total of 34 compounds present in the methanolic extract from Helichrysum devium were identified or tentatively characterized based on their UV and mass spectra and retention times. Three of these compounds were positively identified by comparison with reference standards. The phenolic compounds included derivatives of quinic acid, O-glycosylated flavonoids, a caffeic acid derivative and a protocatechuic acid derivative. The characteristic loss of 206 Da from malonylcaffeoyl quinic acid was used to confirm the malonyl linkage to the caffeoyl group. This contribution presents one of the first reports on the analysis of phenolic compounds from Helichrysum devium using LC-DAD/ESI-MS(n) and highlights the prominence of quinic acid derivatives as the main group of phenolic compounds present in these extracts. We also provide evidence that the methanolic extract from the flowers was significantly more complex when compared to that of other morphological parts. Copyright 2009 John Wiley & Sons, Ltd.

  5. Supercritical fluid chromatography-photodiode array detection-electrospray ionization mass spectrometry as a framework for impurity fate mapping in the development and manufacture of drug substances.

    Pirrone, Gregory F; Mathew, Rose M; Makarov, Alexey A; Bernardoni, Frank; Klapars, Artis; Hartman, Robert; Limanto, John; Regalado, Erik L

    2018-03-30

    Impurity fate and purge studies are critical in order to establish an effective impurity control strategy for approval of the commercial filing application of new medicines. Reversed phase liquid chromatography-diode array-mass spectrometry (RPLC-DAD-MS) has traditionally been the preferred tool for impurity fate mapping. However, separation of some reaction mixtures by LC can be very problematic requiring combination LC-UV for area % analysis and a different LC-MS method for peak identification. In addition, some synthetic intermediates might be chemically susceptible to the aqueous conditions used in RPLC separations. In this study, the use of supercritical fluid chromatography-photodiode array-electrospray ionization mass spectrometry (SFC-PDA-ESIMS) for fate and purge of two specified impurities in the 1-uridine starting material from the synthesis of a bis-piv 2'keto-uridine, an intermediate in the synthesis of uprifosbuvir, a treatment under investigation for chronic hepatitis C infection. Readily available SFC instrumentation with a Chiralpak IC column (4.6 × 150 mm, 3 μm) and ethanol: carbon dioxide based mobile phase eluent enabled the separation of closely related components from complex reaction mixtures where RLPC failed to deliver optimal chromatographic performance. These results illustrate how SFC combined with PDA and ESI-MS detection can become a powerful tool for direct impurity fate mapping across multiple reaction steps. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Rapid detection of porins by matrix-assisted laser desorption/ionization-time of flight mass spectrometry

    Yanyan eHU

    2015-08-01

    Full Text Available The rapid and cost-efficient determination of carbapenem resistance is an important prerequisite for the choice of an adequate antibiotic therapy. A MALDI-TOF MS-based assay was set up to detect porins in the current study. A loss of the components of porin alone such as OmpK35/OmpK36 or together with the production of carbapenemases will augment the carbapenem resistance. Ten strains of E. coli and eight strains of K. pneumoniae were conducted for both SDS-PAGE and MALDI-TOF MS analysis. MALDI-TOF/TOF MS analysis was then performed to verify the corrospondence of proteins between SDS-PAGE and MALDI-TOF MS. The results indicated that the mass spectrum of ca. 35,000-m/z, 37,000-m/z and 38,000-m/z peaks of E. coli ATCC 25922 corresponded to OmpA, OmpC and OmpF with molecular weight of approximately ca. 38 kDa, 40 kDa and 41 kDa in SDS-PAGE gel, respectively. The band of OmpC and OmpF porins were unable to be distinguished by SDS-PAGE, whereas it was easy to be differentiated by MALDI-TOF MS. As for K. pneumoniae isolates, the mass spectrum of ca. 36,000-m/z and 38,600-m/z peaks was observed corresponding to OmpA and OmpK36 with molecular weight of approximately ca. 40 kDa and 42 kDa in SDS-PAGE gel, respectively. Porin OmpK35 was not observed in the current SDS-PAGE, while a 37,000-m/z peak was found in K. pneumoniae ATCC 13883 and carbapenem-susceptible strains by MALDI-TOF MS which was presumed to be the characteristic peak of the OmpK35 porin. Compared with SDS-PAGE, MALDI-TOF MS is able to rapidly identify the porin-deficient strains within half an hour with better sensitivity, less cost, and is easier to operate and has less interference.

  7. A Simultaneous Analytical Method to Profile Non-Volatile Components with Low Polarity Elucidating Differences Between Tobacco Leaves Using Atmospheric Pressure Chemical Ionization Mass Spectrometry Detection

    Ishida Naoyuki

    2016-04-01

    Full Text Available A comprehensive analytical method using liquid chromatography atmospheric pressure chemical ionization mass spectrometry detector (LC/APCI-MSD was developed to determine key non-volatile components with low polarity elucidating holistic difference among tobacco leaves. Nonaqueous reversed-phase chromatography (NARPC using organic solvent ensured simultaneous separation of various components with low polarity in tobacco resin. Application of full-scan mode to APCI-MSD hyphenated with NARPC enabled simultaneous detection of numerous intense product ions given by APCI interface. Parameters for data processing to filter, feature and align peaks were adjusted in order to strike a balance between comprehensiveness and reproducibility in analysis. 63 types of components such as solanesols, chlorophylls, phytosterols, triacylglycerols, solanachromene and others were determined on total ion chromatograms according to authentic components, wavelength spectrum and mass spectrum. The whole area of identified entities among the ones detected on total ion chromatogram reached to over 60% and major entities among those identified showed favorable linearity of determination coefficient of over 0.99. The developed method and data processing procedure were therefore considered feasible for subsequent multivariate analysis. Data matrix consisting of a number of entities was then subjected to principal component analysis (PCA and hierarchical clustering analysis. Cultivars of tobacco leaves were distributed far from each cultivar on PCA score plot and each cluster seemed to be characterized by identified non-volatile components with low polarity. While fluecured Virginia (FCV was loaded by solanachromene, phytosterol esters and triacylglycerols, free phytosterols and chlorophylls loaded Burley (BLY and Oriental (ORI respectively. Consequently the whole methodology consisting of comprehensive method and data processing procedure proved useful to determine key

  8. Ionization detector

    Steele, D.S.

    1987-01-01

    An ionization detector having an array of detectors has, for example, grounding pads positioned in the spaces between some detectors (data detectors) and other detectors (reference detectors). The grounding pads are kept at zero electric potential, i.e. grounded. The grounding serves to drain away electrons and thereby prevent an unwanted accumulation of charge in the spaces, and cause the electric field lines to be more perpendicular to the detectors in regions near the grounding pads. Alternatively, no empty space is provided there being additional, grounded, detectors provided between the data and reference detectors. (author)

  9. Research on flame retardation of wool fibers

    Enomoto, Ichiro; Ametani, Kazuo; Sawai, Takeshi

    1990-01-01

    Flame retardant, vinyl phosphonate oligomer, was uniformly impregnated in wool fibers, and by irradiating low energy electron beam or cobalt-60 gamma ray, the flame retardation of fabrics was attempted, as the results, the following knowledges were obtained. At the rate of sticking of flame retardant lower than that in cotton fabrics, sufficient flame retarding property can be given. The flame retarding property withstands 30 times of washing. The lowering of strength due to the processing hardly arose. For the flame retardation, gamma-ray was more effective than electron beam. Since the accidents of burning clothes have occurred frequently, their flame retardation has been demanded. So far the flame retardation of cotton fabrics has been advanced, but this time the research on the flame retardation of wool fabrics was carried out by the same method. The experimental method is explained. As for the performance of the processed fabrics, the rate of sticking of the flame retardant, the efficiency of utilization, the flame retarding property, the endurance in washing and the tensile and tearing strength were examined. As the oxygen index was higher, the flame retarding property was higher, and in the case of the index being more than 27, the flame retarding property is sufficient, that is, the rate of sticking of 6% in serge and 5% in muslin. (K.I.)

  10. Extension of the Gladstone-Dale equation for flame flow field diagnosis by optical computerized tomography

    Chen Yunyun; Li Zhenhua; Song Yang; He Anzhi

    2009-01-01

    An extended model of the original Gladstone-Dale (G-D) equation is proposed for optical computerized tomography (OCT) diagnosis of flame flow fields. For the purpose of verifying the newly established model, propane combustion is used as a practical example for experiment, and moire deflection tomography is introduced with the probe wavelength 808 nm. The results indicate that the temperature based on the extended model is more accurate than that based on the original G-D equation. In a word, the extended model can be suitable for all kinds of flame flow fields whatever the components, temperature, and ionization are.

  11. Establishment of analysis method for methane detection by gas chromatography

    Liu, Xinyuan; Yang, Jie; Ye, Tianyi; Han, Zeyu

    2018-02-01

    The study focused on the establishment of analysis method for methane determination by gas chromatography. Methane was detected by hydrogen flame ionization detector, and the quantitative relationship was determined by working curve of y=2041.2x+2187 with correlation coefficient of 0.9979. The relative standard deviation of 2.60-6.33% and the recovery rate of 96.36%∼105.89% were obtained during the parallel determination of standard gas. This method was not quite suitable for biogas content analysis because methane content in biogas would be over the measurement range in this method.

  12. Matrix-assisted laser desorption/ionization time-of-flight and nano-electrospray ionization ion trap mass spectrometric characterization of 1-cyano-2-substituted-benz[f]isoindole derivatives of peptides for fluorescence detection

    Linnemayr, K; Brückner, A; Körner, R

    1999-01-01

    A series of hexa- to decapeptides (molecular mass range 800-1200) were labeled with naphthalene-2,3-dicarboxaldehyde, which preferentially reacts with the primary amino groups of a peptide. A highly stable peptide conjugate is formed, which allows selective analysis by fluorescence at excitation...... and emission wavelengths of 420 and 490 nm, respectively. After removal of unreacted compounds, the peptide conjugates were characterized by matrix-assisted laser desorption/ionization (MALDI) time-of-flight and nano-electrospray ionization (ESI) ion trap mass spectrometry. They readily form both [M + H]+ ions...... by MALDI and both [M + H]+ and [M + 2H]2+ ions by ESI. Furthermore, the fragmentation behavior of the N-terminally tagged peptides, exhibiting an uncharged N-terminus, was investigated applying post-source decay fragmentation with a curved field reflector and collision-induced dissociation...

  13. Flame visualization in power stations

    Hulshof, H J.M.; Thus, A W; Verhage, A J.L. [KEMA Fossil Generation, Arnhem (Netherlands)

    1994-01-01

    The study on the title subject is aimed at the determination of the form of the flame and the radiation temperature of the flames of the burners in electric power plants. The adjustment of the burners in a boiler is assessed on the basis of the total performance, in which the NO[sub x]- and CO-concentrations in the flue gases are normative. By comparing the burners mutually, deviating adjustments can be observed, applying optical monitoring techniques. Measurements have been carried out of the coal flames in the unit Gelderland13 of the Dutch energy production company EPON and of the gas flames at the Claus plant A and B of the Dutch energy company EPZ. The final aim of the title study is to draft guidelines, based on the measured flame data, by means of which for every individual burner the adjustment of the fuel supply, the relation with the air supply and the swirl of the combustion air can be optimized

  14. Role of the outer-edge flame on flame extinction in nitrogen-diluted non-premixed counterflow flames with finite burner diameters

    Chung, Yong Ho

    2013-03-01

    This study of nitrogen-diluted non-premixed counterflow flames with finite burner diameters investigates the important role of the outer-edge flame on flame extinction through experimental and numerical analyses. It explores flame stability diagrams mapping the flame extinction response of nitrogen-diluted non-premixed counterflow flames to varying global strain rates in terms of burner diameter, burner gap, and velocity ratio. A critical nitrogen mole fraction exists beyond which the flame cannot be sustained; the critical nitrogen mole fraction versus global strain rate curves have C-shapes for various burner diameters, burner gaps, and velocity ratios. At sufficiently high strain-rate flames, these curves collapse into one curve; therefore, the flames follow the one-dimensional flame response of a typical diffusion flame. Low strain-rate flames are significantly affected by radial conductive heat loss, and therefore flame length. Three flame extinction modes are identified: flame extinction through shrinkage of the outer-edge flame with or without oscillations at the outer-edge flame prior to the extinction, and flame extinction through a flame hole at the flame center. The extinction modes are significantly affected by the behavior of the outer-edge flame. Detailed explanations are provided based on the measured flame-surface temperature and numerical evaluation of the fractional contribution of each term in the energy equation. Radial conductive heat loss at the flame edge to ambience is the main mechanism of extinction through shrinkage of the outer-edge flame in low strain-rate flames. Reduction of the burner diameter can extend the flame extinction mode by shrinking the outer-edge flame in higher strain-rate flames. © 2012 Elsevier Ltd. All rights reserved.

  15. Flame Retardants Used in Flexible Polyurethane Foam

    The partnership project on flame retardants in furniture seeks to update the health and environmental profiles of flame-retardant chemicals that meet fire safety standards for upholstered consumer products with polyurethane foam

  16. Detection of atmospheric gaseous amines and amides by a high-resolution time-of-flight chemical ionization mass spectrometer with protonated ethanol reagent ions

    L. Yao

    2016-11-01

    Full Text Available Amines and amides are important atmospheric organic-nitrogen compounds but high time resolution, highly sensitive, and simultaneous ambient measurements of these species are rather sparse. Here, we present the development of a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS method, utilizing protonated ethanol as reagent ions to simultaneously detect atmospheric gaseous amines (C1 to C6 and amides (C1 to C6. This method possesses sensitivities of 5.6–19.4 Hz pptv−1 for amines and 3.8–38.0 Hz pptv−1 for amides under total reagent ion signals of  ∼  0.32 MHz. Meanwhile, the detection limits were 0.10–0.50 pptv for amines and 0.29–1.95 pptv for amides at 3σ of the background signal for a 1 min integration time. Controlled characterization in the laboratory indicates that relative humidity has significant influences on the detection of amines and amides, whereas the presence of organics has no obvious effects. Ambient measurements of amines and amides utilizing this method were conducted from 25 July to 25 August 2015 in urban Shanghai, China. While the concentrations of amines ranged from a few parts per trillion by volume to hundreds of parts per trillion by volume, concentrations of amides varied from tens of parts per trillion by volume to a few parts per billion by volume. Among the C1- to C6-amines, the C2-amines were the dominant species with concentrations up to 130 pptv. For amides, the C3-amides (up to 8.7 ppb were the most abundant species. The diurnal and backward trajectory analysis profiles of amides suggest that in addition to the secondary formation of amides in the atmosphere, industrial emissions could be important sources of amides in urban Shanghai. During the campaign, photo-oxidation of amines and amides might be a main loss pathway for them in daytime, and wet deposition was also an important sink.

  17. Experiment and Simulation of Autoignition in Jet Flames and its Relevance to Flame Stabilization and Structure

    Al-Noman, Saeed M.

    2016-01-01

    temperature coflow air were studied numerically. Several flame configurations were investigated by varying the initial temperature and fuel mole fraction. Characteristics of chemical kinetics structures for autoignited lifted flames were discussed based on the kinetic structures of homogeneous autoignition and flame propagation of premixed mixtures. Results showed that for autoignited lifted flame with tribrachial structure, a transition from autoignition to flame propagation modes occurs for reasonably stoichiometric mixtures. Characteristics of Mild combustion can be treated as an autoignited lean premixed lifted flame. Transition behavior from Mild combustion to a nozzle-attached flame was also investigated by increasing the fuel mole fraction.

  18. Flame emission, atomic absorption and fluorescence spectrometry

    Horlick, G.

    1980-01-01

    Six hundred and thirty references are cited in this review. The information in the review is divided into 12 major areas: books, reviews, and bibliographies; fundamental studies in flames; developments in instrumentation; measurement techniques and procedure; flame emission spectrometry; flame atomic absorption spectrometry; flame molecular absorption spectrometry; electrothermal atomization atomic absorption spectroscopy; hydride generation techniques; graphite furnace atomic emission spectrometry; atomic fluorescence spectrometry; and analytical comparisons

  19. 30 CFR 14.20 - Flame resistance.

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Flame resistance. 14.20 Section 14.20 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF... § 14.20 Flame resistance. Conveyor belts for use in underground coal mines must be flame-resistant and...

  20. TURBULENT OXYGEN FLAMES IN TYPE Ia SUPERNOVAE

    Aspden, A. J.; Bell, J. B.; Woosley, S. E.

    2011-01-01

    In previous studies, we examined turbulence-flame interactions in carbon-burning thermonuclear flames in Type Ia supernovae. In this study, we consider turbulence-flame interactions in the trailing oxygen flames. The two aims of the paper are to examine the response of the inductive oxygen flame to intense levels of turbulence, and to explore the possibility of transition to detonation in the oxygen flame. Scaling arguments analogous to the carbon flames are presented and then compared against three-dimensional simulations for a range of Damkoehler numbers (Da 16 ) at a fixed Karlovitz number. The simulations suggest that turbulence does not significantly affect the oxygen flame when Da 16 16 >1, turbulence enhances heat transfer and drives the propagation of a flame that is narrower than the corresponding inductive flame would be. Furthermore, burning under these conditions appears to occur as part of a combined carbon-oxygen turbulent flame with complex compound structure. The simulations do not appear to support the possibility of a transition to detonation in the oxygen flame, but do not preclude it either.

  1. Hysteresis and transition in swirling nonpremixed flames

    Tummers, M.J.; Hübner, A.W.; van Veen, E.H.; Hanjalic, K.; van der Meer, Theodorus H.

    2009-01-01

    Strongly swirling nonpremixed flames are known to exhibit a hysteresis when transiting from an attached long, sooty, yellow flame to a short lifted blue flame, and vice versa. The upward transition (by increasing the air and fuel flow rates) corresponds to a vortex breakdown, i.e. an abrupt change

  2. Optimization of the energy resolution and of the radioactive background rejection for ionization-heat detectors equipped with thermometric thin films for the direct WIMPs detection

    Dolgorouky, Y.W.

    2008-09-01

    The EDELWEISS experiment aims at the direct detection of WIMPs as possible candidates for dark matter. It uses heat-and-ionization detectors that can discriminate these particles from the radioactive background. To date, this method is limited by events with incomplete charge collection that occur just beneath the detectors electrodes. In order to identify and reject these undesirable events, we have developed detectors equipped with thin films used both as thermometers - and hence sensitive to the transient athermal regime - and as electrodes for the charge collection. This thesis focuses on the optimization of such thin films regarding surface events rejection and on the modelling of the physical processes enabling this identification. The optimization must both maximize the fiducial volume and conserve an energy resolution such that the recoil energy threshold is of the order of 30 keV. Our work explores four generations of detectors each of which corresponds to successive evolutions in their conception. In all cases, the electrode-thermometer is an amorphous Anderson insulator NbSi thin film polarized by two interleaved comb-shaped niobium electrodes. In spite of constant progress in the successive detectors performances, the latest generation does not display the performances required for the EDELWEISS II experiment. Our work has shown the difficulty of the transient thermal signal modelling due to the complex contribution of the charge collection. This works has lead to new ideas regarding the detectors configuration, so that the athermal regime can be optimized to enhance both the rejection capability and the resolution. (author)

  3. Metabolite fingerprinting of Punica granatum L. (pomegranate) polyphenols by means of high-performance liquid chromatography with diode array and electrospray ionization-mass spectrometry detection.

    Brighenti, Virginia; Groothuis, Sebastiaan Frearick; Prencipe, Francesco Pio; Amir, Rachel; Benvenuti, Stefania; Pellati, Federica

    2017-01-13

    The present study was aimed at the development of a new analytical method for the comprehensive multi-component analysis of polyphenols in Punica granatum L. (pomegranate) juice and peel. While pomegranate juice was directly analysed after simple centrifugation, different extraction techniques, including maceration, heat reflux extraction, ultrasound-assisted extraction and microwave-assisted extraction, were compared in order to obtain a high yield of the target analytes from pomegranate peel. Dynamic maceration with a mixture of water and ethanol 80:20 (v/v) with 0.1% of hydrochloric acid as the extraction solvent provided the best result in terms of recovery of pomegranate secondary metabolites. The quali- and quantitative analysis of pomegranate polyphenols was performed by high-performance liquid chromatography with diode array and electrospray ionization-mass spectrometry detection. The application of fused-core column technology allowed us to obtain an improvement of the chromatographic performance in comparison with that of conventional particulate stationary phases, thus enabling a good separation of all constituents in a shorter time and with low solvent usage. The analytical method was completely validated to show compliance with the International Conference on Harmonization of Technical Requirements for the Registration of Pharmaceuticals for Human Use guidelines and successfully applied to the characterisation of commercial and experimental pomegranate samples, thus demonstrating its efficiency as a tool for the fingerprinting of this plant material. The quantitative data collected were submitted to principal component analysis, in order to highlight the possible presence of pomegranate samples with high content of secondary metabolites. From the statistical analysis, four experimental samples showed a notable content of bioactive compounds in the peels, while commercial ones still represent the best source of healthy juice. Copyright © 2016 Elsevier

  4. Ionizing radiations

    2009-01-01

    After having recalled some fundamental notions and measurement units related to ionizing radiations, this document describes various aspects of natural and occupational exposures: exposure modes and sources, exposure levels, biological effects, health impacts. Then, it presents prevention principles aimed at, in an occupational context of use of radiation sources (nuclear industry excluded), reducing and managing these exposures: risk assessment, implementation of safety from the front end. Some practical cases illustrate the radiation protection approach. The legal and regulatory framework is presented: general notions, worker exposure, measures specific to some worker categories (pregnant and breast feeding women, young workers, temporary workers). A last part describes what is to be done in case of incident or accident (dissemination of radioactive substances from unsealed sources, anomaly occurring when using a generator or a sealed source, post-accident situation)

  5. Experimental characterization of methane inverse diffusion flame

    Elbaz, Ayman M.

    2014-06-26

    This article presents 10-kHz images of OH-PLIF simultaneously with 2-D PIV measurements in an inverse methane diffusion flame. Under a constant fuel flow rate, the central air jet Re was varied, leading to air to fuel velocity ratio, Vr, to vary from 8.3 to 66.5. Starting from Vr = 20.7, the flame is commonly characterized by three distinct zones. The length of the lower fuel entrainment region is inversely proportional to Vr. The flames investigated resemble a string shear layer confining this zone, and converging into the second distinct region, the flame neck zone. The third region is the rest of the flame, which spreads in a jet-like manner. The inverse diffusion flames exhibit varying degrees of partial premixing, depending upon on the velocity ratio Vr, and this region of partial premixing evolves into a well-mixed reaction zone along the flame centerline. The OH distribution correlated with the changes in the mean characteristics of the flow through reduction in the local Reynolds number due to heat release. The existence of a flame suppresses or laminarizes the turbulence at early axial locations and promotes fluctuations at the flame tip for flames with Vr < 49.8. In addition, the flame jet width can be correlated to the OH distribution. In upstream regions of the flames, the breaks in OH are counterbalanced by flame closures and are governed by edge flame propagation. These local extinctions were found to occur at locations where large flow structures were impinging on the flame and are associated with a locally higher strain rate or correlated to the local high strain rates at the flame hole edges without this flow impinging. Another contributor to re-ignition was found to be growing flame kernels. As the flames approach global blow-off, these kernels become the main mechanism for re-ignition further downstream of the flames. At low Vr, laminarization within the early regions of the flame provides an effective shield, preventing the jet flow from

  6. Detection of formaldehyde emissions from an industrial zone in the Yangtze River Delta region of China using a proton transfer reaction ion-drift chemical ionization mass spectrometer

    Ma, Yan; Diao, Yiwei; Zhang, Bingjie; Wang, Weiwei; Ren, Xinrong; Yang, Dongsen; Wang, Ming; Shi, Xiaowen; Zheng, Jun

    2016-12-01

    A proton transfer reaction ion-drift chemical ionization mass spectrometer (PTR-ID-CIMS) equipped with a hydronium (H3+O) ion source was developed and deployed near an industrial zone in the Yangtze River Delta (YRD) region of China in spring 2015 to investigate industry-related emissions of volatile organic compounds (VOCs). Air pollutants including formaldehyde (HCHO), aromatics, and other trace gases (O3 and CO) were simultaneously measured. Humidity effects on the sensitivity of the PTR-ID-CIMS for HCHO detection were investigated and quantified. The performances of the PTR-ID-CIMS were also validated by intercomparing with offline HCHO measurement technique using 2,4-dinitrophenylhydrazone (DNPH) cartridges and the results showed fairly good agreement (slope = 0.81, R2 = 0.80). The PTR-ID-CIMS detection limit of HCHO (10 s, three-duty-cycle averages) was determined to be 0.9-2.4 (RH = 1-81.5 %) parts per billion by volume (ppbv) based on 3 times the standard deviations of the background signals. During the field study, observed HCHO concentrations ranged between 1.8 and 12.8 ppbv with a campaign average of 4.1 ± 1.6 ppbv, which was comparable with previous HCHO observations in other similar locations of China. However, HCHO diurnal profiles showed few features of secondary formation. In addition, time series of both HCHO and aromatic VOCs indicated strong influence from local emissions. Using a multiple linear regression fit model, on average the observed HCHO can be attributed to secondary formation (13.8 %), background level (27.0 %), and industry-related emissions, i.e., combustion sources (43.2 %) and chemical productions (16.0 %). Moreover, within the plumes the industry-related emissions can account for up to 69.2 % of the observed HCHO. This work has provided direct evidence of strong primary emissions of HCHO from industry-related activities. These primary HCHO sources can potentially have a strong impact on local and regional air pollution formation

  7. The VLT FLAMES Tarantula Survey

    Evans, C.; Taylor, W.; Sana, H.; Hénault-Brunet, V.; Bagnoli, T.; Bastian, N.; Bestenlehner, J.; Bonanos, A.; Bressert, E.; Brott, I.; Campbell, M.; Cantiello, M.; Carraro, G.; Clark, S.; Costa, E.; Crowther, P.; de Koter, A.; de Mink, S.; Doran, E.; Dufton, P.; Dunstall, P.; Garcia, M.; Gieles, M.; Gräfener, G.; Herrero, A.; Howarth, I.; Izzard, R.; Köhler, K.; Langer, N.; Lennon, D.; Maíz Apellániz, J.; Markova, N.; Najarro, P.; Puls, J.; Ramirez, O.; Sabín-Sanjulián, C.; Simón-Díaz, S.; Smartt, S.; Stroud, V.; van Loon, J.; Vink, J.S.; Walborn, N.

    2011-01-01

    We introduce the VLT FLAMES Tarantula Survey, an ESO Large Programme from which we have obtained optical spectroscopy of over 800 massive stars in the spectacular 30 Doradus region of the Large Magellanic Cloud. A key feature is the use of multi-epoch observations to provide strong constraints on

  8. Experimental Study of Hydrogen Addition Effects on a Swirl-Stabilized Methane-Air Flame

    Mao Li

    2017-11-01

    Full Text Available The effects of H2 addition on a premixed methane-air flame was studied experimentally with a swirl-stabilized gas turbine model combustor. Experiments with 0%, 25%, and 50% H2 molar fraction in the fuel mixture were conducted under atmospheric pressure. The primary objectives are to study the impacts of H2 addition on flame lean blowout (LBO limits, flame shapes and anchored locations, flow field characteristics, precessing vortex core (PVC instability, as well as the CO emission performance. The flame LBO limits were identified by gradually reducing the equivalence ratio until the condition where the flame physically disappeared. The time-averaged CH chemiluminescence was used to reveal the characteristics of flame stabilization, e.g., flame structure and stabilized locations. In addition, the inverse Abel transform was applied to the time-averaged CH results so that the distribution of CH signal on the symmetric plane of the flame was obtained. The particle image velocimetry (PIV was used to detect the characteristics of the flow field with a frequency of 2 kHz. The snapshot method of POD (proper orthogonal decomposition and fast Fourier transform (FFT were adopted to capture the most prominent coherent structures in the turbulent flow field. CO emission was monitored with an exhaust probe that was installed close to the combustor exit. The experimental results indicated that the H2 addition extended the flame LBO limits and the operation range of low CO emission. The influence of H2 addition on the flame shape, location, and flow field was observed. With the assistance of POD and FFT, the combustion suppression impacts on PVC was found.

  9. Flex-flame burner and combustion method

    Soupos, Vasilios; Zelepouga, Serguei; Rue, David M.; Abbasi, Hamid A.

    2010-08-24

    A combustion method and apparatus which produce a hybrid flame for heating metals and metal alloys, which hybrid flame has the characteristic of having an oxidant-lean portion proximate the metal or metal alloy and having an oxidant-rich portion disposed above the oxidant lean portion. This hybrid flame is produced by introducing fuel and primary combustion oxidant into the furnace chamber containing the metal or metal alloy in a substoichiometric ratio to produce a fuel-rich flame and by introducing a secondary combustion oxidant into the furnace chamber above the fuel-rich flame in a manner whereby mixing of the secondary combustion oxidant with the fuel-rich flame is delayed for a portion of the length of the flame.

  10. Simulation of flame surface density and burning rate of a premixed turbulent flame using contour advection

    Tang, B.H.Y.; Chan, C.K. [Department of Applied Mathematics, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

    2006-10-15

    In this paper, a 2-dimensional rod-stabilized V-shaped flame is simulated using contour advection with surgery as well as the random vortex method. Effects of turbulence on various quantities, such as flame brush thickness and flame surface density, are investigated. The flame surface density S is estimated using the Bray-Moss-Libby formulation, which involves the use of a mean orientation factor {sigma}{sub c}. As a comparison, values of S are also obtained using Shepherd's model, which employs the values of mean flame surface area and mean flame length. Local flame structure is characterized in terms of turbulent flame brush, orientation factor, and flame surface density. Profiles of S obtained using the two different models are compared and show that discrepancy is more evident with increasing turbulence intensity. (author)

  11. A flame particle tracking analysis of turbulence–chemistry interaction in hydrogen–air premixed flames

    Uranakara, Harshavardhana A.; Chaudhuri, Swetaprovo; Dave, Himanshu L.; Arias, Paul G.; Im, Hong G.

    2015-01-01

    Interactions of turbulence, molecular transport, and energy transport, coupled with chemistry play a crucial role in the evolution of flame surface geometry, propagation, annihilation, and local extinction/re-ignition characteristics of intensely turbulent premixed flames. This study seeks to understand how these interactions affect flame surface annihilation of lean hydrogen–air premixed turbulent flames. Direct numerical simulations (DNSs) are conducted at different parametric conditions with a detailed reaction mechanism and transport properties for hydrogen–air flames. Flame particle tracking (FPT) technique is used to follow specific flame surface segments. An analytical expression for the local displacement flame speed (Sd) of a temperature isosurface is considered, and the contributions of transport, chemistry, and kinematics on the displacement flame speed at different turbulence-flame interaction conditions are identified. In general, the displacement flame speed for the flame particles is found to increase with time for all conditions considered. This is because, eventually all flame surfaces and their resident flame particles approach annihilation by reactant island formation at the end of stretching and folding processes induced by turbulence. Statistics of principal curvature evolving in time, obtained using FPT, suggest that these islands are ellipsoidal on average enclosing fresh reactants. Further examinations show that the increase in Sd is caused by the increased negative curvature of the flame surface and eventual homogenization of temperature gradients as these reactant islands shrink due to flame propagation and turbulent mixing. Finally, the evolution of the normalized, averaged, displacement flame speed vs. stretch Karlovitz number are found to collapse on a narrow band, suggesting that a unified description of flame speed dependence on stretch rate may be possible in the Lagrangian description.

  12. A flame particle tracking analysis of turbulence–chemistry interaction in hydrogen–air premixed flames

    Uranakara, Harshavardhana A.

    2015-11-21

    Interactions of turbulence, molecular transport, and energy transport, coupled with chemistry play a crucial role in the evolution of flame surface geometry, propagation, annihilation, and local extinction/re-ignition characteristics of intensely turbulent premixed flames. This study seeks to understand how these interactions affect flame surface annihilation of lean hydrogen–air premixed turbulent flames. Direct numerical simulations (DNSs) are conducted at different parametric conditions with a detailed reaction mechanism and transport properties for hydrogen–air flames. Flame particle tracking (FPT) technique is used to follow specific flame surface segments. An analytical expression for the local displacement flame speed (Sd) of a temperature isosurface is considered, and the contributions of transport, chemistry, and kinematics on the displacement flame speed at different turbulence-flame interaction conditions are identified. In general, the displacement flame speed for the flame particles is found to increase with time for all conditions considered. This is because, eventually all flame surfaces and their resident flame particles approach annihilation by reactant island formation at the end of stretching and folding processes induced by turbulence. Statistics of principal curvature evolving in time, obtained using FPT, suggest that these islands are ellipsoidal on average enclosing fresh reactants. Further examinations show that the increase in Sd is caused by the increased negative curvature of the flame surface and eventual homogenization of temperature gradients as these reactant islands shrink due to flame propagation and turbulent mixing. Finally, the evolution of the normalized, averaged, displacement flame speed vs. stretch Karlovitz number are found to collapse on a narrow band, suggesting that a unified description of flame speed dependence on stretch rate may be possible in the Lagrangian description.

  13. Chemical ionization mass spectrometry of indol-3yl-acetic acid and cis-abscisic acid: evaluation of negative ion detection and quantification of cis-abscisic acid in growing maize roots

    Rivier, L.; Saugy, M.

    1986-01-01

    Mass spectra of the derivatives of indol-3yl-acetic acid and cis-abscisic acid were obtained in electron impact and chemical ionization positive ion and negative ion modes. The respective merits of methane, isobutane, and ammonia as reagent gases for structure determination and sensitive detection were compared using the methyl esters. From one to 10 fluorine atoms were attached to IAA to improve the electron-capturing properties of the molecule. The best qualitative information was obtained when using positive ion chemical ionization with methane. However, the most sensitive detection, with at least two ions per molecule, was achieved by electron impact on the IAA-HFB-ME derivative and by negative ion chemical ionization with NH 3 on the ABA-methyl ester derivative. p ]Quantitative analyses of ABA in different parts of maize (Zea mays cv. LG 11) root tips were performed by the latter technique. It was found that the cap and apex contained less ABA than the physiologically older parts of the root such as the elongation zone and the more differentiated tissues. This technique was also used to show a relation between maize root growth and the endogenous ABA level of the elongation zone and root tip: there is more ABA in the slowly growing roots than in the rapidly growing ones. (author)

  14. Study and optimization of bolometers designed to measure both ionization and heat in order to detect black matter; Etude et optimisation de bolometres a mesure simultanee de l`ionisation et de la chaleur pour la recherche de matiere noire

    Navick, X F

    1997-09-25

    The detection of black matter in the form of wimp (weakly interactive massive particle) requires the identification of the incident particle so that events due to wimp interactions can be set apart from events due to surrounding radioactivity. Bolometers allow to measure both the energy deposited and the ionization made by a particle. The amount of energy is determined by calorimetry. Wimp detection implies bolometers to run at very low temperature. After a presentation of particle interactions with matter, this thesis describes the physical phenomena involved in heat and ionization measurements. The behaviour of semiconductors at low temperature is investigated and qualitative expectations are drawn about the working of metal-semiconductor interface and the pin diode. An experimental setting is presented. The operating voltage needs to be very low in order to be the least disturbing possible. At so low voltage, a decrease of the ionization signal in terms of time appears. It is shown that this phenomenon is linked to the level density in the forbidden band of the semiconductor and to the intensity of infrared radiation reaching the detector. (A.C.) 193 refs.

  15. Theoretical analysis of the conical premixed flame response to upstream velocity disturbances considering flame speed development effects

    Ghazaleh Esmaeelzade; Mohammad Reza Khani; Rouzbeh Riazi; Mohammad Hossein Sabour

    2017-01-01

    The effect of upstream velocity perturbations on the response of a premixed flame was investigated in terms of the flame transfer function dependency on excitation frequency. In this study, the assumption of constant flame speed was extended and the effect of flame speed development was considered; i.e., the flame speed would grow with the time after ignition or with the distance from a flame-holder. In the present study, the kinematics of a conical flame was investigated by linearization of ...

  16. Ionization detector

    Solomon, E E

    1976-02-27

    This invention concerns a fire detection system making use of a beta source. The ionisation detector includes a first and second chamber respectively comprising a first and second electrode, preferably a plate, with a common electrode separating the first and second chamber. Communication is provided between these chambers through a set of orifices and each chamber also has a set of orifices for communication with the ambient atmosphere. One or both chambers can comprise a particle source, preferably beta. The detector also has an adjustable electrode housed in one of the chambers to regulate the voltage between the fixed electrode of this chamber and the common electrode located between the chambers. The electrodes of the structure are connected to a detection circuit that spots a change in the ionisation current when a fire alarm condition arises. The detection circuit of a new type includes a relaxation oscillator with a programmable unijunction transistor and a light emitting diode.

  17. Ring magnetron ionizer

    Alessi, J.G.

    1986-01-01

    A ring magnetron D - charge exchange ionizer has been built and tested. An H - current of 500 μA was extracted with an estimated H 0 density in the ionizer of 10 12 cm -3 . This exceeds the performance of ionizers presently in use on polarized H - sources. The ionizer will soon be tested with a polarized atomic beam

  18. Atomic and molecular resonance ionization

    Botter, R.; Petit, A.

    1990-01-01

    Published in summary form only the paper recalls the principle of resonance photoionization, transition probability, selectivity and critical parameters. Examples of applications are briefly treated: Trace analysis by resonance ionization mass spectroscopy for detection of Fe in Zr F 4 for fabrication of optical fibers and laser isotopic separation of U 235 and Gd 157 [fr

  19. Effects of thin-layer boilover on flame geometry and dynamics in large hydrocarbon pool fires

    Ferrero, Fabio; Munoz, Miguel; Arnaldos, Josep [Centre d' Estudis del Risc Tecnologic (CERTEC), Chemical Engineering Department, Universitat Politecnica de Catalunya, Diagonal 647, 08028-Barcelona, Catalonia (Spain)

    2007-03-15

    This work aims to estimate the effects of thin-layer boilover on flame geometry and dynamics. A series of large scale experiments (in pools ranging from 1.5 to 6 m in diameter) were performed using gasoline and diesel as fuel. As expected, only diesel showed evidence of this phenomenon. This article presents a summary of the results obtained for flame height, tilt and pulsation. Flame height increases during water ebullition, though the increase is no longer detectable when wind speed exceeds certain values. Correlations previously presented in the literature to predict flame length and tilt were modified in order to fit the results obtained during thin-layer boilover. However, the influence on flame tilt is not as great and the equations for the stationary period seem suitable for the entire fire. Results of flame pulsation during the stationary period fill the gap in the literature for fires between 1.5 and 6 m and fit previous correlations. On the other hand, during ebullition, the flame pulsates faster, as air entrainment is greater and, as one would expect, this effect decreases with pool size. A new equation for estimating pulsation frequency during boilover is proposed. (author)

  20. Understanding premixed flame chemistry of gasoline fuels by comparing quantities of interest

    Selim, Hatem

    2016-07-23

    Gasoline fuels are complex mixtures that vary in composition depending on crude oil feedstocks and refining processes. Gasoline combustion in high-speed spark ignition engines is governed by flame propagation, so understanding fuel composition effects on premixed flame chemistry is important. In this study, the combustion chemistry of low-pressure, burner-stabilized, premixed flames of two gasoline fuels was investigated under stoichiometric conditions. Flame speciation was conducted using vacuum-ultraviolet synchrotron photoionization time-of-flight molecular beam mass spectroscopy. Stable end-products, intermediate hydrocarbons, and free radicals were detected and quantified. In addition, several isomeric species in the reaction pool were distinguished and quantified with the help of the highly tunable synchrotron radiation. A comparison between the products of both flames is presented and the major differences are highlighted. Premixed flame numerical simulations were conducted using surrogate fuel kinetic models for each flame. Furthermore, a new approach was developed to elucidate the main discrepancies between experimental measurements and the numerical predictions by comparing quantities of interest. © 2016.

  1. Derivative flame atomic absorption spectrometry and its application in trace analysis

    Sun, H. W.; Li, L. Q.

    2005-01-01

    Flame atomic absorption spectrometry is an accepted and widely used method for the determination of trace elements in a great variety of samples. But its sensitivity doesn't meet the demands of trace and ultra-trace analysis for some samples. The derivative signal processing technique, with a very high capability for enhancing sensitivity, was developed for flame atomic absorption spectrometry. The signal models of conventional flame atomic absorption spectrometry are described. The equations of derivative signals are established for flame atomic absorption spectrometry, flow injection atomic absorption spectrometry (FI-FAAS) and atom trapping flame atomic absorption spectrometry (AT-FAAS). The principle and performance of the derivative atomic absorption spectrometry are evaluated. The derivative technique based on determination of variation rate of signal intensity with time (dl/dt) is different from the derivative spectrophotometry based on determination of variation rate of signal intensity with wavelength (dl/dhλ). Derivative flame atomic absorption spectrometry has higher sensitivity, lower detection limits and better accuracy. It has been applied to the direct determination of trace elements without preconcentration. If the derivative technique was combined with several preconcentration techniques, the sensitivity would be enhanced further for ultra-trace analysis with good linearity. The applications of derivative flame atomic absorption spectroscopy are reviewed for trace element analysis in biological, pharmaceutical, environmental and food samples

  2. Characterization of fatty acid and triacylglycerol composition in animal fats using silver-ion and non-aqueous reversed-phase high-performance liquid chromatography/mass spectrometry and gas chromatography/flame ionization detection

    Lísa, M.; Netušilová, K.; Franěk, L.; Dvořáková, H.; Vrkoslav, Vladimír; Holčapek, M.

    2011-01-01

    Roč. 1218, č. 42 (2011), s. 7499-7510 ISSN 0021-9673 R&D Projects: GA ČR GA203/09/0139 Institutional research plan: CEZ:AV0Z40550506 Keywords : silver-ion HPLC * non-aqueous reversed-phase HPLC * triacylglycerol Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.531, year: 2011

  3. An experimental and kinetic investigation of premixed furan/oxygen/argon flames.

    Tian, Zhenyu; Yuan, Tao; Fournet, Rene; Glaude, Pierre-Alexandre; Sirjean, Baptiste; Battin-Leclerc, Frédérique; Zhang, Kuiwen; Qi, Fei

    2011-04-01

    The detailed chemical structures of three low-pressure (35 Torr) premixed laminar furan/oxygen/argon flames with equivalence ratios of 1.4, 1.8 and 2.2 have been investigated by using tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry. About 40 combustion species including hydrocarbons and oxygenated intermediates have been identified by measurements of photoionization efficiency spectra. Mole fraction profiles of the flame species including reactants, intermediates and products have been determined by scanning burner position with some selected photon energies near ionization thresholds. Flame temperatures have been measured by a Pt-6%Rh/Pt-30%Rh thermocouple. A new mechanism involving 206 species and 1368 reactions has been proposed whose predictions are in reasonable agreement with measured species profiles for the three investigated flames. Rate-of-production and sensitivity analyses have been performed to track the key reaction paths governing furan consumption for different equivalence ratios. Both experimental and modeling results indicate that few aromatics could be formed in these flames. Furthermore, the current model has been validated against previous pyrolysis results of the literature obtained behind shock waves and the agreement is reasonable as well.

  4. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography - Part I: Furan.

    Liu, Dong; Togbé, Casimir; Tran, Luc-Sy; Felsmann, Daniel; Oßwald, Patrick; Nau, Patrick; Koppmann, Julia; Lackner, Alexander; Glaude, Pierre-Alexandre; Sirjean, Baptiste; Fournet, René; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2014-03-01

    Fuels of the furan family, i.e. furan itself, 2-methylfuran (MF), and 2,5-dimethylfuran (DMF) are being proposed as alternatives to hydrocarbon fuels and are potentially accessible from cellulosic biomass. While some experiments and modeling results are becoming available for each of these fuels, a comprehensive experimental and modeling analysis of the three fuels under the same conditions, simulated using the same chemical reaction model, has - to the best of our knowledge - not been attempted before. The present series of three papers, detailing the results obtained in flat flames for each of the three fuels separately, reports experimental data and explores their combustion chemistry using kinetic modeling. The first part of this series focuses on the chemistry of low-pressure furan flames. Two laminar premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of furan were studied at two equivalence ratios (φ=1.0 and 1.7) using an analytical combination of high-resolution electron-ionization molecular-beam mass spectrometry (EI-MBMS) in Bielefeld and gas chromatography (GC) in Nancy. The time-of-flight MBMS with its high mass resolution enables the detection of both stable and reactive species, while the gas chromatograph permits the separation of isomers. Mole fractions of reactants, products, and stable and radical intermediates were measured as a function of the distance to the burner. A single kinetic model was used to predict the flame structure of the three fuels: furan (in this paper), 2-methylfuran (in Part II), and 2,5-dimethylfuran (in Part III). A refined sub-mechanism for furan combustion, based on the work of Tian et al. [Combustion and Flame 158 (2011) 756-773] was developed which was then compared to the present experimental results. Overall, the agreement is encouraging. The main reaction pathways involved in furan combustion were delineated computing the rates of formation and consumption of all species. It is seen that the

  5. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography – Part I: Furan

    Liu, Dong; Togbé, Casimir; Tran, Luc-Sy; Felsmann, Daniel; Oßwald, Patrick; Nau, Patrick; Koppmann, Julia; Lackner, Alexander; Glaude, Pierre-Alexandre; Sirjean, Baptiste; Fournet, René; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2013-01-01

    Fuels of the furan family, i.e. furan itself, 2-methylfuran (MF), and 2,5-dimethylfuran (DMF) are being proposed as alternatives to hydrocarbon fuels and are potentially accessible from cellulosic biomass. While some experiments and modeling results are becoming available for each of these fuels, a comprehensive experimental and modeling analysis of the three fuels under the same conditions, simulated using the same chemical reaction model, has – to the best of our knowledge – not been attempted before. The present series of three papers, detailing the results obtained in flat flames for each of the three fuels separately, reports experimental data and explores their combustion chemistry using kinetic modeling. The first part of this series focuses on the chemistry of low-pressure furan flames. Two laminar premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of furan were studied at two equivalence ratios (φ=1.0 and 1.7) using an analytical combination of high-resolution electron-ionization molecular-beam mass spectrometry (EI-MBMS) in Bielefeld and gas chromatography (GC) in Nancy. The time-of-flight MBMS with its high mass resolution enables the detection of both stable and reactive species, while the gas chromatograph permits the separation of isomers. Mole fractions of reactants, products, and stable and radical intermediates were measured as a function of the distance to the burner. A single kinetic model was used to predict the flame structure of the three fuels: furan (in this paper), 2-methylfuran (in Part II), and 2,5-dimethylfuran (in Part III). A refined sub-mechanism for furan combustion, based on the work of Tian et al. [Combustion and Flame 158 (2011) 756-773] was developed which was then compared to the present experimental results. Overall, the agreement is encouraging. The main reaction pathways involved in furan combustion were delineated computing the rates of formation and consumption of all species. It is seen that the

  6. Intelligent Flamefinder Detection and Alert System (IFDAS), Phase II

    National Aeronautics and Space Administration — Current hydrogen flame detection systems exhibit shortcomings ranging from limited detection range, to localization inaccuracy, limited sensitivity, false alarms,...

  7. Real Time Flame Monitoring of Gasifier and Injectors

    Zelepouga, Serguei; Saveliev, Alexei

    2011-12-31

    This project is a multistage effort with the final goal to develop a practical and reliable nonintrusive gasifier injector monitor to assess burner wear and need for replacement. The project team included the National Energy Technology Laboratory (NETL), Gas Technology Institute (GTI), North Carolina State University, and ConocoPhillips. This report presents the results of the sensor development and testing initially at GTI combustion laboratory with natural gas flames, then at the Canada Energy Technology Center (CANMET), Canada in the atmospheric coal combustor as well as in the pilot scale pressurized entrained flow gasifier, and finally the sensor capabilities were demonstrated at the Pratt and Whitney Rocketdyne (PWR) Gasifier and the Wabash River Repowering plant located in West Terre Haute, IN. The initial tests demonstrated that GTI gasifier sensor technology was capable of detecting shape and rich/lean properties of natural gas air/oxygen enriched air flames. The following testing at the Vertical Combustor Research Facility (VCRF) was a logical transition step from the atmospheric natural gas flames to pressurized coal gasification environment. The results of testing with atmospheric coal flames showed that light emitted by excited OH* and CH* radicals in coal/air flames can be detected and quantified. The maximum emission intensities of OH*, CH*, and black body (char combustion) occur at different axial positions along the flame length. Therefore, the excitation rates of CH* and OH* are distinct at different stages of coal combustion and can be utilized to identify and characterize processes which occur during coal combustion such as devolatilization, char heating and burning. To accomplish the goals set for Tasks 4 and 5, GTI utilized the CANMET Pressurized Entrained Flow Gasifier (PEFG). The testing parameters of the PEFG were selected to simulate optimum gasifier operation as well as gasifier conditions normally resulting from improper operation or

  8. Impact of flame-wall interaction on premixed flame dynamics and transfer function characteristics

    Kedia, K.S.; Altay, H.M.; Ghoniem, A.F.

    2011-01-01

    In this paper, we numerically investigate the response of a perforated-plate stabilized laminar methane-air premixed flame to imposed inlet velocity perturbations. A flame model using detailed chemical kinetics mechanism is applied and heat exchange

  9. Extinction of corrugated hydrogen/air flames

    Mizomoto, M.; Asaka, Y.; Ikai, S.; Law, C.K.

    1982-01-01

    Recent studies on flammability limits reveal the importance of flow nonuniformity, flame curvature, and molecular and thermal diffusivities in determining the extinguishability and the associated limits of premixed fuel/air flames. In particular, it is found that conditions which favor extinction of a lean flame may cause intensification of a rich flame. In the present study the authors have experimentally determined the extinction characteristics and limits of highly curved hydrogen/air flames as represented by the opening of bunsen flame tips. Results show that the tip opens at a constant fuel equivalence ratio of phi = 1.15, regardless of the velocity and uniformity of the upstream flow. This critical mixture concentration, while being rich, is still on the lean side of that corresponding to the maximum burning velocity (phi = 1.8), implying that for highly diffusive systems, the relevant reference concentration is that for maximum burning velocity instead of stoichiometry

  10. Flame Motion In Gas Turbine Burner From Averages Of Single-Pulse Flame Fronts

    Tylli, N.; Hubschmid, W.; Inauen, A.; Bombach, R.; Schenker, S.; Guethe, F. [Alstom (Switzerland); Haffner, K. [Alstom (Switzerland)

    2005-03-01

    Thermo acoustic instabilities of a gas turbine burner were investigated by flame front localization from measured OH laser-induced fluorescence single pulse signals. The average position of the flame was obtained from the superposition of the single pulse flame fronts at constant phase of the dominant acoustic oscillation. One observes that the flame position varies periodically with the phase angle of the dominant acoustic oscillation. (author)

  11. Characteristics of Oscillating Flames in a Coaxial Confined Jet

    Min Suk Cha

    2010-12-01

    Full Text Available Flame characteristics when a non-premixed n-butane jet is ejected into a coaxial cylindrical tube are investigated experimentally. Flame stability depends mainly on the characteristics of flame propagation as well as air entrainment which depend on the jet momentum and on the distance between the nozzle exit and the base of a confined tube. As flow rate increases, the flame lifts off from a nozzle attached diffusion flame and a stationary lifted flame can be stabilized. The liftoff height increases nearly linearly with the average velocity at the nozzle exit. The lifted flame has a tribrachial flame structure, which consists of a rich premixed flame, a lean premixed flame, and a diffusion flame, all extending from a single location. As flow rate further increases, periodically oscillating flames are observed inside the confined tube. Once flame oscillation occurs, the flame undergoes relatively stable oscillation such that it has nearly constant oscillation amplitude and frequency. The criteria of flame oscillation are mapped as functions of nozzle diameter, the distance between nozzle and tube, and jet velocity. This type of flame oscillation can be characterized by Strouhal number in terms of flame oscillation amplitude, frequency, and jet velocity. Buoyancy driven flame oscillation which is one of the viable mechanism for flame oscillation is modeled and the results agrees qualitatively with experimental results, suggesting that the oscillation is due to periodic blowoff and flashback under the influence of buoyancy.

  12. Promising markers for the detection of premature senescence tumor cells induced by ionizing radiation: Cathepsin D and eukaryotic translation elongation factor 1

    Byun, Hae-Ok; Han, Na-Kyung; Lee, Jae-Seon [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

    2008-05-15

    Recently, it has been proved that induction of senescence could be a promising way of tumor treatment. Senescence was originally described in normal human cells undergoing a finite number of divisions before permanent growth arrest. It has now become regarded more broadly as a general biological program of terminal growth arrest. A variety of stresses such as ionizing radiation (IR), oxidative stress, oncogenic transformation, DNA damaging agents triggers stress-induced premature senescence, i.e. rapid and permanent cell growth arrest. Therefore, premature senescence is bona fide barrier to tumorigenesis and hallmark of premalignant tumors. However, there is lack of obvious markers for senescent tumor cells. To identify useful premature senescence markers for tumor cells, we monitored the changes of protein expression profile in IR-induced premature senescence MCF7 human breast cancer cells. We identified biomarkers which evidently changed their expression levels in ionizing radiation-induced senescenct tumor cells.

  13. Promising markers for the detection of premature senescence tumor cells induced by ionizing radiation: Cathepsin D and eukaryotic translation elongation factor 1

    Byun, Hae-Ok; Han, Na-Kyung; Lee, Jae-Seon

    2008-01-01

    Recently, it has been proved that induction of senescence could be a promising way of tumor treatment. Senescence was originally described in normal human cells undergoing a finite number of divisions before permanent growth arrest. It has now become regarded more broadly as a general biological program of terminal growth arrest. A variety of stresses such as ionizing radiation (IR), oxidative stress, oncogenic transformation, DNA damaging agents triggers stress-induced premature senescence, i.e. rapid and permanent cell growth arrest. Therefore, premature senescence is bona fide barrier to tumorigenesis and hallmark of premalignant tumors. However, there is lack of obvious markers for senescent tumor cells. To identify useful premature senescence markers for tumor cells, we monitored the changes of protein expression profile in IR-induced premature senescence MCF7 human breast cancer cells. We identified biomarkers which evidently changed their expression levels in ionizing radiation-induced senescenct tumor cells

  14. Pole solutions for flame front propagation

    Kupervasser, Oleg

    2015-01-01

    This book deals with solving mathematically the unsteady flame propagation equations. New original mathematical methods for solving complex non-linear equations and investigating their properties are presented. Pole solutions for flame front propagation are developed. Premixed flames and filtration combustion have remarkable properties: the complex nonlinear integro-differential equations for these problems have exact analytical solutions described by the motion of poles in a complex plane. Instead of complex equations, a finite set of ordinary differential equations is applied. These solutions help to investigate analytically and numerically properties of the flame front propagation equations.

  15. Gravitational Effects on Cellular Flame Structure

    Dunsky, C. M.; Fernandez-Pello, A. C.

    1991-01-01

    An experimental investigation has been conducted of the effect of gravity on the structure of downwardly propagating, cellular premixed propane-oxygen-nitrogen flames anchored on a water-cooled porous-plug burner. The flame is subjected to microgravity conditions in the NASA Lewis 2.2-second drop tower, and flame characteristics are recorded on high-speed film. These are compared to flames at normal gravity conditions with the same equivalence ratio, dilution index, mixture flow rate, and ambient pressure. The results show that the cellular instability band, which is located in the rich mixture region, changes little under the absence of gravity. Lifted normal-gravity flames near the cellular/lifted limits, however, are observed to become cellular when gravity is reduced. Observations of a transient cell growth period following ignition point to heat loss as being an important mechanism in the overall flame stability, dominating the stabilizing effect of buoyancy for these downwardly-propagating burner-anchored flames. The pulsations that are observed in the plume and diffusion flame generated downstream of the premixed flame in the fuel rich cases disappear in microgravity, verifying that these fluctuations are gravity related.

  16. Laser-induced incandescence of titania nanoparticles synthesized in a flame

    Cignoli, F.; Bellomunno, C.; Maffi, S.; Zizak, G.

    2009-09-01

    Laser induced incandescence experiments were carried out in a flame reactor during titania nanoparticle synthesis. The structure of the reactor employed allowed for a rather smooth particle growth along the flame axis, with limited mixing of different size particles. Particle incandescence was excited by the 4th harmonic of a Nd:YAG laser. The radiation emitted from the particles was recorded in time and checked by spectral analysis. Results were compared with measurements from transmission electron microscopy of samples taken at the same locations probed by incandescence. This was done covering a portion of the flame length within which a particle size growth of a factor of about four was detected . The incandescence decay time was found to increase monotonically with particle size. The attainment of a process control tool in nanoparticle flame synthesis appears to be realistic.

  17. Theoretical analysis of the conical premixed flame response to upstream velocity disturbances considering flame speed development effects

    Ghazaleh Esmaeelzade

    2017-03-01

    Full Text Available The effect of upstream velocity perturbations on the response of a premixed flame was investigated in terms of the flame transfer function dependency on excitation frequency. In this study, the assumption of constant flame speed was extended and the effect of flame speed development was considered; i.e., the flame speed would grow with the time after ignition or with the distance from a flame-holder. In the present study, the kinematics of a conical flame was investigated by linearization of the front tracking equation of flame to uniform and convected fluctuations of the flow velocity and the response was compared with that of a V-shaped flame and the experimental data in the previous studies. The results show that the effect of flame speed development could influence a decreasing gain and increase the phase of the flame response to the uniform velocity oscillations in low and moderate frequencies. Comparing the variations in the gain of flame response upon normalized frequency, show that a conical flame has lower values than the V-flame. In other words, these flames might be less susceptible to combustion instabilities than the V-flames. Furthermore, the variations in phase of the V-flames responses, which show a quasi-linear behavior with normalized frequency, have higher values than the saturated behavior in phase of the conical flame responses. Also, considering that the flame speed development induces an increase in the gain and phase of the conical flame response to the convected velocity oscillations in certain frequencies; because the developed flame front has longer length in comparison to the flame front in constant flame speed model. Therefore, the flame length may be longer than convective wavelength and the heat release would be generated in different points of the flame; consequently the flow oscillations might exert a stronger impact on the unsteady heat release fluctuations.

  18. Display of charged ionizing particles

    Cano S, D.; Ortiz A, M. D.; Amarillas S, L. E.; Vega C, H. R.

    2017-10-01

    The human being is exposed to sources of ionizing and non-ionizing radiation, both of natural or anthropogenic origin. None of these, except non-ionizing such as visible light and infrared radiation, can be detected by the sense of sight and touch respectively. The sun emits charged particles with speeds close to the light that interact with the atoms of the gases present in the atmosphere, producing nuclear reactions that in turn produce other particles that reach the surface of the Earth and reach the living beings. On Earth there are natural radioisotopes that, when they disintegrate, emit ionizing radiation that contributes to the dose we receive. A very old system that allows the visualization of the trajectories of the charged ionizing particles is the Fog Chamber that uses a saturated steam that when crossed by particles with mass and charge, as alpha and beta particles produce condensation centers along its path leaves a trace that can be seen. The objective of this work was to build a fog chamber using easily accessible materials. To measure the functioning of the fog chamber, cosmic rays were measured, as well as a source of natural metal uranium. The fog chamber allowed seeing the presence of traces in alcohol vapor that are produced in a random way. Introducing the uranium foil inside the fog chamber, traces of alpha particles whose energy varies from 4 to 5 MeV were observed. (Author)

  19. Experimental studies of flame stability limits of biogas flame

    Dai Wanneng; Qin Chaokui; Chen Zhiguang; Tong Chao; Liu Pengjun

    2012-01-01

    Highlights: ► Premixed biogas flame stability for RTBs was studied on different conditions. ► An unusual “float off” phenomenon was observed. ► Decrease of port diameter or gas temperature or methane content motivates lifting. ► Increase of methane content or gas temperature or port diameter motivates yellow tipping. ► Lifting curves become straight lines when semi-logarithmic graph paper is applied. - Abstract: Flame stability of premixed biogas flame for Reference Test Burner (RTB) was investigated. In this study, six kinds of test gases were used to simulate biogas in which CO 2 volume fraction varied from 30% to 45%. A series of experiments were conducted on two RTBs with different port diameters and at different outlet unburned mixture temperatures. It was found that the lifting and yellow tipping limits show similar trends regardless of the biogas components, port diameters and mixture temperatures. A “float off” phenomenon could be observed at low gas flow rate and low primary air ratio. Low mixture temperature, small ports and high CO 2 concentration in biogas can lead to the unstable condition of “float off”. The lifting limits are enhanced with an increase of port diameter or mixture temperature and with a decrease of CO 2 concentration. The yellow tipping limits are extended with an increase of CO 2 concentration and with a decrease of mixture temperature or port diameter. In addition, the lifting limit curve becomes a straight line when semi-logarithmic graph paper is applied. The intercept increases with a decrease of the CO 2 concentration in biogas and with an increase of port diameter or gas temperature.

  20. Resonance ionization spectroscopy 1990

    Parks, J.E.; Omenetto, N.

    1991-01-01

    The Fifth International Symposium on Resonance Ionization Spectroscopy (RIS) and its Applications was held in Varese, Italy, 16-21 September 1990. Interest in RIS and its applications continues to grow, and RIS is expanding into a more diverse and mature field of study. This maturity was evident in this meeting both in the basic science and understanding of RIS processes and in the number of new and improved applications and techniques. The application of RIS techniques to molecular detection problems made remarkable progress since the last meeting two years ago. Subtle effects pertaining to isotopic discrimination received more theoretical attention, and there now seems to be good understanding of these effects, which can lead to correction procedures and/or methods to avoid isotopic effects. RIS applications were presented in which significant, real world problems were addressed, demonstrating its capability to solve problems that previously could not be accurately solved by other more traditional techniques. The contributions to the conference are grouped under the following major topic headings: physics applications of rare atoms; laser ionization mechanisms - spectroscopy; atomic, molecular and ion sources; molecular RIS; atomic RIS - Rydberg states; environmental trace analysis; biological and medical applications; state selected chemistry; new laser sources and techniques; ultra-high resolution and isotopic selectivity; surface and bulk analysis. (Author)

  1. Flame dynamics of a meso-scale heat recirculating combustor

    Vijayan, V.; Gupta, A.K. [Department of Mechanical Engineering, University of Maryland, College Park, MD 20742 (United States)

    2010-12-15

    The dynamics of premixed propane-air flame in a meso-scale ceramic combustor has been examined here. The flame characteristics in the combustor were examined by measuring the acoustic emissions and preheat temperatures together with high-speed cinematography. For the small-scale combustor, the volume to surface area ratio is small and hence the walls have significant effect on the global flame structure, flame location and flame dynamics. In addition to the flame-wall thermal coupling there is a coupling between flame and acoustics in the case of confined flames. Flame-wall thermal interactions lead to low frequency flame fluctuations ({proportional_to}100 Hz) depending upon the thermal response of the wall. However, the flame-acoustic interactions can result in a wide range of flame fluctuations ranging from few hundred Hz to few kHz. Wall temperature distribution is one of the factors that control the amount of reactant preheating which in turn effects the location of flame stabilization. Acoustic emission signals and high-speed flame imaging confirmed that for the present case flame-acoustic interactions have more significant effect on flame dynamics. Based on the acoustic emissions, five different flame regimes have been identified; whistling/harmonic mode, rich instability mode, lean instability mode, silent mode and pulsating flame mode. (author)

  2. A computational study of the effects of DC electric fields on non-premixed counterflow methane-air flames

    Belhi, Memdouh

    2017-10-19

    Two-dimensional axisymmetric simulations for counterflow nonpremixed methane-air flames were undertaken as an attempt to reproduce the experimentally observed electro-hydrodynamic effect, also known as the ionic wind effect, on flames. Incompressible fluid dynamic solver was implemented with a skeletal chemical kinetic mechanism and transport property evaluations. The simulation successfully reproduced the key characteristics of the flames subjected to DC bias voltages at different intensity and polarity. Most notably, the simulation predicted the flame positions and showed good qualitative agreement with experimental data for the current-voltage curve. The flame response to the electric field with positive and negative polarity exhibited qualitatively different characteristics. In the negative polarity of the configuration considered, a non-monotonic variation of the current with the voltage was observed along with the existence of an unstable regime at an intermediate voltage level. With positive polarity, a typical monotonic current-voltage curve was obtained. This behavior was attributed to the asymmetry in the distribution of the positive and negative ions resulting from ionization processes. The present study demonstrated that the mathematical and computational models for the ion chemistry, transport, and fluid dynamics were able to describe the key processes responsible for the flame-electric field interaction.

  3. A Versatile Integrated Ambient Ionization Source Platform

    Ai, Wanpeng; Nie, Honggang; Song, Shiyao; Liu, Xiaoyun; Bai, Yu; Liu, Huwei

    2018-04-01

    The pursuit of high-throughput sample analysis from complex matrix demands development of multiple ionization techniques with complementary specialties. A versatile integrated ambient ionization source (iAmIS) platform is proposed in this work, based on the idea of integrating multiple functions, enhancing the efficiency of current ionization techniques, extending the applications, and decreasing the cost of the instrument. The design of the iAmIS platform combines flowing atmospheric pressure afterglow (FAPA) source/direct analysis in real time (DART), dielectric barrier discharge ionization (DBDI)/low-temperature plasma (LTP), desorption electrospray ionization (DESI), and laser desorption (LD) technique. All individual and combined ionization modes can be easily attained by modulating parameters. In particular, the FAPA/DART&DESI mode can realize the detection of polar and nonpolar compounds at the same time with two different ionization mechanisms: proton transfer and charge transfer. The introduction of LD contributes to the mass spectrometry imaging and the surface-assisted laser desorption (SALDI) under ambient condition. Compared with other individual or multi-mode ion source, the iAmIS platform provides the flexibility of choosing different ionization modes, broadens the scope of the analyte detection, and facilitates the analysis of complex samples. [Figure not available: see fulltext.

  4. Tulip flames: changes in shape of premixed flames propagating in closed tubes

    Dunn-Rankin, D.; Sawyer, R. F.

    The experimental results that are the subject of this communication provide high-speed schlieren images of the closed-tube flame shape that has come to be known as the tulip flame. The schlieren images, along with in-chamber pressure records, help demonstrate the effects of chamber length, equivalence ratio, and igniter geometry on formation of the tulip flame. The pressure/time records show distinct features which correlate with flame shape changes during the transition to tulip. The measurements indicate that the basic tulip flame formation is a robust phenomenon that depends on little except the overall geometry of the combustion vessel.

  5. Improvement of flame resistance of non-flame retardant cables by applying fire protection measures

    Takemura, Yujiro; Segoshi, Yoshinori; Jinno, Susumu; Mii, Kazuki

    2017-01-01

    The new regulatory requirements, which were put in force after the Fukushima Daiichi accident, impose the use of flame retardant cables on the plant components having safety functions for the purpose of fire protection. However, some Japanese nuclear power plants built in the early days use non-flame retardant cables that do not pass the demonstration test to check for the flame resistance. To cope with the new regulatory requirements, a fire protection measure for non-flame retardant cables was introduced to assure flame resistance of non-flame retardant cables equivalent to or higher than that of flame retardant cables. To illustrate the fire protection measure, both non-flame retardant cables and its cable tray are covered with fire protection sheet fabricated from incombustible material to form an assembly. Considering the demonstration test results, it can be concluded that flame resistance performance of non-flame retardant cables equivalent to or higher than that of flame retardant cables can be assured by forming the assembly even if an external fire outside the assembly and internal cable fire inside the assembly are assumed. This paper introduces the design of the assembly consisting of a bundle of cables and a cable tray and summarizes the results of demonstration tests. (author)

  6. Impact of flame-wall interaction on premixed flame dynamics and transfer function characteristics

    Kedia, K.S.

    2011-01-01

    In this paper, we numerically investigate the response of a perforated-plate stabilized laminar methane-air premixed flame to imposed inlet velocity perturbations. A flame model using detailed chemical kinetics mechanism is applied and heat exchange between the burner plate and the gas mixture is incorporated. Linear transfer functions, for low mean inlet velocity oscillations, are analyzed for different equivalence ratio, mean inlet velocity, plate thermal conductivity and distance between adjacent holes. The oscillations of the heat exchange rate at the top of the burner surface plays a critical role in driving the growth of the perturbations over a wide range of conditions, including resonance. The flame response to the perturbations at its base takes the form of consumption speed oscillations in this region. Flame stand-off distance increases/decreases when the flame-wall interaction strengthens/weakens, impacting the overall dynamics of the heat release. The convective lag between the perturbations and the flame base response govern the phase of heat release rate oscillations. There is an additional convective lag between the perturbations at the flame base and the flame tip which has a weaker impact on the heat release rate oscillations. At higher frequencies, the flame-wall interaction is weaker and the heat release oscillations are driven by the flame area oscillations. The response of the flame to higher amplitude oscillations are used to gain further insight into the mechanisms. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

  7. Flame surface statistics of constant-pressure turbulent expanding premixed flames

    Saha, Abhishek; Chaudhuri, Swetaprovo; Law, Chung K.

    2014-04-01

    In this paper we investigate the local flame surface statistics of constant-pressure turbulent expanding flames. First the statistics of local length ratio is experimentally determined from high-speed planar Mie scattering images of spherically expanding flames, with the length ratio on the measurement plane, at predefined equiangular sectors, defined as the ratio of the actual flame length to the length of a circular-arc of radius equal to the average radius of the flame. Assuming isotropic distribution of such flame segments we then convolute suitable forms of the length-ratio probability distribution functions (pdfs) to arrive at the corresponding area-ratio pdfs. It is found that both the length ratio and area ratio pdfs are near log-normally distributed and shows self-similar behavior with increasing radius. Near log-normality and rather intermittent behavior of the flame-length ratio suggests similarity with dissipation rate quantities which stimulates multifractal analysis.

  8. Ionization mechanisms in capillary supercritical fluid chromatography-chemical ionization mass spectrometry

    Houben, R.J.; Leclercq, P.A.; Cramers, C.A.M.G.

    1991-01-01

    Ionization mechanisms have been studied for supercritical fluid chromatography (SFC) with mass spectrometric (MS) detection. One of the problems associated with SFC-MS is the interference of mobile phase constituents in the ionization process, which complicates the interpretation of the resulting

  9. Simulations of flame generated particles

    Patterson, Robert

    2016-01-05

    The nonlinear structure of the equations describing the evolution of a population of coagulating particles in a flame make the use of stochastic particle methods attractive for numerical purposes. I will present an analysis of the stochastic fluctuations inherent in these numerical methods leading to an efficient sampling technique for steady-state problems. I will also give some examples where stochastic particle methods have been used to explore the effect of uncertain parameters in soot formation models. In conclusion I will try to indicate some of the issues in optimising these methods for the study of uncertain model parameters.

  10. Simulations of flame generated particles

    Patterson, Robert

    2016-01-01

    The nonlinear structure of the equations describing the evolution of a population of coagulating particles in a flame make the use of stochastic particle methods attractive for numerical purposes. I will present an analysis of the stochastic fluctuations inherent in these numerical methods leading to an efficient sampling technique for steady-state problems. I will also give some examples where stochastic particle methods have been used to explore the effect of uncertain parameters in soot formation models. In conclusion I will try to indicate some of the issues in optimising these methods for the study of uncertain model parameters.

  11. Nonequilibrium theory of flame propagation

    Merzhanov, A.G.

    1995-01-01

    The nonequilibrium theory of flame propagation is considered as applied to the following three processes of wave propagation: the combustion waves of the second kind, the combustion waves with broad reaction zones, and the combustion waves with chemical stages. Kinetic and combustion wave parameters are presented for different in composition mixtures of boron and transition metals, such as Zr, Hf, Ti, Nb, Ta, Mo, as well as for the Ta-N, Zr-C-H, Nb-B-O systems to illustrate specific features of the above-mentioned processes [ru

  12. A novel type of matrix for surface-assisted laser desorption-ionization mass spectrometric detection of biomolecules using metal-organic frameworks.

    Fu, Chien-Ping; Lirio, Stephen; Liu, Wan-Ling; Lin, Chia-Her; Huang, Hsi-Ya

    2015-08-12

    A 3D metal-organic framework (MOF) nanomaterial as matrix for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) and tandem mass spectrometry (MS/MS) was developed for the analysis of complex biomolecules. Unlike other nanoparticle matrices, this MOF nanomaterial does not need chemical modification prior to use. An exceptional signal reproducibility as well as very low background interferences in analyzing mono-/di-saccharides, peptides and complex starch digests demonstrate its high potential for biomolecule assays, especially for small molecules. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Chemical processes in the HNF flame

    Ermolin, N.E.; Zarko, V.E.; Keizers, H.L.J.

    2006-01-01

    Results of modeling the HNF flame structure are presented. From an analysis of literature data on the thermal decomposition and combustion of HNF, it is concluded that the dissociative vaporization of HNF proceeds via the route HNFliq → (N2H4)g + (HC(NO 2)3)g. The flame structure is modeled using a

  14. Laser Doppler thermometry in flat flames

    Maaren, van A.; Goey, de L.P.H.

    1994-01-01

    Laser Doppler Velocimetry measurements are performed in flat flames, stabilized on a newly developed flat-flame burner. It is shown that the velocity component perpendicular to the main flow direction, induced by expansion in the reaction zone and buoyancy in the burnt gas, is significant. A method

  15. Development of PIV for Microgravity Diffusion Flames

    Greenberg, Paul S.; Wernet, Mark P.; Yanis, William; Urban, David L.; Sunderland, Peter B.

    2003-01-01

    Results are presented from the application of Particle Image Velocimetry(PIV) to the overfire region of a laminar gas jet diffusion flame in normal gravity. A methane flame burning in air at 0.98 bar was considered. The apparatus demonstrated here is packaged in a drop rig designed for use in the 2.2 second drop tower.

  16. Foodstuffs preservation by ionization

    1991-12-01

    This document contains all the papers presented at the meeting on foodstuffs preservation by ionization. These papers deal especially with the food ionization process, its development and the view of the food industry on ionization. Refs and figs (F.M.)

  17. Aerodynamic features of flames in premixed gases

    Oppenheim, A. K.

    1984-01-01

    A variety of experimentally established flame phenomena in premixed gases are interpreted by relating them to basic aerodynamic properties of the flow field. On this basis the essential mechanism of some well known characteristic features of flames stabilized in the wake of a bluff-body or propagating in ducts are revealed. Elementary components of the flame propagation process are shown to be: rotary motion, self-advancement, and expansion. Their consequences are analyzed under a most strict set of idealizations that permit the flow field to be treated as potential in character, while the flame is modelled as a Stefan-like interface capable of exerting a feed-back effect upon the flow field. The results provide an insight into the fundamental fluid-mechanical reasons for the experimentally observed distortions of the flame front, rationalizing in particular its ability to sustain relatively high flow velocities at amazingly low normal burning speeds.

  18. Flame spread along thermally thick horizontal rods

    Higuera, F. J.

    2002-06-01

    An analysis is carried out of the spread of a flame along a horizontal solid fuel rod, for which a weak aiding natural convection flow is established in the underside of the rod by the action of the axial gradient of the pressure variation that gravity generates in the warm gas surrounding the flame. The spread rate is determined in the limit of infinitely fast kinetics, taking into account the effect of radiative losses from the solid surface. The effect of a small inclination of the rod is discussed, pointing out a continuous transition between upward and downward flame spread. Flame spread along flat-bottomed solid cylinders, for which the gradient of the hydrostatically generated pressure drives the flow both along and across the direction of flame propagation, is also analysed.

  19. Design of the flame detector based on pyroelectric infrared sensor

    Liu, Yang; Yu, Benhua; Dong, Lei; Li, Kai

    2017-10-01

    As a fire detection device, flame detector has the advantages of short reaction time and long distance. Based on pyroelectric infrared sensor working principle, the passive pyroelectric infrared alarm system is designed, which is mainly used for safety of tunnel to detect whether fire occurred or not. Modelling and Simulation of the pyroelectric Detector Using Labview. An attempt was made to obtain a simple test platform of a pyroelectric detector which would make an excellent basis for the analysis of its dynamic behaviour. After many experiments, This system has sensitive response, high anti-interference ability and safe and reliable performance.

  20. The first detection of ionized helium in the local ISM - EUVE and IUE spectroscopy of the hot DA white dwarf GD 246

    Vennes, Stephane; Dupuis, Jean; Rumph, Todd; Drake, Jeremy; Bowyer, Stuart; Chayer, Pierre; Fontaine, Gilles

    1993-01-01

    We report observations of the extreme ultraviolet spectrum of the hot degenerate star GD 246 obtained with the EUVE. Our initial attempt at modeling the photospheric emission from the white dwarf reveals a relatively uncontaminated pure H spectrum in the range above 200 A, allowing a study of interstellar continuum absorption features in the line of sight of GD 246. Modeling of the He I autoionization transition discussed by Rumph et al. (1993), and the EUV continuum using the white dwarf as a source of background radiation provides measurements of both neutral and, for the first time, singly ionized He column densities in the local ISM (LISM). We estimate the He ionization fraction He II/(He I + He II) at roughly 25 percent with a total He column of 1.40-1.65 x 10 exp 18/sq cm. We have measured and compared H I column densities from the saturated Ly-alpha ISM absorption in IUE high-dispersion spectroscopy and from EUV continuum absorption: the two measurements are in good agreement with a total H column of 1.2-1.6 x 10 exp 19/sq cm. We discuss some implications for the nature of the LISM, particularly in the context of current models of the EUV radiation field.

  1. Evaluation of partially premixed turbulent flame stability from mixture fraction statistics in a slot burner

    Kruse, Stephan

    2018-04-11

    Partially premixed combustion is characterized by mixture fraction inhomogeneity upstream of the reaction zone and occurs in many applied combustion systems. The temporal and spatial fluctuations of the mixture fraction have tremendous impact on the combustion characteristics, emission formation, and flame stability. In this study, turbulent partially premixed flames are experimentally studied in a slot burner configuration. The local temperature and gas composition is determined by means of one-dimensional, simultaneous detection of Rayleigh and Raman scattering. The statistics of the mixture fraction are utilized to characterize the impact of the Reynolds number, the global equivalence ratio, the progress of mixing within the flame, as well as the mixing length on the mixing field. Furthermore, these effects are evaluated by means of a regime diagram for partially premixed flames. In this study, it is shown that the increase of the mixing length results in a significantly more stable flame. The impact of the Reynolds number on flame stability is found to be minor.

  2. Evaluation of partially premixed turbulent flame stability from mixture fraction statistics in a slot burner

    Kruse, Stephan; Mansour, Mohy S.; Elbaz, Ayman M.; Varea, Emilien; Grü nefeld, Gerd; Beeckmann, Joachim; Pitsch, Heinz

    2018-01-01

    Partially premixed combustion is characterized by mixture fraction inhomogeneity upstream of the reaction zone and occurs in many applied combustion systems. The temporal and spatial fluctuations of the mixture fraction have tremendous impact on the combustion characteristics, emission formation, and flame stability. In this study, turbulent partially premixed flames are experimentally studied in a slot burner configuration. The local temperature and gas composition is determined by means of one-dimensional, simultaneous detection of Rayleigh and Raman scattering. The statistics of the mixture fraction are utilized to characterize the impact of the Reynolds number, the global equivalence ratio, the progress of mixing within the flame, as well as the mixing length on the mixing field. Furthermore, these effects are evaluated by means of a regime diagram for partially premixed flames. In this study, it is shown that the increase of the mixing length results in a significantly more stable flame. The impact of the Reynolds number on flame stability is found to be minor.

  3. EXPERIMENTAL AND MODELING STUDY OF PREMIXED LAMINAR FLAMES OF ETHANOL AND METHANE.

    Tran, Luc-Sy; Glaude, Pierre-Alexandre; Fournet, René; Battin-Leclerc, Frédérique

    2013-04-18

    To better understand the chemistry of the combustion of ethanol, the structure of five low pressure laminar premixed flames has been investigated: a pure methane flame (φ=1), three pure ethanol flames (φ=0.7, 1.0, and 1.3), and an ethanol/methane mixture flames (φ=1). The flames have been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner of 64.3 cm/s at 333 K. The results consist of mole fraction profiles of 20 species measured as a function of the height above the burner by probe sampling followed by online gas chromatography analyses. A mechanism for the oxidation of ethanol was proposed. The reactions of ethanol and acetaldehyde were updated and include recent theoretical calculations while that of ethenol, dimethyl ether, acetone, and propanal were added in the mechanism. This mechanism was also tested against experimental results available in the literature for laminar burning velocities and laminar premixed flame where ethenol was detected. The main reaction pathways of consumption of ethanol are analyzed. The effect of the branching ratios of reaction C 2 H 5 OH+OH→Products+H 2 O is also discussed.

  4. Flame Structure and Emissions of Strongly-Pulsed Turbulent Diffusion Flames with Swirl

    Liao, Ying-Hao

    This work studies the turbulent flame structure, the reaction-zone structure and the exhaust emissions of strongly-pulsed, non-premixed flames with co-flow swirl. The fuel injection is controlled by strongly-pulsing the fuel flow by a fast-response solenoid valve such that the fuel flow is completely shut off between pulses. This control strategy allows the fuel injection to be controlled over a wide range of operating conditions, allowing the flame structure to range from isolated fully-modulated puffs to interacting puffs to steady flames. The swirl level is controlled by varying the ratio of the volumetric flow rate of the tangential air to that of the axial air. For strongly-pulsed flames, both with and without swirl, the flame geometry is strongly impacted by the injection time. Flames appear to exhibit compact, puff-like structures for short injection times, while elongated flames, similar in behaviors to steady flames, occur for long injection times. The flames with swirl are found to be shorter for the same fuel injection conditions. The separation/interaction level between flame puffs in these flames is essentially governed by the jet-off time. The separation between flame puffs decreases as swirl is imposed, consistent with the decrease in flame puff celerity due to swirl. The decreased flame length and flame puff celerity are consistent with an increased rate of air entrainment due to swirl. The highest levels of CO emissions are generally found for compact, isolated flame puffs, consistent with the rapid quenching due to rapid dilution with excess air. The imposition of swirl generally results in a decrease in CO levels, suggesting more rapid and complete fuel/air mixing by imposing swirl in the co-flow stream. The levels of NO emissions for most cases are generally below the steady-flame value. The NO levels become comparable to the steady-flame value for sufficiently short jet-off time. The swirled co-flow air can, in some cases, increase the NO

  5. Experiment and Simulation of Autoignition in Jet Flames and its Relevance to Flame Stabilization and Structure

    Al-Noman, Saeed M.

    2016-06-01

    Autoignition characteristics of pre-vaporized iso-octane, primary reference fuels, gasolines, and dimethyl ether (DME) have been investigated experimentally in a coflow with elevated temperature of air. With the coflow air at relatively low initial temperatures below autoignition temperature Tauto, an external ignition source was required to stabilize the flame. Non-autoignited lifted flames had tribrachial edge structures and their liftoff heights correlated well with the jet velocity scaled by the stoichiometric laminar burning velocity, indicating the importance of the edge propagation speed on flame stabilization balanced with local flow velocity. At high initial temperatures over Tauto, the autoignited flames were stabilized without requiring an external ignition source. The autoignited lifted flames exhibited either tribrachial edge structures or Mild combustion behaviors depending on the level of fuel dilution. For the iso-octane and n-heptane fuels, two distinct transition behaviors were observed in the autoignition regime from a nozzle-attached flame to a lifted tribrachial-edge flame and then a sudden transition to lifted Mild combustion as the jet velocity increased at a certain fuel dilution level. The liftoff data of the autoignited flames with tribrachial edges were analyzed based on calculated ignition delay times for the pre-vaporized fuels. Analysis of the experimental data suggested that ignition delay time may be much less sensitive to initial temperature under atmospheric pressure conditions as compared with predictions. For the gasoline fuels for advanced combustion engines (FACEs), and primary reference fuels (PRFs), autoignited liftoff data were correlated with Research Octane Number and Cetane Number. For the DME fuel, planar laser-induced fluorescence (PLIF) of formaldehyde (CH2O) and CH* chemiluminescence were visualized qualitatively. In the autoignition regime for both tribrachial structure and mild combustion, formaldehyde were found

  6. Analysis of flame shapes in turbulent hydrogen jet flames with coaxial air

    Moon, Hee Jang

    2009-01-01

    This paper addresses the characteristics of flame shapes and flame length in three types of coaxial air flames realizable by varying coaxial air and/or fuel velocity. Forcing coaxial air into turbulent jet flames induces substantial changes in flame shapes and NOx emissions through the complex flow interferences that exist within the mixing region. Mixing enhancement driven by coaxial air results in flame volume decrease, and such a diminished flame volume finally reduces NOx emissions significantly by decreasing NOx formation zone where a fuel/air mixture burns. It is found that mixing in the vicinity of high temperature zone mainly results from the increase of diffusive flux than the convective flux, and that the increase of mass diffusion is amplified as coaxial air is increased. Besides, it is reaffirmed that nonequilibrium chemistry including HO 2 /H 2 O 2 should be taken into account for NOx prediction and scaling analysis by comparing turbulent combustion models. In addition, it is found that coaxial air can break down the self-similarity law of flames by changing mixing mechanism, and that EINOx scaling parameters based on the self-similarity law of simple jet flames may not be eligible in coaxial air flames

  7. Analysis of flame shapes in turbulent hydrogen jet flames with coaxial air

    Moon, Hee Jang [Korea Aerospace University, Goyang (Korea, Republic of)

    2009-06-15

    This paper addresses the characteristics of flame shapes and flame length in three types of coaxial air flames realizable by varying coaxial air and/or fuel velocity. Forcing coaxial air into turbulent jet flames induces substantial changes in flame shapes and NOx emissions through the complex flow interferences that exist within the mixing region. Mixing enhancement driven by coaxial air results in flame volume decrease, and such a diminished flame volume finally reduces NOx emissions significantly by decreasing NOx formation zone where a fuel/air mixture burns. It is found that mixing in the vicinity of high temperature zone mainly results from the increase of diffusive flux than the convective flux, and that the increase of mass diffusion is amplified as coaxial air is increased. Besides, it is reaffirmed that nonequilibrium chemistry including HO{sub 2}/H{sub 2}O{sub 2} should be taken into account for NOx prediction and scaling analysis by comparing turbulent combustion models. In addition, it is found that coaxial air can break down the self-similarity law of flames by changing mixing mechanism, and that EINOx scaling parameters based on the self-similarity law of simple jet flames may not be eligible in coaxial air flames

  8. Flame Structure and Chemiluminescence Emissions of Inverse Diffusion Flames under Sinusoidally Driven Plasma Discharges

    Maria Grazia De Giorgi

    2017-03-01

    Full Text Available Reduction of nitric oxides (NOx in aircraft engines and in gas turbines by lean combustion is of great interest in the design of novel combustion systems. However, the stabilization of the flame under lean conditions is a main issue. In this context, the present work investigates the effects of sinusoidal dielectric barrier discharge (DBD on a lean inverse diffusive methane/air flame in a Bunsen-type burner under different actuation conditions. The flame appearance was investigated with fixed methane loading (mass flux, but with varying inner airflow rate. High-speed flame imaging was done by using an intensified (charge-coupled device CCD camera equipped with different optical filters in order to selectively record signals from the chemiluminescent species OH*, CH*, or CO2* to evaluate the flame behavior in presence of plasma actuation. The electrical power consumption was less than 33 W. It was evident that the plasma flame enhancement was significantly influenced by the plasma discharges, particularly at high inner airflow rates. The flame structure changes drastically when the dissipated plasma power increases. The flame area decreases due to the enhancement of mixing and chemical reactions that lead to a more anchored flame on the quartz exit with a reduction of the flame length.

  9. Thermal-diffusional Instability in White Dwarf Flames: Regimes of Flame Pulsation

    Xing, Guangzheng; Zhao, Yibo; Zhou, Cheng; Gao, Yang; Law, Chung K. [Center for Combustion Energy, Tsinghua University, Beijing 100084 (China); Modestov, Mikhail, E-mail: gaoyang-00@mails.tsinghua.edu.cn [Nordita, KTH Royal Institute of Technology and Stockholm University, SE-10691, Stockholm (Sweden)

    2017-05-20

    Thermal-diffusional pulsation behaviors in planar as well as outwardly and inwardly propagating white dwarf (WD) carbon flames are systematically studied. In the 1D numerical simulation, the asymptotic degenerate equation of state and simplified one-step reaction rates for nuclear reactions are used to study the flame propagation and pulsation in WDs. The numerical critical Zel’dovich numbers of planar flames at different densities ( ρ = 2, 3, and 4 × 10{sup 7} g cm{sup −3}) and of spherical flames (with curvature c = −0.01, 0, 0.01, and 0.05) at a particular density ( ρ = 2 × 10{sup 7} g cm{sup −3}) are presented. Flame front pulsation in different environmental densities and temperatures are obtained to form the regime diagram of pulsation, showing that carbon flames pulsate in the typical density of 2 × 10{sup 7} g cm{sup −3} and temperature of 0.6 × 10{sup 9} K. While being stable at higher temperatures, at relatively lower temperatures, the amplitude of the flame pulsation becomes larger. In outwardly propagating spherical flames the pulsation instability is enhanced and flames are also easier to quench due to pulsation at small radius, while the inwardly propagating flames are more stable.

  10. Deformation Study of Lean Methane-Air Premixed Spherically Expanding Flames under a Negative Direct Current Electric Field

    Chao Li

    2016-09-01

    Full Text Available This paper compares numerical simulations with experiments to study the deformation of lean premixed spherically expanding flames under a negative direct current (DC electric field. The experiments, including the flame deformation and the ionic distribution on the flame surface were investigated in a mesh to mesh electric field. Besides, a numerical model of adding an electric body force to the positive ions on the flame surface was also established to perform a relevant simulation. Results show that the spherical flame will acquire an elliptical shape with a marked flame stretch in the horizontal direction and a slight inhibition in the vertical direction under a negative DC electric field. Meanwhile, a non-uniform ionic distribution on the flame surface was also detected by the Langmuir probe. The simulation results from the numerical model show good agreement with experimental data. According to the velocity field analysis in simulation, it was found the particular motion of positive ions and neutral molecules on the flame surface should be responsible for the special flame deformation. When a negative DC electric field was applied, the majority of positive ions and colliding neutral molecules will form an ionic flow along the flame surface by a superposition of the electric field force and the aerodynamic drag. The ionic flow was not uniform and mainly formed on the upper and lower sides, so it will lead to a non-uniform ionic distribution along the flame surface. What’s more, this ionic flow will also induce two vortexes both inside and outside of the flame surface due to viscosity effects. The external vortexes could produce an entraining effect on the premixed gas and take away the heat from the flame surface by forced convection, and then suppress the flame propagation in the vertical direction, while, the inner vortexes would scroll the burned zones and induce an inward flow at the horizontal center, which could be the reason for the

  11. Detection and Quantification of 4-Methylimidazole in Cola by Matrix-assisted Laser Desorption Ionization Mass Spectrometry with Fe2O3 Nanoparticles on Zeolite.

    Fujii, Yosuke; Ding, Yuqi; Umezawa, Taichi; Akimoto, Takafumi; Xu, Jiawei; Uchida, Takashi; Fujino, Tatsuya

    2018-01-01

    Food additives generally used in carbonated drinks, such as 4-methylimidazole (4MI), caffeine (Caf?), citric acid (CA), and aspartame (Apm), were measured by matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) using nanometer-sized particles of iron oxide (Fe 2 O 3 NPs). The quantification of 4MI in Coca Cola (C-cola) was carried out. In order to improve the reproducibility of the peak intensities, Fe 2 O 3 NPs loaded on ZSM5 zeolite were used as the matrix for quantification. By using 2-ethylimidazole (2EI) as the internal standard, the amount of 4MI in C-cola was determined to range from 88 to 65 μg/355 mL. The results agree with the published value (approx. 72 μg/355 mL). It was found that MALDI using Fe 2 O 3 was applicable to the quantification of 4MI in C-cola.

  12. Radionuclide measurements using resonantly enhanced collisional ionization

    Whitaker, T.J.; Bushaw, B.A.; Gerke, G.K.

    1987-01-01

    This report describes development of a laser-enhanced collisional ionization method for direct radionuclide measurements that are independent of radioactive decay. The technique uses two nitrogen-laser-pumped dye lasers to selectively excite the target isotope to an electronic state near the ionization threshold. The excited actinide atoms then undergo collisions with a buffer gas and are efficiently ionized. The resulting ions can be detected by conventional methods. The attributes of this approach include highly sensitive isotope analysis with relatively inexpensive lasers and a simple vacuum system. 9 refs., 3 figs

  13. The FLAME project in Atomki

    Hunyadi, M.; Iski, N.

    2011-01-01

    Complete text of publication follows. Eleven regions of eight Central European countries have launched the FLAME Project in 2010 (Future Laboratory for the diffusion and Application of innovation in Material Sciences and Engineering) to start and manage a new initiative of a network for innovation activities in the MS and E sector. The project aimed at supporting actors in the field of materials science and exploiting their research and commercial potentials. FLAME partners encourage trans-regional cooperation between R and D centres, universities, start-ups and SMEs by helping companies to distribute their innovations and supporting research in transferring results to the market. The project will implement a new cooperation model: the 'Future Lab', where duly trained 'regional facilitation coaches' will assist SMEs in accessing the whole Central European MS and E market and research potential. Each Future Lab will be specialized on thematic fields and help to make efficient use of local and regional potentials. The three Future Labs will be hosted by the Austrian, Italian and Slovenian partner organizations. Figure 1. Competence and innovation landscape on the FLAME website. Source: http://www.flameurope.eu/mse-actors-145.html As the first step of project implementation in 2011 the competence and innovation maps within the participating regions were elaborated in order to list the relevant actors in the MS and E sector (Figure 1). In 2011, each project partner delegated two regional professionals as facilitation coaches to attend four training weeks across Europe. The facilitation coaches play an active role in the exchange of information and in motivating collaboration between research institutions and enterprises on technology based projects. The training sessions were located at four of the project partners: Kapfenberg/Austria (lead partner - Area m Styria); Warsaw/Poland (PP2 - Warsaw University of Technology); Debrecen/Hungary (PP5 - Atomki); Milan/Italy (PP

  14. Multiphoton ionization of atomic cesium

    Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

    1984-01-01

    We describe experimental studies of resonantly enhanced multi-photon ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photo-electron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photo-ionization signal. For both ns and np states the ''field induced'' MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength

  15. Multiphoton ionization of atomic cesium

    Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

    1984-01-01

    We describe experimental studies of resonantly enhanced multiphoton ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photoelectron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photoionization signal. For both ns and np states the field induced MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength. Finally, we note that the classical two-photon field-ionization threshold is lower for the case in which the laser polarization and the electric field are parallel than it is when they are perpendicular. 22 references, 11 figures

  16. The dilution effect on the extinction of wall diffusion flame

    Ghiti Nadjib

    2014-12-01

    Full Text Available The dynamic process of the interaction between a turbulent jet diffusion methane flame and a lateral wall was experimentally studied. The evolution of the flame temperature field with the Nitrogen dilution of the methane jet flame was examined. The interaction between the diffusion flame and the lateral wall was investigated for different distance between the wall and the central axes of the jet flame. The dilution is found to play the central role in the flame extinction process. The flame response as the lateral wall approaches from infinity and the increasing of the dilution rate make the flame extinction more rapid than the flame without dilution, when the nitrogen dilution rate increase the flame temperature decrease.

  17. Prediction of flame formation in highly preheated air combustion

    Yang, Jang Sik; Choi, Gyung Min; Kim, Duck Jool; Katsuki, Masashi

    2008-01-01

    Fundamental information about the ignition position and shape of a flame in highly preheated air combustion was obtained, and the suitability of the suggested reduced kinetic mechanism that reflects the characteristics of the highly preheated air combustion was demonstrated. Flame lift height and flame length with variations of premixed air temperature and oxygen concentration were measured by CH chemiluminescence intensity, and were computed with a reduced kinetic mechanism. Flame attached near a fuel nozzle started to lift when preheated air temperature became close to auto-ignition temperature and/or oxygen concentration reduced. The flame lift height increased but the flame length decreased with decreasing preheated air temperature and flame length reversed after a minimum value. Calculated results showed good agreement with those of experiment within tolerable error. Flame shape shifted from diffusion flame shape to partial premixed flame shape with increasing lift height and this tendency was also observed in the computation results

  18. Prediction of flame formation in highly preheated air combustion

    Yang, Jang Sik; Choi, Gyung Min; Kim, Duck Jool [Pusan National University, Busan (Korea, Republic of); Katsuki, Masashi [Osaka University, Osaka (Japan)

    2008-11-15

    Fundamental information about the ignition position and shape of a flame in highly preheated air combustion was obtained, and the suitability of the suggested reduced kinetic mechanism that reflects the characteristics of the highly preheated air combustion was demonstrated. Flame lift height and flame length with variations of premixed air temperature and oxygen concentration were measured by CH chemiluminescence intensity, and were computed with a reduced kinetic mechanism. Flame attached near a fuel nozzle started to lift when preheated air temperature became close to auto-ignition temperature and/or oxygen concentration reduced. The flame lift height increased but the flame length decreased with decreasing preheated air temperature and flame length reversed after a minimum value. Calculated results showed good agreement with those of experiment within tolerable error. Flame shape shifted from diffusion flame shape to partial premixed flame shape with increasing lift height and this tendency was also observed in the computation results

  19. A new ultrahigh performance liquid chromatography with diode array detection coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry analytical strategy for fast analysis and improved characterization of phenolic compounds in apple products.

    Ramirez-Ambrosi, M; Abad-Garcia, B; Viloria-Bernal, M; Garmon-Lobato, S; Berrueta, L A; Gallo, B

    2013-11-05

    A new, rapid, selective and sensitive ultrahigh performance liquid chromatography with diode array detection coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-DAD-ESI-Q-ToF-MS) strategy using automatic and simultaneous acquisition of exact mass at high and low collision energy, MS(E), has been developed to obtain polyphenolic profile of apples, apple pomace and apple juice from Asturian cider apples in a single run injection of 22 min. MS(E) spectral data acquisition overcomes chromatographic co-elution problems, performing simultaneous collection of precursor ions as well as other ions produced as a result of their fragmentation, which allows resolving complex spectra from mixtures of precursor ions in an unsupervised way and eases their interpretation. Using this technique, 52 phenolic compounds of five different classes were readily characterized in these apple extracts in both positive and negative ionization modes. The spectral data for phenolic compounds obtained using this acquisition mode are comparable to those obtained by conventional LC-MS/MS as exemplified in this work. Among the 52 phenolic compounds identified in this work, 2 dihydrochalcones and 3 flavonols have been tentatively identified for the first time in apple products. Moreover, 2 flavanols, 4 dihydrochalcones, 9 hydroxycinnamic acids and 4 flavonols had not been previously reported in apple by ToF analysis to our knowledge. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Identification and Quantification of Flavonoids and Phenolic Acids in Burr Parsley (Caucalis platycarpos L., Using High-Performance Liquid Chromatography with Diode Array Detection and Electrospray Ionization Mass Spectrometry

    Ana Mornar

    2009-07-01

    Full Text Available A sensitive method coupling high-performance liquid chromatography (HPLC with diode-array detector (DAD and electrospray ionization mass spectrometry (MS was optimized for the separation and identification of phenolic acids, flavonoid glycosides and flavonoid aglycones in the extract of burr parsley (Caucalis platycarpos L.. Fragmentation behavior of flavonoid glycosides and phenolic acids were investigated using ion trap mass spectrometry in negative electrospray ionization. The MS, MSn and UV data together with HPLC retention time (TR of phenolic acids and flavonoids allowed structural characterization of these compounds. Caffeoylquinic acid (CQA isomers, p-coumaroyl-quinic acids (p-CoQA, feruloylquinic acids (FQA, dicaffeoylquinic acids (diCQA, luteolin-7-O-rutinoside, apigenin-7-O-rutinoside as well as isolated chrysoeriol-7-O-rutinoside have been identified as constituents of C. platycarpos for the first time. An accurate, precise and sensitive LC-DAD method for quantification of four phenolic acids (3-O-caffeoylquinic, caffeic, p-coumaric, o-coumaric acid, four flavonoid glycosides (luteolin-7-O-glucoside, apigenin-7-O-glucoside, quercetin-3-O-galactoside, quercetin-3-O-rhamnoside, and three flavonoid aglycones (luteolin, apigenin, chrysoeriol in C. platycarpos extract was validated in terms of linearity, limit of detection, limit of quantification, precision and accuracy. 3-O-caffeoylquinic acid was the predominant phenolic acid and luteolin-7-O-glucoside was the predominant flavonoid glycoside.

  1. Schinus terebinthifolius scale-up countercurrent chromatography (Part I): High performance countercurrent chromatography fractionation of triterpene acids with off-line detection using atmospheric pressure chemical ionization mass spectrometry.

    Vieira, Mariana Neves; Costa, Fernanda das Neves; Leitão, Gilda Guimarães; Garrard, Ian; Hewitson, Peter; Ignatova, Svetlana; Winterhalter, Peter; Jerz, Gerold

    2015-04-10

    'Countercurrent chromatography' (CCC) is an ideal technique for the recovery, purification and isolation of bioactive natural products, due to the liquid nature of the stationary phase, process predictability and the possibility of scale-up from analytical to preparative scale. In this work, a method developed for the fractionation of Schinus terebinthifolius Raddi berries dichloromethane extract was thoroughly optimized to achieve maximal throughput with minimal solvent and time consumption per gram of processed crude extract, using analytical, semi-preparative and preparative 'high performance countercurrent chromatography' (HPCCC) instruments. The method using the biphasic solvent system composed of n-heptane-ethyl acetate-methanol-water (6:1:6:1, v/v/v/v) was volumetrically scaled up to increase sample throughput up to 120 times, while maintaining separation efficiency and time. As a fast and specific detection alternative, the fractions collected from the CCC-separations were injected to an 'atmospheric pressure chemical ionization mass-spectrometer' (APCI-MS/MS) and reconstituted molecular weight MS-chromatograms of the APCI-ionizable compounds from S. terebinthifolius were obtained. This procedure led to the direct isolation of tirucallane type triterpenes such as masticadienonic and 3β-masticadienolic acids. Also oleanonic and moronic acids have been identified for the first time in the species. In summary, this approach can be used for other CCC scale-up processes, enabling MS-target-guided isolation procedures. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Flame Speed and Self-Similar Propagation of Expanding Turbulent Premixed Flames

    Chaudhuri, Swetaprovo; Wu, Fujia; Zhu, Delin; Law, Chung K.

    2012-01-01

    In this Letter we present turbulent flame speeds and their scaling from experimental measurements on constant-pressure, unity Lewis number expanding turbulent flames, propagating in nearly homogeneous isotropic turbulence in a dual-chamber, fan-stirred vessel. It is found that the normalized turbulent flame speed as a function of the average radius scales as a turbulent Reynolds number to the one-half power, where the average radius is the length scale and the thermal diffusivity is the transport property, thus showing self-similar propagation. Utilizing this dependence it is found that the turbulent flame speeds from the present expanding flames and those from the Bunsen geometry in the literature can be unified by a turbulent Reynolds number based on flame length scales using recent theoretical results obtained by spectral closure of the transformed G equation.

  3. Tomographic scanning apparatus with ionization detector means

    1981-01-01

    This patent specification describes a tomographic scanning apparatus using a fan beam and digital output signal. Particular reference is made to the gas-pressurized ionization detector chamber, consisting of an array of side-by-side elongate ionization detection cells, the principal axis of each of the said cells being oriented along a radius extending towards the radiation source, and connection means for applying potentials across the cells for taking their output signals. (U.K.)

  4. Aromatics oxidation and soot formation in flames

    Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T. [Massachusetts Institute of Technology, Cambridge (United States)

    1993-12-01

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and soot and fullerenes formation in flames. The scope includes detailed measurements of profiles of stable and radical species concentrations in low-pressure one-dimensional premixed flames. Intermediate species identifications and mole fractions, fluxes, and net reaction rates calculated from the measured profiles are used to test postulated reaction mechanisms. Particular objectives are to identify and to determine or confirm rate constants for the main benzene oxidation reactions in flames, and to characterize fullerenes and their formation mechanisms and kinetics.

  5. Structure of diffusion flames from a vertical burner

    Mark A. Finney; Dan Jimenez; Jack D. Cohen; Isaac C. Grenfell; Cyle Wold

    2010-01-01

    Non-steady and turbulent flames are commonly observed to produce flame contacts with adjacent fuels during fire spread in a wide range of fuel bed depths. A stationary gas-fired burner (flame wall) was developed to begin study of flame edge variability along an analagous vertical fuel source. This flame wall is surrogate for a combustion interface at the edge of a deep...

  6. Direct numerical simulations of non-premixed ethylene-air flames: Local flame extinction criterion

    Lecoustre, Vivien R.

    2014-11-01

    Direct Numerical Simulations (DNS) of ethylene/air diffusion flame extinctions in decaying two-dimensional turbulence were performed. A Damköhler-number-based flame extinction criterion as provided by classical large activation energy asymptotic (AEA) theory is assessed for its validity in predicting flame extinction and compared to one based on Chemical Explosive Mode Analysis (CEMA) of the detailed chemistry. The DNS code solves compressible flow conservation equations using high order finite difference and explicit time integration schemes. The ethylene/air chemistry is simulated with a reduced mechanism that is generated based on the directed relation graph (DRG) based methods along with stiffness removal. The numerical configuration is an ethylene fuel strip embedded in ambient air and exposed to a prescribed decaying turbulent flow field. The emphasis of this study is on the several flame extinction events observed in contrived parametric simulations. A modified viscosity and changing pressure (MVCP) scheme was adopted in order to artificially manipulate the probability of flame extinction. Using MVCP, pressure was changed from the baseline case of 1 atm to 0.1 and 10 atm. In the high pressure MVCP case, the simulated flame is extinction-free, whereas in the low pressure MVCP case, the simulated flame features frequent extinction events and is close to global extinction. Results show that, despite its relative simplicity and provided that the global flame activation temperature is correctly calibrated, the AEA-based flame extinction criterion can accurately predict the simulated flame extinction events. It is also found that the AEA-based criterion provides predictions of flame extinction that are consistent with those provided by a CEMA-based criterion. This study supports the validity of a simple Damköhler-number-based criterion to predict flame extinction in engineering-level CFD models. © 2014 The Combustion Institute.

  7. Effects of self-absorption on simultaneous estimation of temperature distribution and concentration fields of soot and metal-oxide nanoparticles in nanofluid fuel flames using a spectrometer

    Liu, Guannan; Liu, Dong

    2018-06-01

    An improved inverse reconstruction model with consideration of self-absorption effect for the temperature distribution and concentration fields of soot and metal-oxide nanoparticles in nanofluid fuel flames was proposed based on the flame emission spectrometry. The effects of self-absorption on the temperature profile and concentration fields were investigated for various measurement errors, flame optical thicknesses and detecting lines numbers. The model neglecting the self-absorption caused serious reconstruction errors especially in the nanofluid fuel flames with large optical thicknesses, while the improved model was used to successfully recover the temperature distribution and concentration fields of soot and metal-oxide nanoparticles for the flames regardless of the optical thickness. Through increasing detecting lines number, the reconstruction accuracy can be greatly improved due to more flame emission information received by the spectrometer. With the adequate detecting lines number, the estimations for the temperature distribution and concentration fields of soot and metal-oxide nanoparticles in flames with large optical thicknesses were still satisfying even from the noisy radiation intensities with signal to noise ratio (SNR) as low as 46 dB. The results showed that the improved reconstruction model was effective and robust to concurrently retrieve the temperature distribution and volume fraction fields of soot and metal-oxide nanoparticles for the exact and noisy data in nanofluid fuel sooting flames with different optical thicknesses.

  8. Effect of cylindrical confinement on the determination of laminar flame speeds using outwardly propagating flames

    Burke, Michael P.; Chen, Zheng; Ju, Yiguang; Dryer, Frederick L. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

    2009-04-15

    The effect of nonspherical (i.e. cylindrical) bomb geometry on the evolution of outwardly propagating flames and the determination of laminar flame speeds using the conventional constant-pressure technique is investigated experimentally and theoretically. The cylindrical chamber boundary modifies the propagation rate through the interaction of the wall with the flow induced by thermal expansion across the flame (even with constant pressure), which leads to significant distortion of the flame surface for large flame radii. These departures from the unconfined case, especially the resulting nonzero burned gas velocities, can lead to significant errors in flame speeds calculated using the conventional assumptions, especially for large flame radii. For example, at a flame radius of 0.5 times the wall radius, the flame speed calculated neglecting confinement effects can be low by {proportional_to}15% (even with constant pressure). A methodology to estimate the effect of nonzero burned gas velocities on the measured flame speed in cylindrical chambers is presented. Modeling and experiments indicate that the effect of confinement can be neglected for flame radii less than 0.3 times the wall radius while still achieving acceptable accuracy (within 3%). The methodology is applied to correct the flame speed for nonzero burned gas speeds, in order to extend the range of flame radii useful for flame speed measurements. Under the proposed scaling, the burned gas speed can be well approximated as a function of only flame radius for a given chamber geometry - i.e. the correction function need only be determined once for an apparatus and then it can be used for any mixture. Results indicate that the flow correction can be used to extract flame speeds for flame radii up to 0.5 times the wall radius with somewhat larger, yet still acceptable uncertainties for the cases studied. Flow-corrected burning velocities are measured for hydrogen and syngas mixtures at atmospheric and

  9. Mass spectrometry of solid samples in open air using combined laser ionization and ambient metastable ionization

    He, X.N.; Xie, Z.Q.; Gao, Y.; Hu, W.; Guo, L.B.; Jiang, L.; Lu, Y.F.

    2012-01-01

    Mass spectrometry of solid samples in open air was carried out using combined laser ionization and metastable ionization time-of-flight mass spectrometry (LI-MI-TOFMS) in ambient environment for qualitative and semiquantitative (relative analyte information, not absolute information) analysis. Ambient metastable ionization using a direct analysis in realtime (DART) ion source was combined with laser ionization time-of-flight mass spectrometry (LI-TOFMS) to study the effects of combining metastable and laser ionization. A series of metallic samples from the National Institute of Standards and Technology (NIST 494, 495, 498, 499, and 500) and a pure carbon target were characterized using LI-TOFMS in open air. LI-MI-TOFMS was found to be superior to laser-induced breakdown spectroscopy (LIBS). Laser pulse energies between 10 and 200 mJ at the second harmonic (532 nm) of an Nd:YAG laser were applied in the experiment to obtain a high degree of ionization in plasmas. Higher laser pulse energy improves signal intensities of trace elements (such as Fe, Cr, Mn, Ni, Ca, Al, and Ag). Data were analyzed by numerically calculating relative sensitivity coefficients (RSCs) and limit of detections (LODs) from mass spectrometry (MS) and LIBS spectra. Different parameters, such as boiling point, ionization potential, RSC, LOD, and atomic weight, were shown to analyze the ionization and MS detection processes in open air.

  10. Diamond growth in oxygen-acetylene flame

    Haga, Mario S.; Nagai, Y. Ernesto; Suzuki, Carlos K.

    1995-01-01

    What was supposed to be a laboratory curiosity in the 80's, in recent years the low pressure process for the production of man-made diamond turned out to be a major target for research and development of many high-tech companies. The main reason for such an interest stems on the possibility of coating many materials with a diamond film possessing the same amazing properties of the bulk natural diamond. Polycrystalline diamond film has been deposited on Mo substrate by using oxygen-acetylene flame of a welding torch. The substrate temperature has been held constant about 700 d eg C by means of a water cooled mount designed properly. Precision flowmeters have been used to control the flow ratio oxygen/acetylene, a key parameter for the success in diamond growth. Diamond has been detected by X-ray diffraction, a fast foolproof technique for crystal identification. Another method of analysis often used in Raman spectroscopy, which is able to exhibit amorphous structure besides crystalline phase. (author)

  11. Direct detection of the plant pathogens Burkholderia glumae, Burkholderia gladioli pv. gladioli, and Erwinia chrysanthemi pv. zeae in infected rice seedlings using matrix assisted laser desorption/ionization time-of-flight mass spectrometry.

    Kajiwara, Hideyuki

    2016-01-01

    The plant pathogens Burkholderia glumae, Burkholderia gladioli pv. gladioli, and Erwinia chrysanthemi pv. zeae were directly detected in extracts from infected rice seedlings by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). This method did not require culturing of the pathogens on artificial medium. In the MALDI-TOF MS analysis, peaks originating from bacteria were found in extracts from infected rice seedlings. The spectral peaks showed significantly high scores, in spite of minor differences in spectra. The spectral peaks originating from host plant tissues did not affect this direct MALDI-TOF MS analysis for the rapid identification of plant pathogens. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Ionizing radiation in hospitals

    Blok, K.; Ginkel, G. van; Leun, K. van der; Muller, H.; Oude Elferink, J.; Vesseur, A.

    1985-10-01

    This booklet dels with the risks of the use of ionizing radiation for people working in a hospital. It is subdivided in three parts. Part 1 treats the properties of ionizing radiation in general. In part 2 the various applications are discussed of ionizing radiation in hospitals. Part 3 indicates how a not completely safe situation may be improved. (H.W.). 14 figs.; 4 tabs

  13. Gas-Flame Brazing of Metals

    Asinovskaya, G

    1964-01-01

    .... Since a gas flame implies the presence of considerable heat, the term brazing will be used in this translation save where low heats are specifically indicated, or where both high and low heats...

  14. Systems and methods for controlling flame instability

    Cha, Min; Xiong, Yuan; Chung, Suk-Ho

    2016-01-01

    A system (62) for controlling flame instability comprising: a nozzle (66) coupled to a fuel supply line (70), an insulation housing (74) coupled to the nozzle, a combustor (78) coupled to the nozzle via the insulation housing, where the combustor

  15. Nanocellular foam with solid flame retardant

    Chen, Liang; Kelly-Rowley, Anne M.; Bunker, Shana P.; Costeux, Stephane

    2017-11-21

    Prepare nanofoam by (a) providing an aqueous solution of a flame retardant dissolved in an aqueous solvent, wherein the flame retardant is a solid at 23.degree. C. and 101 kiloPascals pressure when in neat form; (b) providing a fluid polymer composition selected from a solution of polymer dissolved in a water-miscible solvent or a latex of polymer particles in a continuous aqueous phase; (c) mixing the aqueous solution of flame retardant with the fluid polymer composition to form a mixture; (d) removing water and, if present, solvent from the mixture to produce a polymeric composition having less than 74 weight-percent flame retardant based on total polymeric composition weight; (e) compound the polymeric composition with a matrix polymer to form a matrix polymer composition; and (f) foam the matrix polymer composition into nanofoam having a porosity of at least 60 percent.

  16. Distribution of electric potential in hydrocarbon flames

    Fialkov, B.S.; Shcherbakov, N.D.; Plitsyn, V.T.

    1978-01-01

    A study was made of the distribution of electrical potential and temperatures in laminar methane and propane--butane flames when the excess air coefficient in the mixture is changed from 0 to 1.2. 7 references, 3 figures.

  17. CloudFlame: Cyberinfrastructure for combustion research

    Goteng, Gokop; Nettyam, Naveena; Sarathy, Mani

    2013-01-01

    Combustion experiments and chemical kinetics simulations generate huge data that is computationally and data intensive. A cloud-based cyber infrastructure known as Cloud Flame is implemented to improve the computational efficiency, scalability

  18. Synthesis of Nano-Particles in Flames

    Johannessen, Tue

    flame burner and a premixed burner with a precursor jet. The experimental setups and results are shown and discussed in detail. Alumina powder with specific surface area between 45 m2/g and 190 m2/g was obtained.Temperature and flow fields of the flame processes are analysed by numerical simulations...... energy expression.Furthermore, the model is validated by comparison with experimental data of the flame synthesis of titania by combustion of TiCl4 previously presented by Pratsinis et al. (1996).The combination of particle dynamics and CFD simulations has proved to be an efficient method......The scope of this work is to investigate the synthesis of aluminum oxide particles in flames from the combustion of an aluminum alkoxide precursor.A general introduction to particles formation in the gas phase is presented with emphasis on the mechanisms that control the particle morphology after...

  19. Numerical modelling of ion transport in flames

    Han, Jie; Belhi, Memdouh; Bisetti, Fabrizio; Sarathy, Mani

    2015-01-01

    that changes in polarizability propagate with decreasing effect from binary transport coefficients to species number densities. We conclude that the chosen polarizability value has a limited effect on the ion distribution in freely propagating flames. We expect

  20. Dosimetry of ionizing radiation

    Musilek, L.; Seda, J.; Trousil, J.

    1992-01-01

    The publication deals with a major field of ionizing radiation dosimetry, viz., integrating dosimetric methods, which are the basic means of operative dose determination. It is divided into the following sections: physical and chemical effects of ionizing radiation; integrating dosimetric methods for low radiation doses (film dosimetry, nuclear emulsions, thermoluminescence, radiophotoluminescence, solid-state track detectors, integrating ionization dosemeters); dosimetry of high ionizing radiation doses (chemical dosimetric methods, dosemeters based on the coloring effect, activation detectors); additional methods applicable to integrating dosimetry (exoelectron emission, electron spin resonance, lyoluminescence, etc.); and calibration techniques for dosimetric instrumentation. (Z.S.). 422 refs

  1. Is it possible to detect by peri-ungual capillaroscopy the micro-circulatory impact of ionizing radiation among radiation exposed physicians?

    Menez, C.

    2007-10-01

    The objective: evaluation of the peri-ungual capillaroscopy as diagnostic tool and screening of secondary infra clinical lesions to a chronic exposure to X ionizing radiation. Material and methods: the whole of personnel exposed of the Grenoble university hospital center, as well as a non exposed physician population chosen according to age criteria, had benefit of a peri-ungual capillaroscopy. An estimation of the exposure level was realised, allowing the constitution of exposure groups. Seven qualitative capillaroscopic variables were evaluated: dilatation, hemorrhages, edema, capillary rarefaction, tortuosity, capillary density and background color. Results: two homogenous populations in term of age: 32 exposed subjects, for essential cardiologists and interventional radiologists; 35 non exposed subjects. No statistically significant difference was enlightened, in the comparison of exposed- non exposed groups and in the comparison of the most exposed group to the control group. Discussion: the low statistical power of this study does not allow to conclude to the lack of inter group difference. This result disagrees with the literature, but these works are not easily comparable. Conclusion: the importance of the stake and the surveillance of the operators hands justifies the realisation of a multi centric great scope study. (N.C.)

  2. Assisted inhibition effect of acetylcholinesterase with n-octylphosphonic acid and application in high sensitive detection of organophosphorous pesticides by matrix-assisted laser desorption/ionization Fourier transform mass spectrometry.

    Cai, Tingting; Zhang, Li; Wang, Haoyang; Zhang, Jing; Guo, Yinlong

    2011-11-14

    A simple and practical approach to improve the sensitivity of acetylcholinesterase (AChE)-inhibited method has been developed for monitoring organophosphorous (OP) pesticide residues. In this work, matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) was used to detect AChE activity. Due to its good salt-tolerance and low sample consumption, MALDI-FTMS facilitates rapid and high-throughput screening of OP pesticides. Here we describe a new method to obtain low detection limits via employing external reagents. Among candidate compounds, n-octylphosphonic acid (n-Octyl-PA) displays assistant effect to enhance AChE inhibition by OP pesticides. In presence of n-Octyl-PA, the percentages of AChE inhibition still kept correlation with OP pesticide concentrations. The detection limits were improved significantly even by 10(2)-10(3) folds in comparison with conventional enzyme-inhibited methods. Different detection limits of OP pesticides with different toxicities were as low as 0.005 μg L(-1) for high toxic pesticides and 0.05 μg L(-1) for low toxic pesticides. Besides, the reliability of results from this method to analyze cowpea samples had been demonstrated by liquid-chromatography tandem mass spectrometry (LC-MS/MS). The application of this commercial available assistant agent shows great promise to detect OP compounds in complicated biological matrix and broadens the mind for high sensitivity detection of OP pesticide residues in agricultural products. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Characterization of flame radiosity in shrubland fires

    Miguel G. Cruz; Bret W. Butler; Domingos X. Viegas; Pedro Palheiro

    2011-01-01

    The present study is aimed at quantifying the flame radiosity vertical profile and gas temperature in moderate to high intensity spreading fires in shrubland fuels. We report on the results from 11 experimental fires conducted over a range of fire rate of spread and frontal fire intensity varying respectively between 0.04-0.35ms-1 and 468-14,973kWm-1. Flame radiosity,...

  4. Conical quarl swirl stabilized non-premixed flames: flame and flow field interaction

    Elbaz, Ayman M.; Roberts, William L.

    2017-01-01

    The flame-flow field interaction is studied in non-premixed methane swirl flames stabilized in quartz quarl via simultaneous measurements of the flow field using a stereo PIV and OH-PLIF at 5 KHz repetition rate. Under the same swirl intensity, two flames with different fuel jet velocity were investigated. The time-averaged flow field shows a unique flow pattern at the quarl exit, where two recirculation vortices are formed; a strong recirculation zone formed far from the quarl exit and a larger recirculation zone extending inside the quarl. However, the instantaneous images show that, the flow pattern near the quarl exit plays a vital role in the spatial location and structure of the reaction zone. In the low fuel jet velocity flame, a pair of vortical structures, located precisely at the corners of the quarl exit, cause the flame to roll up into the central region of low speed flow, where the flame sheet then tracks the axial velocity fluctuations. The vorticity field reveals a vortical structure surrounding the reaction zones, which reside on a layer of low compressive strain adjacent to that vortical structure. In the high fuel jet velocity flame, initially a laminar flame sheet resides at the inner shear layer of the main jet, along the interface between incoming fresh gas and high temperature recirculating gas. Further downstream, vortex breakdown alters the flame sheet path toward the central flame region. The lower reaction zones show good correlation to the regions of maximum vorticity and track the regions of low compressive strain associated with the inner shear layer of the jet flow. In both flames the reactions zones conform the passage of the large structure while remaining inside the low speed regions or at the inner shear layer.

  5. Conical quarl swirl stabilized non-premixed flames: flame and flow field interaction

    Elbaz, Ayman M.

    2017-09-19

    The flame-flow field interaction is studied in non-premixed methane swirl flames stabilized in quartz quarl via simultaneous measurements of the flow field using a stereo PIV and OH-PLIF at 5 KHz repetition rate. Under the same swirl intensity, two flames with different fuel jet velocity were investigated. The time-averaged flow field shows a unique flow pattern at the quarl exit, where two recirculation vortices are formed; a strong recirculation zone formed far from the quarl exit and a larger recirculation zone extending inside the quarl. However, the instantaneous images show that, the flow pattern near the quarl exit plays a vital role in the spatial location and structure of the reaction zone. In the low fuel jet velocity flame, a pair of vortical structures, located precisely at the corners of the quarl exit, cause the flame to roll up into the central region of low speed flow, where the flame sheet then tracks the axial velocity fluctuations. The vorticity field reveals a vortical structure surrounding the reaction zones, which reside on a layer of low compressive strain adjacent to that vortical structure. In the high fuel jet velocity flame, initially a laminar flame sheet resides at the inner shear layer of the main jet, along the interface between incoming fresh gas and high temperature recirculating gas. Further downstream, vortex breakdown alters the flame sheet path toward the central flame region. The lower reaction zones show good correlation to the regions of maximum vorticity and track the regions of low compressive strain associated with the inner shear layer of the jet flow. In both flames the reactions zones conform the passage of the large structure while remaining inside the low speed regions or at the inner shear layer.

  6. Preparation of Flame Retardant Modified with Titanate for Asphalt Binder

    Bo Li

    2014-01-01

    Full Text Available Improving the compatibility between flame retardant and asphalt is a difficult task due to the complex nature of the materials. This study explores a low dosage compound flame retardant and seeks to improve the compatibility between flame retardants and asphalt. An orthogonal experiment was designed taking magnesium hydroxide, ammonium polyphosphate, and melamine as factors. The oil absorption and activation index were tested to determine the effect of titanate on the flame retardant additive. The pavement performance test was conducted to evaluate the effect of the flame retardant additive. Oxygen index test was conducted to confirm the effect of flame retardant on flame ability of asphalt binder. The results of this study showed that the new composite flame retardant is more effective in improving the compatibility between flame retardant and asphalt and reducing the limiting oxygen index of asphalt binder tested in this study.

  7. Simultaneous detection of low and high molecular weight carbonylated compounds derived from lipid peroxidation by electrospray ionization-tandem mass spectrometry.

    Milic, Ivana; Hoffmann, Ralf; Fedorova, Maria

    2013-01-02

    Reactive oxygen species (ROS) and other oxidative agents such as free radicals can oxidize polyunsaturated fatty acids (PUFA) as well as PUFA in lipids. The oxidation products can undergo consecutive reactions including oxidative cleavages to yield a chemically diverse group of products, such as lipid peroxidation products (LPP). Among them are aldehydes and ketones ("reactive carbonyls") that are strong electrophiles and thus can readily react with nucleophilic side chains of proteins, which can alter the protein structure, function, cellular distribution, and antigenicity. Here, we report a novel technique to specifically derivatize both low molecular and high molecular weight carbonylated LPP with 7-(diethylamino)coumarin-3-carbohydrazide (CHH) and analyze all compounds by electrospray ionization-mass spectrometry (ESI-MS) in positive ion mode. CHH-derivatized compounds were identified by specific neutral losses or fragment ions. The fragment ion spectra displayed additional signals that allowed unambiguous identification of the lipid, fatty acids, cleavage sites, and oxidative modifications. Oxidation of docosahexaenoic (DHA, 22:6), arachidonic (AA, 20:4), linoleic (LA, 18:2), and oleic acids (OA, 18:1) yielded 69 aliphatic carbonyls, whose structures were all deduced from the tandem mass spectra. When four phosphatidylcholine (PC) vesicles containing the aforementioned unsaturated fatty acids were oxidized, we were able to deduce the structures of 122 carbonylated compounds from the tandem mass spectra of a single shotgun analysis acquired within 15 min. The high sensitivity (LOD ∼ 1 nmol/L for 4-hydroxy-2-nonenal, HNE) and a linear range of more than 3 orders of magnitude (10 nmol/L to 10 μmol/L for HNE) will allow further studies on complex biological samples including plasma.

  8. Blowoff dynamics of bluff body stabilized turbulent premixed flames

    Chaudhuri, Swetaprovo; Kostka, Stanislav; Renfro, Michael W.; Cetegen, Baki M. [Department of Mechanical Engineering, University of Connecticut, 191 Auditorium Road, U-3139, Storrs, CT 06269 (United States)

    2010-04-15

    This article concerns the flame dynamics of a bluff body stabilized turbulent premixed flame as it approaches lean blowoff. Time resolved chemiluminescence imaging along with simultaneous particle image velocimetry and OH planar laser-induced fluorescence were utilized in an axisymmetric bluff body stabilized, propane-air flame to determine the sequence of events leading to blowoff and provide a quantitative analysis of the experimental results. It was found that as lean blowoff is approached by reduction of equivalence ratio, flame speed decreases and the flame shape progressively changes from a conical to a columnar shape. For a stably burning conical flame away from blowoff, the flame front envelopes the shear layer vortices. Near blowoff, the columnar flame front and shear layer vortices overlap to induce high local stretch rates that exceed the extinction stretch rates instantaneously and in the mean, resulting in local flame extinction along the shear layers. Following shear layer extinction, fresh reactants can pass through the shear layers to react within the recirculation zone with all other parts of the flame extinguished. This flame kernel within the recirculation zone may survive for a few milliseconds and can reignite the shear layers such that the entire flame is reestablished for a short period. This extinction and reignition event can happen several times before final blowoff which occurs when the flame kernel fails to reignite the shear layers and ultimately leads to total flame extinguishment. (author)

  9. Validation of an immunochemical assay for the detection of DNA damage as a tool for biological dosimetry of human exposure to ionizing radiation

    Schans, G.P. van der; Timmerman, A.J.; Wojewodzka, M.; Zaim, J.

    1997-01-01

    A method for biological dosimetry based on the immunochemical detection of DNA damage in human white blood cells has been validated. To this end the method developed at TNO (Rijswijk, the Netherlands) was also set up at INCT (Warsaw, Poland). Blood samples of 11 individuals were irradiated with 0 or 5 Gy of 170 kV X-rays at INCT and analyzed both at INCT and TNO. It appeared that in both laboratories damage could be detected to the same extent. The average background level of DNA damage amounted to 1.0 Gy-eq with an interindividual standard deviation of 0.25 Gy. The contribution of the sample variance to the total variance is only 14%. The radiosensitivity showed only a variation of about 10% and can, therefore, be neglected in estimating the radiation dose from the amount of DNA damage detected. (author)

  10. Immunotoxicity of organophosphate flame retardants TPHP and TDCIPP on murine dendritic cells in vitro

    Canbaz, Derya; Logiantara, Adrian; van Ree, Ronald; van Rijt, Leonie S.

    2017-01-01

    Organophosphate flame retardants (PFRs) are commonly used as alternatives for the banned polybrominated diphenyl ethers (PBDEs) and are ubiquitously detected in indoor dust. PFRs can be potentially hazardous to respiratory health via the inhalation of house dust. Dendritic cells (DCs) are crucial in

  11. Comparison of Air Sampling Methods for Organophosphate Flame Retardants in Small Environmental Chambers

    Organophosphorus flame retardants (OPFRs), such as tris(2-chloroethyl) phosphate (TCEP), tris(1-chlor-2-propyl) phosphate (TCPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCPP), used as additives in industrial and consumer products are being detected in indoor air, house dust,...

  12. Improvements in ionization chambers

    Whetten, N.R.; Zubal, C.

    1980-01-01

    A method of reducing mechanical vibrations transmitted to the parallel plate electrodes of ionization chamber x-ray detectors, commonly used in computerized x-ray axial tomography systems, is described. The metal plate cathodes and anodes are mounted in the ionizable gas on dielectric sheet insulators consisting of a composite of silicone resin and glass fibres. (UK)

  13. Dual ionization chamber

    Mallory, J.; Turlej, Z.

    1981-01-01

    Dual ionization chambers are provided for use with an electronic smoke detector. The chambers are separated by electrically-conductive partition. A single radiation source extends through the partition into both chambers, ionizing the air in each. The mid-point current of the device may be balanced by adjusting the position of the source

  14. Flame synthesis of zinc oxide nanocrystals

    Merchan-Merchan, Wilson, E-mail: wmerchan-merchan@ou.edu [School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019 (United States); Farahani, Moien Farmahini [School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019 (United States)

    2013-02-01

    Highlights: Black-Right-Pointing-Pointer We report a single-step flame method for the synthesis of Zn oxide nanocrystals. Black-Right-Pointing-Pointer Diverse flame positions lead to a variation of Zn oxide nanocrystal growth. Black-Right-Pointing-Pointer The synthesized crystals have polyhedral, pipet- and needle-like shape. Black-Right-Pointing-Pointer High length-to-diameter aspect-ratio crystals appear in a higher temperature flame. Black-Right-Pointing-Pointer The crystal growth mechanism corresponds to vapor-to-solid conversion. - Abstract: Distinctive zinc oxide (ZnO) nanocrystals were synthesized on the surface of Zn probes using a counter-flow flame medium formed by methane/acetylene and oxygen-enriched air streams. The source material, a zinc wire with a purity of {approx}99.99% and diameter of 1 mm, was introduced through a sleeve into the oxygen rich region of the flame. The position of the probe/sleeve was varied within the flame medium resulting in growth variation of ZnO nanocrystals on the surface of the probe. The shape and structural parameters of the grown crystals strongly depend on the flame position. Structural variations of the synthesized crystals include single-crystalline ZnO nanorods and microprisms (ZMPs) (the ZMPs have less than a few micrometers in length and several hundred nanometers in cross section) with a large number of facets and complex axial symmetry with a nanorod protruding from their tips. The protruding rods are less than 100 nm in diameter and lengths are less than 1 {mu}m. The protruding nanorods can be elongated several times by increasing the residence time of the probe/sleeve inside the oxygen-rich flame or by varying the flame position. At different flame heights, nanorods having higher length-to-diameter aspect-ratio can be synthesized. A lattice spacing of {approx}0.26 nm was measured for the synthesized nanorods, which can be closely correlated with the (0 0 2) interplanar spacing of hexagonal ZnO (Wurtzite) cells

  15. Electron impact ionization of large krypton clusters

    Li Shao-Hui; Li Ru-Xin; Ni Guo-Quan; Xu Zhi-Zhan

    2004-01-01

    We show that the detection of ionization of very large van der Waals clusters in a pulsed jet or a beam can be realized by using a fast ion gauge. Rapid positive feedback electron impact ionization and fragmentation processes,which are initially ignited by electron impact ionization of the krypton clusters with the electron current of the ion gauge, result in the appearance of a progressional oscillation-like ion spectrum, or just of a single fast event under critical conditions. Each line in the spectrum represents a correlated explosion or avalanche ionization of the clusters.The phenomena have been analysed qualitatively along with a Rayleigh scattering experiment of the corresponding cluster jet.

  16. Flame Structure of Vitiated Fuel-Rich Inverse Diffusion Flames in a Cross-Flow (Postprint)

    2011-12-01

    downstream of the slot. The flame length increases as the blowing ratio increases as a result of the greater mass of air which reacts. Ignition of...attributed to the greater penetration of the jet into the cross-stream. It is noted that the flame lengths are similar for the different blowing ratios

  17. Laminar Flame Speeds of Gasoline Surrogates Measured with the Flat Flame Method

    Liao, Y.-H.; Roberts, William L.

    2016-01-01

    © 2016 American Chemical Society. The adiabatic, laminar flame speeds of gasoline surrogates at atmospheric pressure over a range of equivalence ratios of = 0.8-1.3 and unburned gas temperatures of 298-400 K are measured with the flat flame method

  18. On the dynamics of flame edges in diffusion-flame/vortex interactions

    Hermanns, Miguel; Linan, Amable [Departamento de Motopropulsion y Termofluidodinamica, Universidad Politecnica de Madrid, Pza. Cardenal Cisneros 3, 28040 Madrid (Spain); Vera, Marcos [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

    2007-04-15

    We analyze the local flame extinction and reignition of a counterflow diffusion flame perturbed by a laminar vortex ring. Local flame extinction leads to the appearance of flame edges separating the burning and extinguished regions of the distorted mixing layer. The dynamics of these edges is modeled based on previous numerical results, with heat release effects fully taken into account, which provide the propagation velocity of triple and edge flames in terms of the upstream unperturbed value of the scalar dissipation. The temporal evolution of the mixing layer is determined using the classical mixture fraction approach, with both unsteady and curvature effects taken into account. Although variable density effects play an important role in exothermic reacting mixing layers, in this paper the description of the mixing layer is carried out using the constant density approximation, leading to a simplified analytical description of the flow field. The mathematical model reveals the relevant nondimensional parameters governing diffusion-flame/vortex interactions and provides the parameter range for the more relevant regime of local flame extinction followed by reignition via flame edges. Despite the simplicity of the model, the results show very good agreement with previously published experimental results. (author)

  19. Electrolyte system strategies for anionic isotachophoresis with electrospray-ionization mass-spectrometric detection. 1. Regular isotachophoresis and free-acid isotachophoresis

    Malá, Zdeňka; Gebauer, Petr; Boček, Petr

    2013-01-01

    Roč. 34, 20-21 (2013), s. 3072-3078 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GA13-05762S Institutional support: RVO:68081715 Keywords : Diclofenac * ESI-MS detection * Ibuprofen * isotachophoresis * water analysis Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.161, year: 2013

  20. Electrolyte system strategies for anionic isotachophoresis with electrospray-ionization mass-spectrometric detection. 2. Isotachophoresis in moving-boundary systems

    Gebauer, Petr; Malá, Zdeňka; Boček, Petr

    2013-01-01

    Roč. 34, č. 24 (2013), s. 3245-3251 ISSN 0173-0835 R&D Project s: GA ČR(CZ) GA13-05762S Institutional support: RVO:68081715 Keywords : electrolyte systems * ESI-MS detection * isotachophoresis * moving-boundary electrophoresis Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.161, year: 2013