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Sample records for ptr reactor

  1. Experimental investigation of neutronic characteristics of the IR-8 reactor to confirm the results of calculations by MCU-PTR code

    SciTech Connect

    Surkov, A. V. Kochkin, V. N.; Pesnya, Yu. E.; Nasonov, V. A.; Vihrov, V. I.; Erak, D. Yu.

    2015-12-15

    A comparison of measured and calculated neutronic characteristics (fast neutron flux and fission rate of {sup 235}U) in the core and reflector of the IR-8 reactor is presented. The irradiation devices equipped with neutron activation detectors were prepared. The determination of fast neutron flux was performed using the {sup 54}Fe (n, p) and {sup 58}Ni (n, p) reactions. The {sup 235}U fission rate was measured using uranium dioxide with 10% enrichment in {sup 235}U. The determination of specific activities of detectors was carried out by measuring the intensity of characteristic gamma peaks using the ORTEC gamma spectrometer. Neutron fields in the core and reflector of the IR-8 reactor were calculated using the MCU-PTR code.

  2. Experimental investigation of neutronic characteristics of the IR-8 reactor to confirm the results of calculations by MCU-PTR code

    NASA Astrophysics Data System (ADS)

    Surkov, A. V.; Kochkin, V. N.; Pesnya, Yu. E.; Nasonov, V. A.; Vihrov, V. I.; Erak, D. Yu.

    2015-12-01

    A comparison of measured and calculated neutronic characteristics (fast neutron flux and fission rate of 235U) in the core and reflector of the IR-8 reactor is presented. The irradiation devices equipped with neutron activation detectors were prepared. The determination of fast neutron flux was performed using the 54Fe ( n, p) and 58Ni ( n, p) reactions. The 235U fission rate was measured using uranium dioxide with 10% enrichment in 235U. The determination of specific activities of detectors was carried out by measuring the intensity of characteristic gamma peaks using the ORTEC gamma spectrometer. Neutron fields in the core and reflector of the IR-8 reactor were calculated using the MCU-PTR code.

  3. PTR-MS in enology

    NASA Astrophysics Data System (ADS)

    Spitaler, Renate; Araghipour, Nooshin; Mikoviny, Tomas; Wisthaler, Armin; Via, Josef Dalla; Märk, Tilmann D.

    2007-10-01

    The present communication deals with the improvement of proton transfer reaction mass spectrometry (PTR-MS) wine headspace analyses. In contrast to previous PTR-MS investigations of wine, where wine headspace was ionized by protonated ethanol clusters, the headspace was diluted by a factor of 1:40 with N2 and ionized by H3O+ ions. This method is better suited for routine applications than the previously reported method since it is simpler, faster, and the mass spectra obtained are less complex. A test wine was mixed with ethanol and with water to yield ethanol contents ranging from 10 to 15% (v/v) and these mixtures were analyzed to assess whether any quantitative differences in the composition of volatiles were detectable. The data showed no impact of the ethanol content on the wine headspace composition. The new method was applied to eight different wine samples produced from two different grape varieties: Pinot Noir and Cabernet Sauvignon. Each variety was grown in two different locations in South Tyrol (Northern Italy) and harvested at two different dates. Quantitative (but not qualitative) differences in PTR-MS spectra between the two wine varieties were observed. Using principal component analysis of selected m/z signals differentiation between Pinot Noir and Cabernet Sauvignon samples was achievable.

  4. Functional Properties of the Arabidopsis Peptide Transporters AtPTR1 and AtPTR5*

    PubMed Central

    Hammes, Ulrich Z.; Meier, Stefan; Dietrich, Daniela; Ward, John M.; Rentsch, Doris

    2010-01-01

    The Arabidopsis di- and tripeptide transporters AtPTR1 and AtPTR5 were expressed in Xenopus laevis oocytes, and their selectivity and kinetic properties were determined by voltage clamping and by radioactive uptake. Dipeptide transport by AtPTR1 and AtPTR5 was found to be electrogenic and dependent on protons but not sodium. In the absence of dipeptides, both transporters showed proton-dependent leak currents that were inhibited by Phe-Ala (AtPTR5) and Phe-Ala, Trp-Ala, and Phe-Phe (AtPTR1). Phe-Ala was shown to reduce leak currents by binding to the substrate-binding site with a high apparent affinity. Inhibition of leak currents was only observed when the aromatic amino acids were present at the N-terminal position. AtPTR1 and AtPTR5 transport activity was voltage-dependent, and currents increased supralinearly with more negative membrane potentials and did not saturate. The voltage dependence of the apparent affinities differed between Ala-Ala, Ala-Lys, and Ala-Asp and was not conserved between the two transporters. The apparent affinity of AtPTR1 for these dipeptides was pH-dependent and decreased with decreasing proton concentration. In contrast to most proton-coupled transporters characterized so far, −Imax increased at high pH, indicating that regulation of the transporter by pH overrides the importance of protons as co-substrate. PMID:20937801

  5. Characterization of wine with PTR-MS

    NASA Astrophysics Data System (ADS)

    Boscaini, Elena; Mikoviny, Tomas; Wisthaler, Armin; Hartungen, Eugen Von; Märk, Tilmann D.

    2004-12-01

    A new method for measuring volatile profiles of alcoholic beverages (or other ethanol-containing analytes such as perfumes or herbs) has been developed. The method is based on proton transfer reaction mass spectrometry (PTR-MS). However, instead of hydronium ions (H3O+) protonated ethanol clusters (C2H5OH2+(C2H5OH)n = 1,2) are used as chemical ionization reagent ions. A stable reagent ion distribution is obtained by a 10-fold dilution of analyte headspace into ethanol-saturated nitrogen. Samples with different ethanol content can thus be directly compared. Characteristic mass spectral fingerprints have been obtained for four wine varieties. Principal component analysis discriminates between different wine varieties and shows specific correlations between wine variety and selected ions.

  6. PTR-MS monitoring of odour emissions from composting plants

    NASA Astrophysics Data System (ADS)

    Biasioli, Franco; Gasperi, Flavia; Odorizzi, Gino; Aprea, Eugenio; Mott, Daniela; Marini, Federico; Autiero, Gianmarco; Rotondo, Giampaolo; Märk, Tilmann D.

    2004-12-01

    We studied the possibility of monitoring with proton transfer reaction-mass spectrometry (PTR-MS) odours emitted in various situations related to composting plants of municipal solid waste (MSW), i.e., waste storage, waste management, and biofilters. Comparison of PTR-MS volatile profiles of the gaseous mixtures entering and exiting a biofilter suggests the possibility of fast and reliable monitoring biofilter efficiency. Moreover, we investigated the relationships between the olfactometric assessment of odour concentration and PTR-MS spectral line intensity finding a positive correlation between the former and several masses and their overall intensity. The application of multivariate calibration methods allows to determine odour concentrations based only on PTR-MS instrumental data. The possibility of avoiding the use of time consuming and expensive olfactometric methods and applications in monitoring waste treatments plants and, in particular, of biofilters is suggested.

  7. ptr-MIR169 is a posttranscriptional repressor of PtrHAP2 during vegetative bud dormancy period of aspen (Populus tremuloides) trees

    SciTech Connect

    Potkar, Rewati; Recla, Jill; Busov, Victor

    2013-02-15

    Highlights: ► We show a novel microRNA-mediated mechanism for control of bud dormancy in trees. ► ptr-MIR169a and PtrHAP2–5 gene showed inverse expression during dormancy period. ► The PtrHAP2–5 decline in abundance correlated with high ptr-MIR169a levels. ► PtrHAP2–5 cleavage occurred at the miR169 site during PtrHAP2–5 transcript decline. ► Our results show that miR169 attenuates PtrHAP2–5 transcript during dormancy. -- Abstract: Dormancy is a mechanism evolved in woody perennial plants to survive the winter freezing and dehydration stress via temporary suspension of growth. We have identified two aspen microRNAs (ptr-MIR169a and ptr-MIR169h) which were highly and specifically expressed in dormant floral and vegetative buds. ptr-MIR169a and its target gene PtrHAP2–5 showed inverse expression patterns during the dormancy period. ptr-MIR169a transcript steadily increased through the first half of the dormancy period and gradually declined with the approach of active growing season. PtrHAP2–5 abundance was higher in the beginning of the dormancy period but rapidly declined thereafter. The decline of PtrHAP2–5 correlated with the high levels of ptr-MIR169a accumulation, suggesting miR169-mediated attenuation of the target PtrHAP2–5 transcript. We experimentally verified the cleavage of PtrHAP2–5 at the predicted miR169a site at the time when PtrHAP2–5 transcript decline was observed. HAP2 is a subunit of a nuclear transcription factor Y (NF-Y) complex consisting of two other units, HAP3 and HAP5. Using digital expression profiling we show that poplar HAP2 and HAP5 are preferentially detected in dormant tissues. Our study shows that microRNAs play a significant and as of yet unknown and unstudied role in regulating the timing of bud dormancy in trees.

  8. PTR-QMS versus PTR-TOF comparison in a region with oil and natural gas extraction industry in the Uintah Basin in 2013

    NASA Astrophysics Data System (ADS)

    Warneke, C.; Veres, P.; Murphy, S. M.; Soltis, J.; Field, R. A.; Graus, M. G.; Koss, A.; Li, S.-M.; Li, R.; Yuan, B.; Roberts, J. M.; de Gouw, J. A.

    2015-01-01

    Here we compare volatile organic compound (VOC) measurements using a standard proton-transfer-reaction quadrupole mass spectrometer (PTR-QMS) with a new proton-transfer-reaction time of flight mass spectrometer (PTR-TOF) during the Uintah Basin Winter Ozone Study 2013 (UBWOS2013) field experiment in an oil and gas field in the Uintah Basin, Utah. The PTR-QMS uses a quadrupole, which is a mass filter that lets one mass to charge ratio pass at a time, whereas the PTR-TOF uses a time of flight mass spectrometer, which takes full mass spectra with typical 0.1 s-1 min integrated acquisition times. The sensitivity of the PTR-QMS in units of counts per ppbv (parts per billion by volume) is about a factor of 10-35 times larger than the PTR-TOF, when only one VOC is measured. The sensitivity of the PTR-TOF is mass dependent because of the mass discrimination caused by the sampling duty cycle in the orthogonal-acceleration region of the TOF. For example, the PTR-QMS on mass 33 (methanol) is 35 times more sensitive than the PTR-TOF and for masses above 120 amu less than 10 times more. If more than 10-35 compounds are measured with PTR-QMS, the sampling time per ion decreases and the PTR-TOF has higher signals per unit measuring time for most masses. For UBWOS2013 the PTR-QMS measured 34 masses in 37 s and on that timescale the PTR-TOF is more sensitive for all masses. The high mass resolution of the TOF allows for the measurements of compounds that cannot be separately detected with the PTR-QMS, such as oxidation products from alkanes and cycloalkanes emitted by oil and gas extraction. PTR-TOF masses do not have to be preselected, allowing for identification of unanticipated compounds. The measured mixing ratios of the two instruments agreed very well (R2 ≥ 0.92 and within 20%) for all compounds and masses monitored with the PTR-QMS.

  9. PTR-QMS vs. PTR-TOF comparison in a region with oil and natural gas extraction industry in the Uintah Basin in 2013

    NASA Astrophysics Data System (ADS)

    Warneke, C.; Veres, P. R.; Murphy, S. M.; Soltis, J.; Field, R. A.; Graus, M. G.; Koss, A.; Li, S.-M.; Li, R.; Yuan, B.; Roberts, J. M.; de Gouw, J. A.

    2014-07-01

    Here we compare volatile organic compound (VOC) measurements using a standard Proton-Transfer-Reaction Quadrupole Mass Spectrometer (PTR-QMS) with a new Proton-Transfer-Reaction Time Of Flight Mass Spectrometer (PTR-TOF) during the Uintah Basin Winter Ozone Study 2013 (UBWOS2013) field experiment in an oil and gas field in the Uintah Basin, Utah. The PTR-QMS uses a quadrupole, which is a mass filter that lets one mass pass at a time, whereas the PTR-TOF uses a Time Of Flight mass spectrometer, which takes full mass spectra with typical 0.1 s to 1 min integrated acquisition times. The sensitivity of the PTR-QMS in units of counts per ppbv is about a factor of 10-35 times larger than the PTR-TOF, when only one VOC is measured. The sensitivity of the PTR-TOF is mass dependent because of the mass discrimination caused by the sampling duty cycle in the orthogonal-acceleration region of the TOF. For example, the PTR-QMS on mass 33 (methanol) is 35 times more sensitive than the PTR-TOF and for masses above 120 amu less than 10 times more. If more than 10-35 compounds are measured with PTR-QMS, the sampling time per ion decreases and the PTR-TOF has higher signals per unit measuring time for most masses. For UBWOS2013 the PTR-QMS measured 34 masses in 37 s and on that time-scale the PTR-TOF is more sensitive for all masses. The high mass resolution of the TOF allows for the measurements of compounds that cannot be separately detected with the PTR-QMS, such as oxidation products from alkanes and cycloalkanes emitted by oil and gas extraction. PTR-TOF masses do not have to be pre-selected allowing for identification of unanticipated compounds. The measured mixing ratios of the two instruments agreed very well (R2 ≥ 0.92 and within 20%) for all compounds and masses monitored with the PTR-QMS.

  10. Identification of a New Locus, Ptr(t), Required for Rice Blast Resistance Gene Pi-ta-Mediated Resistance

    SciTech Connect

    Jia, Yulin; Martin, Rodger Carl

    2008-01-01

    Resistance to the blast pathogen Magnaporthe oryzae is proposed to be initiated by physical binding of a putative cytoplasmic receptor encoded by a NBS type resistance gene Pi-ta to the processed elicitor encoded by the corresponding avirulence gene AVR-Pita. Here we report the identification of a new locus Ptr(t) that is required for Pi-ta-mediated signal recognition. A Pi-ta expressing susceptible mutant was identified using a genetic screen. Putative mutations at Ptr(t) does not alter recognition specificity to another resistance gene Pi-ks in the Pi-ta homozygote indicate that Ptr(t) is more likely specific to Pi-ta-mediated signal recognition. Genetic crosses of Pi-ta Ptr(t) and Pi-ta ptr(t) homozygotes suggest that Ptr(t) segregate at single dominant nuclear gene. A ratio of 1 resistant: 1 susceptible of a BC1 using Pi-ta Ptr(t) with pi-ta ptr(t) homozygotes indicates that Pi-ta and Ptr(t) are linked and co-segregated. Genotyping of mutants of pi-ta ptr(t) and Pi-ta Ptr(t) homozygotes using ten simple sequence repeat markers spanning 9 megabase of Pi-ta determines that Pi-ta and Ptr(t) are of indica origin. Identification of Ptr(t) is a significant advancement in studying Pi-ta-mediated signal recognition and transduction.

  11. Identification of a new locus, Ptr(t), required for rice blast resistance gene Pi-ta-mediated resistance.

    PubMed

    Jia, Yulin; Martin, Rodger

    2008-04-01

    Resistance to the blast pathogen Magnaporthe oryzae is proposed to be initiated by physical binding of a putative cytoplasmic receptor encoded by a nucleotide binding site-type resistance gene, Pi-ta, to the processed elicitor encoded by the corresponding avirulence gene AVR-Pita. Here, we report the identification of a new locus, Ptr(t), that is required for Pi-ta-mediated signal recognition. A Pi-ta-expressing susceptible mutant was identified using a genetic screen. Putative mutations at Ptr(t) do not alter recognition specificity to another resistance gene, Pi-k(s), in the Pi-ta homozygote, indicating that Ptr(t) is more likely specific to Pi-ta-mediated signal recognition. Genetic crosses of Pi-ta Ptr(t) and Pi-ta ptr(t) homozygotes suggest that Ptr(t) segregates as a single dominant nuclear gene. A ratio of 1:1 (resistant/susceptible) of a population of BC1 of Pi-ta Ptr(t) with pi-ta ptr(t) homozygotes indicates that Pi-ta and Ptr(t) are linked and cosegregate. Genotyping of mutants of pi-ta ptr(t) and Pi-ta Ptr(t) homozygotes using ten simple sequence repeat markers at the Pi-ta region determined that Pi-ta and Ptr(t) are located within a 9-megabase region and are of indica origin. Identification of Ptr(t) is a significant advancement in studying Pi-ta-mediated signal recognition and transduction. PMID:18321185

  12. Stirling-type pulse tube refrigerator (PTR) with cold compression: Cold compressor, colder expander

    NASA Astrophysics Data System (ADS)

    Park, Jiho; Ko, Junseok; Cha, Jeongmin; Jeong, Sangkwon

    2016-03-01

    This research paper focuses on the performance prediction and its validation via experimental investigation of a Stirling-type pulse tube refrigerator (PTR) equipped with a cold linear compressor. When the working gas is compressed at cryogenic temperature, the acoustic power (PV power) can be directly transmitted through the regenerator to the pulsating tube without experiencing unnecessary precooling process. The required PV power generated by the linear compressor, furthermore, can be significantly diminished due to the relatively small specific volume of the working gas at low temperature. The PTR can reach lower temperature efficiently with higher heat lift at the corresponding temperature than other typical single-stage Stirling-type PTRs. Utilizing a cryogenic reservoir as a warm end and regulating the entire operating temperature range of the PTR will enable a PTR to operate efficiently under space environment. In this research, the experimental validation as a proof of concept was carried out to demonstrate the capability of PTR operating between 80 K and 40 K. The linear compressor was submerged in a liquid nitrogen bath and the lowest temperature was measured as 38.5 K. The test results were analyzed to identify loss mechanisms with the simple numerical computation (linear model) which considers the dynamic characteristics of the cold linear compressor with thermo-hydraulic governing equations for each of sub components of the PTR. All the mass flows and pressure waves were assumed to be sinusoidal.

  13. Modeling of operating history of the research nuclear reactor

    NASA Astrophysics Data System (ADS)

    Naymushin, A.; Chertkov, Yu; Shchurovskaya, M.; Anikin, M.; Lebedev, I.

    2016-06-01

    The results of simulation of the IRT-T reactor operation history from 2012 to 2014 are presented. Calculations are performed using continuous energy Monte Carlo code MCU-PTR. Comparison is made between calculation and experimental data for the critical reactor.

  14. ZmPTR1, a maize peptide transporter expressed in the epithelial cells of the scutellum during germination.

    PubMed

    Tnani, Hedia; López-Ribera, Ignacio; García-Muniz, Nora; Vicient, Carlos M

    2013-06-01

    In plants, peptide transporter/nitrate transporter 1 (PTR/NRT1) family proteins transport a variety of substrates such as nitrate, di- and tripepetides, auxin and carboxylates across membranes. We isolated and characterized ZmPTR1, a maize member of this family. ZmPTR1 protein sequence is highly homologous to the previously characterized di- and tripeptide Arabidopsis transporters AtPTR2, AtPTR4 and AtPTR6. ZmPTR1 gene is expressed in the cells of the scutellar epithelium during germination and, to a less extent, in the radicle and the hypocotyl. Arabidopsis thaliana lines overexpressing ZmPTR1 performed better than control plants when grown on a medium with Ala-Ala dipeptide as the unique N source. Our results suggest that ZmPTR1 plays a role in the transport into the embryo of the small peptides produced during enzymatic hydrolysis of the storage proteins in the endosperm. PMID:23602109

  15. Spatially and temporally restricted expression of PtrMYB021 regulates secondary cell wall formation in Arabidopsis

    DOE PAGESBeta

    Wang, Wei; Li, Eryang; Porth, Ilga; Chen, Jin-Gui; Mansfield, Shawn D.; Douglas, Carl J.; Wang, Shucai

    2016-02-02

    Among the R2R3 MYB transcription factors that involve in the regulation of secondary cell wall formation in Arabidopsis, MYB46 alone is sufficient to induce the entire secondary cell wall biosynthesis program. PtrMYB021, the poplar homolog of MYB46, has been reported to regulate secondary cell wall formation when expressed in Arabidopsis. We report here that spatially and temporally restricted expression of PtrMYB021 is critical for its function in regulating secondary cell wall formation. By using quantitative RT-PCR, we found that PtrMYB021 was expressed primarily in xylem tissues. When expressed in Arabidopsis under the control of PtrCesA8, but not the 35S promoter,more » PtrMYB021 increased secondary cell wall thickness, which is likely caused by increased lignification as well as changes in cell wall carbohydrate composition. Consistent with this, elevated expression of lignin and cellulose biosynthetic genes were observed in the transgenic plants. Finally, when expressed in Arabidopsis protoplasts as fusion proteins to the Gal4 DNA binding domain, PtrMYB021 activated the reporter gene Gal4-GUS. In summary, our results suggest that PtrMYB021 is a transcriptional activator, and spatially and temporally restricted expression of PtrMYB021 in Arabidopsis regulates secondary cell wall formation by activating a subset of secondary cell wall biosynthesis genes.« less

  16. Characterization of the ptr5{sup +} gene involved in nuclear mRNA export in fission yeast

    SciTech Connect

    Watanabe, Nobuyoshi; Ikeda, Terumasa; Mizuki, Fumitaka; Tani, Tokio

    2012-02-03

    Highlights: Black-Right-Pointing-Pointer We cloned the ptr5{sup +} gene involved in nuclear mRNA export in fission yeast. Black-Right-Pointing-Pointer The ptr5{sup +} gene was found to encode nucleoporin 85 (Nup85). Black-Right-Pointing-Pointer Seh1p and Mlo3p are multi-copy suppressors for the ptr5 mutation. Black-Right-Pointing-Pointer Ptr5p/Nup85p functions in nuclear mRNA export through the mRNA export factor Rae1p. Black-Right-Pointing-Pointer Ptr5p/Nup85p interacts genetically with pre-mRNA splicing factors. -- Abstract: To analyze the mechanisms of mRNA export from the nucleus to the cytoplasm, we have isolated eleven mutants, ptr [poly(A){sup +} RNA transport] 1 to 11, which accumulate poly(A){sup +} RNA in the nucleus at a nonpermissive temperature in Schizosaccharomyces pombe. Of those, the ptr5-1 mutant shows dots- or a ring-like accumulation of poly(A){sup +} RNA at the nuclear periphery after shifting to the nonpermissive temperature. We cloned the ptr5{sup +} gene and found that it encodes a component of the nuclear pore complex (NPC), nucleoporin 85 (Nup85). The ptr5-1 mutant shows no defects in protein transport, suggesting the specific involvement of Ptr5p/Nup85p in nuclear mRNA export in S. pombe. We identified Seh1p, a nucleoporin interacting with Nup85p, an mRNA-binding protein Mlo3p, and Sac3p, a component of the TREX-2 complex involved in coupling of nuclear mRNA export with transcription, as multi-copy suppressors for the ptr5-1 mutation. In addition, we found that the ptr5-1 mutation is synthetically lethal with a mutation of the mRNA export factor Rae1p, and that the double mutant exaggerates defective nuclear mRNA export, suggesting that Ptr5p/Nup85p is involved in nuclear mRNA export through Rae1p. Interestingly, the ptr5-1 mutation also showed synthetic effects with several prp pre-mRNA splicing mutations, suggesting a functional linkage between the NPCs and the splicing apparatus in the yeast nucleus.

  17. REACTOR

    DOEpatents

    Szilard, L.

    1963-09-10

    A breeder reactor is described, including a mass of fissionable material that is less than critical with respect to unmoderated neutrons and greater than critical with respect to neutrons of average energies substantially greater than thermal, a coolant selected from sodium or sodium--potassium alloys, a control liquid selected from lead or lead--bismuth alloys, and means for varying the quantity of control liquid in the reactor. (AEC)

  18. REACTOR

    DOEpatents

    Christy, R.F.

    1961-07-25

    A means is described for co-relating the essential physical requirements of a fission chain reaction in order that practical, compact, and easily controllable reactors can be built. These objects are obtained by employing a composition of fissionsble isotope and moderator in fluid form in which the amount of fissionsble isotcpe present governs the reaction. The size of the reactor is no longer a critical factor, the new criterion being the concentration of the fissionable isotope.

  19. Attempting To Understand the Class Size and Pupil-Teacher Ratio (PTR) Confusion: A Pilot Study.

    ERIC Educational Resources Information Center

    Achilles, C. M.; Sharp, Mark; Nye, B. A.

    Confusion over the concepts of class size and pupil-teacher ratio (PTR) creates a conundrum for researchers, policy makers, and practitioners. An examination of how these two concepts are different is presented in this paper. A review of the literature suggests that class-size reduction makes a positive overall difference in student achievement,…

  20. REACTOR

    DOEpatents

    Roman, W.G.

    1961-06-27

    A pressurized water reactor in which automatic control is achieved by varying the average density of the liquid moderator-cooiant is patented. Density is controlled by the temperature and power level of the reactor ftself. This control can be effected by the use of either plate, pellet, or tubular fuel elements. The fuel elements are disposed between upper and lower coolant plenum chambers and are designed to permit unrestricted coolant flow. The control chamber has an inlet opening communicating with the lower coolant plenum chamber and a restricted vapor vent communicating with the upper coolant plenum chamber. Thus, a variation in temperature of the fuel elements will cause a variation in the average moderator density in the chamber which directly affects the power level of the reactor.

  1. Suppression of PtrDUF579-3 Expression Causes Structural Changes of the Glucuronoxylan in Populus.

    PubMed

    Song, Dongliang; Gui, Jinshan; Liu, Chenchen; Sun, Jiayan; Li, Laigeng

    2016-01-01

    DUF579 (domain unknown function 579) genes have been reported to play diverse roles in cell wall biosynthesis, such as in glucuronoxylan (GX) synthesis. As GX is a major type of hemicelluloses in hard wood species, how DUF579 genes function in wood formation remains to be demonstrated in planta. This study reports a Populus DUF579 gene, PtrDUF579-3, which is characterized for its function in wood cell wall formation. PtrDUF579-3 is localized in Golgi apparatus and catalyzes methylation of the glucuronic acid (GlcA) in GX biosynthesis. Suppression of PtrDUF579-3 expression in Populus caused a reduction in both the GlcA side chain number and GlcA side chain methylation on the GX backbone. The modified GX polymer through PtrDUF579-3 suppression was more susceptible to acid treatment and the PtrDUF579-3 suppressed plants displayed enhanced cellulose digestibility. These results suggest that PtrDUF579-3 is involved in GX biosynthesis and GX structure can be modified through PtrDUF579-3 suppression in Populus. PMID:27148318

  2. Suppression of PtrDUF579-3 Expression Causes Structural Changes of the Glucuronoxylan in Populus

    PubMed Central

    Song, Dongliang; Gui, Jinshan; Liu, Chenchen; Sun, Jiayan; Li, Laigeng

    2016-01-01

    DUF579 (domain unknown function 579) genes have been reported to play diverse roles in cell wall biosynthesis, such as in glucuronoxylan (GX) synthesis. As GX is a major type of hemicelluloses in hard wood species, how DUF579 genes function in wood formation remains to be demonstrated in planta. This study reports a Populus DUF579 gene, PtrDUF579-3, which is characterized for its function in wood cell wall formation. PtrDUF579-3 is localized in Golgi apparatus and catalyzes methylation of the glucuronic acid (GlcA) in GX biosynthesis. Suppression of PtrDUF579-3 expression in Populus caused a reduction in both the GlcA side chain number and GlcA side chain methylation on the GX backbone. The modified GX polymer through PtrDUF579-3 suppression was more susceptible to acid treatment and the PtrDUF579-3 suppressed plants displayed enhanced cellulose digestibility. These results suggest that PtrDUF579-3 is involved in GX biosynthesis and GX structure can be modified through PtrDUF579-3 suppression in Populus. PMID:27148318

  3. REACTORS

    DOEpatents

    Spitzer, L. Jr.

    1961-10-01

    Thermonuclear reactors, methods, and apparatus are described for controlling and confining high temperature plasma. Main axial confining coils in combination with helical windings provide a rotational transform that avoids the necessity of a figure-eight shaped reactor tube. The helical windings provide a multipolar helical magnetic field transverse to the axis of the main axial confining coils so as to improve the effectiveness of the confining field by counteracting the tendency of the more central lines of force in the stellarator tube to exchange positions with the magnetic lines of force nearer the walls of the tube. (AEC)

  4. Application of PTR-MS for measurements of biogenic VOC in a deciduous forest

    NASA Astrophysics Data System (ADS)

    Ammann, C.; Spirig, C.; Neftel, A.; Steinbacher, M.; Komenda, M.; Schaub, A.

    2004-12-01

    The vegetation-atmosphere-exchange is an important process controlling the atmospheric concentration of various volatile organic compounds (VOCs) that play a major role in atmospheric chemistry. However, the quantification of VOC exchange on the ecosystem scale is still an analytical challenge. In the present study we tested and applied a proton-transfer-reaction mass spectrometry system (PTR-MS) for the measurement of biogenic VOCs in a mixed deciduous forest. VOC concentrations were calculated from the raw instrument signals based on physical principles. This method allows a consistent quantification also of compounds for which regular calibration with a gas standard is not available. It requires a regular and careful investigation of the mass-dependent ion detection characteristics of the PTR-MS, which otherwise could become a considerable error source. The PTR-MS method was tested in the laboratory for a range of oxygenated and non-oxygenated VOCs using a permeation source. The agreement was within 16% or better, which is well within the expected uncertainty. During the field measurement campaign in a deciduous forest stand, an on-line intercomparison with a state-of-the-art gas-chromatography system showed a generally good agreement. However, the relatively low ambient VOC concentrations revealed some systematic difference for acetone and isoprene, that may indicate an error in the determination of the PTR-MS offset or an interference of an unidentified isobaric compound on the detected ion mass. With the presentation of selected field results, we demonstrate the ability of the PTR-MS system to measure continuous vertical concentration profiles of biogenic VOCs throughout a forest canopy at a time resolution of 20 min. The resulting datasets provide valuable information for the study of the interactions between emission, photochemical transformation and transport processes within and above the forest canopy.

  5. PtrA is required for coordinate regulation of gene expression during phosphate stress in a marine Synechococcus.

    PubMed

    Ostrowski, Martin; Mazard, Sophie; Tetu, Sasha G; Phillippy, Katherine; Johnson, Aaron; Palenik, Brian; Paulsen, Ian T; Scanlan, Dave J

    2010-07-01

    Previous microarray analyses have shown a key role for the two-component system PhoBR (SYNW0947, SYNW0948) in the regulation of P transport and metabolism in the marine cyanobacterium Synechococcus sp. WH8102. However, there is some evidence that another regulator, SYNW1019 (PtrA), probably under the control of PhoBR, is involved in the response to P depletion. PtrA is a member of the cAMP receptor protein transcriptional regulator family that shows homology to NtcA, the global nitrogen regulator in cyanobacteria. To define the role of this regulator, we constructed a mutant by insertional inactivation and compared the physiology of wild-type Synechcococcus sp. WH8102 with the ptrA mutant under P-replete and P-stress conditions. In response to P stress the ptrA mutant failed to upregulate phosphatase activity. Microarrays and quantitative RT-PCR indicate that a subset of the Pho regulon is controlled by PtrA, including two phosphatases, a predicted phytase and a gene of unknown function psip1 (SYNW0165), all of which are highly upregulated during P limitation. Electrophoretic mobility shift assays indicate binding of overexpressed PtrA to promoter sequences upstream of the induced genes. This work suggests a two-tiered response to P depletion in this strain, the first being PhoB-dependent induction of high-affinity PO(4) transporters, and the second the PtrA-dependent induction of phosphatases for scavenging organic P. The levels of numerous other transcripts are also directly or indirectly influenced by PtrA, including those involved in cell-surface modification, metal uptake, photosynthesis, stress responses and other metabolic processes, which may indicate a wider role for PtrA in cellular regulation in marine picocyanobacteria. PMID:20376102

  6. Ptr-miR397a is a negative regulator of laccase genes affecting lignin content in Populus trichocarpa

    PubMed Central

    Lu, Shanfa; Li, Quanzi; Wei, Hairong; Chang, Mao-Ju; Tunlaya-Anukit, Sermsawat; Kim, Hoon; Liu, Jie; Song, Jingyuan; Sun, Ying-Hsuan; Yuan, Lichai; Yeh, Ting-Feng; Peszlen, Ilona; Ralph, John; Sederoff, Ronald R.; Chiang, Vincent L.

    2013-01-01

    Laccases, as early as 1959, were proposed to catalyze the oxidative polymerization of monolignols. Genetic evidence in support of this hypothesis has been elusive due to functional redundancy of laccase genes. An Arabidopsis double mutant demonstrated the involvement of laccases in lignin biosynthesis. We previously identified a subset of laccase genes to be targets of a microRNA (miRNA) ptr-miR397a in Populus trichocarpa. To elucidate the roles of ptr-miR397a and its targets, we characterized the laccase gene family and identified 49 laccase gene models, of which 29 were predicted to be targets of ptr-miR397a. We overexpressed Ptr-MIR397a in transgenic P. trichocarpa. In each of all nine transgenic lines tested, 17 PtrLACs were down-regulated as analyzed by RNA-seq. Transgenic lines with severe reduction in the expression of these laccase genes resulted in an ∼40% decrease in the total laccase activity. Overexpression of Ptr-MIR397a in these transgenic lines also reduced lignin content, whereas levels of all monolignol biosynthetic gene transcripts remained unchanged. A hierarchical genetic regulatory network (GRN) built by a bottom-up graphic Gaussian model algorithm provides additional support for a role of ptr-miR397a as a negative regulator of laccases for lignin biosynthesis. Full transcriptome–based differential gene expression in the overexpressed transgenics and protein domain analyses implicate previously unidentified transcription factors and their targets in an extended hierarchical GRN including ptr-miR397a and laccases that coregulate lignin biosynthesis in wood formation. Ptr-miR397a, laccases, and other regulatory components of this network may provide additional strategies for genetic manipulation of lignin content. PMID:23754401

  7. REACTOR

    DOEpatents

    Spitzer, L. Jr.

    1962-01-01

    The system conteraplates ohmically heating a gas to high temperatures such as are useful in thermonuclear reactors of the stellarator class. To this end the gas is ionized and an electric current is applied to the ionized gas ohmically to heat the gas while the ionized gas is confined to a central portion of a reaction chamber. Additionally, means are provided for pumping impurities from the gas and for further heating the gas. (AEC)

  8. Combined FPPE-PTR Calorimetry Involving TWRC Technique II. Experimental: Application to Thermal Effusivity Measurements of Solids

    NASA Astrophysics Data System (ADS)

    Dadarlat, Dorin; Pop, Mircea Nicolae; Streza, Mihaela; Longuemart, Stephane; Depriester, Michael; Sahraoui, Abdelhak Hadj; Simon, Viorica

    2011-10-01

    Photopyroelectric calorimetry in the front detection configuration (FPPE) and photothermal radiometry (PTR) were simultaneously used, together with the thermal-wave resonator cavity method (TWRC), in order to investigate the thermal effusivity of solids inserted as backing layers in a detection cell. A new combined FPPE-PTR-TWRC setup was designed. It was demonstrated experimentally that the PTR technique, combined with the TWRC method, is able to provide calorimetric information about the third layer of a detection cell. Applications on solids with different values of the thermal effusivity (starting from metals, down to thermal isolators) are presented. The values of the thermal effusivity obtained with the PTR technique are similar to those obtained with the PPE technique, and in agreement with literature values; the two methods reciprocally support each other. The accuracy of both methods is higher when the values of the thermal effusivity of the backing layer and coupling fluid are close.

  9. Detection of Dental Secondary Caries Using Frequency-Domain Infrared Photothermal Radiometry (PTR) and Modulated Luminescence (LUM)

    NASA Astrophysics Data System (ADS)

    Kim, J.; Mandelis, A.; Matvienko, A.; Abrams, S.; Amaechi, B. T.

    2012-11-01

    The ability of frequency-domain photothermal radiometry (PTR) and modulated luminescence (LUM) to detect secondary caries is presented. Signal behavior upon sequential demineralization and remineralization of a spot (diameter ~1 mm) on a vertical wall of sectioned tooth samples was investigated experimentally. From these studies, it was found that PTR-LUM signals change, showing a certain pattern upon progressive demineralization and remineralization. PTR amplitudes slightly decreased upon progressive demineralization and slightly increased upon subsequent remineralization. The PTR phase increased during both demineralization and remineralization. LUM amplitudes exhibit a decreasing trend at excitation/probe distances larger than 200 μm away from the edge for both demineralization and remineralization; however, at locations close to the edge (up to ~200 μm), LUM signals slightly decrease upon demineralization and slightly increase during subsequent remineralization.

  10. RNA interference regulates the cell cycle checkpoint through the RNA export factor, Ptr1, in fission yeast

    SciTech Connect

    Iida, Tetsushi; Iida, Naoko; Tsutsui, Yasuhiro; Yamao, Fumiaki; Kobayashi, Takehiko

    2012-10-12

    Highlights: Black-Right-Pointing-Pointer RNAi is linked to the cell cycle checkpoint in fission yeast. Black-Right-Pointing-Pointer Ptr1 co-purifies with Ago1. Black-Right-Pointing-Pointer The ptr1-1 mutation impairs the checkpoint but does not affect gene silencing. Black-Right-Pointing-Pointer ago1{sup +} and ptr1{sup +} regulate the cell cycle checkpoint via the same pathway. Black-Right-Pointing-Pointer Mutations in ago1{sup +} and ptr1{sup +} lead to the nuclear accumulation of poly(A){sup +} RNAs. -- Abstract: Ago1, an effector protein of RNA interference (RNAi), regulates heterochromatin silencing and cell cycle arrest in fission yeast. However, the mechanism by which Ago1 controls cell cycle checkpoint following hydroxyurea (HU) treatment has not been elucidated. In this study, we show that Ago1 and other RNAi factors control cell cycle checkpoint following HU treatment via a mechanism independent of silencing. While silencing requires dcr1{sup +}, the overexpression of ago1{sup +} alleviated the cell cycle defect in dcr1{Delta}. Ago1 interacted with the mRNA export factor, Ptr1. The ptr1-1 mutation impaired cell cycle checkpoint but gene silencing was unaffected. Genetic analysis revealed that the regulation of cell cycle checkpoint by ago1{sup +} is dependent on ptr1{sup +}. Nuclear accumulation of poly(A){sup +} RNAs was detected in mutants of ago1{sup +} and ptr1{sup +}, suggesting there is a functional link between the cell cycle checkpoint and RNAi-mediated RNA quality control.

  11. Isolation and characterization of a subgroup IIa WRKY transcription factor PtrWRKY40 from Populus trichocarpa.

    PubMed

    Karim, Abdul; Jiang, Yuanzhong; Guo, Li; Ling, Zhengyi; Ye, Shenglong; Duan, Yanjiao; Li, Chaofeng; Luo, Keming

    2015-10-01

    Salicylic acid (SA) is a defense-related key signaling molecule involved in plant immunity. In this study, a subgroup IIa WRKY gene PtrWRKY40 was isolated from Populus trichocarpa, which displayed amino acid sequence similar to Arabidopsis AtWRKY40, AtWRKY18 and AtWRKY60. PtrWRKY40 transcripts accumulated significantly in response to SA, methyl jasmonate and hemibiotrophic fungus Dothiorella gregaria Sacc. Overexpression of PtrWRKY40 in transgenic poplar conferred higher susceptibility to D. gregaria infection. This susceptibility was coupled with reduced expression of SA-associated genes (PR1.1, PR2.1, PR5.9, CPR5 and SID2) and jasmonic acid (JA)-related gene JAZ8. Decreased accumulation of endogenous SA was observed in transgenic lines overexpressing PtrWRKY40 when compared with wild-type plants. However, constitutive expression of PtrWRKY40 in Arabidopsis thaliana displayed resistance to necrotrophic fungus Botrytis cinerea, and the expression of JA-defense-related genes such as PDF1.2, VSP2 and PR3 was remarkably increased in transgenic plants upon infection with fugal pathogens. Together, our findings indicate that PtrWRKY40 plays a negative role in resistance to hemibiotrophic fungi in poplar but functions as a positive regulator of resistance toward the necrotrophic fungi in Arabidopsis. PMID:26423133

  12. Combined FPPE-PTR Calorimetry Involving TWRC Technique. Theory and Mathematical Simulations

    NASA Astrophysics Data System (ADS)

    Dadarlat, Dorin; Pop, Mircea Nicolae; Streza, Mihaela; Longuemart, Stephane; Depriester, Michael; Hadj Sahraoui, Abdelhak; Simon, Viorica

    2010-12-01

    Photopyroelectric calorimetry in the front detection configuration (FPPE) was combined with photothermal radiometry (PTR), in order to investigate dynamic thermal parameters of different layers of a detection cell. The layout of the detection cell consists of three layers: directly irradiated pyroelectric sensor, liquid layer, and solid backing material; and the scanning parameter is the thickness of the liquid layer (thermal-wave resonator cavity method). The theory developed for the two techniques indicates that both FPPE and PTR signals can lead, in the thermally thin regime for the sensor and liquid layer, to the direct measurement of the thermal diffusivity or effusivity of the sensor and/or liquid layer, or the thermal effusivity of the backing material. The two methods offer complementary results and/or reciprocally support each other.

  13. Spectral narrowing of solid state lasers by narrow-band PTR Bragg mirrors

    NASA Astrophysics Data System (ADS)

    Chung, T.; Rapaport, A.; Chen, Y.; Smirnov, V.; Hemmer, M.; Glebov, L. B.; Richardson, M. C.; Bass, M.

    2006-05-01

    Dramatic spectral narrowing of normally broad band lasers, Ti:Sapphire,Cr:LiSAF, and alexandrite was achieved by simply replacing the output mirror with a reflective, volumetric Bragg grating recorded in photo thermal refractive (PTR) glass. The output power of each laser was changed very slightly from that obtained using dielectric coated output mirrors with the same output coupling as the Bragg grating while spectral brightness increased by about three orders of magnitude.

  14. Determination of biogenic volatile organic compound fluxes from Harvard Forest using PTR-TOF-MS (Invited)

    NASA Astrophysics Data System (ADS)

    McKinney, K. A.; Munger, J. W.; Liu, Y.

    2013-12-01

    Forest emissions of biogenic volatile organic compounds (BVOCs) are the largest source of reactive non-methane hydrocarbons to the atmosphere, yet studies suggest that the understanding of the nature and quantity of emitted compounds remains incomplete. Recent findings have indicated the presence of reactive BVOCs within and above forest canopies that have not been quantified previously. Here we report new measurements of BVOC emissions from and concentrations above Harvard Forest, a mixed forest in the Eastern U.S., from June 8 to September 30, 2012 using Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS). PTR-TOF-MS represents an advance over previous quadrupole-based PTR-MS measurements in that it captures a full, high-resolution (m/Δm ca. 4000) mass spectrum on every scan, resulting in positive identification of molecular formulas. In addition, scans are recorded at high time resolution (5 Hz), allowing true (non-disjunct) eddy covariance fluxes to be determined for each mass-to-charge ratio. Concentration and flux measurements were made simultaneously using a high-sensitivity quadrupole PTR-MS, and results from the two techniques are compared. Measured concentrations of most species agree to within 5%. As in past seasons, isoprene is the major BVOC emitted at Harvard Forest, reaching average midday mixing ratios of ca. 4 ppbv, and its emissions are closely tied to local temperature and light levels. Diurnal and seasonal patterns in emissions of isoprene, monoterpenes, methanol, acetone, and MEK are reported and compared with past measurements at the site. In addition, eddy covariance fluxes are calculated for all mass peaks to assess emissions of previously unidentified BVOCs from Harvard Forest.

  15. Application of PTR-MS for measuring odorant emissions from soil application of manure slurry.

    PubMed

    Feilberg, Anders; Bildsoe, Pernille; Nyord, Tavs

    2015-01-01

    Odorous volatile organic compounds (VOC) and hydrogen sulfide (H2S) are emitted together with ammonia (NH3) from manure slurry applied as a fertilizer, but little is known about the composition and temporal variation of the emissions. In this work, a laboratory method based on dynamic flux chambers packed with soil has been used to measure emissions from untreated pig slurry and slurry treated by solid-liquid separation and ozonation. Proton-transfer-reaction mass spectrometry (PTR-MS) was used to provide time resolved data for a range of VOC, NH3 and H2S. VOC included organic sulfur compounds, carboxylic acids, phenols, indoles, alcohols, ketones and aldehydes. H2S emission was remarkably observed to take place only in the initial minutes after slurry application, which is explained by its high partitioning into the air phase. Long-term odor effects are therefore assessed to be mainly due to other volatile compounds with low odor threshold values, such as 4-methylphenol. PTR-MS signal assignment was verified by comparison to a photo-acoustic analyzer (NH3) and to thermal desorption GC/MS (VOC). Due to initial rapid changes in odorant emissions and low concentrations of odorants, PTR-MS is assessed to be a very useful method for assessing odor following field application of slurry. The effects of treatments on odorant emissions are discussed. PMID:25585103

  16. PTR-MS study of esters in water and water/ethanol solutions

    NASA Astrophysics Data System (ADS)

    Aprea, Eugenio; Biasioli, Franco; Märk, Tilmann D.; Gasperi, Flavia

    2007-04-01

    Esters strongly influence the perceived aroma of alcoholic beverages and their rapid monitoring can play an important role in the quality control of these products. Proton transfer reaction mass spectrometry (PTR-MS) allows the rapid and non invasive monitoring of foodstuff but there is still a lack of information about the proton transfer induced fragmentation and on the effect of high ethanol concentration. PTR-MS fragmentation patterns of 21 esters are reported, most of them for the first time. For linear methyl and ethyl esters the fragmentation dependence on E/N was also evaluated. Acetate esters, with exception of methyl acetate, show as main peaks the characteristic fragment ions at m/z 61 and m/z 43, whereas propanoate esters, but methyl propanoate, exhibit as main peaks the typical signals at m/z 75 and m/z 57. For all the other esters, here reported, the spectra are dominated by the protonated molecular ion. For methyl and ethyl esters we also report, in many cases for the first time, the water-solution/air partition coefficients (Henry's law constant) and the ethanol-solution/air partition coefficients at different ethanol concentrations. The information provided in this work may be useful as a basis for further studies for the identification and quantification of esters in the headspace of alcoholic beverages extending the application field of PTR-MS.

  17. Application of PTR-MS for Measuring Odorant Emissions from Soil Application of Manure Slurry

    PubMed Central

    Feilberg, Anders; Bildsoe, Pernille; Nyord, Tavs

    2015-01-01

    Odorous volatile organic compounds (VOC) and hydrogen sulfide (H2S) are emitted together with ammonia (NH3) from manure slurry applied as a fertilizer, but little is known about the composition and temporal variation of the emissions. In this work, a laboratory method based on dynamic flux chambers packed with soil has been used to measure emissions from untreated pig slurry and slurry treated by solid-liquid separation and ozonation. Proton-transfer-reaction mass spectrometry (PTR-MS) was used to provide time resolved data for a range of VOC, NH3 and H2S. VOC included organic sulfur compounds, carboxylic acids, phenols, indoles, alcohols, ketones and aldehydes. H2S emission was remarkably observed to take place only in the initial minutes after slurry application, which is explained by its high partitioning into the air phase. Long-term odor effects are therefore assessed to be mainly due to other volatile compounds with low odor threshold values, such as 4-methylphenol. PTR-MS signal assignment was verified by comparison to a photo-acoustic analyzer (NH3) and to thermal desorption GC/MS (VOC). Due to initial rapid changes in odorant emissions and low concentrations of odorants, PTR-MS is assessed to be a very useful method for assessing odor following field application of slurry. The effects of treatments on odorant emissions are discussed. PMID:25585103

  18. Reactor

    DOEpatents

    Evans, Robert M.

    1976-10-05

    1. A neutronic reactor having a moderator, coolant tubes traversing the moderator from an inlet end to an outlet end, bodies of material fissionable by neutrons of thermal energy disposed within the coolant tubes, and means for circulating water through said coolant tubes characterized by the improved construction wherein the coolant tubes are constructed of aluminum having an outer diameter of 1.729 inches and a wall thickness of 0.059 inch, and the means for circulating a liquid coolant through the tubes includes a source of water at a pressure of approximately 350 pounds per square inch connected to the inlet end of the tubes, and said construction including a pressure reducing orifice disposed at the inlet ends of the tubes reducing the pressure of the water by approximately 150 pounds per square inch.

  19. An intercomparison of GC-FID and PTR-MS toluene measurements in ambient air under conditions of enhanced monoterpene loading

    NASA Astrophysics Data System (ADS)

    Ambrose, J. L.; Haase, K.; Russo, R. S.; Zhou, Y.; White, M. L.; Frinak, E. K.; Jordan, C.; Mayne, H. R.; Talbot, R.; Sive, B. C.

    2010-01-01

    Toluene was measured using both a gas chromatographic system (GC), with a flame ionization detector (FID), and a proton transfer reaction-mass spectrometer (PTR-MS) at the AIRMAP atmospheric monitoring station Thompson Farm (THF) in rural Durham, NH during the summer of 2004. Simultaneous measurements of monoterpenes, including α- and β-pinene, camphene, Δ3-carene, and d-limonene, by GC-FID demonstrated large enhancements in monoterpene mixing ratios relative to toluene, with median and maximum enhancement ratios of ~2 and ~30, respectively. A detailed intercomparison among the GC-FID and PTR-MS toluene measurements was conducted to test the specificity of PTR-MS for atmospheric toluene measurements under conditions often dominated by biogenic emissions. We derived quantitative estimates of potential interferences in the PTR-MS toluene measurements related to sampling and analysis of monoterpenes, including fragmentation of the monoterpenes and some of their primary carbonyl oxidation products via reactions with H3O+, O2+ and NO+ in the PTR-MS drift tube. The PTR-MS and GC-FID toluene measurements were in good quantitative agreement and the two systems tracked one another well from the instrumental limits of detection to maximum mixing ratios of ~0.5 ppbv. Discrepancies in the measured mixing ratios were not well correlated with enhancements in the monoterpenes. Better quantitative agreement between the two systems was obtained by correcting the PTR-MS measurements for contributions from monoterpene fragmentation in the PTR-MS drift tube; however, the improvement was minor. Interferences in the PTR-MS measurements from fragmentation of the monoterpene oxidation products pinonaldehyde, caronaldehyde and α-pinene oxide were also likely negligible. The results from THF suggest that toluene can be reliably quantified by PTR-MS using our operating conditions under the ambient compositions probed. This work extends the range of field conditions under which PTR

  20. Field performance and identification capability of the Innsbruck PTR-TOF

    NASA Astrophysics Data System (ADS)

    Graus, M.; Müller, M.; Hansel, A.

    2009-04-01

    Over the last one and a half decades Proton Transfer Reaction Mass Spectrometry (PTR-MS) [1, 2] has gained recognition as fast on-line sensor for monitoring volatile organic compounds (VOC) in the atmosphere. Sample collection is very straight forward and the fact that no pre-concentration is needed is of particular advantage for compounds that are notoriously difficult to pre-concentrate and/or analyze by gas chromatographic (GC) methods. Its ionization method is very versatile, i.e. all compounds that perform exothermic proton transfer with hydronium ions - and most VOCs do so - are readily ionized, producing quasi-molecular ions VOC.H+. In the quasi-molecular ion the elemental composition of the analyte compound is conserved and allows, in combination with some background knowledge of the sample, conclusions about the identity of that compound. De Gouw and Warneke (2007) [3] summarized the applicability of PTR-MS in atmospheric chemistry but they also pointed out shortcomings in the identification capabilities. Goldstein and Galbally (2007) [4] addressed the multitude of VOCs potentially present in the atmosphere and they emphasized the gasphase-to-aerosol partitioning of organic compounds (volatile and semi-volatile) in dependence of carbon-chain length and oxygen containing functional groups. In collaboration with Ionicon and assisted by TOFWERK we developed a PTR time-of-flight (PTR-TOF) instrument that allows for the identification of the atomic composition of oxygenated hydrocarbons by exact-mass determination. A detection limit in the low pptv range was achieved at a time resolution of one minute, one-second detection limit is in the sub-ppbv range. In 2008 the Innsbruck PTR-TOF was field deployed in the icebreaker- and helicopter based Arctic Summer Cloud Ocean Study (ASCOS) to characterize the organic trace gas composition of the High Arctic atmosphere. During the six-week field campaign the PTR-TOF was run without problems even under harsh conditions in

  1. Calibration and intercomparison of acetic acid measurements using proton transfer reaction mass spectrometry (PTR-MS)

    USGS Publications Warehouse

    Haase, K.B.; Keene, W.C.; Pszenny, A.A.P.; Mayne, H.R.; Talbot, R.W.; Sive, B.C.

    2012-01-01

    Acetic acid is one of the most abundant organic acids in the ambient atmosphere, with maximum mixing ratios reaching into the tens of parts per billion by volume (ppbv) range. The identities and associated magnitudes of the major sources and sinks for acetic acid are poorly characterized, due in part to the limitation in available measurement techniques. This paper demonstrates that Proton Transfer Reaction Mass Spectrometry (PTR-MS) can reliably quantify acetic acid vapor in ambient air. Three different PTR-MS configurations were calibrated at low ppbv mixing ratios using permeation tubes, which yielded calibration factors between 7.0 and 10.9 normalized counts per second per ppbv (ncps ppbv−1) at a drift tube field strength of 132 townsend (Td). Detection limits ranged from 0.06 to 0.32 ppbv with dwell times of 5 s. These calibration factors showed negligible humidity dependence. Using the experimentally determined calibration factors, PTR-MS measurements of acetic acid during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) campaign were validated against results obtained using Mist Chambers coupled with Ion Chromatography (MC/IC). An orthogonal least squares linear regression of paired data yielded a slope of 1.14 ± 0.06 (2σ), an intercept of 0.049 ± 20 (2σ) ppbv, and an R2 of 0.78. The median mixing ratio of acetic acid on Appledore Island, ME during the ICARTT campaign was 0.530 ± 0.025 ppbv with a minimum of 0.075 ± 0.004 ppbv, and a maximum of 3.555 ± 0.171 ppbv.

  2. PTR-MS analysis of reference and plant-emitted volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Maleknia, Simin D.; Bell, Tina L.; Adams, Mark A.

    2007-05-01

    Proton transfer reaction-mass spectrometry (PTR-MS) was applied to the analysis of a series of volatile organic compounds (VOCs) that emit from various plants. These include a group of alcohols (methanol, ethanol and butanol), carbonyl-containing compounds (acetic acid, acetone and benzaldehyde), isoprene, acetonitrile, tetrahydrofuran (THF), pyrazine, toluene and xylene and a series of terpenes (p-cymene, camphene, 2-carene, limonene, [beta]-myrcene, [alpha]-pinene, [beta]-pinene, [gamma]-tepinene and terpinolene) and oxygen-containing terpenes (1,8-cineole and linalool). These mass spectral data were compared to an electron ionization (EI) database identifying that not all PTR-MS fragments were common to EI. PTR-MS studies of these reference compounds were utilized to identify VOCs emitted from Eucalyptus grandis leaf at a temperature range of 30-100 °C. In addition to protonated molecules (M + H)+, abundant proton-bound dimers or trimers were detected for alcohols, acetone, acetonitrile and THF. Abundant fragment ions attributed to the loss of water from these proton-bound clusters were also observed. The stability of butyl (C4H9+ m/z 57) and acetyl (CH3CO+ m/z 43) fragment ions directed the proton-transfer reactions of butanol and acetic acid. Abundant (M + H)+ ions were detected for pyrazine, THF, toluene and xylene, as well as for all terpenes except those containing oxygen. For linalool and 1,8-cineole, the loss of water generated an abundant fragment ion at m/z 137. PTR-MS fragmentation patterns for terpenes were proposed for m/z 81 (C6H9+), 93 (C7H9+), 95 (C7H11+), 107 (C8H11+), 109 (C8H13+), 119 (C9H11+), 121 (C9H13+) and 137 (loss of water for oxygen-containing terpenes; C10H17+). The relative abundances of (M + H)+ and fragments for all terpenes (except linalool) were dependent on the drift tube voltage and the optimum voltage for detection of molecular ions was different for various terpenes.

  3. Measurement of atmospheric sesquiterpenes by proton transfer reaction-mass spectrometry (PTR-MS)

    NASA Astrophysics Data System (ADS)

    Kim, S.; Karl, T.; Helmig, D.; Daly, R.; Rasmussen, R.; Guenther, A.

    2009-04-01

    The ability to measure sesquiterpenes (SQT; C15H24) by a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS) was investigated. SQT calibration standards were prepared by a capillary diffusion method and the PTR-MS-estimated mixing ratios were derived from the counts of product ions and proton transfer reaction constants. These values were compared with mixing ratios determined by a calibrated Gas Chromatograph (GC) coupled to a Flame Ionization Detector (GC-FID). Product ion distributions from soft-ionization occurring in a selected ion drift tube via proton transfer were measured as a function of collision energies. Results after the consideration of the mass discrimination of the PTR-MS system suggest that quantitative SQT measurements within 20% accuracy can be achieved with PTR-MS if two major product ions (m/z 149+ and 205+), out of seven major product ions (m/z 81+, 95+, 109+, 123+, 135+, 149+ and 205+), are accounted for. Considerable fragmentation of bicyclic sesquiterpenes, i.e. β-caryophyllene and α-humulene, cause the accuracy to be reduced to 50% if only the parent ion (m/z 205+) is considered. These findings were applied to a field dataset collected above a deciduous forest at the PROPHET (Program for Research on Oxidants: Photochemistry, Emissions, and Transport) research station in 2005. Inferred average daytime ecosystem scale mixing ratios (fluxes) of isoprene, sum of monoterpenes (MT), and sum of SQT exhibited values of 15 μg m-3 (4.5 mg m-2 h-1), 1.2 μg m-3 (0.21 mg m-2 h-1), and 0.0016 μg m-3 (0.10 mg m-2 h-1), respectively. A range of MT and SQT reactivities with respect to the OH radical was calculated and compared to an earlier study inferring significantly underestimated OH reactivities due to unknown terpenes above this deciduous forest. The results indicate that incorporating these MT and SQT results can resolve ~30% of missing OH reactivity reported for this site.

  4. Antisense expression of the peptide transport gene AtPTR2-B delays flowering and arrests seed development in transgenic Arabidopsis plants.

    PubMed Central

    Song, W; Koh, S; Czako, M; Marton, L; Drenkard, E; Becker, J M; Stacey, G

    1997-01-01

    Previously, we identified a peptide transport gene, AtPTR2-B, from Arabidopsis thaliana that was constitutively expressed in all plant organs, suggesting an important physiological role in plant growth and development. To evaluate the function of this transporter, transgenic Arabidopsis plants were constructed expressing antisense or sense AtPTR2-B. Genomic Southern analysis indicated that four independent antisense and three independent sense AtPTR2-B transgenic lines were obtained, which was confirmed by analysis of the segregation of the kanamycin resistance gene carried on the T-DNA. RNA blot data showed that the endogenous AtPTR2-B mRNA levels were significantly reduced in transgenic leaves and flowers, but not in transgenic roots. Consistent with this reduction in endogenous AtPTR2-B mRNA levels, all four antisense lines and one sense line exhibited significant phenotypic changes, including late flowering and arrested seed development. These phenotypic changes could be explained by a defect in nitrogen nutrition due to the reduced peptide transport activity conferred by AtPTR2-B. These results suggest that AtPTR2-B may play a general role in plant nutrition. The AtPTR2-B gene was mapped to chromosome 2, which is closely linked to the restriction fragment length polymorphism marker m246. PMID:9232875

  5. PtrWRKY19, a novel WRKY transcription factor, contributes to the regulation of pith secondary wall formation in Populus trichocarpa

    PubMed Central

    Yang, Li; Zhao, Xin; Yang, Fan; Fan, Di; Jiang, Yuanzhong; Luo, Keming

    2016-01-01

    WRKY proteins are one of the largest transcription factor families in higher plants and play diverse roles in various biological processes. Previous studies have shown that some WRKY members act as negative regulators of secondary cell wall formation in pith parenchyma cells. However, the regulatory mechanism of pith secondary wall formation in tree species remains largely unknown. In this study, PtrWRKY19 encoding a homolog of Arabidopsis WRKY12 was isolated from Populus trichocarpa. PtrWRKY19 was expressed in all tissues tested, with highest expression in stems, especially in pith. PtrWRKY19 was located in the nucleus and functioned as a transcriptional repressor. Ectopic expression of PtrWRKY19 in an atwrky12 mutant successfully rescued the phenotype in pith cell walls caused by the defect of AtWRKY12, suggesting that PtrWRKY19 had conserved functions for homologous AtWRKY12. Overexpression of PtrWRKY19 in poplar plants led to a significant increase in the number of pith parenchyma cells. qRT-PCR analysis showed that lignin biosynthesis-related genes were repressed in transgenic plants. In transcient reporter assays, PtrWRKY19 was identified to repress transcription from the PtoC4H2 promoter containing the conserved W-box elements. These results indicated that PtrWRKY19 may function as a negative regulator of pith secondary wall formation in poplar. PMID:26819184

  6. Test of practical utilization of PTR-MS and observation of the urban air in Tokyo during summer time

    NASA Astrophysics Data System (ADS)

    Miyakawa, Y.; Kato, S.; Hayashi, I.; Ichikawa, M.; Kajii, Y.

    2003-12-01

    Proton transfer reaction mass spectrometry (PTR-MS) is a technique that has been developed recently. It has several advantages for measurement of volatile organic compounds (VOCs) in the atmosphere. PTR-MS instrument can observe VOCs with high time resolution, and can also measure oxygenated volatile organic compounds (OVOCs). Furthermore, PTR-MS does not require carrier gases. Although PTR-MS is available as a commercial instrument from the company (IONICON), the instrument is not enough characterized for general users. In this study, PTR-MS was calibrated with a permeator, several kinds of standard gases and data from PTR-MS were compared with that of GC-FID. Substances used to try calibration with the permeator were follows; acetonitryle (CH3CN), methanol (CH3OH), acetone (CH3COCH3), acetaldehyde (CH3CHO). Results of these substances had good linearity. In the case of standard gases that contained aromatics, isoprene and dimethylsulfide (DMS), they also showed good linearities. Measurements in the urban air in Tokyo from June to August were carried out. Tokyo Metropolitan University (TMU) is located in the west of Tokyo. Although TMU is urban site, there are many trees near the observation site. Therefore, the results were affected by the emission from plants. Aromatics, isoprene, terpenes were also measured by GC-FID in the beginning in June, and the results of PTR-MS were compared with the result of GC-FID. There was good correlation for all substances, especially of benzene, toluene, and xylene. CH3CHO and isoprene showed clear diurnal changes. These concentrations were higher in the daytime and lower at night. HCHO signal was much lower than actual concentration because protonated ion had a reverse reaction with water. But clear diurnal change was observed. If proper correction is applied, HCHO could be measured by PTR-MS. Acetone did not show such clear diurnal changes. This result suggested that acetone had been affected by solvent emission rather than

  7. Applicability of PTR-MS in the quality control of saffron.

    PubMed

    Nenadis, Nikolaos; Heenan, Samuel; Tsimidou, Maria Z; Van Ruth, Saskia

    2016-04-01

    The applicability of the emerging non-destructive technique, proton transfer reaction mass spectrometry (PTR-MS), was explored for the first time in the quality control of saffron. Monitoring of volatile organic compounds (VOCs) was achieved using a minute sample (35 mg). Fresh saffron was stored under selected conditions (25 and 40 °C, aw=0.64) over a five weeks period to produce lower quality material, which was used to prepare mixtures with fresh saffron. Analysis showed that the VOCs fingerprint changed upon storage, and the concentration of initially dominant VOC safranal decreased progressively. Examination of calculated and recorded fingerprints for various admixtures showed that PTR-MS VOCs analysis, in combination with chemometrics, could be used to screen for the presence of lower quality saffron in a commercial product in a few minutes. The technique can be used in a complementary fashion, adding to the battery of advanced analytical techniques available to address the quality and authenticity issues of saffron. PMID:26593578

  8. Eddy covariance emission and deposition flux measurements using proton transfer reaction - time of flight - mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

    NASA Astrophysics Data System (ADS)

    Park, J.-H.; Goldstein, A. H.; Timkovsky, J.; Fares, S.; Weber, R.; Karlik, J.; Holzinger, R.

    2013-02-01

    During summer 2010, a proton transfer reaction - time of flight - mass spectrometer (PTR-TOF-MS) and a quadrupole proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m/Δm) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e., co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 μg C m-2 h-1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 μg C m-2 h-1) and methanol (m/z 33.032, 18%, 72 μg C m-2 h-1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 μg C m-2 h-1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 μg C m-2 h-1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 μg C m-2 h-1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 μg C m-2 h-1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7

  9. Eddy covariance emission and deposition flux measurements using proton transfer reaction-time of flight-mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

    NASA Astrophysics Data System (ADS)

    Park, J.-H.; Goldstein, A. H.; Timkovsky, J.; Fares, S.; Weber, R.; Karlik, J.; Holzinger, R.

    2012-08-01

    During summer 2010, a proton transfer reaction-time of flight-mass spectrometer (PTR-TOF-MS) and a standard proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m Δ m-1) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e. co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 μg C m-2 h-1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 μg C m-2 h-1) and methanol (m/z 33.032, 18%, 72 μg C m-2 h-1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 μg C m-2 h-1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 μg C m-2 h-1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 μg C m-2 h-1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 μg C m-2 h-1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7.1

  10. Randomized Controlled Trial of the Prevent-Teach-Reinforce (PTR) Tertiary Intervention for Students with Problem Behaviors: Preliminary Outcomes

    ERIC Educational Resources Information Center

    Iovannone, Rose; Greenbaum, Paul E.; Wang, Wei; Kincaid, Don; Dunlap, Glen; Strain, Phil

    2009-01-01

    Although there is literature supporting the effectiveness of tertiary behavioral supports, the majority of the studies have been conducted with single-subject designs. The Prevent-Teach-Reinforce (PTR) model is a standardized model of a school-based tertiary intervention. This study reports initial results from a randomized controlled trial to…

  11. Marker Development and Saturation Mapping of the Tan Spot Ptr ToxB Sensitivity locus Tsc2 in Hexaploid Wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ptr ToxB is a host-selective toxin produced by the tan spot fungus that induces chlorosis in wheat lines harboring the Tsc2 gene, which was previously located to chromosome arm 2BS in tetraploid wheat. In this study, molecular mapping in a recombinant inbred (RI) population derived from a cross betw...

  12. Measurement of atmospheric sesquiterpenes by proton transfer reaction-mass spectrometry (PTR-MS)

    NASA Astrophysics Data System (ADS)

    Kim, S.; Karl, T.; Helmig, D.; Daly, R.; Rasmussen, R.; Guenther, A.

    2008-12-01

    The ability to measure sesquiterpenes (SQT; C15H24) by a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS) was investigated with SQT standards, prepared by a capillary diffusion method, and the estimated mixing ratios, derived from the counts of product ions and proton transfer reaction constants were intercompared with measured mixing ratios, measured by a complementary Gas Chromatograph (GC) coupled to a Flame Ionization Detector (GC-FID). Product ion distributions due to soft-ionization occurring in a selected ion drift tube via proton transfer were measured as a function of collision energies. Results after the consideration of the mass discrimination of the PTR-MS system suggest that quantitative SQT measurements within 20% accuracy can be achieved with PTR-MS if two major product ions (m/z 149+ and 205+) out of seven major product ions (m/z 81+, 95+, 109+, 123+, 135+, 149+ and 205+) are accounted for. Bicyclic sesquiterpenes, i.e. β-caryophyllene and α-humulene, showed considerable fragmentation causing the accuracy of their analysis to be reduced to 50% if only the parent ion (m/z 205) is considered. These findings were applied to a field dataset collected above a deciduous forest at the PROPHET (Program for Research on Oxidants: Photochemistry, Emissions, and Transport) research station in 2005. Inferred Average daytime ecosystem scale mixing ratios (fluxes) of isoprene, sum of monoterpenes (MT), and sum of SQT exhibited values of 15 μg m-3 (4.5 mg m-2 h-1), 1.2 μg m-3 (0.21 mg m-2 h-1) and 0.0016 μg m-3 (0.10 mgm-2 h-1) respectively. A range of MT and SQT reactivities with respect to the OH radical was calculated and compared to an earlier study inferring significantly underestimated OH reactivities due to unknown terpenes above this deciduous forest. The results indicate that MT and SQT can resolve ~30% of missing OH reactivity, reported from this site.

  13. RNAi-based functional elucidation of PtrPRP, a gene encoding a hybrid proline rich protein, in cold tolerance of Poncirus trifoliata.

    PubMed

    Peng, Ting; Jia, Mao-Mao; Liu, Ji-Hong

    2015-01-01

    Hybrid proline-rich proteins (HyPRPs) have been suggested to play important roles in various plant development and stress response. In this study, we report the cloning and functional analysis of PtrPRP, a HyPRP-encoding gene of Poncirus trifoliata. PtrPRP contains 176 amino acids, among which 21% are proline residues, and has an 8-cysteine motif (8 CM) domain at the C terminal, a signal peptide and a proline-rich region at the N terminal. PtrPRP is constitutively expressed in root, stem and leaf, with the highest expression levels in leaf. It was progressively induced by cold, but transiently upregulated by salt and ABA. Transgenic P. trifoliata plants with knock-down PtrPRP by RNA interference (RNAi) were generated to investigate the role of PtrPRP in cold tolerance. When challenged by low temperature, the PtrPRP-RNAi plants displayed more sensitive performance compared with wild type (WT), as shown by higher electrolyte leakage and malondialdehyde content. In addition, the RNAi lines accumulated more reactive oxygen species (ROS) and lower levels of proline relative to WT. These results suggested that PtrPRP might be positively involved in cold tolerance by maintaining membrane integrity and ROS homeostasis. PMID:26483822

  14. Regulation of secondary cell wall biosynthesis by poplar R2R3 MYB transcription factor PtrMYB152 in Arabidopsis

    SciTech Connect

    Wang, Shucai; Li, Eryang; Porth, Ilga; Chen, Jin-Gui; Mansfield, Shawn D.; Douglas, Carl

    2014-05-23

    Poplar has 192 annotated R2R3 MYB genes, of which only three have been shown to play a role in the regulation of secondary cell wall formation. Here we report the characterization of PtrMYB152, a poplar homolog of the Arabidopsis R2R3 MYB transcription factor AtMYB43, in the regulation of secondary cell wall biosynthesis. The expression of PtrMYB152 in secondary xylem is about 18 times of that in phloem. When expressed in Arabidopsis under the control of either 35S or PtrCesA8 promoters, PtrMYB152 increased secondary cell wall thickness, which is likely caused by increased lignification. Accordingly, elevated expression of genes encoding sets of enzymes in secondary wall biosynthesis were observed in transgenic plants expressing PtrMYB152. Arabidopsis protoplast transfection assays suggested that PtrMYB152 functions as a transcriptional activator. Taken together, our results suggest that PtrMYB152 may be part of a regulatory network activating expression of discrete sets of secondary cell wall biosynthesis genes.

  15. RNAi-based functional elucidation of PtrPRP, a gene encoding a hybrid proline rich protein, in cold tolerance of Poncirus trifoliata

    PubMed Central

    Peng, Ting; Jia, Mao-Mao; Liu, Ji-Hong

    2015-01-01

    Hybrid proline-rich proteins (HyPRPs) have been suggested to play important roles in various plant development and stress response. In this study, we report the cloning and functional analysis of PtrPRP, a HyPRP-encoding gene of Poncirus trifoliata. PtrPRP contains 176 amino acids, among which 21% are proline residues, and has an 8-cysteine motif (8 CM) domain at the C terminal, a signal peptide and a proline-rich region at the N terminal. PtrPRP is constitutively expressed in root, stem and leaf, with the highest expression levels in leaf. It was progressively induced by cold, but transiently upregulated by salt and ABA. Transgenic P. trifoliata plants with knock-down PtrPRP by RNA interference (RNAi) were generated to investigate the role of PtrPRP in cold tolerance. When challenged by low temperature, the PtrPRP-RNAi plants displayed more sensitive performance compared with wild type (WT), as shown by higher electrolyte leakage and malondialdehyde content. In addition, the RNAi lines accumulated more reactive oxygen species (ROS) and lower levels of proline relative to WT. These results suggested that PtrPRP might be positively involved in cold tolerance by maintaining membrane integrity and ROS homeostasis. PMID:26483822

  16. PtrABF of Poncirus trifoliata functions in dehydration tolerance by reducing stomatal density and maintaining reactive oxygen species homeostasis

    PubMed Central

    Zhang, Qinghua; Wang, Min; Hu, Jianbing; Wang, Wei; Fu, Xingzheng; Liu, Ji-Hong

    2015-01-01

    Abscisic acid-responsive element (ABRE)-binding factors (ABFs) play important roles in abiotic stress responses; however, the underlying mechanisms are poorly understood. In this study, it is reported that overexpression of Poncirus trifoliata PtrABF significantly enhanced dehydration tolerance. The transgenic lines displayed smaller stomatal apertures, reduced stomatal density/index, and lower expression levels of genes associated with stomatal development. PtrABF was found to interact with PtrICE1, a homologue of ICE1 (Inducer of CBF Expression 1) that has been shown to be critical for stomatal development. Microarray analysis revealed that a total of 70 genes were differentially expressed in the transgenic line, 42 induced and 28 repressed. At least two units of ABREs and coupling elements were present in the promoters of most of the induced genes, among which peroxidase and arginine decarboxylase were verified as bona fide targets of PtrABF. Transgenic plants exhibited higher antioxidant enzyme activities and free polyamine levels, but lower levels of reactive oxygen species (ROS) and malondialdehyde. Polyamines were revealed to be associated with ROS scavenging in the transgenic plants due to a modulation of antioxidant enzymes triggered by signalling mediated by H2O2 derived from polyamine oxidase (PAO)-mediated catabolism. Taken together, the results indicate that PtrABF functions positively in dehydration tolerance by limiting water loss through its influence on stomatal movement or formation and maintaining ROS homeostasis via modulation of antioxidant enzymes and polyamines through transcriptional regulation of relevant target genes. PMID:26116025

  17. PtrABF of Poncirus trifoliata functions in dehydration tolerance by reducing stomatal density and maintaining reactive oxygen species homeostasis.

    PubMed

    Zhang, Qinghua; Wang, Min; Hu, Jianbing; Wang, Wei; Fu, Xingzheng; Liu, Ji-Hong

    2015-09-01

    Abscisic acid-responsive element (ABRE)-binding factors (ABFs) play important roles in abiotic stress responses; however, the underlying mechanisms are poorly understood. In this study, it is reported that overexpression of Poncirus trifoliata PtrABF significantly enhanced dehydration tolerance. The transgenic lines displayed smaller stomatal apertures, reduced stomatal density/index, and lower expression levels of genes associated with stomatal development. PtrABF was found to interact with PtrICE1, a homologue of ICE1 (Inducer of CBF Expression 1) that has been shown to be critical for stomatal development. Microarray analysis revealed that a total of 70 genes were differentially expressed in the transgenic line, 42 induced and 28 repressed. At least two units of ABREs and coupling elements were present in the promoters of most of the induced genes, among which peroxidase and arginine decarboxylase were verified as bona fide targets of PtrABF. Transgenic plants exhibited higher antioxidant enzyme activities and free polyamine levels, but lower levels of reactive oxygen species (ROS) and malondialdehyde. Polyamines were revealed to be associated with ROS scavenging in the transgenic plants due to a modulation of antioxidant enzymes triggered by signalling mediated by H2O2 derived from polyamine oxidase (PAO)-mediated catabolism. Taken together, the results indicate that PtrABF functions positively in dehydration tolerance by limiting water loss through its influence on stomatal movement or formation and maintaining ROS homeostasis via modulation of antioxidant enzymes and polyamines through transcriptional regulation of relevant target genes. PMID:26116025

  18. The effect of relative humidity on the detection of pyrrole by PTR-MS for OH reactivity measurements

    NASA Astrophysics Data System (ADS)

    Sinha, V.; Custer, T. G.; Kluepfel, T.; Williams, J.

    2009-04-01

    The hydroxyl radical (OH) is the most important atmospheric oxidant. Recently Sinha et al. [1] developed a new method to measure the total OH reactivity of ambient air (OH sink) employing a proton transfer reaction mass spectrometer (PTR-MS) as a detector. The new method uses pyrrole (C4H4NH) as a reagent and for an OH reactivity measurement this species must be measured under both dry (~ 0% RH) and humid air ( > 30% RH). Here, we investigate the sensitivity dependence of the PTR-MS for pyrrole, as a function of relative humidity in the sampled air. Various normalizations with respect to the H3O+ ion and its different hydrated clusters ions H3O+(H2O)n=1,2,3 are compared. It is shown that both the primary ion signal (H3O+ ion m/z = 19) and the first water cluster ion H3O+(H2O) (m/z = 37) should be used for pyrrole quantification. However, in spite of using this normalization, the PTR-MS sensitivity for pyrrole changes by as much as 16 % between dry (~ 0% RH) and humid air (above 30 % RH), with higher sensitivity when the sampled air is humid. Thus, for accurate quantification of pyrrole using a PTR-MS, calibration factors appropriate to dry and humid air should be employed. We recommend that humidity dependence of the PTR-MS be taken into account when reactivity measurements are performed using the pyrrole based comparative reactivity method (CRM). [1]. V. Sinha, J. Williams, J.N. Crowley, and J. Lelieveld, Atmos. Chem. Phys. 8 (2008) 2213-2227

  19. The effect of relative humidity on the detection of pyrrole by PTR-MS for OH reactivity measurements

    NASA Astrophysics Data System (ADS)

    Sinha, V.; Custer, T. G.; Kluepfel, T.; Williams, J.

    2009-05-01

    The hydroxyl radical (OH) is the most important atmospheric oxidant. Recently Sinha et al. [V. Sinha, J. Williams, J.N. Crowley, J. Lelieveld, Atmos. Chem. Phys. 8 (2008) 2213] developed a new method to measure the total OH reactivity of ambient air (OH sink) employing a proton transfer reaction mass spectrometer (PTR-MS) as a detector. The new method uses pyrrole (C4H4NH) as a reagent and for an OH reactivity measurement this species must be measured under both dry (~0% RH) and humid air (>30% RH). Here, we investigate the sensitivity dependence of the PTR-MS for pyrrole, as a function of relative humidity in the sampled air. Various normalizations with respect to the H3O+ ion and its different hydrated cluster ions H3O+(H2O)n=1,2,3 are compared. It is shown that both the primary ion signal (H3O+ ion m/z = 19) and the first water cluster ion H3O+(H2O) (m/z = 37) should be used for pyrrole quantification. However, in spite of using this normalization, the PTR-MS sensitivity for pyrrole changes by as much as 16% between dry (~0% RH) and humid air (above 30% RH), with higher sensitivity when the sampled air is humid. Thus, for accurate quantification of pyrrole using a PTR-MS, calibration factors appropriate to dry and humid air should be employed. We recommend that humidity dependence of the PTR-MS be taken into account when reactivity measurements are performed using the pyrrole based comparative reactivity method (CRM).

  20. PTRwid: A new widget tool for processing PTR-TOF-MS data

    NASA Astrophysics Data System (ADS)

    Holzinger, R.

    2015-09-01

    PTRwid is a fast and user friendly tool that has been developed to process data from proton-transfer-reaction time-of-flight mass spectrometers (PTR-TOF-MS) that use HTOF (high-resolution time-of-flight) mass spectrometers from Tofwerk AG (Switzerland). PTRwid is designed for a comprehensive evaluation of whole laboratory or field-based studies. All processing runs autonomously, and entire laboratory or field campaigns can, in principle, be processed with a few mouse clicks. Unique features of PTRwid include (i) an autonomous and accurate mass scale calibration, (ii) the computation of a "unified mass list" that - in addition to a uniform data structure - provides a robust method to determine the precision of attributed peak masses, and (iii) fast data analysis due to well considered choices in data processing.

  1. PTRwid: a new widget-tool for processing PTR-TOF-MS data

    NASA Astrophysics Data System (ADS)

    Holzinger, R.

    2015-02-01

    PTRwid is a fast and user friendly tool that has been developed to process data from proton-transfer-reaction time-of-flight mass-spectrometers (PTR-TOF-MS) that use HTOF time-of-flight mass-spectrometers from Tofwerk AG (Switzerland). PTRwid is designed for a comprehensive evaluation of whole laboratory or field based studies. All processing runs autonomously and whole laboratory or field campaigns can, in principle, be processed with a few mouse clicks. Unique features of PTRwid include (i) an autonomous and accurate mass scale calibration, (ii) the computation of an "Unified Mass list" that - in addition to an uniform data structure - provides a robust method to determine the precision of attributed peak masses, and (iii) fast data analysis due to well considered choices in data processing.

  2. Measuring long chain alkanes in diesel engine exhaust by thermal desorption PTR-MS

    NASA Astrophysics Data System (ADS)

    Erickson, M. H.; Gueneron, M.; Jobson, B. T.

    2014-01-01

    A method using thermal desorption sampling and analysis by proton transfer reaction mass spectrometry (PTR-MS) to measure long chain alkanes (C12-C18) and other larger organics associated with diesel engine exhaust emissions is described. Long chain alkanes undergo dissociative proton transfer reactions forming a series of fragment ions with formula CnH2n+1. The PTR-MS is insensitive to n-alkanes less than C8 but displays an increasing sensitivity for larger alkanes. Fragment ion distribution and sensitivity is a function of drift conditions. At 80 Td the most abundant ion fragments from C10 to C16 n-alkanes were m/z 57, 71 and 85. The mass spectrum of gasoline and diesel fuel at 80 Td displayed ion group patterns that can be related to known fuel constituents, such as alkanes, alkylbenzenes and cycloalkanes, and other compound groups that are inferred from molecular weight distributions such as dihydronapthalenes and naphthenic monoaromatics. It is shown that thermal desorption sampling of gasoline and diesel engine exhausts at 80 Td allows for discrimination against volatile organic compounds, allowing for quantification of long chain alkanes from the abundance of CnH2n+1 fragment ions. The total abundance of long chain alkanes in diesel engine exhaust was measured to be similar to the total abundance of C1-C4 alkylbenzene compounds. The abundance patterns of compounds determined by thermal desorption sampling may allow for emission profiles to be developed to better quantify the relative contributions of diesel and gasoline exhaust emissions on organic compounds concentrations in urban air.

  3. Eddy covariance VOC emission and deposition fluxes above grassland using PTR-TOF

    NASA Astrophysics Data System (ADS)

    Ruuskanen, T. M.; Müller, M.; Schnitzhofer, R.; Karl, T.; Graus, M.; Bamberger, I.; Hörtnagl, L.; Brilli, F.; Wohlfahrt, G.; Hansel, A.

    2011-01-01

    Eddy covariance (EC) is the preferable technique for flux measurements since it is the only direct flux determination method. It requires a continuum of high time resolution measurements (e.g. 5-20 Hz). For volatile organic compounds (VOC) soft ionization via proton transfer reaction has proven to be a quantitative method for real time mass spectrometry; here we use a proton transfer reaction time of flight mass spectrometer (PTR-TOF) for 10 Hz EC measurements of full mass spectra up to m/z 315. The mass resolution of the PTR-TOF enabled the identification of chemical formulas and separation of oxygenated and hydrocarbon species exhibiting the same nominal mass. We determined 481 ion mass peaks from ambient air concentration above a managed, temperate mountain grassland in Neustift, Stubai Valley, Austria. During harvesting we found significant fluxes of 18 compounds distributed over 43 ions, including protonated parent compounds, as well as their isotopes and fragments and VOC-H+ - water clusters. The dominant BVOC fluxes were methanol, acetaldehyde, ethanol, hexenal and other C6 leaf wound compounds, acetone, acetic acid, monoterpenes and sequiterpenes. The smallest reliable fluxes we determined were less than 0.1 nmol m-2 s-1, as in the case of sesquiterpene emissions from freshly cut grass. Terpenoids, including mono- and sesquiterpenes, were also deposited to the grassland before and after the harvesting. During cutting, total VOC emission fluxes up to 200 nmolC m-2 s-1 were measured. Methanol emissions accounted for half of the emissions of oxygenated VOCs and a third of the carbon of all measured VOC emissions during harvesting.

  4. VOC Emission and Deposition Eddy Covariance Fluxes above Grassland using PTR-TOF

    NASA Astrophysics Data System (ADS)

    Ruuskanen, T. M.; Müller, M.; Schnitzhofer, R.; Karl, T.; Graus, M.; Bamberger, I.; Hörtnagl, L.; Brilli, F.; Wohlfahrt, G.; Hansel, A.

    2010-12-01

    Eddy covariance (EC) is the preferable technique for flux measurements since it is the only direct flux determination method. It requires a continuum of high time resolution measurements (e.g. 5-20 Hz). For volatile organic compounds (VOC) soft ionization via proton transfer reaction has proven to be a quantitative method for real time mass spectrometry; here we use a proton transfer reaction time of flight mass spectrometer (PTR-TOF) for 10 Hz EC measurements of full mass spectra up to m/z 315. The mass resolution of the PTR-TOF enabled the identification of chemical formulas and separation of oxygenated and hydrocarbon species exhibiting the same nominal mass. We determined 481 ion mass peaks from ambient air concentration above a managed, temperate mountain grassland in Neustift, Stubai Valley, Austria. During harvesting we found significant fluxes of 18 compounds distributed over 43 ions, including protonated parent compounds, as well as their isotopes and fragments and VOC-H+ - water clusters. The dominant BVOC fluxes were methanol, acetaldehyde, ethanol, hexenal and other C6 leaf wound compounds, acetone, acetic acid, monoterpenes and sequiterpenes. The smallest reliable fluxes we determined were less than 0.1 nmol m-2 s-1, as in the case of sesquiterpene emissions from freshly cut grass. Terpenoids, including mono- and sesquiterpenes, were also deposited to the grassland before and after the harvesting. During cutting, total VOC emission fluxes up to 200 nmolC m-2 s-1 were measured. Methanol emissions accounted for half of the emissions of oxygenated VOCs and a third of the carbon of all measured VOC emissions during harvesting.

  5. Eddy covariance VOC emission and deposition fluxes above grassland using PTR-TOF

    NASA Astrophysics Data System (ADS)

    Ruuskanen, T. M.; Müller, M.; Schnitzhofer, R.; Karl, T.; Graus, M.; Bamberger, I.; Hörtnagl, L.; Brilli, F.; Wohlfahrt, G.; Hansel, A.

    2010-09-01

    Eddy covariance (EC) is the preferable technique for flux measurements since it is the only direct flux determination method. It requires a continuum of high time resolution measurements (e.g. 5-20 Hz). For volatile organic compounds (VOC) soft ionization via proton transfer reaction has proven to be a quantitative method for real time mass spectrometry; here we use a proton transfer reaction time of flight mass spectrometer (PTR-TOF) for 10 Hz EC measurements of full mass spectra up to m/z 315. The mass resolution of the PTR-TOF enabled the identification of chemical formulas and separation of oxygenated and hydrocarbon species exhibiting the same nominal mass. We determined 481 ion mass peaks from ambient air concentration above a managed, temperate mountain grassland in Neustift, Stubai Valley, Austria. During harvesting we found significant fluxes of 18 compounds distributed over 43 ions, including protonated parent compounds, as well as their isotopes and fragments and VOC-H+-water clusters. The dominant BVOC fluxes were methanol, acetaldehyde, ethanol, hexenal and other C6 leaf wound compounds, acetone, acetic acid, monoterpenes and sequiterpenes. The smallest reliable fluxes we determined were less than 0.1 nmol m-2 s-1, as in the case of sesquiterpene emissions from freshly cut grass. Terpenoids, including mono- and sesquiterpenes, were also deposited to the grassland before and after the harvesting. During cutting, total VOC emission fluxes up to 200 nmol C m-2 s-1 were measured. Methanol emissions accounted for half of the emissions of oxygenated VOCs and a third of the carbon of all measured VOC emissions during harvesting.

  6. Comparison of Total OH Reactivity Measurement Methods in Ambient Air between a Comparative Reactivity Method using PTR-MS and a LASER Technique

    NASA Astrophysics Data System (ADS)

    Okazaki, H.; Osada, T.; Nakashima, Y.; Kato, S.; Kajii, Y.

    2008-12-01

    OH radical plays an important role in atmospheric chemistry. OH reactivity measurement is essential to understand atmospheric chemical reaction processes. We have developed LASER technique to measure OH reactivity. This system requires both pump and probe lasers and high vacuum system. We have to pay a lot of efforts to bring the instrument in the field for ambient observation. Therefore we have developed a comparative reactivity method for measuring total OH reactivity recently. Since this method does not need a large space and complicated devices, it makes relatively easy to measure OH reactivity anywhere. The result of this non-laser OH reactivity measurement was compared with that of laser pump and probe technique as conducted an intensive field measurement of sub-urban air in Tokyo, July 2008. In comparative reactivity method, a regent species (X), which is ideally not present in ambient air, is introduced into the flow tube reactor and its concentration (C1) is monitored by a suitable detector under nitrogen atmospheric condition. A constant amount of OH radicals is then introduced into the flow tube to react with X under either nitrogen atmosphere (the concentration of X became C2) or ambient air (the concentration of X became C3). Total OH reactivity can be calculated by comparing C1, C2 and C3. OH radicals were produced in the photolysis of water vapor by a UV lamp. In our experiment, Pyrrole is selected as X and PTR-MS is used as a detector. The concentrations of NO, NO2, CO, SO2 were also measured. In some case, the two methods indicated some differences, for example, OH reactivity of 10 to 30 s-1 measured by LASER technique while the comparative reactivity method showed the value of only 5 to 12 s-1.This reason appears to be humidity dependence of PTR-MS sensitivity. Good agreements, for trends and absolute values, were found for comparison between the two methods during another day of experiment where both methods reveal OH reactivity ranging between

  7. PTR-MS in Italy: A Multipurpose Sensor with Applications in Environmental, Agri-Food and Health Science

    PubMed Central

    Cappellin, Luca; Loreto, Francesco; Aprea, Eugenio; Romano, Andrea; del Pulgar, José Sánchez; Gasperi, Flavia; Biasioli, Franco

    2013-01-01

    Proton Transfer Reaction Mass Spectrometry (PTR-MS) has evolved in the last decade as a fast and high sensitivity sensor for the real-time monitoring of volatile compounds. Its applications range from environmental sciences to medical sciences, from food technology to bioprocess monitoring. Italian scientists and institutions participated from the very beginning in fundamental and applied research aiming at exploiting the potentialities of this technique and providing relevant methodological advances and new fundamental indications. In this review we describe this activity on the basis of the available literature. The Italian scientific community has been active mostly in food science and technology, plant physiology and environmental studies and also pioneered the applications of the recently released PTR-ToF-MS (Proton Transfer Reaction-Time of Flight-Mass Spectrometry) in food science and in plant physiology. In the very last years new results related to bioprocess monitoring and health science have been published as well. PTR-MS data analysis, particularly in the case of the ToF based version, and the application of advanced chemometrics and data mining are also aspects characterising the activity of the Italian community. PMID:24021966

  8. Simultaneous factor analysis of organic particle and gas mass spectra: AMS and PTR-MS measurements at an urban site

    NASA Astrophysics Data System (ADS)

    Slowik, J. G.; Vlasenko, A.; McGuire, M.; Evans, G. J.; Abbatt, J. P. D.

    2009-03-01

    During the winter component of the SPORT (Seasonal Particle Observations in the Region of Toronto) field campaign, particulate non-refractory chemical composition and concentration of selected volatile organic compounds (VOCs) were measured by an Aerodyne time-of-flight aerosol mass spectrometer (AMS) and a proton transfer reaction-mass spectrometer (PTR-MS), respectively. Sampling was performed in downtown Toronto ~15 m from a major road. The mass spectra from the AMS and PTR-MS were combined into a unified dataset, which was analyzed using positive matrix factorization (PMF). The two instruments were given equal weight in the PMF analysis by application of a scaling factor to the uncertainties of each instrument. A residual based metric, Δesc, was used to evaluate the relative weight. The PMF analysis yielded a 5-factor solution that included factors characteristic of regional transport, local traffic emissions, charbroiling, and oxidative processing. The unified dataset provides information on particle and VOC sources and atmospheric processing that cannot be obtained from the datasets of the individual instruments, such as apportionment of oxygenated VOCs to direct emission sources vs. secondary reaction products, improved correlation of oxygenated aerosol factors with photochemical age, and increased detail regarding the composition of oxygenated organic aerosol factors. This analysis represents the first application of PMF to a unified AMS/PTR-MS dataset.

  9. Simultaneous factor analysis of organic particle and gas mass spectra: AMS and PTR-MS measurements at an urban site

    NASA Astrophysics Data System (ADS)

    Slowik, J. G.; Vlasenko, A.; McGuire, M.; Evans, G. J.; Abbatt, J. P. D.

    2010-02-01

    During the winter component of the SPORT (Seasonal Particle Observations in the Region of Toronto) field campaign, particulate non-refractory chemical composition and concentration of selected volatile organic compounds (VOCs) were measured by an Aerodyne time-of-flight aerosol mass spectrometer (AMS) and a proton transfer reaction-mass spectrometer (PTR-MS), respectively. Sampling was performed in downtown Toronto ~15 m from a major road. The mass spectra from the AMS and PTR-MS were combined into a unified dataset, which was analysed using positive matrix factorization (PMF). The two instruments were given balanced weight in the PMF analysis by the application of a scaling factor to the uncertainties of each instrument. A residual based metric, Δesc, was used to evaluate the instrument relative weight within each solution. The PMF analysis yielded a 6-factor solution that included factors characteristic of regional transport, local traffic emissions, charbroiling and oxidative processing. The unified dataset provides information on emission sources (particle and VOC) and atmospheric processing that cannot be obtained from the datasets of the individual instruments: (1) apportionment of oxygenated VOCs to either direct emission sources or secondary reaction products; (2) improved correlation of oxygenated aerosol factors with photochemical age; and (3) increased detail regarding the composition of oxygenated organic aerosol factors. This analysis represents the first application of PMF to a unified AMS/PTR-MS dataset.

  10. Simultaneous Measurement of Thermal Diffusivity and Optical Absorption Coefficient of Solids Using PTR and PPE: A Comparison

    NASA Astrophysics Data System (ADS)

    Fuente, R.; Mendioroz, A.; Apiñaniz, E.; Salazar, A.

    2012-11-01

    Modulated photothermal radiometry (PTR) and a modulated photopyroelectric (PPE) technique have been widely used to measure the thermal diffusivity of bulk materials. The method is based on illuminating the sample with a plane light beam and measuring the infrared emission with an infrared detector (PTR) or the electric voltage produced by a pyroelectric sensor in contact with the sample (PPE). The amplitude and phase of both photothermal signals are recorded as a function of the modulation frequency and then fitted to the theoretical model. In this work, we compare the ability of modulated PTR and PPE to retrieve simultaneously the thermal diffusivity and the optical absorption coefficient of homogeneous slabs. In order to eliminate the instrumental factor, self-normalization is used, i.e., the ratio of the photothermal signal recorded at the rear and front surfaces. The influence of the multiple reflections of the light beam and the transparency to infrared wavelengths are analyzed. Measurements performed on a wide variety of homogeneous materials, transparent and opaque, good and bad thermal conductors, confirm the validity of the method. The advantages and disadvantages of both techniques are discussed.

  11. A comparison of GC-FID and PTR-MS toluene measurements in ambient air under conditions of enhanced monoterpene loading

    NASA Astrophysics Data System (ADS)

    Ambrose, J. L.; Haase, K.; Russo, R. S.; Zhou, Y.; White, M. L.; Frinak, E. K.; Jordan, C.; Mayne, H. R.; Talbot, R.; Sive, B. C.

    2010-07-01

    Toluene was measured using both a gas chromatographic system (GC), with a flame ionization detector (FID), and a proton transfer reaction-mass spectrometer (PTR-MS) at the AIRMAP atmospheric monitoring station Thompson Farm (THF) in rural Durham, NH during the summer of 2004. Simultaneous measurements of monoterpenes, including α- and β-pinene, camphene, Δ 3-carene, and d-limonene, by GC-FID demonstrated large enhancements in monoterpene mixing ratios relative to toluene, with median and maximum enhancement ratios of ~2 and ~30, respectively. A detailed comparison between the GC-FID and PTR-MS toluene measurements was conducted to test the specificity of PTR-MS for atmospheric toluene measurements under conditions often dominated by biogenic emissions. We derived quantitative estimates of potential interferences in the PTR-MS toluene measurements related to sampling and analysis of monoterpenes, including fragmentation of the monoterpenes and some of their primary carbonyl oxidation products via reactions with H3O+, O2+ and NO+ in the PTR-MS drift tube. The PTR-MS and GC-FID toluene measurements were in good quantitative agreement and the two systems tracked one another well from the instrumental limits of detection to maximum mixing ratios of ~0.5 ppbv. A correlation plot of the PTR-MS versus GC-FID toluene measurements was described by the least squares regression equation y=(1.13± 0.02)x-(0.008±0.003) ppbv, suggesting a small ~13% positive bias in the PTR-MS measurements. The bias corresponded with a ~0.055 ppbv difference at the highest measured toluene level. The two systems agreed quantitatively within the combined 1σ measurement precisions for 60% of the measurements. Discrepancies in the measured mixing ratios were not well correlated with enhancements in the monoterpenes. Better quantitative agreement between the two systems was obtained by correcting the PTR-MS measurements for contributions from monoterpene fragmentation in the PTR-MS drift tube

  12. Rapid and facile detection of four date rape drugs in different beverages utilizing proton transfer reaction mass spectrometry (PTR-MS).

    PubMed

    Jürschik, Simone; Agarwal, Bishu; Kassebacher, Thomas; Sulzer, Philipp; Mayhew, Christopher A; Märk, Tilmann D

    2012-09-01

    In this work, we illustrate the application of proton transfer reaction mass spectrometry (PTR-MS) in the field of food and drink safety. We present proof-of-principle measurements of four different drinks (water, tea, red wine and white wine) each spiked separately with four different date rape drugs (chloral hydrate, tricholorethanol, γ-butyrolactone and butanediol). At first, the ideal PTR-MS operating conditions (reduced electric field strength and monitoring the most abundant [fragment] ion) for detection of the drugs were determined utilizing a time-of-flight-based PTR-MS instrument. We then dissolved small quantities of the drugs (below the activation threshold for effects on humans) into the various types of drinks and detected them using a quadrupole-based PTR-MS instrument via two different sampling methods: (1) dynamic headspace sampling and (2) direct liquid injection. Both methods have their advantages and drawbacks. Only with dynamic headspace sampling can rape drug contaminations be detected within a timeframe of seconds, and therefore, this method is the most promising use of PTR-MS as a fast, sensitive and selective monitor for the detection of food and drink contamination. PMID:22972776

  13. Online breath gas analysis in unrestrained mice by hs-PTR-MS.

    PubMed

    Szymczak, Wilfried; Rozman, Jan; Höllriegl, Vera; Kistler, Martin; Keller, Stefan; Peters, Dominika; Kneipp, Moritz; Schulz, Holger; Hoeschen, Christoph; Klingenspor, Martin; de Angelis, Martin Hrabě

    2014-04-01

    The phenotyping of genetic mouse models for human disorders may greatly benefit from breath gas analysis as a noninvasive tool to identify metabolic alterations in mice. Phenotyping screens such as the German Mouse Clinic demand investigations in unrestrained mice. Therefore, we adapted a breath screen in which exhaled volatile organic compounds (VOCs) were online monitored by proton transfer reaction mass spectrometry (hs-PTR-MS). The source strength of VOCs was derived from the dynamics in the accumulation profile of exhaled VOCs of a single mouse in a respirometry chamber. A careful survey of the accumulation revealed alterations in the source strength due to confounders, e.g., urine and feces. Moreover changes in the source strength of humidity were triggered by changes in locomotor behavior as mice showed a typical behavioral pattern from activity to settling down in the course of subsequent accumulation profiles. We demonstrated that metabolic changes caused by a dietary intervention, e.g., after feeding a high-fat diet (HFD) a sample of 14 male mice, still resulted in a statistically significant shift in the source strength of exhaled VOCs. Applying a normalization which was derived from the distribution of the source strength of humidity and accounted for varying locomotor behaviors improved the shift. Hence, breath gas analysis may provide a noninvasive, fast access to monitor the metabolic adaptation of a mouse to alterations in energy balance due to overfeeding or fasting and dietary macronutrient composition as well as a high potential for systemic phenotyping of mouse mutants, intervention studies, and drug testing in mice. PMID:24275888

  14. Development and deployment of a compact PTR-ToF-MS for Suborbital Research on the Earth's Atmospheric Composition

    NASA Astrophysics Data System (ADS)

    Müller, Markus; Mikoviny, Tomas; Haidacher, Stefan; Hanel, Gernot; Hartungen, Eugen; Jordan, Alfons; Märk, Lukas; Mutschlechner, Paul; Schottkowsky, Ralf; Sulzer, Philipp; Crawford, James H.; Wisthaler, Armin

    2014-05-01

    We report the development of a compact Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS) in support of NASA's suborbital research program on the Earth's atmospheric composition. A lightweight, low mass resolution orthogonal acceleration ToF-MS was developed and combined with a conventional PTR ion source to measure volatile organic compounds (VOCs) in real time. The instrument was specially designed to resist aircraft vibrations and rough conditions during boundary layer flights, take-off and landing. The compact PTR-ToF-MS generates full mass spectral information at 1-second time resolution and below. With sensitivities of up to 150 cps/ppbv, typical 2σ detection limits in the range from 0.06 to 0.48 ppbv for a 1-second signal integration are achieved. A mass resolving power m/Δm of up to 1700 combined with an absolute mass accuracy and reproducibility of less than 3 mDa make it possible to distinguish isobaric ions at high time resolution, e.g. humidity- dependent isobaric background ions. The prototype instrument was successfully deployed for in-situ measurements of VOCs onboard the NASA P-3B Airborne Science Laboratory during two DISCOVER-AQ campaigns in the San Joaquin Valley, CA, and in Houston, TX, 2013. A 1-second time resolution results in a horizontal spatial resolution of typically 110 m and a vertical spatial resolution of typically 8 m which allowed for the quantitative detection of the entire suite of VOCs in strongly localized emission plumes from industrial, agricultural and biomass-burning sources. This work was funded by BMVIT / FFG-ALR in the frame of the Austrian Space Application Programme (ASAP 8, project 833451). Additional resources were provided through NASA's Earth Venture program (EV-1) and the NASA Postdoctoral Program (NPP).

  15. A Novel PTR-ToF-MS Inlet System for On-line Chemical Analysis of SOA

    NASA Astrophysics Data System (ADS)

    Eichler, Philipp; Müller, Markus; D'Anna, Barbara; Wisthaler, Armin

    2014-05-01

    Secondary organic aerosol (SOA) is formed from biogenic and anthropogenic precursors in the atmosphere. Because of its impact on human health and the environment there is a strong interest in understanding the chemistry of SOA formation and transformation. Its volatility, chemical complexity and reactivity and low ambient concentrations challenge the chemical analysis of SOA. Here we present a novel analytical setup for on-line measurements of SOA under ambient conditions by chemical ionization mass spectrometry. The method overcomes current limitations in the chemical analysis of SOA by combining on-line enrichment of the particle concentration and on-line mass spectrometric detection using soft chemical ionization. On-line sampling allows for highly time-resolved analysis of organic aerosol compounds and avoids potential sampling artifacts from sample pre-collection and pretreatment. The deployment of a soft ionization method minimizes the fragmentation of fragile organic aerosol compounds in the mass spectrometer. A proton-transfer-reaction time-of-flight mass-spectrometer (PTR-ToF-MS) is combined with a three-stage aerosol inlet system consisting of an activated carbon monolith denuder, an aerodynamic lens (ADL) and a thermodesorption unit. The denuder strips off gas-phase organic compounds and the ADL enriches the particle concentration in the sample flow. Ultimately, organic aerosol compounds are volatilized at 120 °C in the thermodesorption unit before being introduced into the PTR-ToF-MS system for chemical analysis. The ADL is designed to increase the particle concentration in the sample flow by a factor of up to 50 for particles in the size range between 50 and 1000 nm. This novel enrichment step enables the real-time in situ analysis of SOA at sub µg/m³-levels by PTR-ToF-MS. This work is funded through the PIMMS ITN, which is supported by the European Commission's 7th Framework Programme under grant agreement number 287382.

  16. Teuchos::RefCountPtr beginner's guide : an introduction to the Trilinos smart reference-counted pointer class for (almost) automatic dynamic memory management in C++.

    SciTech Connect

    Bartlett, Roscoe A

    2004-06-01

    Dynamic memory management in C++ is one of the most common areas of difficulty and errors for amateur and expert C++ developers alike. The improper use of operator new and operator delete is arguably the most common cause of incorrect program behavior and segmentation faults in C++ programs. Here we introduce a templated concrete C++ class Teuchos::RefCountPtr<>, which is part of the Trilinos tools package Teuchos, that combines the concepts of smart pointers and reference counting to build a low-overhead but effective tool for simplifying dynamic memory management in C++. We discuss why the use of raw pointers for memory management, managed through explicit calls to operator new and operator delete, is so difficult to accomplish without making mistakes and how programs that use raw pointers for memory management can easily be modified to use RefCountPtr<>. In addition, explicit calls to operator delete is fragile and results in memory leaks in the presents of C++ exceptions. In its most basic usage, RefCountPtr<> automatically determines when operator delete should be called to free an object allocated with operator new and is not fragile in the presents of exceptions. The class also supports more sophisticated use cases as well. This document describes just the most basic usage of RefCountPtr<> to allow developers to get started using it right away. However, more detailed information on the design and advanced features of RefCountPtr<> is provided by the companion document 'Teuchos::RefCountPtr : The Trilinos Smart Reference-Counted Pointer Class for (Almost) Automatic Dynamic Memory Management in C++'.

  17. Comprehensive laboratory measurements of biomass-burning emissions: 2. First intercomparison of open-path FTIR, PTR-MS, and GC-MS/FID/ECD

    NASA Astrophysics Data System (ADS)

    Christian, T. J.; Kleiss, B.; Yokelson, R. J.; Holzinger, R.; Crutzen, P. J.; Hao, W. M.; Shirai, T.; Blake, D. R.

    2004-01-01

    Oxygenated volatile organic compounds (OVOC) can dominate atmospheric organic chemistry, but they are difficult to measure reliably at low levels in complex mixtures. Several techniques that have been used to speciate nonmethane organic compounds (NMOC) including OVOC were codeployed/intercompared in well-mixed smoke generated by 47 fires in the U.S. Department of Agriculture Forest Service Fire Sciences Combustion Facility. The agreement between proton transfer reaction mass spectrometry (PTR-MS) and open-path Fourier transform infrared spectroscopy (OP-FTIR) was excellent for methanol (PT/FT = 1.04 ± 0.118) and good on average for phenol (0.843 ± 0.845) and acetol (˜0.81). The sum of OP-FTIR mixing ratios for acetic acid and glycolaldehyde agreed (within experimental uncertainty) with the PTR-MS mixing ratios for protonated mass 61 (PT/FT = 1.17 ± 0.34), and the sum of OP-FTIR mixing ratios for furan and isoprene agreed with the PTR-MS mixing ratios for protonated mass 69 (PT/FT = 0.783 ± 0.465). The sum of OP-FTIR mixing ratios for acetone and methylvinylether accounted for most of the PTR-MS protonated mass 59 signal (PT/FT = 1.29 ± 0.81), suggesting that one of these compounds was underestimated by OP-FTIR or that it failed to detect other compounds that could contribute at mass 59. Canister grab sampling followed by gas chromatography (GC) with mass spectrometry (MS), flame ionization detection (FID), and electron capture detection (ECD) analysis by two different groups agreed well with OP-FTIR for ethylene, acetylene, and propylene. However, these propylene levels were below those observed by PTR-MS (PT/FT = 2.33 ± 0.89). Good average agreement between PTR-MS and GC was obtained for benzene and toluene. At mixing ratios above a few parts per billion the OP-FTIR had advantages for measuring sticky compounds (e.g., ammonia and formic acid) or compounds with low proton affinity (e.g., hydrogen cyanide and formaldehyde). Even at these levels, only the PTR

  18. Comparison of Aromatic Hydrocarbon Measurements made by PTR-MS, DOAS and GC-FID during the MCMA 2003 Field Experiment

    SciTech Connect

    Jobson, Bertram T.; Volkamer, Rainer M.; Velasco, E.; Allwine, Gene; Westberg, Halvor H.; Lamb, Brian K.; Alexander, M. L.; Berkowitz, Carl M.; Molina, Luisa T.

    2010-02-15

    A comparison of aromatic hydrocarbon measurements is reported for the CENICA upersite in the district of Iztapalapa during the Mexico City Metropolitan Area field experiment in April 2003 (MCMA 2003). Data from three different measurement methods were compared: a Proton Transfer Reaction Mass Spectrometer (PTR-MS), long path measurements using a UV Differential Optical Absorption Spectrometer (DOAS), and Gas Chromatography-Flame Ionization analysis (GC-FID) of canister samples. The principle focus was on the comparison between PTR-MS and DOAS data. Lab tests established that the PTR-MS and DOAS calibrations were consistent for a suite of aromatic compounds including benzene, toluene, p-xylene, ethylbenzene, 1,2,4-trimethylbenzene, phenol and styrene. The point sampling measurements by the PTR-MS and GC-FID showed good correlations (r=0.6), and were in reasonable agreement for toluene, C₂-alkylbenzenes and C3-alkylbenzenes. The PTR-MS benzene data were consistently high, indicating interference from ethylbenzene fragmentation for the 145 Td drift field intensity used in the experiment. Correlations between the open-path data measured at 16-m height over a 860-m path length (retroreflector in 430m distance), and the point measurements collected at 37-m sampling height were best for benzene (r=0.61), and reasonably good for toluene, C2-alkylbenzenes, naphthalene, styrene, cresols and phenol (r>0.5). There was good agreement between DOAS and PTR-MS measurements of benzene after correction for the PTR-MS ethylbenzene interference. Mixing ratios easured by DOAS were on average a factor of 1.7 times greater than the PTR-MS data for toluene, C2-alkylbenzenes, naphthalene and styrene. The level of agreement for the toluene data displayed a modest dependence on wind direction, establishing that spatial gradients - horizontal, vertical, or both – in toluene mixing ratios were significant, and up to a factor of 2 despite the fact that all measurements were conducted above

  19. Classification of 7 monofloral honey varieties by PTR-ToF-MS direct headspace analysis and chemometrics.

    PubMed

    Schuhfried, Erna; Sánchez del Pulgar, José; Bobba, Marco; Piro, Roberto; Cappellin, Luca; Märk, Tilmann D; Biasioli, Franco

    2016-01-15

    Honey, in particular monofloral varieties, is a valuable commodity. Here, we present proton transfer reaction-time of flight-mass spectrometry, PTR-ToF-MS, coupled to chemometrics as a successful tool in the classification of monofloral honeys, which should serve in fraud protection against mispresentation of the floral origin of honey. We analyzed 7 different honey varieties from citrus, chestnut, sunflower, honeydew, robinia, rhododendron and linden tree, in total 70 different honey samples and a total of 206 measurements. Only subtle differences in the profiles of the volatile organic compounds (VOCs) in the headspace of the different honeys could be found. Nevertheless, it was possible to successfully apply 6 different classification methods with a total correct assignment of 81-99% in the internal validation sets. The most successful methods were stepwise linear discriminant analysis (LDA) and probabilistic neural network (PNN), giving total correct assignments in the external validation sets of 100 and 90%, respectively. Clearly, PTR-ToF-MS/chemometrics is a powerful tool in honey classification. PMID:26592598

  20. A wheat genotype sensitive to Ptr ToxA and resistant to Pyrenophora tritici-repentis (Tan spot) races 1 and 2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ptr ToxA is a host selective toxin produced by races 1, 2, 7, and 8 of Pyrenophora tritici-repentis , causal agent of tan spot of wheat. Toxin sensitivity in the host is conditioned by a single dominant gene designated TSN1. Most wheat genotypes that are toxin sensitive are also tan spot su...

  1. An online ultra-high sensitivity Proton-transfer-reaction mass-spectrometer combined with switchable reagent ion capability (PTR + SRI - MS)

    NASA Astrophysics Data System (ADS)

    Jordan, A.; Haidacher, S.; Hanel, G.; Hartungen, E.; Herbig, J.; Märk, L.; Schottkowsky, R.; Seehauser, H.; Sulzer, P.; Märk, T. D.

    2009-09-01

    Proton-transfer-reaction mass-spectrometry (PTR-MS) developed in the 1990s is used today in a wide range of scientific and technical fields. PTR-MS allows for real-time, online determination of absolute concentrations of volatile (organic) compounds (VOCs) in air with high sensitivity (into the low pptv range) and a fast response time (in the 40-100 ms time regime). Most PTR-MS instruments employed so far use an ion source consisting of a hollow cathode (HC) discharge in water vapour which provides an intense source of proton donor H3O+ ions. As the use of other ions, e.g. NO+ and O2+, can be useful for the identification of VOCs and for the detection of VOCs with proton affinities (PA) below that of H2O, selected ion flow tube mass spectrometry (SIFT-MS) with mass selected ions has been applied in these instances. SIFT-MS suffers, however, from at least two orders lower reagent ion counts rates and therefore SIFT-MS suffers from lower sensitivity than PTR-MS. Here we report the development of a PTR-MS instrument using a modified HC ion source and drift tube design, which allows for the easy and fast switching between H3O+, NO+ and O2+ ions produced in high purity and in large quantities in this source. This instrument is capable of measuring low concentrations (with detection limits approaching the ppqv regime) of VOCs using any of the three reagent ions investigated in this study. Therefore this instrument combines the advantages of the PTR-MS technology (the superior sensitivity) with those of SIFT-MS (detection of VOCs with PAs smaller than that of the water molecule and the capability to distinguish between isomeric compounds). We will first discuss the setup of this new PTR+SRI-MS mass spectrometer instrument, its performance for aromates, aldehydes and ketones (with a sensitivity of up to nearly 1000 cps/ppbv and a detection limit of about several 100 ppqv) and finally give some examples concerning the ability to distinguish structural isomeric compounds.

  2. Overexpression of Poplar PtrWRKY89 in Transgenic Arabidopsis Leads to a Reduction of Disease Resistance by Regulating Defense-Related Genes in Salicylate- and Jasmonate-Dependent Signaling

    PubMed Central

    Liu, Rui; Jiao, Bo; Zhao, Xin; Ling, Zhengyi; Luo, Keming

    2016-01-01

    The plant hormones jasmonic acid (JA) and salicylic acid (SA) play key roles in plant defenses against pathogens and several WRKY transcription factors have been shown to have a role in SA/JA crosstalk. In a previous study, overexpression of the poplar WRKY gene PtrWRKY89 enhanced resistance to pathogens in transgenic poplars. In this study, the promoter of PtrWRKY89 (ProPtrWRKY89) was isolated and used to drive GUS reporter gene. High GUS activity was observed in old leaves of transgenic Arabidopsis containing ProPtrWRKY89-GUS construct and GUS expression was extremely induced by SA solution and SA+MeJA mixture but not by MeJA treatment. Subcellular localization and transactivation assays showed that PtrWRKY89 acted as a transcription activator in the nucleus. Constitutive expression of PtrWRKY89 in Arabidopsis resulted in more susceptible to Pseudomonas syringae and Botrytis cinerea compared to wild-type plants. Quantitative real-time PCR (qRT-PCR) analysis confirmed that marker genes of SA and JA pathways were down-regulated in transgenic Arabidopsis after pathogen inoculations. Overall, our results indicated that PtrWRKY89 modulates a cross talk in resistance to P. syringe and B. cinerea by negatively regulating both SA and JA pathways in Arabidopsis. PMID:27019084

  3. The requirement for the LysR-type regulator PtrA for Pseudomonas chlororaphis PA23 biocontrol revealed through proteomic and phenotypic analysis

    PubMed Central

    2014-01-01

    Background Pseudomonas chlororaphis strain PA23 is a biocontrol agent capable of suppressing the fungal pathogen Sclerotinia sclerotiorum. This bacterium produces the antibiotics phenazine and pyrrolnitrin together with other metabolites believed to contribute to biocontrol. A mutant no longer capable of inhibiting fungal growth was identified harboring a transposon insertion in a gene encoding a LysR-type transcriptional regulator (LTTR), designated ptrA (Pseudomonas transcriptional regulator). Isobaric tag for relative and absolute quantitation (iTRAQ) based protein analysis was used to reveal changes in protein expression patterns in the ptrA mutant compared to the PA23 wild type. Results Relative abundance profiles showed 59 differentially-expressed proteins in the ptrA mutant, which could be classified into 16 clusters of orthologous groups (COGs) based on their predicted functions. The largest COG category was the unknown function group, suggesting that many yet-to-be identified proteins are involved in the loss of fungal activity. In the secondary metabolite biosynthesis, transport and catabolism COG, seven proteins associated with phenazine biosynthesis and chitinase production were downregulated in the mutant. Phenotypic assays confirmed the loss of phenazines and chitinase activity. Upregulated proteins included a lipoprotein involved in iron transport, a flagellin and hook-associated protein and four proteins categorized into the translation, ribosome structure and biogenesis COG. Phenotypic analysis revealed that the mutant exhibited increased siderophore production and flagellar motility and an altered growth profile, supporting the proteomic findings. Conclusion PtrA is a novel LTTR that is essential for PA23 fungal antagonism. Differential protein expression was observed across 16 COG categories suggesting PtrA is functioning as a global transcriptional regulator. Changes in protein expression were confirmed by phenotypic assays that showed reduced

  4. Monitoring photooxidation-induced dynamic changes in the volatile composition of extended shelf life bovine milk by PTR-MS.

    PubMed

    Beauchamp, Jonathan; Zardin, Erika; Silcock, Patrick; Bremer, Phil J

    2014-09-01

    Exposure of milk to light leads to photooxidation and the development of off-flavours. To follow these reactions, semi-skimmed (1.5% fat) and whole (3.8% fat) extended shelf life (ESL) bovine milk samples were exposed to fluorescent light for up to 20 h at room temperature, and the volatiles in the samples' headspace were measured in real time using proton-transfer-reaction mass spectrometry (PTR-MS). Compounds tentatively identified as methanethiol, acetone/propanal, pentanal/octanal/nonanal/1-octen-3-ol, hexanal, diacetyl, dimethyl disulphide, heptanal and benzaldehyde displayed dynamic release profiles relating to the changes occurring in milk upon exposure to light. PMID:25230193

  5. Biogenic volatile organic compound analyses by PTR-TOF-MS: Calibration, humidity effect and reduced electric field dependency.

    PubMed

    Pang, Xiaobing

    2015-06-01

    Green leaf volatiles (GLVs) emitted by plants after stress or damage induction are a major part of biogenic volatile organic compounds (BVOCs). Proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) is a high-resolution and sensitive technique for in situ GLV analyses, while its performance is dramatically influenced by humidity, electric field, etc. In this study the influence of gas humidity and the effect of reduced field (E/N) were examined in addition to measuring calibration curves for the GLVs. Calibration curves measured for seven of the GLVs in dry air were linear, with sensitivities ranging from 5 to 10 ncps/ppbv (normalized counts per second/parts per billion by volume). The sensitivities for most GLV analyses were found to increase by between 20% and 35% when the humidity of the sample gas was raised from 0% to 70% relative humidity (RH) at 21°C, with the exception of (E)-2-hexenol. Product ion branching ratios were also affected by humidity, with the relative abundance of the protonated molecular ions and higher mass fragment ions increasing with humidity. The effect of reduced field (E/N) on the fragmentation of GLVs was examined in the drift tube of the PTR-TOF-MS. The structurally similar GLVs are acutely susceptible to fragmentation following ionization and the fragmentation patterns are highly dependent on E/N. Overall the measured fragmentation patterns contain sufficient information to permit at least partial separation and identification of the isomeric GLVs by looking at differences in their fragmentation patterns at high and low E/N. PMID:26040746

  6. The effect of slurry treatment including ozonation on odorant reduction measured by in-situ PTR-MS

    NASA Astrophysics Data System (ADS)

    Liu, Dezhao; Feilberg, Anders; Adamsen, Anders P. S.; Jonassen, Kristoffer E. N.

    2011-07-01

    The emission of odorous compounds from intensive pig production facilities is a nuisance for neighbors. Slurry ozonation for odor abatement has previously been demonstrated in laboratory scale. In this study, the effect of slurry ozonation (combined with solid-liquid pre-separation and acidification) on emissions of odorous compounds was tested in an experimental full-scale growing pig facility using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) for online analysis of odorants. The measurements were performed to gain a better understanding of the effects of ozone treatment on emissions odorous compounds and to identify potential options for optimization of ozone treatment. The compounds monitored included volatile sulfur compounds, amine, carboxylic acids, ketones, phenols and indoles. Measurements were performed during nearly a one-month period in summertime. The compounds with the highest concentrations observed in the ventilation exhaust duct were acetic acid, hydrogen sulfide, propanoic acid and butanoic acid. The compounds with the highest removal efficiencies were hydrogen sulfide, 3-methyl-indole, phenol and acetic acid. Based on odor threshold values, methanethiol, butanoic acid, 4-methylphenol, hydrogen sulfide and C 5 carboxylic acids are estimated to contribute significantly to the odor nuisance. Emissions of odorous compounds were observed to be strongly correlated with temperature with the exception of hydrogen sulfide. Emission peaks of sulfur compounds were seen during slurry handling activities. Discharging of the slurry pit led to reduced hydrogen sulfide emissions, but emissions of most other odorants were not affected. The results indicate that emissions of odorants other than hydrogen sulfide mainly originate from sources other than the treated slurry, which limits the potential for further optimization. The PTR-MS measurements are demonstrated to provide a quantitative, accurate and detailed evaluation of ozone treatment for emission

  7. Ground measurements of carboxylic acids during the ChArMEx field campaign using PTR-ToFMS

    NASA Astrophysics Data System (ADS)

    Dusanter, Sébastien; Sauvage, Stéphane; Locoge, Nadine; Michoud, Vincent; Touati, Nabil; Zhang, Shouwen; Riffault, Véronique

    2014-05-01

    Carboxylic acids are long-lived and persistent species that have been shown to be important for ambient acidity and secondary organic aerosol formation. Formic, acetic, and propionic acids are among the most abundant carboxylic acids in the troposphere. However, their atmospheric sources are poorly characterized due to limited measurement data. Techniques usually used to measure gas-phase concentrations of carboxylic acids suffer from low time resolution and the use of fast instruments would be of prime interest to apportion the contribution of anthropogenic and biogenic emissions, as well as photochemical processes to the carboxylic acid budget. A Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToFMS) was characterized for field measurements of n-carboxylic acids (C1-C4). Laboratory experiments were carried out to get insights into fragmentation patterns of parent (RCOOHH+) and acylium (RCO+) ions, sensitivities, and detection limits under various operating conditions. Carefully designed experiments were conducted to assess the impact of relative humidity on the sensitivity. Detection limits of 500, 90, 50 and 40 ppt were achieved for 10-min measurements of formic, acetic, propionic and butyric acids, respectively. This instrument was deployed for the first time during the 2013 ChArMEx intensive field campaign at a ground site in Cap Corsica and successfully measured concentrations of carboxylic acids from July 15th to August 5th. Elevated mixing ratios in the range 500-4000 ppt, 260-2500 ppt, and 50-500 ppt were observed for formic, acetic, and propionic acids, respectively. Mixing ratios of butyric acids were close to the detection limit. In this presentation, we will discuss the potential of carboxylic acid measurements by PTR-ToFMS in remote areas and we will provide a preliminary analysis of carboxylic acid sources in an area impacted by local biogenic emissions as well as aged anthropogenic air masses.

  8. Suppressors of ssy1 and ptr3 null mutations define novel amino acid sensor-independent genes in Saccharomyces cerevisiae.

    PubMed Central

    Forsberg, H; Hammar, M; Andréasson, C; Molinér, A; Ljungdahl, P O

    2001-01-01

    Ssy1p and Ptr3p are components of the yeast plasma membrane SPS amino acid sensor. In response to extracellular amino acids this sensor initiates metabolic signals that ultimately regulate the functional expression of several amino acid-metabolizing enzymes and amino acid permeases (AAPs). As a result of diminished leucine uptake capabilities, ssy1Delta leu2 and ptr3Delta leu2 mutant strains are unable to grow on synthetic complete medium (SC). Genes affecting the functional expression of AAPs were identified by selecting spontaneous suppressing mutations in amino acid sensor-independent (ASI) genes that restore growth on SC. The suppressors define 11 recessive (asi) complementation groups and 5 dominant (ASI) linkage groups. Strains with mutations in genes assigned to these 16 groups fall into two phenotypic classes. Mutations in the class I genes (ASI1, ASI2, ASI3, TUP1, SSN6, ASI13) derepress the transcription of AAP genes. ASI1, ASI2, and ASI3 encode novel membrane proteins, and Asi1p and Asi3p are homologous proteins that have conserved ubiquitin ligase-like RING domains at their extreme C termini. Several of the class II genes (DOA4, UBA1, BRO1, BUL1, RSP5, VPS20, VPS36) encode proteins implicated in controlling aspects of post-Golgi endosomal-vacuolar protein sorting. The results from genetic and phenotypic analysis indicate that SPS sensor-initiated signals function positively to facilitate amino acid uptake and that two independent ubiquitin-mediated processes negatively modulate amino acid uptake. PMID:11454748

  9. Rapid characterization of dry cured ham produced following different PDOs by proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS).

    PubMed

    Del Pulgar, José Sánchez; Soukoulis, Christos; Biasioli, Franco; Cappellin, Luca; García, Carmen; Gasperi, Flavia; Granitto, Pablo; Märk, Tilmann D; Piasentier, Edi; Schuhfried, Erna

    2011-07-15

    In the present study, the recently developed proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS) technique was used for the rapid characterization of dry cured hams produced according to 4 of the most important Protected Designations of Origin (PDOs): an Iberian one (Dehesa de Extremadura) and three Italian ones (Prosciutto di San Daniele, Prosciutto di Parma and Prosciutto Toscano). In total, the headspace composition and respective concentration for nine Spanish and 37 Italian dry cured ham samples were analyzed by direct injection without any pre-treatment or pre-concentration. Firstly, we show that the rapid PTR-ToF-MS fingerprinting in conjunction with chemometrics (Principal Components Analysis) indicates a good separation of the dry cured ham samples according to their production process and that it is possible to set up, using data mining methods, classification models with a high success rate in cross validation. Secondly, we exploited the higher mass resolution of the new PTR-ToF-MS, as compared with standard quadrupole based versions, for the identification of the exact sum formula of the mass spectrometric peaks providing analytical information on the observed differences. The work indicates that PTR-ToF-MS can be used as a rapid method for the identification of differences among dry cured hams produced following the indications of different PDOs and that it provides information on some of the major volatile compounds and their link with the implemented manufacturing practices such as rearing system, salting and curing process, manufacturing practices that seem to strongly affect the final volatile organic profile and thus the perceived quality of dry cured ham. PMID:21645714

  10. Undisturbed and disturbed above canopy ponderosa pine emissions: PTR-TOF-MS measurements and MEGAN 2.1 model results

    SciTech Connect

    Kaser, L.; Karl, T.; Guenther, A.; Graus, M.; Schnitzhofer, R.; Turnipseed, A.; Fischer, L.; Harley, P.; Madronich, M.; Gochis, D.; Keutsch, F. N.; Hansel, A.

    2013-01-01

    We present the first eddy covariance flux measurements of volatile organic compounds (VOCs) using a proton-transfer-reaction time-of-flight mass-spectrometer (PTR-TOFMS) above a ponderosa pine forest in Colorado, USA. The high mass resolution of the PTR-TOF-MS enabled the identification of chemical sum formulas. During a 30 day measurement period in August and September 2010, 649 different ion mass peaks were detected in the ambient air mass spectrum (including primary ions and mass calibration ompounds). Eddy covariance with the vertical wind speed was calculated for all ion mass peaks. On a typical day, 17 ion mass peaks including protonated parent compounds, their fragments and isotopes as well as VOC-H+-water clusters showed a significant flux with daytime average emissions above a reliable flux threshold of 0.1mgcompoundm-2 h-1. These ion mass peaks could be assigned to seven compound classes. The main flux contributions during daytime (10:00-18:00 LT) are attributed to the sum of 2-methyl-3-buten-2-ol (MBO) and isoprene (50 %), methanol (12%), the sum of acetic acid and glycolaldehyde (10%) and the sum of monoterpenes (10 %). The total MBO+isoprene flux was composed of 10% isoprene and 90% MBO. There was good agreement between the light and temperature dependency of the sum of MBO and isoprene observed for this work and those of earlier studies. The above canopy flux measurements of the sum of MBO and isoprene and the sum of 20 monoterpenes were compared to emissions calculated using the Model of Emissions of Gases and Aerosols from Nature (MEGAN 2.1). The best agreement between MEGAN 2.1 and measurements was reached using emission factors determined from site specific leaf cuvette measurements. While the modelled and measured MBO+isoprene fluxes agree well the emissions of the sum of monoterpenes is underestimated by MEGAN 2.1. This is expected as some factors impacting monoterpene emissions, such as physical damage of needles and branches due to storms, are

  11. Undisturbed and disturbed above canopy ponderosa pine emissions: PTR-TOF-MS measurements and MEGAN 2.1 model results

    NASA Astrophysics Data System (ADS)

    Kaser, L.; Karl, T.; Guenther, A.; Graus, M.; Schnitzhofer, R.; Turnipseed, A.; Fischer, L.; Harley, P.; Madronich, M.; Gochis, D.; Keutsch, F. N.; Hansel, A.

    2013-12-01

    We present the first eddy covariance flux measurements of volatile organic compounds (VOCs) using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) above a ponderosa pine forest in Colorado, USA. The high mass resolution of the PTR-TOF-MS enabled the identification of chemical sum formulas. During a 30 day measurement period in August and September 2010, 649 different ion mass peaks were detected in the ambient air mass spectrum (including primary ions and mass calibration compounds). Eddy covariance with the vertical wind speed was calculated for all ion mass peaks. On a typical day, 17 ion mass peaks, including protonated parent compounds, their fragments and isotopes as well as VOC-H+-water clusters, showed a significant flux with daytime average emissions above a reliable flux threshold of 0.1 mg compound m-2 h-1. These ion mass peaks could be assigned to seven compound classes. The main flux contributions during daytime (10:00-18:00 LT) are attributed to the sum of 2-methyl-3-buten-2-ol (MBO) and isoprene (50%), methanol (12%), the sum of acetic acid and glycolaldehyde (10%) and the sum of monoterpenes (10%). The total MBO + isoprene flux was composed of 10% isoprene and 90% MBO. There was good agreement between the light- and temperature dependency of the sum of MBO and isoprene observed for this work and those of earlier studies. The above canopy flux measurements of the sum of MBO and isoprene and the sum of monoterpenes were compared to emissions calculated using the Model of Emissions of Gases and Aerosols from Nature (MEGAN 2.1). The best agreement between MEGAN 2.1 and measurements was reached using emission factors determined from site-specific leaf cuvette measurements. While the modeled and measured MBO + isoprene fluxes agree well, the emissions of the sum of monoterpenes is underestimated by MEGAN 2.1. This is expected as some factors impacting monoterpene emissions, such as physical damage of needles and branches due to

  12. Undisturbed and disturbed above canopy ponderosa pine emissions: PTR-TOF-MS measurements and MEGAN 2.1 model results

    NASA Astrophysics Data System (ADS)

    Kaser, L.; Karl, T.; Guenther, A.; Graus, M.; Schnitzhofer, R.; Turnipseed, A.; Fischer, L.; Harley, P.; Madronich, M.; Gochis, D.; Keutsch, F. N.; Hansel, A.

    2013-06-01

    We present the first eddy covariance flux measurements of volatile organic compounds (VOCs) using a proton-transfer-reaction time-of-flight mass-spectrometer (PTR-TOF-MS) above a ponderosa pine forest in Colorado, USA. The high mass resolution of the PTR-TOF-MS enabled the identification of chemical sum formulas. During a 30 day measurement period in August and September 2010, 649 different ion mass peaks were detected in the ambient air mass spectrum (including primary ions and mass calibration compounds). Eddy covariance with the vertical wind speed was calculated for all ion mass peaks. On a typical day, 17 ion mass peaks including protonated parent compounds, their fragments and isotopes as well as VOC-H+-water clusters showed a significant flux with daytime average emissions above a reliable flux threshold of 0.1 mg compound m-2 h-1. These ion mass peaks could be assigned to seven compound classes. The main flux contributions during daytime (10:00-18:00 LT) are attributed to the sum of 2-methyl-3-buten-2-ol (MBO) and isoprene (50%), methanol (12%), the sum of acetic acid and glycolaldehyde (10%) and the sum of monoterpenes (10%). The total MBO + isoprene flux was composed of 10% isoprene and 90% MBO. There was good agreement between the light and temperature dependency of the sum of MBO and isoprene observed for this work and those of earlier studies. The above canopy flux measurements of the sum of MBO and isoprene and the sum of monoterpenes were compared to emissions calculated using the Model of Emissions of Gases and Aerosols from Nature (MEGAN 2.1). The best agreement between MEGAN 2.1 and measurements was reached using emission factors determined from site specific leaf cuvette measurements. While the modelled and measured MBO + isoprene fluxes agree well the emissions of the sum of monoterpenes is underestimated by MEGAN 2.1. This is expected as some factors impacting monoterpene emissions, such as physical damage of needles and branches due to storms

  13. Breath gas monitoring during a glucose challenge by a combined PTR-QMS/GC×GC-TOFMS approach for the verification of potential volatile biomarkers.

    PubMed

    Gruber, Beate; Keller, Stefan; Groeger, Thomas; Matuschek, Georg; Szymczak, Wilfried; Zimmermann, Ralf

    2016-01-01

    Breath gas profiles, which reflect metabolic disorders like diabetes, are the subject of scientific focus. Nevertheless, profiling is still a challenging task that requires complex and standardized methods. This study was carried out to verify breath gas patterns that were obtained in previous proton-transfer reaction-quadrupole mass spectrometry (PTR-QMS) studies and that can be linked to glucose metabolism. An experimental setup using simultaneous PTR-QMS and complementary highly time-resolved needle trap micro extraction (NTME) combined with comprehensive 2D gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) was established for the analysis of highly polar volatile organic compounds (VOCs). The method was applied to the breath gas analysis of three volunteers during a glucose challenge, whereby subjects ingested a glucose solution orally. Challenge responsive PTR-QMS target VOCs could be linked to small n-carbonic (C2-C4) alcohols and short chain fatty acids (SCFA). Specific isomers could be identified by simultaneously applied NTME-GC×GC-TOFMS and further verified by their characteristic time profiles and concentrations. The identified VOCs potentially originate from bacteria that are found in the oral cavity and gastrointestinal tract. In this study breath gas monitoring enabled the identification of potential VOC metabolites that can be linked to glucose metabolism. PMID:27341456

  14. Fast Direct Injection Mass-Spectrometric Characterization of Stimuli for Insect Electrophysiology by Proton Transfer Reaction-Time of Flight Mass-Spectrometry (PTR-ToF-MS)

    PubMed Central

    Tasin, Marco; Cappellin, Luca; Biasioli, Franco

    2012-01-01

    Electrophysiological techniques are used in insect neuroscience to measure the response of olfactory neurons to volatile odour stimuli. Widely used systems to deliver an olfactory stimulus to a test insect include airstream guided flow through glass cartridges loaded with a given volatile compound on a sorbent support. Precise measurement of the quantity of compound reaching the sensory organ of the test organism is an urgent task in insect electrophysiology. In this study we evaluated the performances of the recent realised proton transfer reaction-time of flight mass-spectrometry (PTR-ToF-MS) as a fast and selective gas sensor. In particular, we characterised the gas emission from cartridges loaded with a set of volatile compounds belonging to different chemical classes and commonly used in electrophysiological experiments. PTR-ToF-MS allowed a fast monitoring of all investigated compounds with sufficient sensitivity and time resolution. The detection and the quantification of air contaminants and solvent or synthetic standards impurities allowed a precise quantification of the stimulus exiting the cartridge. The outcome of this study was twofold: on one hand we showed that PTR-ToF-MS allows monitoring fast processes with high sensitivity by real time detection of a broad number of compounds; on the other hand we provided a tool to solve an important issue in insect electrophysiology. PMID:22666020

  15. Measurements of hydrogen sulfide (H2S) using PTR-MS: calibration, humidity dependence, inter-comparison and results from field studies in an oil and gas production region

    NASA Astrophysics Data System (ADS)

    Li, R.; Warneke, C.; Graus, M.; Field, R.; Geiger, F.; Veres, P. R.; Soltis, J.; Li, S.-M.; Murphy, S. M.; Sweeney, C.; Pétron, G.; Roberts, J. M.; de Gouw, J.

    2014-06-01

    Natural gas production is associated with emissions of several trace gases, some of them classified as air toxics. While volatile organic compounds (VOCs) have received much attention, hydrogen sulfide (H2S) can also be of concern due to the known health impacts of exposure to this hazardous air pollutant. Here, we present quantitative, fast time-response measurements of H2S using Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) instruments. An Ultra-Light-Weight PTR-MS (ULW-PTR-MS) in a mobile laboratory was operated for measurements of VOCs and H2S in a gas and oil field during the Uintah Basin Winter Ozone Study (UBWOS) 2012 campaign. Measurements of VOCs and H2S by a PTR-MS were also made at the Horse Pool ground site in the Uintah Basin during UBWOS 2013. The H2S measurement by PTR-MS is strongly humidity dependent because the proton affinity of H2S is only slightly higher than that of water. The H2S sensitivity of PTR-MS ranged between 0.6-1.4 ncps ppbv-1 (normalized counts per second/parts per billion by volume) during UBWOS 2013. We compare the humidity dependence determined in the laboratory with in-field calibrations and determine the H2S mixing ratios for the mobile and ground measurements. The PTR-MS measurements at Horse Pool are evaluated by comparison with simultaneous H2S measurements using a PTR Time-of-Flight MS (PTR-ToF-MS) and a Picarro cavity ring down spectroscopy (CRDS) instrument for H2S/CH4. On average 0.6 ± 0.3 ppbv H2S was present at Horse Pool during UBWOS 2013. The correlation between H2S and methane enhancements suggests that the source of H2S is associated with oil and gas extraction in the basin. Significant H2S mixing ratios of up to 9 ppmv downwind of storage tanks were observed during the mobile measurements. This study suggests that H2S emissions associated with oil and gas production can lead to short-term high levels close to point sources, and elevated background levels away from those sources. In addition, our work has

  16. Measurements of hydrogen sulfide (H2S) using PTR-MS: calibration, humidity dependence, inter-comparison and results from field studies in an oil and gas production region

    NASA Astrophysics Data System (ADS)

    Li, R.; Warneke, C.; Graus, M.; Field, R.; Geiger, F.; Veres, P. R.; Soltis, J.; Li, S.-M.; Murphy, S. M.; Sweeney, C.; Pétron, G.; Roberts, J. M.; de Gouw, J.

    2014-10-01

    Natural gas production is associated with emissions of several trace gases, some of them classified as air toxics. While volatile organic compounds (VOCs) have received much attention, hydrogen sulfide (H2S) can also be of concern due to the known health impacts of exposure to this hazardous air pollutant. Here, we present quantitative, fast time-response measurements of H2S using proton-transfer-reaction mass-spectrometry (PTR-MS) instruments. An ultra-light-weight PTR-MS (ULW-PTR-MS) in a mobile laboratory was operated for measurements of VOCs and H2S in a gas and oil field during the Uintah Basin Winter Ozone Study (UBWOS) 2012 campaign. Measurements of VOCs and H2S by a PTR-MS were also made at the Horse Pool ground site in the Uintah Basin during UBWOS 2013. The H2S measurement by PTR-MS is strongly humidity dependent because the proton affinity of H2S is only slightly higher than that of water. The H2S sensitivity of PTR-MS ranged between 0.6-1.4 ncps ppbv-1 during UBWOS 2013. We compare the humidity dependence determined in the laboratory with in-field calibrations and determine the H2S mixing ratios for the mobile and ground measurements. The PTR-MS measurements at Horse Pool are evaluated by comparison with simultaneous H2S measurements using a PTR time-of-flight MS (PTR-ToF-MS) and a Picarro cavity ring down spectroscopy (CRDS) instrument for H2S / CH4. On average 0.6 ± 0.3 ppbv H2S was present at Horse Pool during UBWOS 2013. The correlation between H2S and methane enhancements suggests that the source of H2S is associated with oil and gas extraction in the basin. Significant H2S mixing ratios of up to 9 ppmv downwind of storage tanks were observed during the mobile measurements. This study suggests that H2S emissions associated with oil and gas production can lead to short-term high levels close to point sources, and elevated background levels away from those sources. In addition, our work has demonstrated that PTR-MS can make reliable measurements of

  17. A compact PTR-ToF-MS instrument for airborne measurements of volatile organic compounds at high spatiotemporal resolution

    NASA Astrophysics Data System (ADS)

    Müller, M.; Mikoviny, T.; Feil, S.; Haidacher, S.; Hanel, G.; Hartungen, E.; Jordan, A.; Märk, L.; Mutschlechner, P.; Schottkowsky, R.; Sulzer, P.; Crawford, J. H.; Wisthaler, A.

    2014-11-01

    Herein, we report on the development of a compact proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) for airborne measurements of volatile organic compounds (VOCs). The new instrument resolves isobaric ions with a mass resolving power (m/Δm) of ~1000, provides accurate m/z measurements (Δm < 3 mDa), records full mass spectra at 1 Hz and thus overcomes some of the major analytical deficiencies of quadrupole-MS-based airborne instruments. 1 Hz detection limits for biogenic VOCs (isoprene, α total monoterpenes), aromatic VOCs (benzene, toluene, xylenes) and ketones (acetone, methyl ethyl ketone) range from 0.05 to 0.12 ppbV, making the instrument well-suited for fast measurements of abundant VOCs in the continental boundary layer. The instrument detects and quantifies VOCs in locally confined plumes (< 1 km), which improves our capability of characterizing emission sources and atmospheric processing within plumes. A deployment during the NASA 2013 DISCOVER-AQ mission generated high vertical- and horizontal-resolution in situ data of VOCs and ammonia for the validation of satellite retrievals and chemistry transport models.

  18. PTR-MS Characterization of VOCs Associated with Commercial Aromatic Bakery Yeasts of Wine and Beer Origin.

    PubMed

    Capozzi, Vittorio; Makhoul, Salim; Aprea, Eugenio; Romano, Andrea; Cappellin, Luca; Sanchez Jimena, Ana; Spano, Giuseppe; Gasperi, Flavia; Scampicchio, Matteo; Biasioli, Franco

    2016-01-01

    In light of the increasing attention towards "green" solutions to improve food quality, the use of aromatic-enhancing microorganisms offers the advantage to be a natural and sustainable solution that did not negatively influence the list of ingredients. In this study, we characterize, for the first time, volatile organic compounds (VOCs) associated with aromatic bakery yeasts. Three commercial bakery starter cultures, respectively formulated with three Saccharomyces cerevisiae strains, isolated from white wine, red wine, and beer, were monitored by a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS), a direct injection analytical technique for detecting volatile organic compounds with high sensitivity (VOCs). Two ethanol-related peaks (m/z 65.059 and 75.080) described qualitative differences in fermentative performances. The release of compounds associated to the peaks at m/z 89.059, m/z 103.075, and m/z 117.093, tentatively identified as acetoin and esters, are coherent with claimed flavor properties of the investigated strains. We propose these mass peaks and their related fragments as biomarkers to optimize the aromatic performances of commercial preparations and for the rapid massive screening of yeast collections. PMID:27077836

  19. Atmospheric pressure glow discharge generated in nitrogen-methane gas mixture: PTR-MS analyzes of the exhaust gas

    NASA Astrophysics Data System (ADS)

    Torokova, Lucie; Mazankova, Vera; Krcma, Frantisek; Mason, Nigel J.; Matejcik, Stefan

    2015-07-01

    This paper reports the results of an extensive study of with the in situ mass spectrometry analysis of gaseous phase species produced by an atmospheric plasma glow discharge in N2-CH4 gas mixtures (with methane concentrations ranging from 1% to 4%). The products are studied using proton-transfer-reaction mass spectrometry (PTR-MS). HCN and CH3CN are identified as the main gaseous products. Hydrazine, methanimine, methyldiazene, ethylamine, cyclohexadiene, pyrazineacetylene, ethylene, propyne and propene are identified as minor compounds. All the detected compounds and their relative abundances are determined with respect to the experimental conditions (gas composition and applied power). The same molecules were observed by the Cassini-Huygens probe in Titan's atmosphere (which has same N2-CH4 gas mixtures). Such, experiments show that the formation of such complex organics in atmospheres containing C, N and H, like that of Titan, could be a source of prebiotic molecules. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  20. First Airborne PTR-ToF-MS Measurements of VOCs in a Biomass Burning Plume: Primary Emissions and Aging

    NASA Astrophysics Data System (ADS)

    Müller, Markus; Eichler, Philipp; Mikoviny, Tomas; Beyersdorf, Andreas J.; Crawford, James H.; Diskin, Glenn S.; Yang, Melissa; Yokelson, Robert; Weinheimer, Andrew; Fried, Alan; Wisthaler, Armin

    2015-04-01

    The NASA DISCOVER-AQ mission saw the first airborne deployment of a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS). The newly developed instrument records full mass spectra at 10 Hz and resolves pure hydrocarbons from their oxygenated isobars (e.g. isoprene and furan). Airborne measurements of volatile organic compounds (VOCs) at high spatio-temporal resolution (0.1 s or 10 m) improve our capabilities in characterizing primary emissions from fires and in studying chemical transformations in aging plumes. A biomass-burning plume from a forest understory fire was intercepted by the NASA P-3B near Dublin, GA, USA on September 29, 2013. VOCs were measured at high time resolution along with CO, CO2, NOx, O3, HCHO, aerosols and other air quality and meteorological parameters. Repeated measurements in the immediate proximity of the fire were used to determine VOC emission ratios and their temporal variations. Repeated longitudinal and transversal plume transects were carried out to study plume aging within the first hour of emission. We will discuss the observed OH-NOx-VOC chemistry (including O3 formation), the observed changes in the elemental composition of VOCs (e.g. O:C ratios) and the observed formation of SOA.

  1. First Airborne PTR-ToF-MS Measurements of VOCs in a Biomass Burning Plume: Primary Emissions and Aging

    NASA Astrophysics Data System (ADS)

    Wisthaler, A.; Müller, M.; Eichler, P.; Mikoviny, T.; Beyersdorf, A. J.; Crawford, J. H.; Diskin, G. S.; Yang, M. M.; Yokelson, R. J.; Weinheimer, A. J.; Fried, A.

    2014-12-01

    The NASA DISCOVER-AQ mission saw the first airborne deployment of a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS). The newly developed instrument records full mass spectra at 10 Hz and resolves pure hydrocarbons from their oxygenated isobars (e.g. isoprene and furan). Airborne measurements of volatile organic compounds (VOCs) at high spatio-temporal resolution (0.1 s or 10 m) improve our capabilities in characterizing primary emissions from fires and in studying chemical transformations in aging plumes. A biomass-burning plume from a forest understory fire was intercepted by the NASA P-3B near Dublin, GA, USA on September 29, 2013. VOCs were measured at high time resolution along with CO, CO2, NOx, O3, HCHO, aerosols and other air quality and meteorological parameters. Repeated measurements in the immediate proximity of the fire were used to determine VOC emission ratios and their temporal variations. Repeated longitudinal and transversal plume transects were carried out to study plume aging within the first hour of emission. We will discuss the observed OH-NOx-VOC chemistry (including O3 formation), the observed changes in the elemental composition of VOCs (e.g. O:C ratios) and the observed formation of SOA.

  2. Reduced Ssy1-Ptr3-Ssy5 (SPS) Signaling Extends Replicative Life Span by Enhancing NAD+ Homeostasis in Saccharomyces cerevisiae*

    PubMed Central

    Tsang, Felicia; James, Christol; Kato, Michiko; Myers, Victoria; Ilyas, Irtqa; Tsang, Matthew; Lin, Su-Ju

    2015-01-01

    Attenuated nutrient signaling extends the life span in yeast and higher eukaryotes; however, the mechanisms are not completely understood. Here we identify the Ssy1-Ptr3-Ssy5 (SPS) amino acid sensing pathway as a novel longevity factor. A null mutation of SSY5 (ssy5Δ) increases replicative life span (RLS) by ∼50%. Our results demonstrate that several NAD+ homeostasis factors play key roles in this life span extension. First, expression of the putative malate-pyruvate NADH shuttle increases in ssy5Δ cells, and deleting components of this shuttle, MAE1 and OAC1, largely abolishes RLS extension. Next, we show that Stp1, a transcription factor of the SPS pathway, directly binds to the promoter of MAE1 and OAC1 to regulate their expression. Additionally, deletion of SSY5 increases nicotinamide riboside (NR) levels and phosphate-responsive (PHO) signaling activity, suggesting that ssy5Δ increases NR salvaging. This increase contributes to NAD+ homeostasis, partially ameliorating the NAD+ deficiency and rescuing the short life span of the npt1Δ mutant. Moreover, we observed that vacuolar phosphatase, Pho8, is partially required for ssy5Δ-mediated NR increase and RLS extension. Together, our studies present evidence that supports SPS signaling is a novel NAD+ homeostasis factor and ssy5Δ-mediated life span extension is likely due to concomitantly increased mitochondrial and vacuolar function. Our findings may contribute to understanding the molecular basis of NAD+ metabolism, cellular life span, and diseases associated with NAD+ deficiency and aging. PMID:25825491

  3. Reduced Ssy1-Ptr3-Ssy5 (SPS) signaling extends replicative life span by enhancing NAD+ homeostasis in Saccharomyces cerevisiae.

    PubMed

    Tsang, Felicia; James, Christol; Kato, Michiko; Myers, Victoria; Ilyas, Irtqa; Tsang, Matthew; Lin, Su-Ju

    2015-05-15

    Attenuated nutrient signaling extends the life span in yeast and higher eukaryotes; however, the mechanisms are not completely understood. Here we identify the Ssy1-Ptr3-Ssy5 (SPS) amino acid sensing pathway as a novel longevity factor. A null mutation of SSY5 (ssy5Δ) increases replicative life span (RLS) by ∼50%. Our results demonstrate that several NAD(+) homeostasis factors play key roles in this life span extension. First, expression of the putative malate-pyruvate NADH shuttle increases in ssy5Δ cells, and deleting components of this shuttle, MAE1 and OAC1, largely abolishes RLS extension. Next, we show that Stp1, a transcription factor of the SPS pathway, directly binds to the promoter of MAE1 and OAC1 to regulate their expression. Additionally, deletion of SSY5 increases nicotinamide riboside (NR) levels and phosphate-responsive (PHO) signaling activity, suggesting that ssy5Δ increases NR salvaging. This increase contributes to NAD(+) homeostasis, partially ameliorating the NAD(+) deficiency and rescuing the short life span of the npt1Δ mutant. Moreover, we observed that vacuolar phosphatase, Pho8, is partially required for ssy5Δ-mediated NR increase and RLS extension. Together, our studies present evidence that supports SPS signaling is a novel NAD(+) homeostasis factor and ssy5Δ-mediated life span extension is likely due to concomitantly increased mitochondrial and vacuolar function. Our findings may contribute to understanding the molecular basis of NAD(+) metabolism, cellular life span, and diseases associated with NAD(+) deficiency and aging. PMID:25825491

  4. Comparison of PTR-MS and GC-MS measurements of oxidized VOC and aromatic VOC concentrations at a boreal forest

    NASA Astrophysics Data System (ADS)

    Kajos, M.

    2013-12-01

    M.K. Kajos1, M. Hill2, H. Hellén3, P. Rantala1, C. C Hoerger2, S. Reimann2, H. Hakola3, T. Petäjä1, T.M. Ruuskanen1 1 Department of Physics, University of Helsinki, P.O.Box 64, 00014 University of Helsinki, Finland 2 Empa, Laboratory for Air Pollution/ Environmental Technology, Ueberlandstr. 129, 8600 Duebendorf, Switzerland 3 Finnish Metorological Institute, P.O.Box 503, 00101 Helsinki, Finland Oxidized volatile organic compounds (OVOCs) such as acetaldehyde and acetone and aromatic VOCs such as benzene and toluene originate from various natural and anthropogenic sources. The lifetimes of these compounds are relatively long, from hundreds of days in the winter to a few days in summer thus they are effectively transported. Some of them are continuously monitored e.g. benzene due to it being carcinogenic. In this study the volume mixing ratios of acetaldehyde, acetone, benzene and toluene, were measured with two different methods; Gas Chromatography-Mass Spectrometry (GC-MS) and Proton Transfer Reaction-Mass Spectrometry (PTR-MS). GC-MS is a well-established and old method to measure these compounds with a low, often one hour, time resolution. However it is rather labor intensive method and often used in short term campaigns. The other method, PTR-MS has a sub-minute time resolution and it is suitable for long term continuous measurements. The disadvantage of the PTR-MS is that the identification of the compounds is based on mass only, thus compounds with the same nominal mass cannot be distinguished. Both methods are widely used at atmospheric measurement stations around the world. The concentrations were measured with two GC-MSs and two PTR-MSs (Ionicon Analytik, Austria) at SMEAR II site (Station for Measuring Forest Ecosystem-Atmosphere Relations, 61°51'N, 24°17'E, 181 m a.s.l.) in Hyytiälä, Southern Finland in April-May 2012. The site is a well characterized atmosphere flagship station located in a rural boreal forest (Hari and Kulmala, 2005). The

  5. Tropical Greenhouse Measurements of Volatile Organic Compounds Using Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectromety (PTR-TOF-MS)

    NASA Astrophysics Data System (ADS)

    Veres, P.; Auld, J.; Williams, J.

    2012-04-01

    In this presentation, we will summarize the results of measurements made in an approximately 1300 m3 tropical greenhouse at the Johannes Gutenberg University botanical garden in Mainz Germany conducted over a one month period. The greenhouse is home to a large variety of plant species from hot and humid regions of the world. The greenhouse is also host to several crops such as Cocoa and Cola Nut as well as ornamental plants. A particular focus of the species maintained are those which are considered ant plants, or plants which have an intimate relationship with ants in tropical habitats. Volatile organic compounds (VOCs) were measured using a Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-TOF-MS) using H3O+, NO+, and O2+ ion chemistry. Measurements will be presented both for primary emissions observed in the closed greenhouse atmosphere as well as the oxidation products observed after the introduction of ambient ozone. The high resolving power (5000 m/Δm) of the time-of-flight instrument allows for the separation of isobaric species. In particular, both isoprene (68.1170 amu) and furan (68.0740 amu) were observed and separated as primary emissions during this study. The significance of this will be discussed in terms of both atmospheric implications as well as with respect to previous measurements of isoprene obtained using quadrupole PTR-MS where isobaric separation of these compounds is not possible. Additionally observed species (e.g. Methanol, Acetaldehyde, MVK and MEK) will be discussed in detail with respect to their behavior as a function of light, temperature and relative humidity. The overall instrument performance of the PTR-TOF-MS technique using the H3O+, NO+, and O2+ primary ions for the measurement of VOCs will be evaluated.

  6. Optimization of H3O+/O2+ Dual-mode Ionization in PTR-MS for Simultaneous Detection of Alkanes, Olefins and Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Amador-Muñoz, O.; Misztal, P. K.; Weber, R.; Drozd, G.; Worton, D. R.; Goldstein, A. H.

    2014-12-01

    Measurements of VOC composition from fossil fuels are analytically challenging because of the complex mixture of hydrocarbons (saturated, unsaturated, aromatics, etc). Speciated chemical measurements typically rely on relatively slow GC separation. Proton transfer reaction mass spectrometry (PTR-MS) is advantageous due to its fast response and high sensitivity. The most common ionization mechanism applied to VOC detection by PTR-MS is proton transfer from hydronium ion (H3O+). However, alkanes cannot be detected using H3O+ ionization chemistry because their proton affinities are too low. Ionization of alkanes is possible via electron transfer and/or hydride abstraction using O2+ or NO+. We used PTR-MS to analyze aromatic, alkene and alkane (linear, branched and cyclic) compounds simultaneously not by switching the ionization agents, but by adjusting the drift tube voltage and optimizing the ratio of H3O+/O2+ produced in the instrument's ion source. The highest detection sensitivity for aromatic and alkene compounds was produced by proton transfer from H3O+, while hydride abstraction by O2+ allowed detection of alkanes. For alkanes, sensitivities ranged from 1.1±0.01 cps/ppbv for n-decane to 74.7±0.25 cps/ppbv for decalin. Sensitivities in O2+ mode were from 6 (Adamantane) to 146 (4-Methyl nonane) times higher than those obtained in H3O+ mode under the same ion source and drift tube voltage conditions. Sensitivities for butyl benzene and 1-decene were 157±0.57 and 66.8±0.21 cps/ppbv, respectively. Sensitivity differences among C10 hydrocarbons are related to their structure, which affects their ionization energies (IE) and hence ease of hydride abstraction. Sensitivities at the parent ion mass were inversely correlated with IE (142 cps/ppbv/eV). This suggests higher electronic stability for cyclic non substituted compounds, followed by cyclic substituted, branch linear and linear C10 hydrocarbons. Although selectivity is a known shortcoming of quadrupole

  7. Measurement of BVOCs by PTR-ToF-MS in a ponderosa pine forest during the BEACHON-ROCS campaign

    NASA Astrophysics Data System (ADS)

    Su, L.; Evans, T.; Knopf, D. A.; Mak, J. E.

    2012-12-01

    We present measurements of biogenic volatile organic compounds (BVOCs) using Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS) during the 2010 Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen-Rocky Mountain Organic Carbon Study (BEACHON-ROCS) campaign in a ponderosa pine forest near Woodland Park, Colorado. BVOCs were continuously measured through the gradient sampling lines mounted at 1.8 m, 5.0 m, 8.5 m, 12.0 m, 17.7 m, and 25.3 m, respectively, of the Manitou Forest Observatory Chemistry Tower. 2-methyl-3-butene-2-ol (MBO) and the monoterpenes (MT) were identified as the major BVOCs emitted from the forest. The 5-minute averaged mixing ratios of MBO ranged from 0.03 to 3.9 ppbv, while mixing ratios of MT ranged from 0.02 to 3.8 ppbv, with an analytical precision of ±15%. The mixing ratios of MBO were highest during the daytime, with the maximum concentrations occurred right under the canopy top, decreasing towards the ground and above the canopy. The diurnal variations of MT mixing ratios showed an opposite pattern compared to MBO, with nighttime values significantly higher than during the daytime. The high nighttime mixing ratios of MT could be due to the sufficient temperature-dependent emission together with lack of oxidation and small vertical transport. MT usually accumulated near the ground level and decreased vertically towards the canopy top. Soil enclosure measurements were performed to characterize the needle litter emission of BVOCs. The flux of MT from needle litter were quantified and showed a clear temperature dependency. The highest flux of MT from needle litter occurred in the morning (09:00-12:00 MST), while during the nighttime the flux was significantly reduced. Measurements of BVOCs gradients throughout the canopy together with ground needle litter emissions could provide a better understanding of the contribution to above-canopy emission of BVOCs from different sources.

  8. Investigation of Volatiles Emitted from Freshly Cut Onions (Allium cepa L.) by Real Time Proton-Transfer Reaction-Mass Spectrometry (PTR-MS)

    PubMed Central

    Løkke, Mette Marie; Edelenbos, Merete; Larsen, Erik; Feilberg, Anders

    2012-01-01

    Volatile organic compounds (VOCs) in cut onions (Allium cepa L.) were continuously measured by PTR-MS during the first 120 min after cutting. The headspace composition changed rapidly due to the very reactive volatile sulfurous compounds emitted from onion tissue after cell disruption. Mass spectral signals corresponding to propanethial S-oxide (the lachrymatory factor) and breakdown products of this compound dominated 0–10 min after cutting. Subsequently, propanethiol and dipropyl disulfide predominantly appeared, together with traces of thiosulfinates. The concentrations of these compounds reached a maximum at 60 min after cutting. Propanethiol was present in highest concentrations and had an odor activity value 20 times higher than dipropyl disulfide. Thus, propanethiol is suggested to be the main source of the characteristic onion odor. Monitoring the rapid changes of VOCs in the headspace of cut onion necessitates a high time resolution, and PTR-MS is demonstrated to be a very suitable method for monitoring the headspace of freshly cut onions directly after cutting without extraction or pre-concentration. PMID:23443367

  9. Challenges associated with the sampling and analysis of organosulfur compounds in air using real-time PTR-ToF-MS and off-line GC-FID

    NASA Astrophysics Data System (ADS)

    Perraud, V.; Meinardi, S.; Blake, D. R.; Finlayson-Pitts, B. J.

    2015-12-01

    Organosulfur compounds (OSC) are naturally emitted via various processes involving phytoplankton and algae in marine regions, from animal metabolism and from biomass decomposition inland. These compounds are malodorant and reactive. Their oxidation to methanesulfonic and sulfuric acids leads to the formation and growth of atmospheric particles, which are known to have negative effects on visibility, climate and human health. In order to predict particle formation events, accurate measurements of the OSC precursors are essential. Here, two different approaches, proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) and canister sampling coupled with GC-FID are compared for both laboratory standards [dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and methanethiol (MTO)] and for a complex sample. Results show that both techniques produce accurate quantification of DMS. While PTR-ToF-MS provides real-time measurements of all four OSCs individually, significant fragmentation of DMDS and DMTS occurs, which can complicate their identification in complex mixtures. Canister sampling coupled with GC-FID provides excellent sensitivity for DMS, DMDS and DMTS. However, MTO was observed to react on metal surfaces to produce DMDS and, in the presence of hydrogen sulfide, even DMTS. Avoiding metal in sampling systems seems to be necessary for measuring all but dimethyl sulfide in air.

  10. Challenges associated with the sampling and analysis of organosulfur compounds in air using real-time PTR-ToF-MS and offline GC-FID

    NASA Astrophysics Data System (ADS)

    Perraud, Véronique; Meinardi, Simone; Blake, Donald R.; Finlayson-Pitts, Barbara J.

    2016-03-01

    Organosulfur compounds (OSCs) are naturally emitted via various processes involving phytoplankton and algae in marine regions, from animal metabolism, and from biomass decomposition inland. These compounds are malodorant and reactive. Their oxidation to methanesulfonic and sulfuric acids leads to the formation and growth of atmospheric particles, which are known to influence clouds and climate, atmospheric chemical processes. In addition, particles in air have been linked to negative impacts on visibility and human health. Accurate measurements of the OSC precursors are thus essential to reduce uncertainties in their sources and contributions to particle formation in air. Two different approaches, proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) and canister sampling coupled to gas chromatography with flame ionization detector (GC-FID), are compared for both laboratory standards (dimethyl sulfide, DMS; dimethyl disulfide, DMDS; dimethyl trisulfide, DMTS; and methanethiol, MTO) and for a complex sample. Results show that both techniques produce accurate quantification of DMS. While PTR-ToF-MS provides real-time measurements of all four OSCs individually, significant fragmentation of DMDS and DMTS occurs, which can complicate their identification in complex mixtures. Canister sampling coupled with GC-FID provides excellent sensitivity for DMS, DMDS, and DMTS. However, MTO was observed to react on metal surfaces to produce DMDS and, in the presence of hydrogen sulfide, even DMTS. Avoiding metal in sampling systems seems to be necessary for measuring all but dimethyl sulfide in air.

  11. Detection of Plant Volatiles after Leaf Wounding and Darkening by Proton Transfer Reaction “Time-of-Flight” Mass Spectrometry (PTR-TOF)

    PubMed Central

    Brilli, Federico; Ruuskanen, Taina M.; Schnitzhofer, Ralf; Müller, Markus; Breitenlechner, Martin; Bittner, Vinzenz; Wohlfahrt, Georg; Loreto, Francesco; Hansel, Armin

    2011-01-01

    Proton transfer reaction-time of flight (PTR-TOF) mass spectrometry was used to improve detection of biogenic volatiles organic compounds (BVOCs) induced by leaf wounding and darkening. PTR-TOF measurements unambiguously captured the kinetic of the large emissions of green leaf volatiles (GLVs) and acetaldehyde after wounding and darkening. GLVs emission correlated with the extent of wounding, thus confirming to be an excellent indicator of mechanical damage. Transient emissions of methanol, C5 compounds and isoprene from plant species that do not emit isoprene constitutively were also detected after wounding. In the strong isoprene-emitter Populus alba, light-dependent isoprene emission was sustained and even enhanced for hours after photosynthesis inhibition due to leaf cutting. Thus isoprene emission can uncouple from photosynthesis and may occur even after cutting leaves or branches, e.g., by agricultural practices or because of abiotic and biotic stresses. This observation may have important implications for assessments of isoprene sources and budget in the atmosphere, and consequences for tropospheric chemistry. PMID:21637822

  12. Ambient measurements of aromatic and oxidized VOCs by PTR-MS and GC-MS: intercomparison between four instruments in a boreal forest in Finland

    NASA Astrophysics Data System (ADS)

    Kajos, M. K.; Rantala, P.; Hill, M.; Hellén, H.; Aalto, J.; Patokoski, J.; Taipale, R.; Hoerger, C. C.; Reimann, S.; Ruuskanen, T. M.; Rinne, J.; Petäjä, T.

    2015-10-01

    Proton transfer reaction mass spectrometry (PTR-MS) and gas chromatography mass spectrometry GC-MS) are commonly used methods for automated in situ measurements of various volatile organic compounds (VOCs) in the atmosphere. In order to investigate the reliability of such measurements, we operated four automated analyzers using their normal field measurement protocol side by side at a boreal forest site. We measured methanol, acetaldehyde, acetone, benzene and toluene by two PTR-MS and two GC-MS instruments. The measurements were conducted in southern Finland between 13 April and 14 May 2012. This paper presents correlations and biases between the concentrations measured using the four instruments. A very good correlation was found for benzene and acetone measurements between all instruments (the mean R value was 0.88 for both compounds), while for acetaldehyde and toluene the correlation was weaker (with a mean R value of 0.50 and 0.62, respectively). For some compounds, notably for methanol, there were considerable systematic differences in the mixing ratios measured by the different instruments, despite the very good correlation between the instruments (mean R = 0.90). The systematic difference manifests as a difference in the linear regression slope between measurements conducted between instruments, rather than as an offset. This mismatch indicates that the systematic uncertainty in the sensitivity of a given instrument can lead to an uncertainty of 50-100 % in the methanol emissions measured by commonly used methods.

  13. Ambient measurements of aromatic and oxidized VOCs by PTR-MS and GC-MS: intercomparison between four instruments in a boreal forest in Finland

    NASA Astrophysics Data System (ADS)

    Kajos, M. K.; Rantala, P.; Hill, M.; Hellén, H.; Aalto, J.; Patokoski, J.; Taipale, R.; Hoerger, C. C.; Reimann, S.; Ruuskanen, T. M.; Rinne, J.; Petäjä, T.

    2015-04-01

    Proton transfer reaction mass spectrometry (PTR-MS) and gas chromatography mass spectrometry GC-MS) allow real-time measurements of various atmospheric volatile organic compounds (VOC). By taking parallel measurements in ambient conditions, two PTR-MSs and two GC-MSs were studied for their ability to measure methanol, acetaldehyde, acetone, benzene and toluene. The measurements were conducted at a rural boreal forest site in southern Finland between 13 April and 14 May 2012. This paper presents correlations and possible biases between the concentrations measured using the four instruments. This paper presents correlations and possible biases between the concentrations measured using the four instruments. A very good correlation was found for benzene and acetone measurements between all instruments (the mean R value was 0.88 for both compounds), while for acetaldehyde and toluene the correlation was weaker (with a mean R value of 0.50 and 0.62, respectively). For some compounds, notably for methane, there were considerable systematic differences in the mixing ratios measured by the different instruments, despite the very good correlation between the instruments (mean R = 0.90). The systematic difference arises as a difference in the linear regression slope between measurements conducted between instruments, rather than as an offset. This mismatch indicates that the systematic uncertainty in the sensitivity of a given instrument can lead to an uncertainty of 50-100% in the methanol emissions measured by commonly used methods.

  14. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Zinn, W.H.; Anderson, H.L.

    1958-09-16

    Means are presenied for increasing the reproduction ratio of a gaphite- moderated neutronic reactor by diminishing the neutron loss due to absorption or capture by gaseous impurities within the reactor. This means comprised of a fluid-tight casing or envelope completely enclosing the reactor and provided with a valve through which the casing, and thereby the reactor, may be evacuated of atmospheric air.

  15. Determination of de novo and pool emissions of terpenes from four common boreal/alpine trees by 13CO2 labelling and PTR-MS analysis.

    PubMed

    Ghirardo, Andrea; Koch, Kristine; Taipale, Risto; Zimmer, Ina; Schnitzler, Jörg-Peter; Rinne, Janne

    2010-05-01

    Boreal forests emit a large amount of monoterpenes into the atmosphere. Traditionally these emissions are assumed to originate as evaporation from large storage pools. Thus, their diurnal cycle would depend mostly on temperature. However, there is indication that a significant part of the monoterpene emission would originate directly from de novo synthesis. By applying 13CO2 fumigation and analyzing the isotope fractions with proton transfer reaction mass spectrometry (PTR-MS) and classical GC-MS, we determined the fractions of monoterpene emissions originating from de novo biosynthesis in Pinus sylvestris (58%), Picea abies (33.5%), Larix decidua (9.8%) and Betula pendula (100%). Application of the observed split between de novo and pool emissions from P. sylvestris in a hybrid emission algorithm resulted in a better description of ecosystem scale monoterpene emissions from a boreal Scots pine forest stand. PMID:20040067

  16. PTR 9000, a system for large dynamic digitisation and real-time recording of infrared images: applications to the nondestructive testing of materials by photothermography

    NASA Astrophysics Data System (ADS)

    Potet, Pierre

    1990-10-01

    CEDIP 13S has designed the RTIS 8902 under license of ONERA, a Pc compatible system for the digital recording of infrared images in real time and over a large dynamic of digitization (12 bits). The RTIS 8902 operates with AGEMA cameras, an extension to JI1FRAMETRICS camera is currently under development The unit is able to store to hard disk evezy infrared image from a single camera or a dual camera, the maximum storage time is related to the hard disk capacity and is about 10 minutes for a 600 MBytes hard disic Several applications for the RTIS 8902 have already been developed among whose infrared signature analysis, combustion analysis and nondestructive testing of matezials. The present paper describes a commercially available equipment, the PTR 9000, developped and build with the RTLS 8902 unit, and dedicated to the NDT of materials.

  17. Experimental determination of the partitioning coefficient and volatility of important BVOC oxidation products using the Aerosol Collection Module (ACM) coupled to a PTR-ToF-MS

    NASA Astrophysics Data System (ADS)

    Gkatzelis, G.; Hohaus, T.; Tillmann, R.; Schmitt, S. H.; Yu, Z.; Schlag, P.; Wegener, R.; Kaminski, M.; Kiendler-Scharr, A.

    2015-12-01

    Atmospheric aerosol can alter the Earth's radiative budget and global climate but can also affect human health. A dominant contributor to the submicrometer particulate matter (PM) is organic aerosol (OA). OA can be either directly emitted through e.g. combustion processes (primary OA) or formed through the oxidation of organic gases (secondary organic aerosol, SOA). A detailed understanding of SOA formation is of importance as it constitutes a major contribution to the total OA. The partitioning between the gas and particle phase as well as the volatility of individual components of SOA is yet poorly understood adding uncertainties and thus complicating climate modelling. In this work, a new experimental methodology was used for compound-specific analysis of organic aerosol. The Aerosol Collection Module (ACM) is a newly developed instrument that deploys an aerodynamic lens to separate the gas and particle phase of an aerosol. The particle phase is directed to a cooled sampling surface. After collection particles are thermally desorbed and transferred to a detector for further analysis. In the present work, the ACM was coupled to a Proton Transfer Reaction-Time of Flight-Mass Spectrometer (PTR-ToF-MS) to detect and quantify organic compounds partitioning between the gas and particle phase. This experimental approach was used in a set of experiments at the atmosphere simulation chamber SAPHIR to investigate SOA formation. Ozone oxidation with subsequent photochemical aging of β-pinene, limonene and real plant emissions from Pinus sylvestris (Scots pine) were studied. Simultaneous measurement of the gas and particle phase using the ACM-PTR-ToF-MS allows to report partitioning coefficients of important BVOC oxidation products. Additionally, volatility trends and changes of the SOA with photochemical aging are investigated and compared for all systems studied.

  18. BOILING REACTORS

    DOEpatents

    Untermyer, S.

    1962-04-10

    A boiling reactor having a reactivity which is reduced by an increase in the volume of vaporized coolant therein is described. In this system unvaporized liquid coolant is extracted from the reactor, heat is extracted therefrom, and it is returned to the reactor as sub-cooled liquid coolant. This reduces a portion of the coolant which includes vaporized coolant within the core assembly thereby enhancing the power output of the assembly and rendering the reactor substantially self-regulating. (AEC)

  19. NEUTRONIC REACTOR

    DOEpatents

    Daniels, F.

    1959-10-27

    A reactor in which at least a portion of the moderator is in the form of movable refractory balls is described. In addition to their moderating capacity, these balls may serve as carriers for fissionable material or fertile material, or may serve in a coolant capacity to remove heat from the reactor. A pneumatic system is used to circulate the balls through the reactor.

  20. CONVECTION REACTOR

    DOEpatents

    Hammond, R.P.; King, L.D.P.

    1960-03-22

    An homogeneous nuclear power reactor utilizing convection circulation of the liquid fuel is proposed. The reactor has an internal heat exchanger looated in the same pressure vessel as the critical assembly, thereby eliminating necessity for handling the hot liquid fuel outside the reactor pressure vessel during normal operation. The liquid fuel used in this reactor eliminates the necessity for extensive radiolytic gas rocombination apparatus, and the reactor is resiliently pressurized and, without any movable mechanical apparatus, automatically regulates itself to the condition of criticality during moderate variations in temperature snd pressure and shuts itself down as the pressure exceeds a predetermined safe operating value.

  1. Research reactors

    SciTech Connect

    Tonneson, L.C.; Fox, G.J.

    1996-04-01

    There are currently 284 research reactors in operation, and 12 under construction around the world. Of the operating reactors, nearly two-thirds are used exclusively for research, and the rest for a variety of purposes, including training, testing, and critical assembly. For more than 50 years, research reactor programs have contributed greatly to the scientific and educational communities. Today, six of the world`s research reactors are being shut down, three of which are in the USA. With government budget constraints and the growing proliferation concerns surrounding the use of highly enriched uranium in some of these reactors, the future of nuclear research could be impacted.

  2. Characterization of the organic matter in submicron urban aerosols using a Thermo-Desorption Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (TD-PTR-TOF-MS)

    NASA Astrophysics Data System (ADS)

    Salvador, Christian Mark; Ho, T.-T.; Chou, Charles C.-K.; Chen, M.-J.; Huang, W.-R.; Huang, S.-H.

    2016-09-01

    Organic matter is the most complicated and unresolved major component of atmospheric aerosol particles. Its sources and global budget are still highly uncertain and thereby necessitate further research efforts with state-of-the-art instrument. This study employed a Thermo-Desorption Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (TD-PTR-TOF-MS) for characterization of ambient organic aerosols. First, five authentic standard substances, which include phthalic acid, levoglucosan, arabitol, cis-pinonic acid and glutaric acid, were utilized to examine the response of the instrument. The results demonstrated the linearity of the TD-PTR-TOF-MS signals against a range of mass loading of specific species on filters. However, it was found that significant fragmentation happened to those challenging compounds, although the proton-transfer-reaction (PTR) was recognized as a soft ionization technique. Consequently, quantitative characterization of aerosols with the TD-PTR-TOF-MS depended on the availability of the fragmentation pattern in mass spectra and the recovery rate with the quantification ion peak(s). The instrument was further deployed to analyze a subset of submicron aerosol samples collected at the TARO (Taipei Aerosol and Radiation Observatory) in Taipei, Taiwan during August 2013. The results were compared with the measurements from a conventional DRI thermo-optical carbon analyzer. The inter-comparison indicated that the TD-PTR-TOF-MS underestimated the mass of total organic matter (TOM) in aerosol samples by 27%. The underestimation was most likely due to the thermo-decomposition during desorption processes and fragmentation in PTR drift tube, where undetectable fragments were formed. Besides, condensation loss of low vapor pressure species in the transfer components was also responsible for the underestimation to a certain degree. Nevertheless, it was showed that the sum of the mass concentrations of the major detected ion peaks correlated strongly

  3. Causal Link Between Flood Basalts and Large Impacts: Were The K-t and P-tr Impactors `verneshots' Fired From Terrestrial Plume-fed Co2-guns?

    NASA Astrophysics Data System (ADS)

    Phipps Morgan, J.; Reston, T.; Ranero, C.

    Both bolide impacts (Alvarez et al., 1980) and Continental Flood Basalt (CFB) events (Courtillot, 1996; Courtillot et al., 1994; Morgan, 1986) have been proposed to be the cause of the three largest Phanerozoic mass-extinctions. The Cretaceous-Tertiary (K-T) boundary is the age of both one of the largest known terrestrial impact struc- tures (the Chixculub site on the Yucatan peninsula) and a very large continental flood basalt (the Deccan Traps event, the first well-documented trace of the Reunion plume- hotspot). In the past year, two papers (Becker et al., 2001; Kaiho et al., 2001) have suggested that the Permian-Triassic (P-Tr) boundary, the age of the largest well- documented CFB (the Siberian Traps), is also marked, in some marine sediments, by the geochemical signature of a large bolide impact. If correct, this would require that both a bolide impact and a CFB occurred at the P-Tr boundary. Finally, the Frasnian- Famennian (Late Devonian) event appears to be contemporaneous with an impact or impacts (e.g. Siljan Ring - Grieve and Robertson, 1987), the eruption of both a Siberian Kimberlite field (Agashev et al., 2001), and the Dniepr-Donets CFB (Wilson et al., 1996). Both large bolide impacts (

  4. Pyrenophora bromi, causal agent of brownspot of bromegrass, expresses a gene encoding a protein with homology and similar activity to Ptr ToxB, a host-selective toxin of wheat.

    PubMed

    Andrie, Rachael M; Ciuffetti, Lynda M

    2011-03-01

    Ptr ToxB, encoded by ToxB, is one of multiple host-selective toxins (HST) produced by the wheat pathogen Pyrenophora tritici-repentis. Homologs of ToxB are found in several ascomycetes, including sister species Pyrenophora bromi, causal agent of brownspot of bromegrass. Due to the close evolutionary relatedness of P. tritici-repentis and P. bromi and that of their grass hosts, we hypothesized that homologs of ToxB in P. bromi may act as HST in the disease interaction between P. bromi and bromegrass. A representative set of transcriptionally active P. bromi ToxB genes were heterologously expressed in Pichia pastoris and the resultant proteins tested for their ability to act as HST on bromegrass. The tested Pyrenophora bromi ToxB (Pb ToxB) proteins were not toxic to bromegrass; thus, Pb ToxB does not appear to function as an HST in the P. bromi-bromegrass interaction. Instead, we revealed that the Pb ToxB proteins can be toxic to Ptr ToxB-sensitive wheat, at levels similar to Ptr ToxB, and the corresponding P. bromi ToxB genes are expressed in P. bromi-inoculated wheat. Our data suggest that P. bromi possesses the potential to become a wheat pathogen and highlights the importance of investigating the interaction between P. bromi and wheat. PMID:21091157

  5. Investigation of volatile compounds in two raspberry cultivars by two headspace techniques: solid-phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS) and proton-transfer reaction-mass spectrometry (PTR-MS).

    PubMed

    Aprea, Eugenio; Biasioli, Franco; Carlin, Silvia; Endrizzi, Isabella; Gasperi, Flavia

    2009-05-27

    The volatile compounds emitted by two raspberry varieties ( Rubus idaeus , cv. Polka and Tulameen) were analyzed, in both the case of fresh fruits and juices, by two headspace methods that are rapid, solvent-free, and with reduced or no sample pretreatment: solid-phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS) and proton-transfer reaction-mass spectrometry (PTR-MS). Multivariate analysis of the SPME/GC-MS results allows for an unambiguous sample discrimination for both mashed fruits and juices. PTR-MS instrumental fingerprint provides, in a faster way, similar qualitative information on the overall flavor profile. The two cultivars show both qualitative and quantitative differences. SPME/GC-MS analysis shows that alcohols and aldehydes are more abundant in the headspace of Tulameen as, e.g., hexanal and hexanol that induce herbaceous odor notes. This observation has been confirmed by sensory analysis. PTR-MS was also used to monitor rapid processes that modify the original aromatic profile, such as lipo-oxigenase activity induced by tissue damages occurring during industrial transformation, accidental mechanical damages, or as a consequence of chewing. PMID:19348421

  6. NEUTRONIC REACTOR

    DOEpatents

    Fraas, A.P.; Mills, C.B.

    1961-11-21

    A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)

  7. REACTOR COOLING

    DOEpatents

    Quackenbush, C.F.

    1959-09-29

    A nuclear reactor with provisions for selectively cooling the fuel elements is described. The reactor has a plurality of tubes extending throughout. Cylindrical fuel elements are disposed within the tubes and the coolant flows through the tubes and around the fuel elements. The fuel elements within the central portion of the reactor are provided with roughened surfaces of material. The fuel elements in the end portions of the tubes within the reactor are provlded with low conduction jackets and the fuel elements in the region between the central portion and the end portions are provided with smooth surfaces of high heat conduction material.

  8. The stability and generation pattern of thermally formed isocyanic acid (ICA) in air - potential and limitations of proton transfer reaction-mass spectrometry (PTR-MS) for real-time workroom atmosphere measurements.

    PubMed

    Jankowski, Mikolaj Jan; Olsen, Raymond; Thomassen, Yngvar; Molander, Paal

    2016-07-13

    Isocyanic acid (ICA) in vapour phase has been reported to be of unstable nature, making the occupational hygienic relevance of ICA questionable. The stability of pure ICA in clean air at different humidity conditions was investigated by Fourier transform-infrared spectrometric (FT-IR) measurements. Furthermore, the stability of ICA in a complex atmosphere representative thermal degradation hot-work procedures were examined by performing parallel measurements by proton transfer reaction-mass spectrometric (PTR-MS) instrumentation and off-line denuder air sampling using di-n-butylamine (as a derivatization agent prior to liquid chromatography mass spectrometric (LC-MS) determination). The apparent half-life of ICA in pure ICA atmospheres was 16 to 4 hours at absolute humidity (AH) in the range 4.2 to 14.6 g m(-3), respectively. In a complex atmosphere at an initial AH of 9.6 g m(-3) the apparent half-life of ICA was 8 hours, as measured with the denuder method. Thus, thermally formed ICA is to be considered as a potential occupational hazard with regard to inhalation. The generation pattern of ICA formed during controlled gradient (100-540 °C) thermal decomposition of different polymers in the presence of air was examined by parallel PTR-MS and denuder air sampling. According to measurement by denuder sampling ICA was the dominant aliphatic isocyanate formed during the thermal decomposition of all polymers. The real-time measurements of the decomposed polymers revealed different ICA generation patterns, with initial appearance of thermally released ICA in the temperature range 200-260 °C. The PTR-MS ICA measurements was however affected by mass overlap from other decomposition products at m/z 44, illustrated by a [ICA]Denuder/[ICA]PTR-MS ratio ranging from 0.04 to 0.90. These findings limits the potential use of PTR-MS for real time measurements of thermally released ICA in field, suggesting parallel sampling with short-term sequential off-line methodology. PMID

  9. First Characterization of Biomass Burning Smoke from Cooking Fires, Peat, Crop Residue and Other Fuels By High Resolution PTR-TOF Mass Spectrometry and FTIR

    NASA Astrophysics Data System (ADS)

    Stockwell, C.; Veres, P. R.; Williams, J.; Yokelson, R. J.

    2014-12-01

    Biomass burning (BB) is a major influence on Earth's atmosphere, but for many fire-types the emissions have only been measured for a few species. For all types of BB, progress has been limited by a lack of information on the emissions of semi-volatile organic gases that are precursors for secondary aerosol and ozone. During the Fourth Fire Lab at Missoula Experiment (FLAME-4), the BB emissions from 158 laboratory fires were quantified by ~40 scientists for an assortment of globally relevant fuels including rarely sampled sources such as US and Asian crop residue; Indonesian and extratropical peat; and cooking fires in traditional and advanced stoves. In this work, we present the primary emissions of gas-phase non-methane organic compounds (NMOCs) measured using an advanced Proton-Transfer-Reaction time-of-flight mass spectrometer (PTR-TOF-MS) in tandem with measurements of other major emissions by Fourier transform infrared (FTIR) spectroscopy. We developed a composition and mass dependent sensitivity and best assignments for many observed peaks. The known and tentatively assigned peaks together account for ~80-96% of total observed NMOC mass. Much of the NMOC mass is rarely measured or previously unmeasured high molecular mass compounds including ringed aromatic hydrocarbons, phenolic compounds, and furans, which are all secondary organic aerosol precursors. Large air quality benefits are demonstrated for more advanced cooking technologies. This work produced globally relevant emission ratios and emission factors to better represent biomass burning in current atmospheric models.

  10. Insight into the time-resolved extraction of aroma compounds during espresso coffee preparation: online monitoring by PTR-ToF-MS.

    PubMed

    Sánchez-López, José A; Zimmermann, Ralf; Yeretzian, Chahan

    2014-12-01

    Using proton-transfer-reaction time-of-flight mass-spectrometry (PTR-ToF-MS), we investigated the extraction dynamic of 95 ion traces in real time (time resolution = 1 s) during espresso coffee preparation. Fifty-two of these ions were tentatively identified. This was achieved by online sampling of the volatile organic compounds (VOCs) in close vicinity to the coffee flow, at the exit of the extraction hose of the espresso machine (single serve capsules). Ten replicates of six different single serve coffee types were extracted to a final weight between 20-120 g, according to the recommended cup size of the respective coffee capsule (Ristretto, Espresso, and Lungo), and analyzed. The results revealed considerable differences in the extraction kinetics between compounds, which led to a fast evolution of the volatile profiles in the extract flow and consequently to an evolution of the final aroma balance in the cup. Besides exploring the time-resolved extraction dynamics of VOCs, the dynamic data also allowed the coffees types (capsules) to be distinguished from one another. Both hierarchical cluster analysis (HCA) and principal component analysis (PCA) showed full separation between the coffees types. The methodology developed provides a fast and simple means of studying the extraction dynamics of VOCs and differentiating between different coffee types. PMID:25372898

  11. Rapid and direct volatile compound profiling of black and green teas (Camellia sinensis) from different countries with PTR-ToF-MS.

    PubMed

    Yener, Sine; Sánchez-López, José A; Granitto, Pablo M; Cappellin, Luca; Märk, Tilmann D; Zimmermann, Ralf; Bonn, Günther K; Yeretzian, Chahan; Biasioli, Franco

    2016-05-15

    Volatile profiles of 63 black and 38 green teas from different countries were analysed with Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) both for tea leaves and tea infusion. The headspace volatile fingerprints were collected and the tea classes and geographical origins were tracked with pattern recognition techniques. The high mass resolution achieved by ToF mass analyser provided determination of sum formula and tentative identifications of the mass peaks. The results provided successful separation of the black and green teas based on their headspace volatile emissions both from the dry tea leaves and their infusions. The volatile fingerprints were then used to build different classification models for discrimination of black and green teas according to their geographical origins. Two different cross validation methods were applied and their effectiveness for origin discrimination was discussed. The classification models showed a separation of black and green teas according to geographical origins the errors being mostly between neighbouring countries. PMID:26992494

  12. NEUTRONIC REACTOR

    DOEpatents

    Metcalf, H.E.; Johnson, H.W.

    1961-04-01

    BS>A nuclear reactor incorporating fuel rods passing through a moderator and including tubes of a material of higher Thermal conductivity than the fuel in contact with the fuel is described. The tubes extend beyond the active portion of the reactor into contant with a fiuld coolant.

  13. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1958-04-22

    A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.

  14. Compact Reactor

    SciTech Connect

    Williams, Pharis E.

    2007-01-30

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date.

  15. NUCLEAR REACTOR

    DOEpatents

    Moore, R.V.; Bowen, J.H.; Dent, K.H.

    1958-12-01

    A heterogeneous, natural uranium fueled, solid moderated, gas cooled reactor is described, in which the fuel elements are in the form of elongated rods and are dlsposed within vertical coolant channels ln the moderator symmetrically arranged as a regular lattice in groups. This reactor employs control rods which operate in vertical channels in the moderator so that each control rod is centered in one of the fuel element groups. The reactor is enclosed in a pressure vessel which ls provided with access holes at the top to facilitate loading and unloadlng of the fuel elements, control rods and control rod driving devices.

  16. NUCLEAR REACTOR

    DOEpatents

    Sherman, J.; Sharbaugh, J.E.; Fauth, W.L. Jr.; Palladino, N.J.; DeHuff, P.G.

    1962-10-23

    A nuclear reactor incorporating seed and blanket assemblies is designed. Means are provided for obtaining samples of the coolant from the blanket assemblies and for varying the flow of coolant through the blanket assemblies. (AEC)

  17. NEUTRONIC REACTOR

    DOEpatents

    Anderson, H.L.

    1960-09-20

    A nuclear reactor is described comprising fissionable material dispersed in graphite blocks, helium filling the voids of the blocks and the spaces therebetween, and means other than the helium in thermal conductive contact with the graphite for removing heat.

  18. NEUTRONIC REACTOR

    DOEpatents

    Hurwitz, H. Jr.; Brooks, H.; Mannal, C.; Payne, J.H.; Luebke, E.A.

    1959-03-24

    A reactor of the heterogeneous, liquid cooled type is described. This reactor is comprised of a central region of a plurality of vertically disposed elongated tubes surrounded by a region of moderator material. The central region is comprised of a central core surrounded by a reflector region which is surrounded by a fast neutron absorber region, which in turn is surrounded by a slow neutron absorber region. Liquid sodium is used as the primary coolant and circulates through the core which contains the fuel elements. Control of the reactor is accomplished by varying the ability of the reflector region to reflect neutrons back into the core of the reactor. For this purpose the reflector is comprised of moderator and control elements having varying effects on reactivity, the control elements being arranged and actuated by groups to give regulation, shim, and safety control.

  19. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.

    1960-04-01

    A nuclear reactor is described consisting of blocks of graphite arranged in layers, natural uranium bodies disposed in holes in alternate layers of graphite blocks, and coolant tubes disposed in the layers of graphite blocks which do not contain uranium.

  20. REACTOR SHIELD

    DOEpatents

    Wigner, E.P.; Ohlinger, L.E.; Young, G.J.; Weinberg, A.M.

    1959-02-17

    Radiation shield construction is described for a nuclear reactor. The shield is comprised of a plurality of steel plates arranged in parallel spaced relationship within a peripheral shell. Reactor coolant inlet tubes extend at right angles through the plates and baffles are arranged between the plates at right angles thereto and extend between the tubes to create a series of zigzag channels between the plates for the circulation of coolant fluid through the shield. The shield may be divided into two main sections; an inner section adjacent the reactor container and an outer section spaced therefrom. Coolant through the first section may be circulated at a faster rate than coolant circulated through the outer section since the area closest to the reactor container is at a higher temperature and is more radioactive. The two sections may have separate cooling systems to prevent the coolant in the outer section from mixing with the more contaminated coolant in the inner section.

  1. NUCLEAR REACTOR

    DOEpatents

    Miller, H.I.; Smith, R.C.

    1958-01-21

    This patent relates to nuclear reactors of the type which use a liquid fuel, such as a solution of uranyl sulfate in ordinary water which acts as the moderator. The reactor is comprised of a spherical vessel having a diameter of about 12 inches substantially surrounded by a reflector of beryllium oxide. Conventionnl control rods and safety rods are operated in slots in the reflector outside the vessel to control the operation of the reactor. An additional means for increasing the safety factor of the reactor by raising the ratio of delayed neutrons to prompt neutrons, is provided and consists of a soluble sulfate salt of beryllium dissolved in the liquid fuel in the proper proportion to obtain the result desired.

  2. NUCLEAR REACTOR

    DOEpatents

    Anderson, C.R.

    1962-07-24

    A fluidized bed nuclear reactor and a method of operating such a reactor are described. In the design means are provided for flowing a liquid moderator upwardly through the center of a bed of pellets of a nentron-fissionable material at such a rate as to obtain particulate fluidization while constraining the lower pontion of the bed into a conical shape. A smooth circulation of particles rising in the center and falling at the outside of the bed is thereby established. (AEC)

  3. NUCLEAR REACTOR

    DOEpatents

    Breden, C.R.; Dietrich, J.R.

    1961-06-20

    A water-soluble non-volatile poison may be introduced into a reactor to nullify excess reactivity. The poison is removed by passing a side stream of the water containing the soluble poison to an evaporation chamber. The vapor phase is returned to the reactor to decrease the concentration of soluble poison and the liquid phase is returned to increase the concentration of soluble poison.

  4. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1959-07-14

    High temperature reactors which are uniquely adapted to serve as the heat source for nuclear pcwered rockets are described. The reactor is comprised essentially of an outer tubular heat resistant casing which provides the main coolant passageway to and away from the reactor core within the casing and in which the working fluid is preferably hydrogen or helium gas which is permitted to vaporize from a liquid storage tank. The reactor core has a generally spherical shape formed entirely of an active material comprised of fissile material and a moderator material which serves as a diluent. The active material is fabricated as a gas permeable porous material and is interlaced in a random manner with very small inter-connecting bores or capillary tubes through which the coolant gas may flow. The entire reactor is divided into successive sections along the direction of the temperature gradient or coolant flow, each section utilizing materials of construction which are most advantageous from a nuclear standpoint and which at the same time can withstand the operating temperature of that particular zone. This design results in a nuclear reactor characterized simultaneously by a minimum critiral size and mass and by the ability to heat a working fluid to an extremely high temperature.

  5. Measurement of aerosol organic compounds during TexAQS 2006 using a novel collection/thermal-desorption PTR-ITMS instrument

    NASA Astrophysics Data System (ADS)

    Thornberry, T.; Murphy, D. M.; Thomson, D. S.; Welsh-Bon, D.; Warneke, C.; Bates, T. S.; Coffman, D.; Lerner, B.; Williams, E. J.

    2007-12-01

    Knowledge of the organic species present in atmospheric aerosols is needed in order to understand their effect on aerosol microphysical and optical properties, to resolve outstanding questions about important organic aerosol sources and formation mechanisms, and to elucidate the role of aerosols in the chemistry of the atmosphere through their interaction with gas-phase compounds. The measurement of aerosol organic compounds poses a significant experimental challenge due to the complexity and large number of organic species and the low concentration at which individual species are present. A new instrument that utilizes proton- transfer-reaction mass spectrometry (PTR-MS) to probe the organic composition of atmospheric aerosols has been developed to investigate semi-volatile and condensed-phase organic species in the atmosphere. Aerosols are collected by impaction and then thermally desorbed into a carrier gas that transports the organic analyte molecules into a drift tube where they are ionized by reaction with H3O+ ions. Analyte ions are detected using an ion trap mass spectrometer. The instrument was deployed for the first time during summer 2006 in the Texas Air Quality Study (TexAQS 2006) aboard NOAA R.V. Ronald H. Brown. Signals significantly above detection limit were observed at a number of masses during periods of elevated photochemical activity when aerosol loading increased in the 0.5-1 μm size range and aerosol mass spectrometer (AMS) measurements indicated increased organic mass. Different masses exhibited different temporal behaviors, indicating varying composition of the aerosol organic fraction even during periods when the AMS organic mass (OA) loading was relatively constant. Plumes of aerosol-phase pyridine were observed during sampling near the entrance to the Houston Ship Channel, indicating a relatively local source and rapid partitioning to the aerosol phase. These field results and results of laboratory instrument performance experiments

  6. Characterisation of Criegee intermediates in the gas phase by stabilisation with a spin trap and analysis by proton transfer reaction mass spectrometry (PTR-MS)

    NASA Astrophysics Data System (ADS)

    Giorio, Chiara; Tapparo, Andrea; Barbon, Antonio; Toffoletti, Antonio; Kalberer, Markus

    2014-05-01

    Biogenic and anthropogenic volatile organic compounds (VOCs) can react with o xidants present in the atmosphere to form less volatile compounds which could partition in the condensed phase and contribute to organic aerosol mass. One of the most important and efficient reaction for the formation of secondary organic aerosol (SOA) is the ozonolysis of alkenes. This process occurs with a generally accepted mechanism, proposed for the first time by Rudolf Criegee (Criegee, 1975). According to the Criegee mechanism, ozone coordinates to the double bond of alkenes forming a primary ozonide, which promptly decomposes to form biradical intermediates called Criegee intermediates (CIs). CIs further react quickly to form first generation oxidation products. The analysis of Criegee intermediates represent an analytical challenge due to their characteristic high reactivity and low concentrations. Their role in the formation of SOA remains highly uncertain because of uncertainty in the kinetic of their reaction with different atmospheric compounds. Up to date, only a few studies have been able to detect the CIs directly (Welz et al., 2012) or indirectly (Mauldin et al., 2012). The aim of this study is the development of a method for the on-line measurement of CIs by stabilization with a spin trap (5,5-dimethyl-pyrroline N-oxide, DMPO) and detection via proton transfer reaction mass spectrometry (PTR-MS). The novel method is used to study the ozonolysis of α-pinene in a flow tube, one of the most important precursors in the formation of SOA, often used as a proxy in global aerosol models to study the effects of biogenic organic aerosols on climate change. Criegee R., 1975. Angewandte Chemie 14, 745-752. Welz O., et al., 2012. Science 335, 204 207. Mauldin R. L., et al., 2012. Nature 488, 193-196.

  7. Volatile organic compound (VOC) emissions characterization during the flow-back phase of a hydraulically refractured well in the Uintah Basin, Utah using mobile PTR-MS measurements

    NASA Astrophysics Data System (ADS)

    Geiger, F.; Warneke, C.; Brown, S. S.; De Gouw, J. A.; Dube, W. P.; Edwards, P.; Gilman, J.; Graus, M.; Helleis, F.; Kofler, J.; Lerner, B. M.; Orphal, J.; Petron, G.; Roberts, J. M.; Zahn, A.

    2014-12-01

    Ongoing improvements in advanced technologies for crude oil and natural gas extraction from unconventional reserves, such as directional drilling and hydraulic fracturing, have greatly increased the production of fossil fuels within recent years. The latest forecasts even estimate an enhancement of 56% in total natural gas production due to increased development of shale gas, tight gas and offshore natural gas resources from 2012 to 2040 with the largest contribution from shale formations [US EIA: Annual Energy Outlook 2014]. During the field intensive 'Energy and Environment - Uintah Basin Winter Ozone Study (UBWOS)', measurements of volatile organic compounds (VOCs) were made using proton-transfer-reactions mass spectrometry (PTR-MS) at the ground site Horse Pool and using a mobile laboratory in the Uintah Basin, Utah, which is a region well known for intense fossil fuel production. A reworked gas well in the Red Wash fields was sampled regularly within two weeks performing mobile laboratory measurements downwind of the well site. The well had been recently hydraulically refractured at that time and waste water was collected into an open flow-back pond. Very high mixing ratios of aromatic hydrocarbons (C6-C13) up to the ppm range were observed coming from condensate and flow-back reservoirs. The measurements are used to determine sources of specific VOC emissions originating from the different parts of the well site and mass spectra are used to classify the air composition in contrast to samples taken at the Horse Pool field site and crude oil samples from South Louisiana. Enhancement ratios and time series of measured peak values for aromatics showed no clear trend, which indicates changes in emissions with operations at the site.

  8. Research reactors - an overview

    SciTech Connect

    West, C.D.

    1997-03-01

    A broad overview of different types of research and type reactors is provided in this paper. Reactor designs and operating conditions are briefly described for four reactors. The reactor types described include swimming pool reactors, the High Flux Isotope Reactor, the Mark I TRIGA reactor, and the Advanced Neutron Source reactor. Emphasis in the descriptions is placed on safety-related features of the reactors. 7 refs., 7 figs., 2 tabs.

  9. NEUTRONIC REACTOR

    DOEpatents

    Ohlinger, L.A.; Wigner, E.P.; Weinberg, A.M.; Young, G.J.

    1958-09-01

    This patent relates to neutronic reactors of the heterogeneous water cooled type, and in particular to a fuel element charging and discharging means therefor. In the embodiment illustrated the reactor contains horizontal, parallel coolant tubes in which the fuel elements are disposed. A loading cart containing a magnzine for holding a plurality of fuel elements operates along the face of the reactor at the inlet ends of the coolant tubes. The loading cart is equipped with a ram device for feeding fuel elements from the magazine through the inlot ends of the coolant tubes. Operating along the face adjacent the discharge ends of the tubes there is provided another cart means adapted to receive irradiated fuel elements as they are forced out of the discharge ends of the coolant tubes by the incoming new fuel elements. This cart is equipped with a tank coataining a coolant, such as water, into which the fuel elements fall, and a hydraulically operated plunger to hold the end of the fuel element being discharged. This inveation provides an apparatus whereby the fuel elements may be loaded into the reactor, irradiated therein, and unloaded from the reactor without stopping the fiow of the coolant and without danger to the operating personnel.

  10. POWER REACTOR

    DOEpatents

    Zinn, W.H.

    1958-07-01

    A fast nuclear reactor system ls described for producing power and radioactive isotopes. The reactor core is of the heterogeneous, fluid sealed type comprised of vertically arranged elongated tubular fuel elements having vertical coolant passages. The active portion is surrounded by a neutron reflector and a shield. The system includes pumps and heat exchangers for the primary and secondary coolant circuits. The core, primary coolant pump and primary heat exchanger are disposed within an irapenforate tank which is filled with the primary coolant, in this case a liquid metal such as Na or NaK, to completely submerge these elements. The tank is completely surrounded by a thick walled concrete shield. This reactor system utilizes enriched uranium or plutonium as the fissionable material, uranium or thorium as a diluent and thorium or uranium containing less than 0 7% of the U/sup 235/ isotope as a fertile material.

  11. NEUTRONIC REACTORS

    DOEpatents

    Wigner, E.P.; Young, G.J.

    1958-10-14

    A method is presented for loading and unloading rod type fuel elements of a neutronic reactor of the heterogeneous, solld moderator, liquid cooled type. In the embodiment illustrated, the fuel rods are disposed in vertical coolant channels in the reactor core. The fuel rods are loaded and unloaded through the upper openings of the channels which are immersed in the coolant liquid, such as water. Unloading is accomplished by means of a coffer dam assembly having an outer sleeve which is placed in sealing relation around the upper opening. A radiation shield sleeve is disposed in and reciprocable through the coffer dam sleeve. A fuel rod engaging member operates through the axial bore in the radiation shield sleeve to withdraw the fuel rod from its position in the reactor coolant channel into the shield, the shield snd rod then being removed. Loading is accomplished in the reverse procedure.

  12. Catalytic reactor

    DOEpatents

    Aaron, Timothy Mark; Shah, Minish Mahendra; Jibb, Richard John

    2009-03-10

    A catalytic reactor is provided with one or more reaction zones each formed of set(s) of reaction tubes containing a catalyst to promote chemical reaction within a feed stream. The reaction tubes are of helical configuration and are arranged in a substantially coaxial relationship to form a coil-like structure. Heat exchangers and steam generators can be formed by similar tube arrangements. In such manner, the reaction zone(s) and hence, the reactor is compact and the pressure drop through components is minimized. The resultant compact form has improved heat transfer characteristics and is far easier to thermally insulate than prior art compact reactor designs. Various chemical reactions are contemplated within such coil-like structures such that as steam methane reforming followed by water-gas shift. The coil-like structures can be housed within annular chambers of a cylindrical housing that also provide flow paths for various heat exchange fluids to heat and cool components.

  13. NUCLEAR REACTOR

    DOEpatents

    Christy, R.F.

    1958-07-15

    A nuclear reactor of the homogeneous liquid fuel type is described wherein the fissionable isotope is suspended or dissolved in a liquid moderator such as water. The reactor core is comprised essentially of a spherical vessel for containing the reactive composition surrounded by a reflector, preferably of beryllium oxide. The reactive composition may be an ordinary water solution of a soluble salt of uranium, the quantity of fissionable isotope in solution being sufficient to provide a critical mass in the vessel. The liquid fuel is stored in a tank of non-crtttcal geometry below the reactor vessel and outside of the reflector and is passed from the tank to the vessel through a pipe connecting the two by air pressure means. Neutron absorbing control and safety rods are operated within slots in the reflector adjacent to the vessel.

  14. Bioconversion reactor

    DOEpatents

    McCarty, Perry L.; Bachmann, Andre

    1992-01-01

    A bioconversion reactor for the anaerobic fermentation of organic material. The bioconversion reactor comprises a shell enclosing a predetermined volume, an inlet port through which a liquid stream containing organic materials enters the shell, and an outlet port through which the stream exits the shell. A series of vertical and spaced-apart baffles are positioned within the shell to force the stream to flow under and over them as it passes from the inlet to the outlet port. The baffles present a barrier to the microorganisms within the shell causing them to rise and fall within the reactor but to move horizontally at a very slow rate. Treatment detention times of one day or less are possible.

  15. REACTOR CONTROL

    DOEpatents

    Fortescue, P.; Nicoll, D.

    1962-04-24

    A control system employed with a high pressure gas cooled reactor in which a control rod is positioned for upward and downward movement into the neutron field from a position beneath the reactor is described. The control rod is positioned by a coupled piston cylinder releasably coupled to a power drive means and the pressurized coolant is directed against the lower side of the piston. The coolant pressure is offset by a higher fiuid pressure applied to the upper surface of the piston and means are provided for releasing the higher pressure on the upper side of the piston so that the pressure of the coolant drives the piston upwardly, forcing the coupled control rod into the ncutron field of the reactor. (AEC)

  16. Bioconversion reactor

    SciTech Connect

    McCarty, P.L.; Bachmann, A.

    1992-02-25

    A bioconversion reactor is described for the anaerobic fermentation of organic material. The bioconversion reactor comprises a shell enclosing a predetermined volume, an inlet port through which a liquid stream containing organic materials enters the shell, and an outlet port through which the stream exits the shell. A series of vertical and spaced-apart baffles are positioned within the shell to force the stream to flow under and over them as it passes from the inlet to the outlet port. The baffles present a barrier to the microorganisms within the shell causing them to rise and fall within the reactor but to move horizontally at a very slow rate. Treatment detention times of one day or less are possible. 7 figs.

  17. NUCLEAR REACTOR

    DOEpatents

    Young, G.

    1963-01-01

    This patent covers a power-producing nuclear reactor in which fuel rods of slightly enriched U are moderated by heavy water and cooled by liquid metal. The fuel rods arranged parallel to one another in a circle are contained in a large outer closed-end conduit that extends into a tank containing the heavy water. Liquid metal is introduced into the large conduit by a small inner conduit that extends within the circle of fuel rods to a point near the lower closed end of the outer conduit. (AEC) Production Reactors

  18. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.; Weinberg, A.W.; Young, G.J.

    1958-04-15

    A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

  19. Sonochemical Reactors.

    PubMed

    Gogate, Parag R; Patil, Pankaj N

    2016-10-01

    Sonochemical reactors are based on the generation of cavitational events using ultrasound and offer immense potential for the intensification of physical and chemical processing applications. The present work presents a critical analysis of the underlying mechanisms for intensification, available reactor configurations and overview of the different applications exploited successfully, though mostly at laboratory scales. Guidelines have also been presented for optimum selection of the important operating parameters (frequency and intensity of irradiation, temperature and liquid physicochemical properties) as well as the geometric parameters (type of reactor configuration and the number/position of the transducers) so as to maximize the process intensification benefits. The key areas for future work so as to transform the successful technique at laboratory/pilot scale into commercial technology have also been discussed. Overall, it has been established that there is immense potential for sonochemical reactors for process intensification leading to greener processing and economic benefits. Combined efforts from a wide range of disciplines such as material science, physics, chemistry and chemical engineers are required to harness the benefits at commercial scale operation. PMID:27573503

  20. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1960-09-27

    A unit assembly is described for a neutronic reactor comprising a tube and plurality of spaced parallel sandwiches in the tube extending lengthwise thereof, each sandwich including a middle plate having a central opening for plutonium and other openings for fertile material at opposite ends of the plate.

  1. NEUTRONIC REACTOR

    DOEpatents

    Creutz, E.C.; Ohlinger, L.A.; Weinberg, A.M.; Wigner, E.P.; Young, G.J.

    1959-10-27

    BS>A reactor cooled by water, biphenyl, helium, or other fluid with provision made for replacing the fuel rods with the highest plutonium and fission product content without disassembling the entire core and for promptly cooling the rods after their replacement in order to prevent build-up of heat from fission product activity is described.

  2. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.; Babcock, Dale F.; Menegus, Robert L.

    1983-01-01

    A nuclear reactor includes an active portion with fissionable fuel and neutron moderating material surrounded by neutron reflecting material. A control element in the active portion includes a group of movable rods constructed of neutron-absorbing material. Each rod is movable with respect to the other rods to vary the absorption of neutrons and effect control over neutron flux.

  3. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.

    1976-08-17

    A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

  4. Neutronic reactor

    DOEpatents

    Carleton, John T.

    1977-01-25

    A graphite-moderated nuclear reactor includes channels between blocks of graphite and also includes spacer blocks between adjacent channeled blocks with an axis of extension normal to that of the axis of elongation of the channeled blocks to minimize changes in the physical properties of the graphite as a result of prolonged neutron bombardment.

  5. Chemodiversity in the fingerprint analysis of volatile organic compounds (VOCs) of 35 old and 7 modern apple cultivars determined by proton-transfer-reaction mass spectrometry (PTR-MS) in two different seasons.

    PubMed

    Ciesa, Flavio; Höller, Irene; Guerra, Walter; Berger, Jennifer; Dalla Via, Josef; Oberhuber, Michael

    2015-05-01

    Volatile organic compounds (VOCs) are chemical species that play an important role in determining the characteristic aroma and flavor of fruits. Apple (Malus × domestica Borkh.) cultivars differ in their aroma and composition of VOCs. To determine varietal differences in the aroma profiles, VOCs emitted by 7 modern and 35 old apple cultivars were analyzed using Proton Transfer Reaction Mass Spectrometry (PTR-MS). PTR-MS is a rapid, reproducible, and non-destructive spectrometric technique for VOC analysis of single fruits, developed for direct injection analysis. In the present study, we analyzed the differences in the emission of VOCs from single fruits at harvest and after a storage period of 60±10 days, followed by 3 d of shelf life. Our results show that VOC profile differences among apple cultivars were more pronounced after storage than at harvest. Furthermore, chemodiversity was higher in old cultivars compared to modern cultivars, probably due to their greater genetic variability. Our data highlight the importance of storage and shelf life are crucial for the development of the typical aroma and flavor of several apple cultivars. The validity of the method is demonstrated by comparison of two different harvest years. PMID:26010667

  6. NEUTRONIC REACTOR

    DOEpatents

    Wade, E.J.

    1958-09-16

    This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of slow neutrons surrounds the absorber of fast neutrons and is formed of a plurality of beryllium blocks having natural uranium members distributcd therethrough. in addition, a movable body is positioned directly below the core and is comprised of a beryllium reflector and an absorbing member attached to the botiom thereof, the absorbing member containing a substance selected from the goup consisting of natural urantum and Th/sup 232/.

  7. REACTOR MONITORING

    DOEpatents

    Bugbee, S.J.; Hanson, V.F.; Babcock, D.F.

    1959-02-01

    A neutron density inonitoring means for reactors is described. According to this invention a tunnel is provided beneath and spaced from the active portion of the reactor and extends beyond the opposite faces of the activc portion. Neutron beam holes are provided between the active portion and the tunnel and open into the tunnel near the middle thereof. A carriage operates back and forth in the tunnel and is adapted to convey a neutron detector, such as an ion chamber, and position it beneath one of the neutron beam holes. This arrangement affords convenient access of neutron density measuring instruments to a location wherein direct measurement of neutron density within the piles can be made and at the same time affords ample protection to operating personnel.

  8. REACTOR UNLOADING

    DOEpatents

    Leverett, M.C.

    1958-02-18

    This patent is related to gas cooled reactors wherein the fuel elements are disposed in vertical channels extending through the reactor core, the cooling gas passing through the channels from the bottom to the top of the core. The invention is a means for unloading the fuel elements from the core and comprises dump values in the form of flat cars mounted on wheels at the bottom of the core structure which support vertical stacks of fuel elements. When the flat cars are moved, either manually or automatically, for normal unloading purposes, or due to a rapid rise in the reproduction ratio within the core, the fuel elements are permtted to fall by gravity out of the core structure thereby reducing the reproduction ratio or stopping the reaction as desired.

  9. Nuclear reactor

    DOEpatents

    Wade, Elman E.

    1979-01-01

    A nuclear reactor including two rotatable plugs and a positive top core holddown structure. The top core holddown structure is divided into two parts: a small core cover, and a large core cover. The small core cover, and the upper internals associated therewith, are attached to the small rotating plug, and the large core cover, with its associated upper internals, is attached to the large rotating plug. By so splitting the core holddown structures, under-the-plug refueling is accomplished without the necessity of enlarging the reactor pressure vessel to provide a storage space for the core holddown structure during refueling. Additionally, the small and large rotating plugs, and their associated core covers, are arranged such that the separation of the two core covers to permit rotation is accomplished without the installation of complex lifting mechanisms.

  10. NUCLEAR REACTOR

    DOEpatents

    Treshow, M.

    1958-08-19

    A neuclear reactor is described of the heterogeneous type and employing replaceable tubular fuel elements and heavy water as a coolant and moderator. A pluraltty of fuel tubesa having their axes parallel, extend through a tank type pressure vessel which contatns the liquid moderator. The fuel elements are disposed within the fuel tubes in the reaetive portion of the pressure vessel during normal operation and the fuel tubes have removable plug members at each end to permit charging and discharging of the fuel elements. The fuel elements are cylindrical strands of jacketed fissionable material having helical exterior ribs. A bundle of fuel elements are held within each fuel tube with their longitudinal axes parallel, the ribs serving to space them apart along their lengths. Coolant liquid is circulated through the fuel tubes between the spaced fuel elements. Suitable control rod and monitoring means are provided for controlling the reactor.

  11. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1959-12-15

    A reactor which is particularly adapted tu serve as a heat source for a nuclear powered alrcraft or rocket is described. The core of this reactor consists of a porous refractory modera;or body which is impregnated with fissionable nuclei. The core is designed so that its surface forms tapered inlet and outlet ducts which are separated by the porous moderator body. In operation a gaseous working fluid is circulated through the inlet ducts to the surface of the moderator, enters and passes through the porous body, and is heated therein. The hot gas emerges into the outlet ducts and is available to provide thrust. The principle advantage is that tremendous quantities of gas can be quickly heated without suffering an excessive pressure drop.

  12. NUCLEAR REACTORS

    DOEpatents

    Koch, L.J.; Rice, R.E. Jr.; Denst, A.A.; Rogers, A.J.; Novick, M.

    1961-12-01

    An active portion assembly for a fast neutron reactor is described wherein physical distortions resulting in adverse changes in the volume-to-mass ratio are minimized. A radially expandable locking device is disposed within a cylindrical tube within each fuel subassembly within the active portion assembly, and clamping devices expandable toward the center of the active portion assembly are disposed around the periphery thereof. (AEC)

  13. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1961-01-24

    A core structure for neutronic reactors adapted for the propulsion of aircraft and rockets is offered. The core is designed for cooling by gaseous media, and comprises a plurality of hollow tapered tubular segments of a porous moderating material impregniated with fissionable fuel nested about a common axis. Alternate ends of the segments are joined. In operation a coolant gas passes through the porous structure and is heated.

  14. NUCLEAR REACTORS

    DOEpatents

    Long, E.; Ashby, J.W.

    1958-09-16

    ABS>A graphite moderator structure is presented for a nuclear reactor compriscd of an assembly of similarly orientated prismatic graphite blocks arranged on spaced longitudinal axes lying in common planes wherein the planes of the walls of the blocks are positioned so as to be twisted reintive to the planes of said axes so thatthe unlmpeded dtrect paths in direction wholly across the walls of the blocks are limited to the width of the blocks plus spacing between the blocks.

  15. REACTOR CONTROL

    DOEpatents

    Ruano, W.J.

    1957-12-10

    This patent relates to nuclear reactors of the type which utilize elongited rod type fuel elements immersed in a liquid moderator and shows a design whereby control of the chain reaction is obtained by varying the amount of moderator or reflector material. A central tank for containing liquid moderator and fuel elements immersed therein is disposed within a surrounding outer tank providing an annular space between the two tanks. This annular space is filled with liquid moderator which functions as a reflector to reflect neutrons back into the central reactor tank to increase the reproduction ratio. Means are provided for circulating and cooling the moderator material in both tanks and additional means are provided for controlling separately the volume of moderator in each tank, which latter means may be operated automatically by a neutron density monitoring device. The patent also shows an arrangement for controlling the chain reaction by injecting and varying an amount of poisoning material in the moderator used in the reflector portion of the reactor.

  16. Nuclear reactor

    DOEpatents

    Pennell, William E.; Rowan, William J.

    1977-01-01

    A nuclear reactor in which the core components, including fuel-rod assemblies, control-rod assemblies, fertile rod-assemblies, and removable shielding assemblies, are supported by a plurality of separate inlet modular units. These units are referred to as inlet module units to distinguish them from the modules of the upper internals of the reactor. The modular units are supported, each removable independently of the others, in liners in the supporting structure for the lower internals of the reactor. The core assemblies are removably supported in integral receptacles or sockets of the modular units. The liners, units, sockets and assmblies have inlet openings for entry of the fluid. The modular units are each removably mounted in the liners with fluid seals interposed between the opening in the liner and inlet module into which the fluid enters and the upper and lower portion of the liner. Each assembly is similarly mounted in a corresponding receptacle with fluid seals interposed between the openings where the fluid enters and the lower portion of the receptacle or fitting closely in these regions. As fluid flows along each core assembly a pressure drop is produced along the fluid so that the fluid which emerges from each core assembly is at a lower pressure than the fluid which enters the core assembly. However because of the seals interposed in the mountings of the units and assemblies the pressures above and below the units and assemblies are balanced and the units are held in the liners and the assemblies are held in the receptacles by their weights as they have a higher specific gravity than the fluid. The low-pressure spaces between each module and its liner and between each core assembly and its module is vented to the low-pressure regions of the vessel to assure that fluid which leaks through the seals does not accumulate and destroy the hydraulic balance.

  17. ELECTRONUCLEAR REACTOR

    DOEpatents

    Lawrence, E.O.; McMillan, E.M.; Alvarez, L.W.

    1960-04-19

    An electronuclear reactor is described in which a very high-energy particle accelerator is employed with appropriate target structure to produce an artificially produced material in commercial quantities by nuclear transformations. The principal novelty resides in the combination of an accelerator with a target for converting the accelerator beam to copious quantities of low-energy neutrons for absorption in a lattice of fertile material and moderator. The fertile material of the lattice is converted by neutron absorption reactions to an artificially produced material, e.g., plutonium, where depleted uranium is utilized as the fertile material.

  18. REACTOR COMPONETN

    DOEpatents

    Creutz, E.C.

    1959-10-27

    A reactor fuel element comprised of a slug of fissionable material disposed in a sheath of corrosion resistantmaterial is described. The sheath is in the form of a tubular container closed at one end and is in tight-fitting engagement with the peripheral sunface of the slug. An inner cap is insented into the open end of the sheath against the slug, which end is then bent around the inner cap and welded thereto. An outer cap is then welded around its peripheny to the bent portion of the container.

  19. NUCLEAR REACTORS

    DOEpatents

    Long, E.; Ashley, J.W.

    1958-12-16

    A graphite moderator structure is described for a gas-cooled nuclear reactor having a vertical orlentation wherein the structure is physically stable with regard to dlmensional changes due to Wigner growth properties of the graphite, and leakage of coolant gas along spaces in the structure is reduced. The structure is comprised of stacks of unlform right prismatic graphite blocks positioned in layers extending in the direction of the lengths of the blocks, the adjacent end faces of the blocks being separated by pairs of tiles. The blocks and tiles have central bores which are in alignment when assembled and are provided with cooperatlng keys and keyways for physical stability.

  20. Nuclear Reactors. Revised.

    ERIC Educational Resources Information Center

    Hogerton, John F.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Among the topics discussed are: How Reactors Work; Reactor Design; Research, Teaching, and Materials Testing; Reactors (Research, Teaching and Materials); Production Reactors; Reactors for Electric Power…

  1. Hybrid adsorptive membrane reactor

    DOEpatents

    Tsotsis, Theodore T.; Sahimi, Muhammad; Fayyaz-Najafi, Babak; Harale, Aadesh; Park, Byoung-Gi; Liu, Paul K. T.

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  2. Hybrid adsorptive membrane reactor

    NASA Technical Reports Server (NTRS)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  3. Detailed gas and diesel vehicle emissions: PTR-MS measurements of real-time VOC profiles and comprehensive characterization of primary emissions for IVOC, SVOC, and LVOC by gas chromatography with vacuum ultra-violet ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Drozd, G.; Frodin, B.; Zhao, Y.; Franklin, J. P.; Cross, E. S.; Saleh, R.; Saliba, G.; Lambe, A. T.; Sardar, S.; Maldonado, H.; Russell, L. M.; Kroll, J. H.; Robinson, A. L.; Goldstein, A. H.

    2015-12-01

    Over the past fifteen years US vehicle emissions standards have dramatically improved, with the goal of reducing urban air pollution. Recent studies demonstrate secondary organic aerosol (SOA) to be the dominant contributor to urban organic aerosol, but controversy remains regarding the contributions of different vehicle types to SOA. Increased potency for SOA formation from non methane hydrocarbons (NMHC) from newer vehicles that meet tighter emission standards has also been observed. Both speciation and temporal resolution of vehicular emissions are critical for predicting SOA formation. The relative importance of diesel and gasoline emissions to SOA formation depends critically on speciation. Experiments were conducted at the California Air Resources Board Haagen-Smit Laboratory to better understand SOA formation for low, ultra-low, super ultra-low and partial zero emission vehicles (LEV, ULEV, SULEV, PZEV). Exhaust was sampled on filters and adsorbent tubes to measure intermediate-, semi-, and low-volatility NMHC (IVOC, SVOC, LVOC). A proton-transfer-reaction mass spectrometer (PTR-MS) measured volatile organics (VOC) emissions with high time-resolution. Analysis of filters and adsorbent tubes using gas chromatography with vacuum-ultra-violet ionization mass spectrometry provided unprecedented characterization of emissions according to degree of branching, number of cyclic rings, aromaticity, and molecular weight. ULEV vehicles show the composition distributions of primary particulate emissions peak for compounds in the SVOC range. PZEV vehicle emissions peak in the IVOC range. Diesel vehicles have up to ten times higher emissions than gasoline vehicles; their distributions have significant IVOC levels and peak in the SVOC/LVOC range. Our measurements are used to predict potential SOA formation by vehicle standard class and the relative SOA formation for diesel and gasoline vehicles. PTR-MS measurement show VOC emissions after cold start occur almost entirely

  4. Proton Transfer Reaction Time-of-Flight Mass Spectrometric (PTR-TOF-MS) determination of volatile organic compounds (VOCs) emitted from a biomass fire developed under stable nocturnal conditions

    NASA Astrophysics Data System (ADS)

    Brilli, Federico; Gioli, Beniamino; Ciccioli, Paolo; Zona, Donatella; Loreto, Francesco; Janssens, Ivan A.; Ceulemans, Reinhart

    2014-11-01

    Combustion of solid and liquid fuels is the largest source of potentially toxic volatile organic compounds (VOCs), which can strongly affect health and the physical and chemical properties of the atmosphere. Among combustion processes, biomass burning is one of the largest at global scale. We used a Proton Transfer Reaction “Time-of-Flight” Mass Spectrometer (PTR-TOF-MS), which couples high sensitivity with high mass resolution, for real-time detection of multiple VOCs emitted by burned hay and straw in a barn located near our measuring station. We detected 132 different organic ions directly attributable to VOCs emitted from the fire. Methanol, acetaldehyde, acetone, methyl vinyl ether (MVE), acetic acid and glycolaldehyde dominated the VOC mixture composition. The time-course of the 25 most abundant VOCs, representing ∼85% of the whole mixture of VOCs, was associated with that of carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4) emissions. The strong linear relationship between the concentrations of pyrogenic VOC and of a reference species (i.e. CO) allowed us to compile a list of emission ratios (ERs) and emission factors (EFs), but values of ER (and EF) were overestimated due to the limited mixing of the gases under the stable (non-turbulent) nocturnal conditions. In addition to the 25 most abundant VOCs, chemical formula and concentrations of the residual, less abundant VOCs in the emitted mixture were also estimated by PTR-TOF-MS. Furthermore, the evolution of the complex combustion process was described on the basis of the diverse types of pyrogenic gases recorded.

  5. Control Means for Reactor

    DOEpatents

    Manley, J. H.

    1961-06-27

    An apparatus for controlling a nuclear reactor includes a tank just below the reactor, tubes extending from the tank into the reactor, and a thermally expansible liquid neutron absorbent material in the tank. The liquid in the tank is exposed to a beam of neutrons from the reactor which heats the liquid causing it to expand into the reactor when the neutron flux in the reactor rises above a predetermincd danger point. Boron triamine may be used for this purpose.

  6. NEUTRONIC REACTOR

    DOEpatents

    Stewart, H.B.

    1958-12-23

    A nuclear reactor of the type speclfically designed for the irradiation of materials is discussed. In this design a central cyllndrical core of moderating material ls surrounded by an active portlon comprlsed of an annular tank contalning fissionable material immersed ln a liquid moderator. The active portion ls ln turn surrounded by a reflector, and a well ls provided in the center of the core to accommodate the materlals to be irradiated. The over-all dimensions of the core ln at least one plane are equal to or greater than twice the effective slowing down length and equal to or less than twlce the effective diffuslon length for neutrons in the core materials.

  7. NEUTRONIC REACTOR

    DOEpatents

    Daniels, F.

    1962-12-18

    A power plant is described comprising a turbine and employing round cylindrical fuel rods formed of BeO and UO/sub 2/ and stacks of hexagonal moderator blocks of BeO provided with passages that loosely receive the fuel rods so that coolant may flow through the passages over the fuels to remove heat. The coolant may be helium or steam and fiows through at least one more heat exchanger for producing vapor from a body of fluid separate from the coolant, which fluid is to drive the turbine for generating electricity. By this arrangement the turbine and directly associated parts are free of particles and radiations emanating from the reactor. (AEC)

  8. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1957-09-17

    A reactor of the type having coolant liquid circulated through clad fuel elements geometrically arranged in a solid moderator, such as graphite, is described. The core is enclosed in a pressure vessel and suitable shielding, wherein means is provided for circulating vapor through the core to superheat the same. This is accomplished by drawing off the liquid which has been heated in the core due to the fission of the fuel, passing it to a nozzle within a chamber where it flashes into a vapor, and then passing the vapor through separate tubes extending through the moderator to pick up more heat developed in the core due to the fission of the fuel, thereby producing superheated vapor.

  9. Nuclear reactor

    DOEpatents

    Yant, Howard W.; Stinebiser, Karl W.; Anzur, Gregory C.

    1977-01-01

    A nuclear reactor, particularly a liquid-metal breeder reactor, whose upper internals include outlet modules for channeling the liquid-metal coolant from selected areas of the outlet of the core vertically to the outlet plenum. The modules are composed of a highly-refractory, high corrosion-resistant alloy, for example, INCONEL-718. Each module is disposed to confine and channel generally vertically the coolant emitted from a subplurality of core-component assemblies. Each module has a grid with openings, each opening disposed to receive the coolant from an assembly of the subplurality. The grid in addition serves as a holdown for the assemblies of the corresponding subplurality preventing their excessive ejection upwardly from the core. In the region directly over the core the outlet modules are of such peripheral form that they nest forming a continuum over the core-component assemblies whose outlet coolant they confine. Each subassembly includes a chimney which confines the coolant emitted by its corresponding subassemblies to generally vertical flow between the outlet of the core and the outlet plenum. Each subplurality of assemblies whose emitted coolant is confined by an outlet module includes assemblies which emit lower-temperature coolant, for example, a control-rod assembly, or fertile assemblies, and assemblies which emit coolant of substantially higher temperature, for example, fuel-rod assemblies. The coolants of different temperatures are mixed in the chimneys reducing the effect of stripping (hot-cold temperature fluctuations) on the remainder of the upper internals which are composed typically of AISI-304 or AISI-316 stainless steel.

  10. Reactor and method of operation

    DOEpatents

    Wheeler, John A.

    1976-08-10

    A nuclear reactor having a flattened reactor activity curve across the reactor includes fuel extending over a lesser portion of the fuel channels in the central portion of the reactor than in the remainder of the reactor.

  11. Reactor safety method

    DOEpatents

    Vachon, Lawrence J.

    1980-03-11

    This invention relates to safety means for preventing a gas cooled nuclear reactor from attaining criticality prior to start up in the event the reactor core is immersed in hydrogenous liquid. This is accomplished by coating the inside surface of the reactor coolant channels with a neutral absorbing material that will vaporize at the reactor's operating temperature.

  12. NEUTRONIC REACTOR MANIPULATING DEVICE

    DOEpatents

    Ohlinger, L.A.

    1962-08-01

    A cable connecting a control rod in a reactor with a motor outside the reactor for moving the rod, and a helical conduit in the reactor wall, through which the cable passes are described. The helical shape of the conduit prevents the escape of certain harmful radiations from the reactor. (AEC)

  13. Nuclear reactor

    DOEpatents

    Thomson, Wallace B.

    2004-03-16

    A nuclear reactor comprising a cylindrical pressure vessel, an elongated annular core centrally disposed within and spaced from the pressure vessel, and a plurality of ducts disposed longitudinally of the pressure vessel about the periphery thereof, said core comprising an annular active portion, an annular reflector just inside the active portion, and an annular reflector just outside the active a portion, said annular active portion comprising rectangular slab, porous fuel elements radially disposed around the inner reflector and extending the length of the active portion, wedge-shaped, porous moderator elements disposed adjacent one face of each fuel element and extending the length of the fuel element, the fuel and moderator elements being oriented so that the fuel elements face each other and the moderator elements do likewise, adjacent moderator elements being spaced to provide air inlet channels, and adjacent fuel elements being spaced to provide air outlet channels which communicate with the interior of the peripheral ducts, and means for introducing air into the air inlet channels which passes through the porous moderator elements and porous fuel elements to the outlet channel.

  14. Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: high acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley

    NASA Astrophysics Data System (ADS)

    Sarkar, Chinmoy; Sinha, Vinayak; Kumar, Vinod; Rupakheti, Maheswar; Panday, Arnico; Mahata, Khadak S.; Rupakheti, Dipesh; Kathayat, Bhogendra; Lawrence, Mark G.

    2016-03-01

    The Kathmandu Valley in Nepal suffers from severe wintertime air pollution. Volatile organic compounds (VOCs) are key constituents of air pollution, though their specific role in the valley is poorly understood due to insufficient data. During the SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley-Atmospheric Brown Clouds) field campaign conducted in Nepal in the winter of 2012-2013, a comprehensive study was carried out to characterise the chemical composition of ambient Kathmandu air, including the determination of speciated VOCs, by deploying a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) - the first such deployment in South Asia. In the study, 71 ion peaks (for which measured ambient concentrations exceeded the 2σ detection limit) were detected in the PTR-TOF-MS mass scan data, highlighting the chemical complexity of ambient air in the valley. Of the 71 species, 37 were found to have campaign average concentrations greater than 200 ppt and were identified based on their spectral characteristics, ambient diel profiles and correlation with specific emission tracers as a result of the high mass resolution (m / Δm > 4200) and temporal resolution (1 min) of the PTR-TOF-MS. The concentration ranking in the average VOC mixing ratios during our wintertime deployment was acetaldehyde (8.8 ppb) > methanol (7.4 ppb) > acetone + propanal (4.2 ppb) > benzene (2.7 ppb) > toluene (1.5 ppb) > isoprene (1.1 ppb) > acetonitrile (1.1 ppb) > C8-aromatics ( ˜ 1 ppb) > furan ( ˜ 0.5 ppb) > C9-aromatics (0.4 ppb). Distinct diel profiles were observed for the nominal isobaric compounds isoprene (m / z = 69.070) and furan (m / z = 69.033). Comparison with wintertime measurements from several locations elsewhere in the world showed mixing ratios of acetaldehyde ( ˜ 9 ppb), acetonitrile ( ˜ 1 ppb) and isoprene ( ˜ 1 ppb) to be among the highest reported to date. Two "new" ambient compounds, namely formamide (m / z = 46.029) and acetamide (m / z

  15. Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: high acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley

    NASA Astrophysics Data System (ADS)

    Sarkar, C.; Sinha, V.; Kumar, V.; Rupakheti, M.; Panday, A.; Mahata, K. S.; Rupakheti, D.; Kathayat, B.; Lawrence, M. G.

    2015-09-01

    The Kathmandu Valley in Nepal suffers from severe wintertime air pollution. Volatile organic compounds (VOCs) are key constituents of air pollution, though their specific role in the Valley is poorly understood due to insufficient data. During the SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley-Atmospheric Brown Clouds) field campaign conducted in Nepal in the winter of 2012-2013, a comprehensive study was carried out to characterize the chemical composition of ambient Kathmandu air, including the determination of speciated VOCs by deploying a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS)-the first such deployment in South Asia. 71 ion peaks (for which measured ambient concentrations exceeded the 2 σ detection limit) were detected in the PTR-TOF-MS mass scan data, highlighting the chemical complexity of ambient air in the Valley. Of the 71 species, 37 were found to have campaign average concentrations greater than 200 ppt and were identified based on their spectral characteristics, ambient diel profiles and correlation with specific emission tracers as a result of the high mass resolution (m/Δm > 4200) and temporal resolution (1 min) of the PTR-TOF-MS. The highest average VOC mixing ratios during the measurement period were (in rank order): acetaldehyde (8.8 ppb), methanol (7.4 ppb), acetone (4.2 ppb), benzene (2.7 ppb), toluene (1.5 ppb), isoprene (1.1 ppb), acetonitrile (1.1 ppb), C8-aromatics (~ 1 ppb), furan (~ 0.5 ppb), and C9-aromatics (0.4 ppb). Distinct diel profiles were observed for the nominal isobaric compounds isoprene (m/z = 69.070) and furan (m/z = 69.033). Comparison with wintertime measurements from several locations elsewhere in the world showed mixing ratios of acetaldehyde (~ 9 ppb), acetonitrile (~ 1 ppb) and isoprene (~ 1 ppb) to be among the highest reported till date. Two "new" ambient compounds namely, formamide (m/z = 46.029) and acetamide (m/z = 60.051), which can photochemically produce isocyanic

  16. Calculations of the integral invariant coordinates I and L* in the magnetosphere and mapping of the regions where I is conserved, using a particle tracer (ptr3D v2.0), LANL*, SPENVIS, and IRBEM

    NASA Astrophysics Data System (ADS)

    Konstantinidis, K.; Sarris, T.

    2015-09-01

    The integral invariant coordinate I and Roederer's L or L* are proxies for the second and third adiabatic invariants, respectively, that characterize charged particle motion in a magnetic field. Their usefulness lies in the fact that they are expressed in more instructive ways than their counterparts: I is equivalent to the path length of the particle motion between two mirror points, whereas L*, although dimensionless, is equivalent to the distance from the center of the Earth to the equatorial point of a given field line, in units of Earth radii, in the simplified case of a dipole magnetic field. However, care should be taken when calculating the above invariants, as the assumption of their conservation is not valid everywhere in the Earth's magnetosphere. This is not clearly stated in state-of-the-art models that are widely used for the calculation of these invariants. The purpose of this work is thus to investigate where in the near-Earth magnetosphere we can safely calculate I and L* with tools with widespread use in the field of space physics, for various magnetospheric conditions and particle initial conditions. More particularly, in this paper we compare the values of I and L* as calculated using LANL*, an artificial neural network developed at the Los Alamos National Laboratory, SPENVIS, a space environment online tool, IRBEM, a software library dedicated to radiation belt modeling, and ptr3D, a 3-D particle tracing code that was developed for this study. We then attempt to quantify the variations between the calculations of I and L* of those models. The deviation between the results given by the models depends on particle initial position, pitch angle and magnetospheric conditions. Using the ptr3D v2.0 particle tracer we map the areas in the Earth's magnetosphere where I and L* can be assumed to be conserved by monitoring the constancy of I for energetic protons propagating forwards and backwards in time. These areas are found to be centered on the noon

  17. Volatile Organic Compound emissions from soil: using Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS) for the real time observation of microbial processes

    NASA Astrophysics Data System (ADS)

    Veres, P. R.; Behrendt, T.; Klapthor, A.; Meixner, F. X.; Williams, J.

    2014-08-01

    In this study we report on the emissions of volatile organic compounds (VOC) and nitric oxide (NO) from two contrasting soils (equatorial rainforest and arid cotton field) analyzed in a laboratory based dynamic chamber system. The effect of soil moisture and soil temperature on VOC and NO emission was examined in laboratory incubation experiments by measuring as a pre-saturated soil dried out. Our results suggest that real time monitoring of VOC emissions from soil using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) instrument can be used to improve our understanding of the release mechanisms of trace gases (e.g. NO, N2O) that are involved in the nitrogen cycle. Moreover, we report on the release rate of various VOC species, many of which exhibit a temperature dependent response indicative of biological production, namely a temperature amplification factor (Q10) ∼ 2-3. Contrary to the conventional modeling of NO emissions from soils, that the release of NO from the overall community across the range of soil water content can be modeled as an optimum function, we suggest that VOC measurements indicate there exist multiple distinct contributing microbial guilds releasing NO. These microbial guilds could likely be individually identified with the observed VOC profiles. Using a cotton field soil sample from a Sache oasis (Taklimakan desert, Xinijang, P. R. China), we identify five VOC emission groups with varying degrees of NO co-emission. An equatorial rainforest soil (Suriname) was shown to emit a variety of VOC including acetaldehyde, acetone, DMS, formaldehyde, and isoprene that vary strongly and individually as a function of temperature and soil moisture content. PTR-TOF-MS with high time resolution, sensitivity, and molecular specificity is an ideal tool for the real time analysis of VOC and NO emitting processes in soil systems. These experiments can be used as a template for future experiments to more completely and specifically

  18. Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: high acetaldehyde, ketene, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley

    NASA Astrophysics Data System (ADS)

    Sarkar, C.; Sinha, V.; Kumar, V.; Rupakheti, M.; Panday, A. K.; Mahata, K.; Rupakheti, D.; Kathayat, B.; Lawrence, M. G.

    2015-12-01

    During SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley-Atmospheric Brown Clouds) field campaign conducted in the winter of 2012-2013, a comprehensive study was carried out to characterize the chemical composition of ambient Kathmandu air for speciated VOCs by deploying a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS), the first time to be deployed in South Asia. Due to its high mass resolution (m/Δm > 4200) and temporal resolution (1 minute), 71 ion peaks were detected in the PTR-TOF-MS mass scan data, highlighting the chemical complexity of ambient air in the Valley. Of the 71, 38 species were found to have campaign average concentrations > 200 ppt and were identified based on their spectral characteristics, ambient diel profiles and correlation with specific emission tracers. Distinct diel profiles were observed for the nominal isobaric compounds isoprene (m/z=69.070) and furan (m/z=69.033). Comparison with several sites elsewhere in the world showed mixing ratios of acetaldehyde (~ 9 ppb), acetonitrile (~1 ppb) and isoprene (~ 1 ppb) to be among the highest measured anywhere in the world. Two "new" ambient compounds namely, methanamide (m/z = 46.029) and acetamide (m/z=60.051) which can photochemically produce isocyanic acid in the atmosphere, are reported in this study alongwith nitromethane (a tracer for diesel exhaust) and ketene (a very reactive compound). Two distinct periods were identified during the campaign based on high daytime biogenic emissions of isoprene even in winter and biomass fired brick kiln emissions of acetonitrile, benzene and isocyanic acid. Biomass burning and biomass fired brick kiln emissions were found to be the dominant source for compounds such as propyne, propene, benzene and propanenitrile which correlated strongly with biomass burning tracer acetonitrile (r2 > 0.7). The calculated total VOC OH reactivity was dominated by acetaldehyde (20.1%), ketene (ethenone) (17.1%), isoprene (16.8 %) and

  19. Hybrid plasmachemical reactor

    SciTech Connect

    Lelevkin, V. M. Smirnova, Yu. G.; Tokarev, A. V.

    2015-04-15

    A hybrid plasmachemical reactor on the basis of a dielectric barrier discharge in a transformer is developed. The characteristics of the reactor as functions of the dielectric barrier discharge parameters are determined.

  20. Attrition reactor system

    SciTech Connect

    Scott, C.D.; Davison, B.H.

    1993-09-28

    A reactor vessel for reacting a solid particulate with a liquid reactant has a centrifugal pump in circulatory flow communication with the reactor vessel for providing particulate attrition, resulting in additional fresh surface where the reaction can occur. 2 figures.

  1. Attrition reactor system

    SciTech Connect

    Scott, Charles D.; Davison, Brian H.

    1993-01-01

    A reactor vessel for reacting a solid particulate with a liquid reactant has a centrifugal pump in circulatory flow communication with the reactor vessel for providing particulate attrition, resulting in additional fresh surface where the reaction can occur.

  2. NEUTRONIC REACTOR POWER PLANT

    DOEpatents

    Metcalf, H.E.

    1962-12-25

    This patent relates to a nuclear reactor power plant incorporating an air-cooled, beryllium oxide-moderated, pebble bed reactor. According to the invention means are provided for circulating a flow of air through tubes in the reactor to a turbine and for directing a sidestream of the circu1ating air through the pebble bed to remove fission products therefrom as well as assist in cooling the reactor. (AEC)

  3. Period meter for reactors

    DOEpatents

    Rusch, Gordon K.

    1976-01-06

    An improved log N amplifier type nuclear reactor period meter with reduced probability for noise-induced scrams is provided. With the reactor at low power levels a sampling circuit is provided to determine the reactor period by measuring the finite change in the amplitude of the log N amplifier output signal for a predetermined time period, while at high power levels, differentiation of the log N amplifier output signal provides an additional measure of the reactor period.

  4. Reactor System Transient Code.

    Energy Science and Technology Software Center (ESTSC)

    1999-07-14

    RELAP3B describes the behavior of water-cooled nuclear reactors during postulated accidents or power transients, such as large reactivity excursions, coolant losses or pump failures. The program calculates flows, mass and energy inventories, pressures, temperatures, and steam qualities along with variables associated with reactor power, reactor heat transfer, or control systems. Its versatility allows one to describe simple hydraulic systems as well as complex reactor systems.

  5. Identification of volatile markers in potato brown rot and ring rot by combined GC-MS and PTR-MS techniques: study on in vitro and in vivo samples.

    PubMed

    Blasioli, Sonia; Biondi, Enrico; Samudrala, Devasena; Spinelli, Francesco; Cellini, Antonio; Bertaccini, Assunta; Cristescu, Simona M; Braschi, Ilaria

    2014-01-15

    Ralstonia solanacearum (Rs) and Clavibacter michiganensis subsp. sepedonicus (Cms) are the bacterial causal agents of potato brown and ring rot, respectively, and are included in the A2 list of quarantine pathogens in Europe. Identification by GC-MS analysis of volatile organic compounds from Rs or Cms cultured on different nutrient media was performed. GC-MS and PTR-MS analysis were carried out also on unwounded potato tubers infected with the same pathogens. Infected tubers were produced by experimental inoculations of the plants. In in vitro experiments, Rs or Cms emitted volatile compounds, part of which were specific disease markers of potato (2-propanol and 3-methylbutanoic acid), mainly originating from bacterial metabolism (i.e., amino acid degradation, carbohydrate and fatty acid oxidation). In potato tubers, pathogen metabolism modified the volatile compound pattern emitted from healthy samples. Both bacteria seem to accelerate metabolic processes ongoing in potatoes and, in the case of Rs, disease markers (1-hepten-3-ol, 3,6-dimethyl-3-octanone, 3-ethyl-3-methylpentane, 1-chloroctane, and benzothiazole) were identified. PMID:24313381

  6. Advanced Test Reactor Tour

    SciTech Connect

    Miley, Don

    2011-01-01

    The Advanced Test Reactor at Idaho National Laboratory is the foremost nuclear materials test reactor in the world. This virtual tour describes the reactor, how experiments are conducted, and how spent nuclear fuel is handled and stored. For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

  7. Advanced Test Reactor Tour

    ScienceCinema

    Miley, Don

    2013-05-28

    The Advanced Test Reactor at Idaho National Laboratory is the foremost nuclear materials test reactor in the world. This virtual tour describes the reactor, how experiments are conducted, and how spent nuclear fuel is handled and stored. For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

  8. NEUTRONIC REACTOR SHIELDING

    DOEpatents

    Borst, L.B.

    1961-07-11

    A special hydrogenous concrete shielding for reactors is described. In addition to Portland cement and water, the concrete essentially comprises 30 to 60% by weight barytes aggregate for enhanced attenuation of fast neutrons. The biological shields of AEC's Oak Ridge Graphite Reactor and Materials Testing Reactor are particular embodiments.

  9. Improved vortex reactor system

    DOEpatents

    Diebold, James P.; Scahill, John W.

    1995-01-01

    An improved vortex reactor system for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor.

  10. NUCLEAR REACTOR CONTROL SYSTEM

    DOEpatents

    Epler, E.P.; Hanauer, S.H.; Oakes, L.C.

    1959-11-01

    A control system is described for a nuclear reactor using enriched uranium fuel of the type of the swimming pool and other heterogeneous nuclear reactors. Circuits are included for automatically removing and inserting the control rods during the course of normal operation. Appropriate safety circuits close down the nuclear reactor in the event of emergency.

  11. University Reactor Instrumentation Grant

    SciTech Connect

    S. M. Bajorek

    2000-02-01

    A noble gas air monitoring system was purchased through the University Reactor Instrumentation Grant Program. This monitor was installed in the Kansas State TRIGA reactor bay at a location near the top surface of the reactor pool according to recommendation by the supplier. This system is now functional and has been incorporated into the facility license.

  12. High solids fermentation reactor

    DOEpatents

    Wyman, Charles E.; Grohmann, Karel; Himmel, Michael E.; Richard, Christopher J.

    1993-03-02

    A fermentation reactor and method for fermentation of materials having greater than about 10% solids. The reactor includes a rotatable shaft along the central axis, the shaft including rods extending outwardly to mix the materials. The reactor and method are useful for anaerobic digestion of municipal solid wastes to produce methane, for production of commodity chemicals from organic materials, and for microbial fermentation processes.

  13. High solids fermentation reactor

    DOEpatents

    Wyman, Charles E.; Grohmann, Karel; Himmel, Michael E.; Richard, Christopher J.

    1993-01-01

    A fermentation reactor and method for fermentation of materials having greater than about 10% solids. The reactor includes a rotatable shaft along the central axis, the shaft including rods extending outwardly to mix the materials. The reactor and method are useful for anaerobic digestion of municipal solid wastes to produce methane, for production of commodity chemicals from organic materials, and for microbial fermentation processes.

  14. Neutron behavior, reactor control, and reactor heat transfer. Volume four

    SciTech Connect

    Not Available

    1986-01-01

    Volume four covers neutron behavior (neutron absorption, how big are nuclei, neutron slowing down, neutron losses, the self-sustaining reactor), reactor control (what is controlled in a reactor, controlling neutron population, is it easy to control a reactor, range of reactor control, what happens when the fuel burns up, controlling a PWR, controlling a BWR, inherent safety of reactors), and reactor heat transfer (heat generation in a nuclear reactor, how is heat removed from a reactor core, heat transfer rate, heat transfer properties of the reactor coolant).

  15. Reactor vessel support system

    DOEpatents

    Golden, Martin P.; Holley, John C.

    1982-01-01

    A reactor vessel support system includes a support ring at the reactor top supported through a box ring on a ledge of the reactor containment. The box ring includes an annular space in the center of its cross-section to reduce heat flow and is keyed to the support ledge to transmit seismic forces from the reactor vessel to the containment structure. A coolant channel is provided at the outside circumference of the support ring to supply coolant gas through the keyways to channels between the reactor vessel and support ledge into the containment space.

  16. Nuclear reactor overflow line

    DOEpatents

    Severson, Wayne J.

    1976-01-01

    The overflow line for the reactor vessel of a liquid-metal-cooled nuclear reactor includes means for establishing and maintaining a continuous bleed flow of coolant amounting to 5 to 10% of the total coolant flow through the overflow line to prevent thermal shock to the overflow line when the reactor is restarted following a trip. Preferably a tube is disposed concentrically just inside the overflow line extending from a point just inside the reactor vessel to an overflow tank and a suction line is provided opening into the body of liquid metal in the reactor vessel and into the annulus between the overflow line and the inner tube.

  17. Reactor water cleanup system

    DOEpatents

    Gluntz, Douglas M.; Taft, William E.

    1994-01-01

    A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling.

  18. Reactor water cleanup system

    DOEpatents

    Gluntz, D.M.; Taft, W.E.

    1994-12-20

    A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling. 1 figure.

  19. Spinning fluids reactor

    DOEpatents

    Miller, Jan D; Hupka, Jan; Aranowski, Robert

    2012-11-20

    A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

  20. Hybrid reactors. [Fuel cycle

    SciTech Connect

    Moir, R.W.

    1980-09-09

    The rationale for hybrid fusion-fission reactors is the production of fissile fuel for fission reactors. A new class of reactor, the fission-suppressed hybrid promises unusually good safety features as well as the ability to support 25 light-water reactors of the same nuclear power rating, or even more high-conversion-ratio reactors such as the heavy-water type. One 4000-MW nuclear hybrid can produce 7200 kg of /sup 233/U per year. To obtain good economics, injector efficiency times plasma gain (eta/sub i/Q) should be greater than 2, the wall load should be greater than 1 MW.m/sup -2/, and the hybrid should cost less than 6 times the cost of a light-water reactor. Introduction rates for the fission-suppressed hybrid are usually rapid.

  1. HORIZONTAL BOILING REACTOR SYSTEM

    DOEpatents

    Treshow, M.

    1958-11-18

    Reactors of the boiling water type are described wherein water serves both as the moderator and coolant. The reactor system consists essentially of a horizontal pressure vessel divided into two compartments by a weir, a thermal neutronic reactor core having vertical coolant passages and designed to use water as a moderator-coolant posltioned in one compartment, means for removing live steam from the other compartment and means for conveying feed-water and water from the steam compartment to the reactor compartment. The system further includes auxiliary apparatus to utilize the steam for driving a turbine and returning the condensate to the feed-water inlet of the reactor. The entire system is designed so that the reactor is self-regulating and has self-limiting power and self-limiting pressure features.

  2. A selected ion flow tube study of the reactions of H3O+, NO+ and O2+- with some phenols, phenyl alcohols and cyclic carbonyl compounds in support of SIFT-MS and PTR-MS

    NASA Astrophysics Data System (ADS)

    Wang, Tianshu; Spanel, Patrik; Smith, David

    2004-12-01

    We have carried out a selected ion flow tube (SIFT) study of the reactions of H3O+, NO+ and O2+- with the following 10 compounds: 2-hydroxyphenol, 2-, 3- and 4-methylphenol (o-, m- and p-cresol, respectively), 4-ethylphenol, 1-phenylmethanol (benzyl alcohol), 1- and 2-phenylethanol, 1,4-benzoquinone and cyclohexanone. The primary purpose of this work was to extend the kinetics database to allow these compounds (M), to be analysed in air by selected ion flow tube mass spectrometry (SIFT-MS). The initial step in all the H3O+ reactions is exothermic proton transfer to produce MH+ ions, which are observed as the only products for seven of the ten reactions, but for the three aromatic alcohols, H2O molecule elimination occurred from the nascent MH+ ions producing the corresponding hydrocarbon ion. This is an essential point to recognise when exploiting proton transfer to analyse these compounds using SIFT-MS and proton transfer reaction mass spectrometry, PTR-MS. NO+ reacts with six of the compounds via non-dissociative charge transfer producing M+ ions and this is a valuable route to their analysis by SIFT-MS. In the case of the NO+/quinone reaction, adduct formation occurs giving NO+M product ions, whilst for the remaining three reactions two or more ion products were formed. All the O2+- reactions proceeded via charge transfer with multiple ion products in most cases. A sample analysis is carried out to indicate the value of simultaneous use of both H3O+ and NO+ precursor ions to analyse a mixture containing some of these compounds.

  3. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Dreffin, R.S.

    1959-12-15

    A control means for a nuclear reactor is described. Particularly a device extending into the active portion of the reactor consisting of two hollow elements coaxially disposed and forming a channel therebetween, the cross sectional area of the channel increasing from each extremity of the device towards the center thereof. An element of neutron absorbing material is slidably positionable within the inner hollow element and a fluid reactor poison is introduced into the channel defined by the two hollow elements.

  4. Improved vortex reactor system

    DOEpatents

    Diebold, J.P.; Scahill, J.W.

    1995-05-09

    An improved vortex reactor system is described for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor. 12 figs.

  5. FLOW SYSTEM FOR REACTOR

    DOEpatents

    Zinn, W.H.

    1963-06-11

    A reactor is designed with means for terminating the reaction when returning coolant is below a predetermined temperature. Coolant flowing from the reactor passes through a heat exchanger to a lower reservoir, and then circulates between the lower reservoir and an upper reservoir before being returned to the reactor. Means responsive to the temperature of the coolant in the return conduit terminate the chain reaction when the temperature reaches a predetermined minimum value. (AEC)

  6. The Integral Fast Reactor

    SciTech Connect

    Chang, Y.I.

    1988-01-01

    The Integral Fast Reactor (IFR) is an innovative liquid metal reactor concept being developed at Argonne National Laboratory. It seeks to specifically exploit the inherent properties of liquid metal cooling and metallic fuel in a way that leads to substantial improvements in the characteristics of the complete reactor system. This paper describes the key features and potential advantages of the IFR concept, with emphasis on its safety characteristics. 3 refs., 4 figs., 1 tab.

  7. HOMOGENEOUS NUCLEAR POWER REACTOR

    DOEpatents

    King, L.D.P.

    1959-09-01

    A homogeneous nuclear power reactor utilizing forced circulation of the liquid fuel is described. The reactor does not require fuel handling outside of the reactor vessel during any normal operation including complete shutdown to room temperature, the reactor being selfregulating under extreme operating conditions and controlled by the thermal expansion of the liquid fuel. The liquid fuel utilized is a uranium, phosphoric acid, and water solution which requires no gus exhaust system or independent gas recombining system, thereby eliminating the handling of radioiytic gas.

  8. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, Juhani

    1996-01-01

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine.

  9. Pressurized fluidized bed reactor

    DOEpatents

    Isaksson, J.

    1996-03-19

    A pressurized fluid bed reactor power plant includes a fluidized bed reactor contained within a pressure vessel with a pressurized gas volume between the reactor and the vessel. A first conduit supplies primary gas from the gas volume to the reactor, passing outside the pressure vessel and then returning through the pressure vessel to the reactor, and pressurized gas is supplied from a compressor through a second conduit to the gas volume. A third conduit, comprising a hot gas discharge, carries gases from the reactor, through a filter, and ultimately to a turbine. During normal operation of the plant, pressurized gas is withdrawn from the gas volume through the first conduit and introduced into the reactor at a substantially continuously controlled rate as the primary gas to the reactor. In response to an operational disturbance of the plant, the flow of gas in the first, second, and third conduits is terminated, and thereafter the pressure in the gas volume and in the reactor is substantially simultaneously reduced by opening pressure relief valves in the first and third conduits, and optionally by passing air directly from the second conduit to the turbine. 1 fig.

  10. Secondary Organic Aerosol Formation from Ambient Air in an Oxidation Flow Reactor at GoAmazon2014/5

    NASA Astrophysics Data System (ADS)

    Palm, Brett B.; de Sa, Suzane S.; Campuzano-Jost, Pedro; Day, Douglas A.; Hu, Weiwei; Seco, Roger; Park, Jeong-Hoo; Guenther, Alex; Kim, Saewung; Brito, Joel; Wurm, Florian; Artaxo, Paulo; Yee, Lindsay; Isaacman-VanWertz, Gabrial; Goldstein, Allen; Newburn, Matt K.; Lizabeth Alexander, M.; Martin, Scot T.; Brune, William H.; Jimenez, Jose L.

    2016-04-01

    During GoAmazon2014/5, ambient air was exposed to controlled concentrations of OH or O3 in situ using an oxidation flow reactor (OFR). Oxidation ranged from hours-several weeks of aging. Oxidized air was sampled by several instruments (e.g., HR-AMS, ACSM, PTR-TOF-MS, SMPS, CCN) at both the T3 site (IOP1: Feb 1-Mar 31, 2014, and IOP2: Aug 15-Oct 15, 2014) and T2 site (between IOPs and into 2nd IOP). The oxidation of ambient air in the OFR led to substantial and variable secondary organic aerosol (SOA) formation from any SOA-precursor gases, known and unknown, that entered the OFR. In general, more SOA was produced during the nighttime than daytime, suggesting that SOA-precursor gases were found in relatively higher concentrations at night. Similarly, more SOA was formed in the dry season (IOP2) than wet season (IOP1). The maximum amount of SOA produced during nighttime from OH oxidation ranged from less than 1 μg/m3 on some nights to greater than 10 μg/m3 on other nights. O3 oxidation of ambient air also led to SOA formation, although several times less than from OH oxidation. The amount of SOA formation sometimes, but not always, correlated with measured gas-phase biogenic and/or anthropogenic SOA precursors (e.g., SV-TAG sesquiterpenes, PTR-TOFMS aromatics, isoprene, and monoterpenes). The SOA mass formed in the OFR from OH oxidation was up to an order of magnitude larger than could be explained from aerosol yields of measured primary VOCs. This along with measurements from previous campaigns suggests that most SOA was formed from intermediate S/IVOC sources (e.g., VOC oxidation products, evaporated POA, or direct emissions). To verify the SOA yields of VOCs under OFR experimental conditions, atmospherically-relevant concentrations of several VOCs were added individually into ambient air in the OFR and oxidized by OH or O3. SOA yields in the OFR were similar to published chamber yields. Preliminary PMF factor analysis showed production of secondary factors in

  11. Measurements of in-situ SOA Formation Using an Oxidation Flow Reactor at GoAmazon2014/5

    NASA Astrophysics Data System (ADS)

    Palm, B. B.; de Sá, S. S.; Campuzano Jost, P.; Day, D. A.; Hu, W.; Seco, R.; Park, J. H.; Guenther, A. B.; Kim, S.; Brito, J.; Wurm, F.; Artaxo, P.; Yee, L.; Isaacman-VanWertz, G. A.; Goldstein, A. H.; Souza, R. A. F. D.; Manzi, A. O.; Bustillos, J. O. V.; Tota, J.; Newburn, M. K.; Alexander, M. L. L.; Martin, S. T.; Brune, W. H.; Jimenez, J. L.

    2015-12-01

    During GoAmazon2014/5, ambient air was exposed to controlled concentrations of OH or O3 in-situ using an oxidation flow reactor (OFR). Oxidation ranged from hours-several weeks of aging. Oxidized air was sampled by several instruments (e.g., HR-AMS, ACSM, PTR-TOF-MS, SMPS, CCN) at both the T3 site (IOP1: Feb 1-Mar 31, 2014, and IOP2: Aug 15-Oct 15, 2014) and T2 site (between IOPs and into 2nd IOP). Oxidation of ambient air in the OFR led to significant and dynamic SOA formation. In general, more SOA was produced during the nighttime than daytime, and more in the dry season (IOP2) than wet season (IOP1). The maximum amount of SOA produced during nighttime from OH oxidation ranged from less than 1 µg/m3 to greater than 10 µg/m3. O3 oxidation of ambient air also led to SOA formation, although much less than from OH oxidation. Preliminary PMF factor analysis showed that the less-oxidized OOA (LO-OOA) factor was produced at up to several days OH aging, while at longer ages the more-oxidized OOA (MO-OOA) factor was formed and LO-OOA was depleted. HOA, BBOA, and IEPOX-SOA factors were not formed in the reactor, just depleted at high ages (though at different rates). More detailed PMF results will be presented. Variations in the amount of SOA formation often, but not always, correlated with measured gas-phase biogenic and/or anthropogenic SOA precursors (e.g., SV-TAG sesquiterpenes, PTR-TOFMS aromatics, isoprene, and monoterpenes). The SOA mass formed in the OFR was ~10x larger than could be explained by aerosol yields of measured primary VOCs, suggesting that most SOA was formed from intermediate sources such as S/IVOCs (e.g., VOC oxidation products or evaporated POA), consistent with previous OFR field and lab studies. To verify the SOA yields of VOCs under OFR experimental conditions, atmospherically-relevant concentrations of several VOCs were added individually into ambient air in the OFR and oxidized by OH or O3. SOA yields were similar to published chamber yields.

  12. Characterizing the Amount and Chemistry of Biogenic SOA Formation from Pine Forest Air Using a Flow Reactor

    NASA Astrophysics Data System (ADS)

    Palm, B. B.; Ortega, A. M.; Campuzano Jost, P.; Day, D. A.; Fry, J.; Zarzana, K. J.; Draper, D. C.; Brown, S. S.; Kaser, L.; Karl, T.; Jud, W.; Hansel, A.; Hodzic, A.; Dube, W. P.; Wagner, N. L.; Brune, W. H.; Jimenez, J. L.

    2013-12-01

    The amount and chemistry of biogenic secondary organic aerosol (SOA) formation was characterized as a function of oxidant exposure using a Potential Aerosol Mass (PAM) oxidative flow reactor, sampling air in a terpene- and MBO-dominated pine forest during the 2011 BEACHON-RoMBAS field campaign at the U.S. Forest Service Manitou Forest Experimental Observatory in the Colorado Rocky Mountains. In the reactor, a chosen oxidant (OH, O3, or NO3) was generated and stepped over a range of values up to 10,000 times ambient levels, accelerating the gas-phase and heterogeneous oxidative aging of volatile organic compounds (VOCs), inorganic gases, and preexisting aerosol. The resulting SOA formation was measured using an Aerodyne HR-ToF-AMS, a TSI SMPS and a PTR-TOF-MS. Oxidative processing in the flow reactor was equivalent to a few hours up to ~20 days of atmospheric aging during the ~4-min reactor residence time. During BEACHON-RoMBAS, OH oxidation led to a net production of up to several μg/m3 of SOA at intermediate exposures (1-10 equivalent days) but resulted in net loss of OA mass (up to ~30%) at higher OH exposures (10-20 equivalent days), demonstrating the competing effects of functionalization/condensation vs. fragmentation/evaporation reactions as OH exposure increased. O3 and NO3 oxidation led to smaller (up to 0.5 μg/m3) SOA production, and loss of SOA mass due to fragmentation reactions was not observed. OH oxidation resulted in f44 vs. f43 and Van Krevelen diagram (H:C vs. O:C) slopes similar to ambient oxidation, suggesting the flow reactor oxidation pathways are similar to those in ambient air. Organic nitrate SOA production was observed from NO3 radical oxidation only. New particle formation was observed from OH oxidation, but not O3 or NO3 oxidation under our experimental conditions. An enhancement of SOA production under the influence of anthropogenic pollution (Denver) was also observed. High-resolution AMS measurements showed that the O:C and H

  13. Light water reactor program

    SciTech Connect

    Franks, S.M.

    1994-12-31

    The US Department of Energy`s Light Water Reactor Program is outlined. The scope of the program consists of: design certification of evolutionary plants; design, development, and design certification of simplified passive plants; first-of-a-kind engineering to achieve commercial standardization; plant lifetime improvement; and advanced reactor severe accident program. These program activities of the Office of Nuclear Energy are discussed.

  14. Polymerization Reactor Engineering.

    ERIC Educational Resources Information Center

    Skaates, J. Michael

    1987-01-01

    Describes a polymerization reactor engineering course offered at Michigan Technological University which focuses on the design and operation of industrial polymerization reactors to achieve a desired degree of polymerization and molecular weight distribution. Provides a list of the course topics and assigned readings. (TW)

  15. NEUTRONIC REACTOR SYSTEM

    DOEpatents

    Treshow, M.

    1959-02-10

    A reactor system incorporating a reactor of the heterogeneous boiling water type is described. The reactor is comprised essentially of a core submerged adwater in the lower half of a pressure vessel and two distribution rings connected to a source of water are disposed within the pressure vessel above the reactor core, the lower distribution ring being submerged adjacent to the uppcr end of the reactor core and the other distribution ring being located adjacent to the top of the pressure vessel. A feed-water control valve, responsive to the steam demand of the load, is provided in the feedwater line to the distribution rings and regulates the amount of feed water flowing to each distribution ring, the proportion of water flowing to the submerged distribution ring being proportional to the steam demand of the load. This invention provides an automatic means exterior to the reactor to control the reactivity of the reactor over relatively long periods of time without relying upon movement of control rods or of other moving parts within the reactor structure.

  16. Operating US power reactors

    SciTech Connect

    Silver, E.G.

    1982-07-01

    The operation of US power reactors during March and April 1982 is summarized. Events of special note are discussed in the text, and the operational performance of all licensed power reactors is presented. These data are taken from the monthly Operating Units Status Report prepared by the Nuclear Regulatory Commission (NRC).

  17. The Integral Fast Reactor

    SciTech Connect

    Till, C.E.; Chang, Y.I. ); Lineberry, M.J. )

    1990-01-01

    Argonne National Laboratory, since 1984, has been developing the Integral Fast Reactor (IFR). This paper will describe the way in which this new reactor concept came about; the technical, public acceptance, and environmental issues that are addressed by the IFR; the technical progress that has been made; and our expectations for this program in the near term. 5 refs., 3 figs.

  18. Status of French reactors

    SciTech Connect

    Ballagny, A.

    1997-08-01

    The status of French reactors is reviewed. The ORPHEE and RHF reactors can not be operated with a LEU fuel which would be limited to 4.8 g U/cm{sup 3}. The OSIRIS reactor has already been converted to LEU. It will use U{sub 3}Si{sub 2} as soon as its present stock of UO{sub 2} fuel is used up, at the end of 1994. The decision to close down the SILOE reactor in the near future is not propitious for the start of a conversion process. The REX 2000 reactor, which is expected to be commissioned in 2005, will use LEU (except if the fast neutrons core option is selected). Concerning the end of the HEU fuel cycle, the best option is reprocessing followed by conversion of the reprocessed uranium to LEU.

  19. REACTOR FUEL SCAVENGING MEANS

    DOEpatents

    Coffinberry, A.S.

    1962-04-10

    A process for removing fission products from reactor liquid fuel without interfering with the reactor's normal operation or causing a significant change in its fuel composition is described. The process consists of mixing a liquid scavenger alloy composed of about 44 at.% plutoniunm, 33 at.% lanthanum, and 23 at.% nickel or cobalt with a plutonium alloy reactor fuel containing about 3 at.% lanthanum; removing a portion of the fuel and scavenger alloy from the reactor core and replacing it with an equal amount of the fresh scavenger alloy; transferring the portion to a quiescent zone where the scavenger and the plutonium fuel form two distinct liquid layers with the fission products being dissolved in the lanthanum-rich scavenger layer; and the clean plutonium-rich fuel layer being returned to the reactor core. (AEC)

  20. Reactor neutrino monitoring

    NASA Astrophysics Data System (ADS)

    Lhuillier, D.

    2009-03-01

    Nuclear reactors are the most intense man-controlled sources of antineutrinos and as such have hosted number of key physics experiments, from the antineutrino discovery to modern oscillation measurements. At the present time, both detection technology and understanding of fundamental physics are mature enough to think about antineutrinos as a new tool for reactor monitoring. We describe below how antineutrinos can provide online information on reactor operation and amount of plutonium accumulated in the core. Reactors are the only sources of plutonium on earth and this element can be chemically separated from the rest of the nuclear fuel and diverted into nuclear weapons. We present in the next sections the unique features antineutrino detectors could provide to safeguards agencies such as IAEA. We review the worldwide efforts to develop small ( 1m scale) antineutrino detectors dedicated to automated and non-intrusive reactor monitoring.

  1. Nuclear reactor control column

    SciTech Connect

    Bachovchin, D.M.

    1982-08-10

    The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest crosssectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor.

  2. Reactor Safety Research Programs

    SciTech Connect

    Edler, S. K.

    1981-07-01

    This document summarizes the work performed by Pacific Northwest Laboratory (PNL) from January 1 through March 31, 1981, for the Division of Reactor Safety Research within the U.S. Nuclear Regulatory Commission (NRC). Evaluations of nondestructive examination (NDE) techniques and instrumentation are reported; areas of investigation include demonstrating the feasibility of determining the strength of structural graphite, evaluating the feasibility of detecting and analyzing flaw growth in reactor pressure boundary systems, examining NDE reliability and probabilistic fracture mechanics, and assessing the integrity of pressurized water reactor (PWR) steam generator tubes where service-induced degradation has been indicated. Experimental data and analytical models are being provided to aid in decision-making regarding pipeto- pipe impacts following postulated breaks in high-energy fluid system piping. Core thermal models are being developed to provide better digital codes to compute the behavior of full-scale reactor systems under postulated accident conditions. Fuel assemblies and analytical support are being provided for experimental programs at other facilities. These programs include loss-ofcoolant accident (LOCA) simulation tests at the NRU reactor, Chalk River, Canada; fuel rod deformation, severe fuel damage, and postaccident coolability tests for the ESSOR reactor Super Sara Test Program, Ispra, Italy; the instrumented fuel assembly irradiation program at Halden, Norway; and experimental programs at the Power Burst Facility, Idaho National Engineering Laboratory (INEL). These programs will provide data for computer modeling of reactor system and fuel performance during various abnormal operating conditions.

  3. Nuclear reactor control column

    DOEpatents

    Bachovchin, Dennis M.

    1982-01-01

    The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest cross-sectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor.

  4. Slurry reactor design studies

    SciTech Connect

    Fox, J.M.; Degen, B.D.; Cady, G.; Deslate, F.D.; Summers, R.L. ); Akgerman, A. ); Smith, J.M. )

    1990-06-01

    The objective of these studies was to perform a realistic evaluation of the relative costs of tublar-fixed-bed and slurry reactors for methanol, mixed alcohols and Fischer-Tropsch syntheses under conditions where they would realistically be expected to operate. The slurry Fischer-Tropsch reactor was, therefore, operated at low H{sub 2}/CO ratio on gas directly from a Shell gasifier. The fixed-bed reactor was operated on 2.0 H{sub 2}/CO ratio gas after adjustment by shift and CO{sub 2} removal. Every attempt was made to give each reactor the benefit of its optimum design condition and correlations were developed to extend the models beyond the range of the experimental pilot plant data. For the methanol design, comparisons were made for a recycle plant with high methanol yield, this being the standard design condition. It is recognized that this is not necessarily the optimum application for the slurry reactor, which is being proposed for a once-through operation, coproducing methanol and power. Consideration is also given to the applicability of the slurry reactor to mixed alcohols, based on conditions provided by Lurgi for an Octamix{trademark} plant using their standard tubular-fixed reactor technology. 7 figs., 26 tabs.

  5. REACTOR BASE, SOUTHEAST CORNER. INTERIOR WILL CONTAIN REACTOR TANK, COOLING ...

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

    REACTOR BASE, SOUTHEAST CORNER. INTERIOR WILL CONTAIN REACTOR TANK, COOLING WATER PIPES, COOLING AIR DUCTS, AND SHIELDING. INL NEGATIVE NO. 776. Unknown Photographer, 10/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  6. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Metcalf, H.E.

    1958-10-14

    Methods of controlling reactors are presented. Specifically, a plurality of neutron absorber members are adjustably disposed in the reactor core at different distances from the center thereof. The absorber members extend into the core from opposite faces thereof and are operated by motive means coupled in a manner to simultaneously withdraw at least one of the absorber members while inserting one of the other absorber members. This feature effects fine control of the neutron reproduction ratio by varying the total volume of the reactor effective in developing the neutronic reaction.

  7. Microfluidic electrochemical reactors

    DOEpatents

    Nuzzo, Ralph G.; Mitrovski, Svetlana M.

    2011-03-22

    A microfluidic electrochemical reactor includes an electrode and one or more microfluidic channels on the electrode, where the microfluidic channels are covered with a membrane containing a gas permeable polymer. The distance between the electrode and the membrane is less than 500 micrometers. The microfluidic electrochemical reactor can provide for increased reaction rates in electrochemical reactions using a gaseous reactant, as compared to conventional electrochemical cells. Microfluidic electrochemical reactors can be incorporated into devices for applications such as fuel cells, electrochemical analysis, microfluidic actuation, pH gradient formation.

  8. NUCLEAR REACTOR FUEL SYSTEMS

    DOEpatents

    Thamer, B.J.; Bidwell, R.M.; Hammond, R.P.

    1959-09-15

    Homogeneous reactor fuel solutions are reported which provide automatic recombination of radiolytic gases and exhibit large thermal expansion characteristics, thereby providing stability at high temperatures and enabling reactor operation without the necessity of apparatus to recombine gases formed by the radiolytic dissociation of water in the fuel and without the necessity of liquid fuel handling outside the reactor vessel except for recovery processes. The fuels consist of phosphoric acid and water solutions of enriched uranium, wherein the uranium is in either the hexavalent or tetravalent state.

  9. Nuclear reactor reflector

    DOEpatents

    Hopkins, Ronald J.; Land, John T.; Misvel, Michael C.

    1994-01-01

    A nuclear reactor reflector is disclosed that comprises a stack of reflector blocks with vertical water flow passages to cool the reflector. The interface between blocks is opposite support points for reactor fuel rods. Water flows between the reflector and the reactor barrel from passages in a bottom block. The top block contains a flange to limit this flow and the flange has a slot to receive an alignment pin that is welded to the barrel. The pin is held in the slot by two removable shims. Alignment bars extend the length of the stack in slots machined in each block when the stack is assembled.

  10. Nuclear reactor reflector

    DOEpatents

    Hopkins, R.J.; Land, J.T.; Misvel, M.C.

    1994-06-07

    A nuclear reactor reflector is disclosed that comprises a stack of reflector blocks with vertical water flow passages to cool the reflector. The interface between blocks is opposite support points for reactor fuel rods. Water flows between the reflector and the reactor barrel from passages in a bottom block. The top block contains a flange to limit this flow and the flange has a slot to receive an alignment pin that is welded to the barrel. The pin is held in the slot by two removable shims. Alignment bars extend the length of the stack in slots machined in each block when the stack is assembled. 12 figs.