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1

Major odorants released as urinary volatiles by urinary incontinent patients.  

PubMed

In this study, volatile urinary components were collected using three different types of samples from patients suffering from urinary incontinence (UI): (1) urine (A); (2) urine + non-used pad (B); and (3) urine + used pad (C). In addition, urine + non-used pad (D) samples from non-patients were also collected as a reference. The collection of urinary volatiles was conducted with the aid of a glass impinger-based mini-chamber method. Each of the four sample types (A through D) was placed in a glass impinger and incubated for 4 hours at 37 °C. Ultra pure air was then passed through the chamber, and volatile urine gas components were collected into Tedlar bags at the other end. These bag samples were then analyzed for a wide range of VOCs and major offensive odorants (e.g., reduced sulfur compounds (RSCs), carbonyls, trimethylamine (TMA), ammonia, etc.). Among the various odorants, sulfur compounds (methanethiol and hydrogen sulfide) and aldehydes (acetaldehyde, butylaldehyde, and isovaleraldehyde) were detected above odor threshold and predicted to contribute most effectively to odor intensity of urine incontinence. PMID:23823973

Pandey, Sudhir Kumar; Kim, Ki-Hyun; Choi, Si On; Sa, In Young; Oh, Soo Yeon

2013-01-01

2

Identification of major volatile odor compounds in frankfurters.  

PubMed

More than 100 volatile compounds have been identified in the headspace of frankfurter sausages. Most abundant were the terpene hydrocarbons, monoterpene alcohols, phenyl propanoids, and phenols. Separate analyses of solutions of spices and smoke demonstrated that most of the terpenes were derived from the spices, whereas the phenols originated mostly from the smoke ingredients. Many of the compounds contributing to the overall odor of the frankfurters have been identified. Some odors, characteristic of the smokiness and spiciness of frankfurters, were caused by phenols and terpenes, whereas others were due to compounds derived from the meat fraction; these compounds included aldehydes, ketones, furanthiols, and alicyclic sulfur compounds. PMID:10606587

Chevance, F F; Farmer, L J

1999-12-01

3

Differential Binding between Volatile Ligands and Major Urinary Proteins Due to Genetic Variation in Mice.  

National Technical Information Service (NTIS)

Two different structural classes of chemical signals in mouse urine, i.e., volatile organic compounds (VOCs) and the major urinary proteins (MUPs), interact closely because MUPs sequester VOCs. Although qualitative and/or quantitative differences in each ...

C. C. Grigsby G. Preti J. Kwak M. Koksal M. M. Rizki

2012-01-01

4

Major sources of exposure to benzene and other volatile organic chemicals  

Microsoft Academic Search

The major sources of human exposure to about a dozen volatile organic chemicals (VOCs) have recently been identified. For nearly every chemical, the major sources of exposure are completely different from the major sources of emissions. This finding implies that current environmental regulations and control strategies are misdirected. Important sources of exposure are typically not regulated in any way, whereas

Lance Wallace

1990-01-01

5

Majority ion heating near the ion-ion hybrid layer in tokamaks  

Microsoft Academic Search

Efficient direct majority ion heating in a deuterium-tritium (D-T) reactor-grade plasma via absorption of fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is discussed. Majority ion heating results from resonance overlap between the cyclotron layers and the D-T ion-ion hybrid layer in hot, dense plasmas for fast waves launched with high parallel wavenumbers. Analytic and numerical models

C. K. Phillips; J. C. Hosea; D. Ignat; R. Majeski; J. H. Rogers; G. Schilling; J. R. Wilson

1996-01-01

6

Majority ion heating near the ion-ion hybrid layer in tokamaks  

Microsoft Academic Search

Efficient direct majority ion heating in a deuterium-tritium (D-T) reactor-grade plasma via absorption of fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is discussed. Majority ion heating results from resonance overlap between the cyclotron layers and the D-T ion-ion hybrid layer in hot, dense plasmas for fast waves launched with high parallel wavenumbers. Analytic and numerical models

C. K. Phillips; J. C. Hosea; D. Ignat; R. Majeski; J. H. Rogers; G. Schilling; J. R. Wilson

1995-01-01

7

Majority ion heating near the ion-ion hybrid layer in tokamaks  

NASA Astrophysics Data System (ADS)

Efficient direct majority ion heating in a deuterium-tritium (D-T) reactor-grade plasma via absorption of fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is discussed. Majority ion heating results from resonance overlap between the cyclotron layers and the D-T ion-ion hybrid layer in hot, dense plasmas for fast waves launched with high parallel wavenumbers. Analytic and numerical models are used to explore the regime in ITER plasmas.

Phillips, C. K.; Hosea, J. C.; Ignat, D.; Majeski, R.; Rogers, J. H.; Schilling, G.; Wilson, J. R.

1996-02-01

8

Majority ion heating near the ion-ion hybrid layer in tokamaks  

SciTech Connect

Efficient direct majority ion heating in a deuterium-tritium (D-T) reactor-grade plasma via absorption of fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is discussed. Majority ion heating results from resonance overlap between the cyclotron layers and the D-T ion-ion hybrid layer in hot, dense plasmas for fast waves launched with high parallel wavenumbers. Analytic and numerical models are used to explore the regime in ITER plasmas.

Phillips, C.K.; Hosea, J.C.; Ignat, D.; Majeski, R.; Rogers, J.H.; Schilling, G.; Wilson, J.R.

1995-08-01

9

Assessment of ambient volatile organic compounds (VOCs) near major roads in urban Nanjing, China  

Microsoft Academic Search

Volatile organic compounds (VOCs) are a major component of atmospheric pollutants in Nanjing, a large city in the east of China. Accordingly, 12-h diurnal monitoring for ten consecutive days was performed adjacent to major roads in five districts, ca.1.5 m above ground level, in April, July and October 2006, and January 2007. The most numerous species of VOCs (benzene, toluene, ethylbenzene,

P. Wang; W. Zhao

2008-01-01

10

Majority ion heating near the ion-ion hybrid layer in tokamaks.  

National Technical Information Service (NTIS)

Efficient direct majority ion heating in a deuterium-tritium (D-T) reactor-grade plasma via absorption of fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is discussed. Majority ion heating results from resonance overlap between th...

C. K. Phillips J. C. Hosea D. Ignat R. Majeski J. H. Rogers

1995-01-01

11

Majority ion heating near the ion-ion hybrid layer in tokamaks  

SciTech Connect

Efficient direct majority ion heating in a deuterium-tritium (D-T) reactor-grade plasma via absorption of fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is discussed. Majority ion heating results from resonance overlap between the cyclotron layers and the D-T ion-ion hybrid layer in hot, dense plasmas for fast waves launched with high parallel wavenumbers. Analytic and numerical models are used to explore the regime in ITER plasmas. {copyright} {ital 1996 American Institute of Physics.}

Phillips, C.K.; Hosea, J.C.; Ignat, D.; Majeski, R.; Rogers, J.H.; Schilling, G.; Wilson, J.R. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

1996-02-01

12

Acceleration of beam ions during major radius compression in TFTR  

SciTech Connect

Tangentially co-injected deuterium beam ions were accelerated from 82 keV up to 150 keV during a major radius compression experiment in TFTR. The ion energy spectra and the variation in fusion yield were in good agreement with Fokker-Planck code simulations. In addition, the plasma rotation velocity was observed to rise during compression.

Wong, K.L.; Bitter, M.; Hammett, G.W.; Heidbrink, W.; Hendel, H.; Kaita, R.; Scott, S.; Strachan, J.D.; Tait, G.; Bell, M.G.

1985-09-01

13

Comparative study of the pyrolysis of lignocellulose and its major components: characterization and overall distribution of their biochars and volatiles.  

PubMed

In order to investigate the pyrolysis differences among lignocellulose and its major components, the biochars and volatiles of lignocellulose (bamboo), lignin, hemicellulose and holocellulose (from bamboo), and cellulose (from cotton linter) were studied using elemental analysis, FTIR, XRD, SEM, Py-GC/MS and TGA-FTIR. Result showed that the biochar yield of lignin (48.8%) was much higher than those of hemicellulose (21.1%), cellulose (8.3%), holocellulose (20.4%) and bamboo (15.1%), while no obvious elemental difference among these biochars was found. Results from Py-GC/MS indicated that carbonyl compounds, ethers and alcohols were the major volatiles of polysaccharide component pyrolysis, while aromatic compounds were the major volatiles of lignin pyrolysis. The pyrolysis of polysaccharide component mainly occurred at 200-400°C, while the pyrolysis of lignin happened at 300-700°C. PMID:24413478

Cao, Xuefei; Zhong, Linxin; Peng, Xinwen; Sun, Shaoni; Li, Shouming; Liu, Shijie; Sun, Runcang

2014-03-01

14

Volatile evolution from polymer materials induced by irradiation with He ++ ions and comparative pyrolysis experiments  

NASA Astrophysics Data System (ADS)

Irradiation of polymer samples using an accelerated beam of He ++ ions passed through a 10 ?m thick window of Havar foil has been performed. Such an irradiation simulates the effects of large ? radiation doses on a vastly reduced time-scale. The experimental set up was designed so that the irradiated materials were contained within a small sample chamber. This chamber was isolated from the main vacuum chamber of the ion beam by means of the Havar foil window. A mass spectrometer linked directly to the sample chamber was used to analyse gaseous products evolved from the materials under irradiation. Samples of a material in which the polymer phase was an ethylenevinylacetate/polyvinylalcohol composite material indicated increased CO 2 and CO evolution upon irradiation. This material, however, evolved a considerable amount of volatiles even without irradiation and so a detailed mechanistic interpretation of the results is not possible. A foamed poly(siloxane) material evolved a number of volatile species upon irradiation and possible chemical degradation mechanisms are commented upon. The sample was extremely resistant to radiation induced degradation as measured by volatile evolution though, so again a detailed mechanistic analysis is not possible. Samples of a polyester based polyurethane evolved CO 2, CO and a number of high mass volatile species. Assignment of chemical structures to the main molecular ions allows deductions about the chemistry underlying radiation induced change to be made. Furthermore, identification of trends in volatile production allows information about potential degradation mechanisms to be deduced. To assess the contribution of sample heating on volatile evolution a series of pyrolysis experiments were performed. These indicate no evolution of volatiles below 100 °C and evolution of volatiles possessing masses of greater than 50 amu only at temperature of above 300 °C.

Murphy, J. J.; Patel, M.; Skinner, A. R.; Horn, I. M.; Powell, S. J.; Smith, P. F.

2004-02-01

15

Gas Chromatographic-Ion Trap Mass Spectrometric Analysis of Volatile Organic Compounds by Ion-Molecule Reactions Using the Electron-Deficient Reagent Ion CCl{3/+}  

NASA Astrophysics Data System (ADS)

When using tetrachloromethane as the reagent gas in gas chromatography-ion trap mass spectrometry equipped with hybrid ionization source, the cation CCl{3/+} was generated in high abundance and further gas-phase experiments showed that such an electron-deficient reagent ion CCl{3/+} could undergo interesting ion-molecule reactions with various volatile organic compounds, which not only present some informative gas-phase reactions, but also facilitate qualitative analysis of diverse volatile compounds by providing unique mass spectral data that are characteristic of particular chemical structures. The ion-molecule reactions of the reagent ion CCl{3/+} with different types of compounds were studied, and results showed that such reactions could give rise to structurally diagnostic ions, such as [M + CCl3 - HCl]+ for aromatic hydrocarbons, [M - OH]+ for saturated cyclic ether, ketone, and alcoholic compounds, [M - H]+ ion for monoterpenes, M·+ for sesquiterpenes, [M - CH3CO]+ for esters, as well as the further fragment ions. The mechanisms of ion-molecule reactions of aromatic hydrocarbons, aliphatic ketones and alcoholic compounds with the reagent ion CCl{3/+} were investigated and proposed according to the information provided by MS/MS experiments and theoretical calculations. Then, this method was applied to study volatile organic compounds in Dendranthema indicum var. aromaticum and 20 compounds, including monoterpenes and their oxygen-containing derivatives, aromatic hydrocarbon and sesquiterpenes were identified using such ion-molecule reactions. This study offers a perspective and an alternative tool for the analysis and identification of various volatile compounds.

Wang, Cheng-Zhong; Su, Yue; Wang, Hao-Yang; Guo, Yin-Long

2011-10-01

16

Temporal variation of volatile organic compounds and their major emission sources in Seoul, Korea.  

PubMed

This study examines the characteristics of volatile organic compounds (VOCs) and their major emission sources at the Bulgwang site in Seoul, Korea. The annual levels of VOCs (96.2-121.1 ppb C) have shown a decreasing trend from 2004 to 2008. The most abundant component in Seoul was toluene, which accounted for over 23.5 % of the total VOCs on the parts per billion on a carbon basis, and the portions of alkanes with two to six carbons constituted the largest major lumped group, ranging from 40.1 to 48.4 % (45.3 ± 3.7 %) of the total VOCs. Major components of the solvent (toluene, m/p-xylene, o-xylene, and ethylbenzene) showed high in daytime and summer and low in nighttime and winter due mainly to the variation of the ambient temperature. The species mostly emitted from gasoline vapor (i/n-butane, i/n-pentane, n-hexane, and 2-methylpentane) and vehicular exhaust (ethylene, acetylene, and benzene) showed bimodal peaks in the diurnal variation around the commuting hours because of the high traffic volume. For the 14 out of 15 highest concentration species, the weekend effect was only evident on Sundays because of the stepwise implementation of the 5-day work-week system. Principal components analysis (PCA) was applied in order to identify the sources of the 15 highest concentration VOCs and, as a result, three principal components such as gasoline vapor (48.9 %), vehicular exhaust (17.9 %), and evaporation of solvents (9.8 %) were obtained to explain a total of 76.6 % of the data variance. Most influential contributing sources at the sampling site were traffic-related ones although the use of solvent was the dominant emission source based on the official emission inventory. PMID:23728967

Shin, H J; Roh, S A; Kim, J C; Lee, S J; Kim, Y P

2013-12-01

17

Volcanism in the Sumisu Rift, I. Major element, volatile, and stable isotope geochemistry  

USGS Publications Warehouse

A bimodal volcanic suite with KAr ages of 0.05-1.40 Ma was collected from the Sumisu Rift using alvin. These rocks are contemporaneous with island arc tholeiite lavas of the Izu-Ogasawara arc 20 km to the east, and provide a present day example of volcanism associated with arc rifting and back-arc basin initiation. Major element geochemistry of the basalts is most similar to that of basalts found in other, more mature back-arc basins, which indicates that back-arc basins need not begin their magmatic evolution with lavas bearing strong arc signatures. Volatile concentrations distinguish Sumisu Rift basalts from island arc basalts and MORB. H2O contents, which are at least four times greater than in MORB, suppress plagioclase crystallization. This suppression results in a more mafic fractionating assemblage, which prevents Al2O3 depletion and delays the initiation of Fe2O3(tot) and TiO2 enrichment. However, unlike arc basalts, Fe3+ ??Fe ratios are only slightly higher than in MORB and are insufficient to cause magnetite saturation early enough to suppress Fe2O3(tot) and TiO2 enrichment. Thus, major element trends are more similar to those of MORB than arcs. H2O, CO2 and S are undersaturated relative to pure phase solubility curves, indicating exsolution of an H2O-rich mixed gas phase. High H2O S, high ??D, and low (MORB-like) ??34S ratios are considered primary and distinctive of the back-arc basin setting. ?? 1990.

Hochstaedter, A. G.; Gill, J. B.; Kusakabe, M.; Newman, S.; Pringle, M.; Taylor, B.; Fryer, P.

1990-01-01

18

Volatile Emissions from Subduction-related Volcanoes: Major and Trace Elements  

NASA Astrophysics Data System (ADS)

Present-day volatile emissions associated with subduction zone volcanism can be estimated in two ways. One approach is to assume magma production rate at arcs is 20% that of MOR and scale to the MOR 3He flux (1000 mol/yr) to obtain a mantle-derived arc He-3 flux of 200+/-40 mol/yr. This flux and measured gas ratios (xI/3He where xI is the gas species of interest) obtained from volcanic and hydrothermal samples is then used to calculate volatile emissions. A global arc CO2 flux of 0.3 to 3.1 x 1012 mol/yr has been obtained in this way. Another approach is to use individual arc volcano SO2 fluxes (determined by remote sensing) in combination with CO2/SO2 ratios of high temperature fumaroles to calculate volcanic CO2 fluxes. Integrating over an individual arc, and using a power-law distribution to include non-measured volcanoes, it is possible to produce a volatile flux estimate for a particular arc. Summing over all arcs allows a global estimate (e.g. ˜ 1.6 x1012 mol/yr for arc CO2). There are caveats with both methods. In the former case, it is assumed that the mantle wedge is characterized by a similar 3He content to MORB-source. In the latter case, the distribution of SO2 fluxes is decidedly uneven necessitating poorly-justified extrapolations. For example, there is little data available from the I-B-M, Lesser Antilles and Philippines whereas Central American volcanoes have numerous published SO2 fluxes. A further issue (in addition to geographical bias), is the absence of volatile fluxes from submarine arcs. Despite these problems, global estimates of SO2 and CO2 fluxes by both methods vary by only one order of magnitude [1]. It is emphasized that these are present-day estimates as paleo-degassing rates of arc magmas are poorly constrained and depend entirely on estimates of magma intrusion and extrusion rates [2]. The same approach has been used for other species although the flux of magmatic N2, H2O, HCl, HF from arcs remains poorly constrained (N2: ˜ 6 x108 to 2 x1010 mol/yr; H2O: ˜ 8 x1012 mol/yr; HCl ˜1 x1010 to 4x1011 mol/yr, HF: ˜3 x109 to 3 x1011 mol/yr)[1,3]. Due to the preferential partitioning of HCl and HF into volcano hosted hydrothermal systems, fluxes from magma bodies are probably much larger than what is emitted into the atmosphere. Trace element emissions from subduction related volcanoes are also poorly constrained but are potentially significant. High temperature (>700C) volcanic gas samples show that concentrations of Be, Rb, Sr, Ru, Rh, Pd, Cd, W, Re, Pt, Pb, Bi, Se, Sc are in the 5 to 1300 ug/L range and up to 25000 ug/L of B have been measured [4,5]. Using these concentrations and the global arc SO2 flux gives estimates of trace element fluxes on the order of 3 x104 to 8 x106 mol/yr (and 3 x109 mol/yr of B). These flux estimates are certainly upper limits because low temperature (<200C) gases that make up the majority of emissions have much lower trace element concentrations. Further work is needed to better constrain volatile contributions of volcanoes to the atmosphere, and to improve global geochemical models which assess the impact of volcanic gases on the atmosphere. {[1]} Hilton, Fischer & Marty (2002) Rev. Min. vol 47 for review [2] Kerrick Rev. Geophys. (2001) vol. 39 #4. [3] Symnods, Rose & Reed (1988) nature vol 334, p. 415 [4] Fischer, Shuttleworth & O'Day (1998) Fres. J. Anal. Chem. vol 362, p. 457 [5] Taran et al., (1995) Gochim. Cosmochim. Acta vol. 59, p. 1749

Fischer, T. P.; Hilton, D. R.

2003-12-01

19

A volatile organic analyzer for Space Station: Description and evaluation of a gas chromatography/ ion mobility  

NASA Technical Reports Server (NTRS)

A Volatile Organic Analyzer (VOA) is being developed as an essential component of the Space Station's Environmental Health System (EHS) air quality monitoring strategy to provide warning to the crew and ground personnel if volatile organic compounds exceed established exposure limits. The short duration of most Shuttle flights and the relative simplicity of the contaminant removal mechanism have lessened the concern about crew exposure to air contaminants on the Shuttle. However, the longer missions associated with the Space Station, the complex air revitalization system and the proposed number of experiments have led to a desire for real-time monitoring of the contaminants in the Space Station atmosphere. Achieving the performance requirements established for the VOA within the Space Station resource (e.g., power, weight) allocations led to a novel approach that joined a gas chromatograph (GC) to an ion mobility spectrometer (IMS). The authors of this paper will discuss the rational for selecting the GC/IMS technology as opposed to the more established gas chromatography/mass spectrometry (GC/MS) for the foundation of the VOA. The data presented from preliminary evaluations will demonstrate the versatile capability of the GC/IMS to analyze the major contaminants expected in the Space Station atmosphere. The favorable GC/IMS characteristics illustrated in this paper included excellent sensitivity, dual-mode operation for selective detection, and mobility drift times to distinguish co-eluting GC peaks. Preliminary studies have shown that the GC/IMS technology can meet surpass the performance requirements of the Space Station VOA.

Limero, Thomas F.; James, John T.

1994-01-01

20

Detection of microbial volatile organic compounds (MVOCs) by ion-mobility spectrometry  

Microsoft Academic Search

Traces of microbial volatile organic compounds (MVOCs) in air can indicate the presence of growth of moulds in the indoor\\u000a environment. Ion-mobility spectrometry is a very promising method for detection of these MVOCs, because of its high sensitivity.\\u000a For development of an in-situ method for detection of MVOCs, a portable ion-mobility spectrometer (IMS) was used and test\\u000a gases of 14

Carlo Tiebe; Hans Miessner; Bernhard Koch; Thomas Hübert

2009-01-01

21

Potential for ion-induced nucleation of volatile organic compounds by radon decay in indoor environments  

SciTech Connect

There is considerable interest in the unattached'' fraction of radon progeny in indoor air because of its significance to the estimation of the risks of radon exposure. Because of its high mobility in air, the unattached fraction is more efficiently deposited in the respiratory tract. Variation in the diameter of the unattached'' fraction and in its diffusion coefficient can be due to clustering of other atmospheric species around the {sup 218}PoO{sub 2}{sup +} ion. The purpose of this study was to investigate the potential for the formation of clusters of vapor phase organic compounds, found in indoor air, around the {sup 218}PoO{sub 2}{sup +} ion and to determine which were most likely to form clusters. A secondary purpose was to provide a compilation of measurements of indoor organic compounds for future experiments and theoretical calculations by the radon research community. The classical charged liquid droplet theory (Thomson equation) was used to estimate the Gibbs free energy of ion-induced nucleation and to provide an indication of the indoor organic compounds most likely to undergo ion-induced nucleation. Forty-four volatile and semi-volatile organic compounds out of the more than 300 which have been reported in indoor air were investigated. Water vapor was included for comparison. The results indicate that there is a potential for the formation of clusters of organic compounds around the {sup 218}PoO{sub 2}{sup +} ion. The compounds with the greatest potential for cluster formation are the volatile oxidized hydrocarbons (e.g., n-butanol, phenol, hexanal, nonanal, benzaldehyde, the ketones and the acetates) and the semi-volatile organic compounds (pentachlorophenol, nicotine, chlordane, chlorpyrifos).

Daisey, J.M.

1991-11-01

22

Potential for ion-induced nucleation of volatile organic compounds by radon decay in indoor environments  

SciTech Connect

There is considerable interest in the ``unattached`` fraction of radon progeny in indoor air because of its significance to the estimation of the risks of radon exposure. Because of its high mobility in air, the unattached fraction is more efficiently deposited in the respiratory tract. Variation in the diameter of the ``unattached`` fraction and in its diffusion coefficient can be due to clustering of other atmospheric species around the {sup 218}PoO{sub 2}{sup +} ion. The purpose of this study was to investigate the potential for the formation of clusters of vapor phase organic compounds, found in indoor air, around the {sup 218}PoO{sub 2}{sup +} ion and to determine which were most likely to form clusters. A secondary purpose was to provide a compilation of measurements of indoor organic compounds for future experiments and theoretical calculations by the radon research community. The classical charged liquid droplet theory (Thomson equation) was used to estimate the Gibbs free energy of ion-induced nucleation and to provide an indication of the indoor organic compounds most likely to undergo ion-induced nucleation. Forty-four volatile and semi-volatile organic compounds out of the more than 300 which have been reported in indoor air were investigated. Water vapor was included for comparison. The results indicate that there is a potential for the formation of clusters of organic compounds around the {sup 218}PoO{sub 2}{sup +} ion. The compounds with the greatest potential for cluster formation are the volatile oxidized hydrocarbons (e.g., n-butanol, phenol, hexanal, nonanal, benzaldehyde, the ketones and the acetates) and the semi-volatile organic compounds (pentachlorophenol, nicotine, chlordane, chlorpyrifos).

Daisey, J.M.

1991-11-01

23

Analyzing the structural behavior of volatility in the Major European Markets during the Greek crisis  

Microsoft Academic Search

In this paper we use a copula-based GARCH model to estimate conditional variances and covariances of the multivariate relationship among English, German and French markets. To that, we used daily prices of FTSE100, DAX and CAC from July 2009 to July 2011, totalizing 508 observations. The volatility of markets and their dependences indicate vestiges of the current European financial crisis,

Marcelo Brutti Righi; Paulo Sergio Ceretta

2011-01-01

24

Migration of volatile organic compounds from attached garages to residences: A major exposure source  

Microsoft Academic Search

Vehicle garages often contain high concentrations of volatile organic compounds (VOCs) that may migrate into adjoining residences. This study characterizes VOC concentrations, exposures, airflows, and source apportionments in 15 single-family houses with attached garages in southeast Michigan. Fieldwork included inspections to determine possible VOC sources, deployment of perfluorocarbon tracer (PFT) sources in garages and occupied spaces, and measurements of PFT,

Stuart Batterman; Chunrong Jia; Gina Hatzivasilis

2007-01-01

25

Volatile Emissions from Subduction-related Volcanoes: Major and Trace Elements  

Microsoft Academic Search

Present-day volatile emissions associated with subduction zone volcanism can be estimated in two ways. One approach is to assume magma production rate at arcs is 20% that of MOR and scale to the MOR 3He flux (1000 mol\\/yr) to obtain a mantle-derived arc He-3 flux of 200+\\/-40 mol\\/yr. This flux and measured gas ratios (xI\\/3He where xI is the gas

T. P. Fischer; D. R. Hilton

2003-01-01

26

Syrtis Major and Isidis Basin Contact: Evidence for Interaction Between Lava Flows and Volatile-Rich Sediments  

NASA Astrophysics Data System (ADS)

The floor of Isidis Basin (IB) is covered by materials of theVastitas Borealis Formation that appear to be emplaced essentially as a single unit. Along its western boundary, IB is in contact with volcanic flows from Syrtis Major Planum (SMP). We studied the transition zone from IB to SMP using the Viking and MOC imagery and the MOLA topographic data. The contact between the Isidis unit and volcanic flows from SMP is sharp to gradational and in places is characterized by a high (~500 m) scarp or by a network of faults that separate pieces of lava plains off the main plateau of SMP. Clusters of knobs and mesas, sometimes arranged in flow-like features, are also typical features of the transition zone. Several important characteristics of the transition from SMP to IB are presented. (1) The small-scale surface texture seen in the MOC images appears to be the same for both the SMP lava plateau and the knobs and mesas that characterize the transition. (2) There is strong evidence for the breakup of the coherent surface of SMP where it is in contact with materials in IB. (3) The plateau breakup (the knobby terrain) appears basinward after the major break of slope of SMP where it enters IB. (4) There is no evidence for plateau breakup anywhere up on the slopes of SMP. (5) The lavas of SMP remain morphologically intact where they are in contact with other units, such as the Noachian cratered terrain or where lava flows are stacked within SMP itself. These characteristic features of the transition zone from SMP to IB are readily explained if the zone of plateau breakup consists of relatively young lava flows that have been superimposed onto the surface of volatile-rich substratum, such as the interior unit of IB. Such a substratum may have served as a weak, non-resistant basement for the late lava flows from Syrtis Major. During the emplacement of lava flows on this basement the volatile components of it (H2O, CO2 or both) should escape, weaken the non-volatile residuum, and allow the flows to subside and break up. Thus, simple superposition of hot volcanic materials on top of volatile-bearing sediments can explain the key geological and topographic aspects of the transition zone from SMP and IB. Such an explanation does not involve any massive/ sudden erosion from Syrtis Major but requires the existence of volatile-rich sediments within Isidis Basin at the time of late stages of volcanic activity in Syrtis.

Ivanov, M. A.; Head, J. W.

2002-05-01

27

Synchronized discharge ionization for analysis of volatile organic compounds using a hand-held ion trap mass spectrometer.  

PubMed

The sensitivity of mass analysis is highly dependent on the efficiencies of the sample introduction, analyte ionization, and subsequent ion transfer to the mass analyzer. For miniature mass spectrometry (MS) systems, it is highly desirable to maximize the amount of the samples that can be introduced at the pumping capability highly compromised and to have the MS analysis performed with simple electronics and robust in-vacuum components. In this study, a discharge ionization source synchronized with the sample introduction has been developed for hand-held mass spectrometers with discontinuous atmospheric pressure interfaces (DAPI). The flow rate of the sample introduced with a DAPI can be much higher than that allowed with a conventional continuous atmospheric pressure interface. The pressure variation associated with the DAPI operation was used to turn on and off the synchronized discharge ionization (SDI). For analysis of volatile organic compounds (VOCs) in air samples, the SDI has been shown to be soft and molecular ions of the VOCs have been observed as the major species. Since the ions could be transferred directly to the ion trap mass analyzer without a barrier for maintaining pressure differences, high sensitivity in chemical analysis was also achieved, with limits of detection (LODs) better than 1 ppbv obtained for PAHs (polycyclic aromatic hydrocarbons) in air. PMID:23256567

Chen, Tsung-Chi; Ouyang, Zheng

2013-02-01

28

Revalidation of the Volatile Organic Analyzer Following a Major On-Orbit Maintenance Activity  

NASA Technical Reports Server (NTRS)

The Volatile Organic Analyzer (VOA) contributes to the assessment of air quality aboard the International Space Station (ISS) by identifying and quantifying target airborne volatile organic contaminants in the module air. This on-orbit contaminant monitoring capability becomes particularly important during an air quality degradation event such as a system leak. During several ISS air quality degradations, the VOA has generated near real-time data that was used to make decisions or to better understand the contingency. The VOA was operational from January 2002 through June 2003, during which time it was validated by comparing VOA data to simultaneously acquired grab sample containers (GSCs). In January 2003, one of the two analytical channels of the VOA was shutdown because of a component failure, but a redundant channel continued to supply the necessary analytical data. In June 2003, the sole remaining channel was deactivated. Initial assessments of the channel shutdowns pointed to failed fuses or heaters, but neither was considered repairable on orbit. In 2005, it was determined that failed fuses could be replaced on orbit and the crew conducted a diagnostic procedure to identify the failed component. The crew discovered that both channels incurred failed fuses, which lead to a subsequent on orbit maintenance activity and return of the VOA to operational status in December 2005. The VOA has been providing data on the ISS atmosphere since its reactivation in 2005 and this paper will present the VOA data collected during 2006. Special emphasis will be placed upon the revalidation of the repaired VOA using GSCs as well as a summary of the diagnostic and repair procedures.

Limero, Thomas; James, John T.

2007-01-01

29

Volatilization of PM2.5 Inorganic Ions in a Filter Pack System with Backup Filter and Denuders  

NASA Astrophysics Data System (ADS)

Concentrations of PM2.5 inorganic ions were measured at the rooftop of the 5-story building on the hill (37.02oN, 127.16oE, 167 m above sea level) in the Global Campus of Hankuk University of Foreign Studies, about 35 km southeast of downtown Seoul, Korea. The measurements were made four times during one-year span between 2011 and 2012 by considering the climate of Korea with distinct seasonal variations: July 29 to August 26 (summer); September 14 to October 13 (fall); November 28 to January 4 (winter); February 14 to May 31 (spring). A filter pack system was composed of PM2.5 cyclone, two annular denuders, Teflon filter, nylon filter, and an annular denuder, in series. Two annular denuders were to remove acidic and basic gases prior to collecting particles on the Teflon filter. Nylon filter and an annular denuder were to back up the Teflon filter by absorbing acidic and basic gases, respectively, which were volatilized from collected particles on the Teflon filter. Samplings were made for 24 hours every day. Extracts from filters and denuders were analyzed by ion chromatography to measure concentrations of anions (SO42-, NO3-, Cl-) and cations (Ca2+, Mg2+, NH4+, Na+, K+). The amounts of ionic species absorbed at the backup nylon filter and denuder were examined in terms of meteorological parameters, the amounts of gases removed in front of the Teflon filter, and the amounts of particulate ions collected on the Teflon filter. Major factors to affect the volatilization from particles collected on the Teflon filter were discussed.

Kim, C.; Choi, Y.; Ghim, Y.

2012-12-01

30

Screening volatile organics by direct sampling ion trap and glow discharge mass spectrometry  

SciTech Connect

Two different types of direct sampling mass spectrometers are currently being evaluated in our laboratory for use as rapid screening tools for volatile organics in a wide range of environmental matrices. These include a commercially available ITMS ion trap mass spectrometer and a specially designed tandem source glow discharge quadrupole mass spectrometer. Both of these instruments are equipped with versatile sampling interfaces which enable direct monitoring of volatile organics at part-per-billion (ppb) levels in air, water, and soil samples. Direct sampling mass spectrometry does not utilize chromatographic or other separation steps prior to admission of samples into the analyzer. Instead, individual compounds are measured using one or more of the following methods: spectral subtraction, selective chemical ionization, and tandem mass spectroscopy (MS/MS). For air monitoring applications, an active sniffer'' probe is used to achieve instantaneous response. Water and soil samples are analyzed by means of high speed direct purge into the mass spectrometer. Both instruments provide a range of ionization options for added selectivity and the ITMS can also provide high efficiency collision induced dissociation MS/MS for target compound analysis. Detection limits and response factors have been determined for a large number volatile organics in air, water, and number of different soil types. 4 refs., 14 figs., 3 tabs.

Wise, M.B.; Hurst, G.B.; Thompson, C.V.; Buchanan, M.V.; Guerin, M.R.

1991-01-01

31

A Volatile Organic Analyzer for Space Station - Description and evaluation of a gas chromatography\\/ion mobility spectrometer  

Microsoft Academic Search

An on-board Volatile Organic Analyzer (VOA), an essential component of the Environmental Health System (EHS) air-quality monitoring strategy, is described. The strategy is aimed at warning the crew and ground personnel if volatile compounds exceed safe exposure limits. The VOA uses a combination of gas chromatography (GC) and ion-mobility spectrometry (IMS) for environmental monitoring and analysis. It is concluded that

Thomas Limero; John Brokenshire; Colin Cumming; Ed Overton; Ken Carney; Jay Cross; Gary Eiceman; John James

1992-01-01

32

Potential for ion-induced nucleation of volatile organic compounds by radon decay in indoor environments  

SciTech Connect

The theoretical potential for the formation of clusters of vapor-phase organic compounds found in indoor air around the [sup 218]PoO[sub x][sup +] ion was investigated as well as which compounds were most likely to form clusters. A compilation of measurements of indoor organic compounds has been made for future experiments and theoretical calculations by the radon research community. Forty-four volatile and semivolatile organic compounds out of the more than 300 that have been reported in indoor air were investigated. Water vapor was included for comparison. The results indicate that there is a potential for the formation of clusters of organic compounds around the [sup 218]PoO[sub x][sup +] ion. The compounds with the greatest potential for cluster formation are the volatile oxidized hydrocarbons (e.g., n-butanol, phenol, hexanal, nonanal, benzaldehyde, the ketones, and the acetates) and the semivolatile organic compounds (pentachlorophenol, nicotine, chlordane, chlorpyrifos). Although the estimated diameters are consistent with the measured diameters for the unattached fraction, the state of experimental and theoretical knowledge in this area is not sufficiently developed to judge the quantitative validity of these predictions. 48 refs., 1 fig., 5 tabs.

Daisey, J.M. (Lawrence Berkeley Lab., CA (United States)); Hopke, P.K. (Clarkson Univ., Potsdam, NY (United States))

1993-07-01

33

VOLATILE ORGANIC COMPOUNDS IN 600 U.S. HOMES: MAJOR SOURCES OF PERSONAL EXPOSURE  

EPA Science Inventory

The USEPA carried out the Total Exposure Assessment Methodology (TEAM) Study (1980-85) on 600 subjects in five cities representing a total population of more than 700,000 persons. Personal exposures to all prevalent target compounds exceeded outdoor concentrations. Major sources ...

34

The major-ion composition of Permian seawater  

NASA Astrophysics Data System (ADS)

The major-ion (Mg 2+, Ca 2+, Na +, K +, SO 42-, and Cl -) composition of Permian seawater was determined from chemical analyses of fluid inclusions in marine halites. New data from the Upper Permian San Andres Formation of Texas (274-272 Ma) and Salado Formation of New Mexico (251 Ma), analyzed by the environmental scanning electron microscopy (ESEM) X-ray energy-dispersive spectrometry (EDS) method, along with published chemical compositions of fluid inclusions in Permian marine halites from North America (two formations of different ages) and the Central and Eastern European basins (eight formations of four different ages) show that Permian seawater shares chemical characteristics with modern seawater, including SO 42- > Ca 2+ at the point of gypsum precipitation, evolution into Mg 2+-Na +-K +-SO 42--Cl - brines, and Mg 2+/K + ratios ˜5. Permian seawater, however, is slightly depleted in SO 42- and enriched in Ca 2+, although modeling results do not rule out Ca 2+ concentrations close to those in present-day seawater. Na + and Mg 2+ in Permian seawater are close to (slightly below) their concentrations in modern seawater. Permian and modern seawater are both classified as aragonite seas, with Mg 2+/Ca 2+ ratios >2, conditions favorable for precipitation of aragonite and magnesian calcite as ooids and cements. The chemistry of Permian seawater was modeled using the chemical composition of brine inclusions for three periods: Lower Permian Asselian-Sakmarian (296-283 Ma), Lower Permian Artinskian-Kungurian (283-274 Ma), and Upper Permian Tatarian (258-251 Ma). Parallel changes in the chemistry of brine inclusions from equivalent age evaporites in North America, Central Europe, and Eastern Europe show that seawater underwent secular variations in chemistry over the 50 million years of the Permian. Modeled SO 42- concentrations are 20 mmol per kg H 2O (mmolal) and 19 mmolal in the Asselian-Sakmarian and Artinskian-Kungurian, with higher concentrations in the Upper Permian Tatarian (23 mmolal). Modeled Ca 2+ is at or above its concentration in modern seawater throughout the Permian. Mg 2+ is close to (slightly below) its concentration in modern seawater (55 mmolal) in the Asselian-Sakmarian (52 mmolal), and Tatarian (52 mmolal), but slightly higher than modern seawater in the Artinskian-Kungurian (60 mmolal). Mg 2+/Ca 2+ ratios are 3.5 (total range = 2.7 to 5.5) in the Lower Permian and rose slightly to 3.7 (total range = 3.1 to 5.8) in the Upper Permian, primarily due to decreases in Ca 2+. These results are consistent with models that predict oscillations in the major-ion composition of Phanerozoic seawater on the basis of changes in the midocean ridge/river water flux ratio driven by changes in the rate of midocean ridge crust production. The Permian was characterized by low sea levels, icehouse conditions, and southern hemisphere glaciation. Such conditions, analogous to the present ice age, and the similarities between Permian seawater and modern seawater, all suggest that general Phanerozoic supercycles, driven by mantle convection and global volcanicity, also control the major-ion chemistry of seawater.

Lowenstein, Tim K.; Timofeeff, Michael N.; Kovalevych, Volodymyr M.; Horita, Juske

2005-04-01

35

A Volatile Organic Analyzer for Space Station - Description and evaluation of a gas chromatography/ion mobility spectrometer  

NASA Astrophysics Data System (ADS)

An on-board Volatile Organic Analyzer (VOA), an essential component of the Environmental Health System (EHS) air-quality monitoring strategy, is described. The strategy is aimed at warning the crew and ground personnel if volatile compounds exceed safe exposure limits. The VOA uses a combination of gas chromatography (GC) and ion-mobility spectrometry (IMS) for environmental monitoring and analysis. It is concluded that the VOA dual-mode detection capability and the ion mobilities in the drift region are unique features that can assist in the resolution of coeluting GC peaks. The VOA is capable of accurately identifying and quantifying target compounds in a complex mixture.

Limero, Thomas; Brokenshire, John; Cumming, Colin; Overton, Ed; Carney, Ken; Cross, Jay; Eiceman, Gary; James, John

1992-07-01

36

A Volatile Organic Analyzer for Space Station - Description and evaluation of a gas chromatography/ion mobility spectrometer  

NASA Technical Reports Server (NTRS)

An on-board Volatile Organic Analyzer (VOA), an essential component of the Environmental Health System (EHS) air-quality monitoring strategy, is described. The strategy is aimed at warning the crew and ground personnel if volatile compounds exceed safe exposure limits. The VOA uses a combination of gas chromatography (GC) and ion-mobility spectrometry (IMS) for environmental monitoring and analysis. It is concluded that the VOA dual-mode detection capability and the ion mobilities in the drift region are unique features that can assist in the resolution of coeluting GC peaks. The VOA is capable of accurately identifying and quantifying target compounds in a complex mixture.

Limero, Thomas; Brokenshire, John; Cumming, Colin; Overton, ED; Carney, Ken; Cross, Jay; Eiceman, Gary; James, John

1992-01-01

37

Volatile metabolites.  

PubMed

Volatile organic compounds (volatiles) comprise a chemically diverse class of low molecular weight organic compounds having an appreciable vapor pressure under ambient conditions. Volatiles produced by plants attract pollinators and seed dispersers, and provide defense against pests and pathogens. For insects, volatiles may act as pheromones directing social behavior or as cues for finding hosts or prey. For humans, volatiles are important as flavorants and as possible disease biomarkers. The marine environment is also a major source of halogenated and sulfur-containing volatiles which participate in the global cycling of these elements. While volatile analysis commonly measures a rather restricted set of analytes, the diverse and extreme physical properties of volatiles provide unique analytical challenges. Volatiles constitute only a small proportion of the total number of metabolites produced by living organisms, however, because of their roles as signaling molecules (semiochemicals) both within and between organisms, accurately measuring and determining the roles of these compounds is crucial to an integrated understanding of living systems. This review summarizes recent developments in volatile research from a metabolomics perspective with a focus on the role of recent technical innovation in developing new areas of volatile research and expanding the range of ecological interactions which may be mediated by volatile organic metabolites. PMID:24957243

Rowan, Daryl D

2011-01-01

38

Volatile Metabolites  

PubMed Central

Volatile organic compounds (volatiles) comprise a chemically diverse class of low molecular weight organic compounds having an appreciable vapor pressure under ambient conditions. Volatiles produced by plants attract pollinators and seed dispersers, and provide defense against pests and pathogens. For insects, volatiles may act as pheromones directing social behavior or as cues for finding hosts or prey. For humans, volatiles are important as flavorants and as possible disease biomarkers. The marine environment is also a major source of halogenated and sulfur-containing volatiles which participate in the global cycling of these elements. While volatile analysis commonly measures a rather restricted set of analytes, the diverse and extreme physical properties of volatiles provide unique analytical challenges. Volatiles constitute only a small proportion of the total number of metabolites produced by living organisms, however, because of their roles as signaling molecules (semiochemicals) both within and between organisms, accurately measuring and determining the roles of these compounds is crucial to an integrated understanding of living systems. This review summarizes recent developments in volatile research from a metabolomics perspective with a focus on the role of recent technical innovation in developing new areas of volatile research and expanding the range of ecological interactions which may be mediated by volatile organic metabolites.

Rowan, Daryl D.

2011-01-01

39

Exposure to major volatile organic compounds and carbonyls in European indoor environments and associated health risk.  

PubMed

This paper summarizes recent data on the occurrence of major organic compounds (benzene, toluene, xylenes, styrene, acetaldehyde, formaldehyde, naphthalene, limonene, ?-pinene and ammonia, classified by the European Commission's INDEX strategy report as the priority pollutants to be regulated) and evaluates accordingly cancer and non-cancer risks posed by indoor exposure in dwellings and public buildings in European Union (EU) countries. The review process indicated that significant differences in indoor air quality exist within and among the countries where data were available, indicating corresponding differences in sources and emission strength of airborne chemicals, identified or not. Conservative exposure limits were not exceeded for non-carcinogenic effects, except for formaldehyde; for carcinogenic agents the estimated risks were up to three orders of magnitude higher than the one (10(-6)) proposed as acceptable by risk management bodies. However, the risk assessment evaluation process faces crucial difficulties, either due to the relative paucity of indoor air quality measurements in many EU countries, or by the lack of sampling consistency in the already existing studies, indicating the need for additional measurements of indoor air quality following a harmonized sampling and analytical protocol. Additionally, uncertainties embodied in the cancer potency factors and exposure limit values impose further difficulties in substance prioritization and risk management. PMID:21354626

Sarigiannis, Dimosthenis A; Karakitsios, Spyros P; Gotti, Alberto; Liakos, Ioannis L; Katsoyiannis, Athanasios

2011-05-01

40

Direct determination of volatile analytes from solid samples by UV-ion mobility spectrometry.  

PubMed

A simple, reliable, inexpensive sample introduction system (SIS) coupled to an ion mobility spectrometry (IMS) equipment was used for the determination of volatile analytes present in solid samples. Following minimal pretreatment, the solid sample (e.g. fish) is directly placed in a membrane unit and released analytes (trimethylamine, dimethylamine and ammonia) pass through the membrane into a nitrogen acceptor stream; finally, passing the gaseous stream trough the UV-IMS system allows the analytes to be readily determined. Volatiles are released by heating the sample at 75 degrees C for 5 min following addition of a few drops of NaOH solution. This method is quite expeditious and uses small amounts of sample. The calibration graph is linear over the concentration range 5-225 microg mL(-1). The proposed SIS-IMS method is quite repeatable (RSD<4%) and reproducible (RSD<9%). Also, it provides acceptable analyte recoveries (111+/-17%) from spiked fish samples. The results of this study testify to the potential of IMS for qualitative and quantitative analytical determinations. PMID:19010475

Menéndez, M; Garrido-Delgado, R; Arce, L; Valcárcel, M

2008-12-26

41

[Photoionization ion mobility spectrometry (UV-IMS) for the isomeric volatile organic compounds].  

PubMed

The construction and performance study is reported for a newly developed ultraviolet photoionization ion mobility spectrometry (UV-IMS). In the present paper, an UV-IMS technique was firstly developed to detect eleven isomeric volatile organic compounds including the differences in the structure of carbon chain, the style of function group and the position of function group. Their reduced mobility values were determined and increased in this order: linears < branches < cycles, primary < secondary < tertiary, para- < meta- < ortho- and alcohols < acetones < aromas. The concentrations of analytes were obtained by means of exponential dilution method, and the experiments show that the limit of detection of the homemade UV-IMS was around ppb-ppm. PMID:22497120

Li, Hu; Niu, Wen-qi; Wang, Hong-mei; Huang, Chao-qun; Jiang, Hai-he; Chu, Yan-nan

2012-01-01

42

Volatile organic compound analysis by ion molecule reaction mass spectrometry for Gram-positive bacteria differentiation.  

PubMed

Approximately 50 % of all clinically proven infections in critically ill patients are caused by Gram-positive bacteria. The timely and appropriate treatment of these infections is vital in order to avoid negative outcomes. Hence, fast and reliable methods are needed for the early detection and identification of microorganisms. Recently, direct mass spectrometry-based analysis of volatile organic compounds emitted by microorganisms has been employed to study Gram-negative bacteria. Here, we report a feasibility study of ion molecule reaction mass spectrometry (IMR-MS) for in vitro growth detection and species differentiation of selected Gram-positive bacteria that are frequently isolated in blood culture samples, namely, Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, and Staphylococcus epidermidis. Ion molecule reaction mass spectrometry was used to analyze the headspace above cultures containing Gram-positive bacteria incubated at 37 °C starting with 10(2) colony-forming units (CFU)/ml. Measurements to determine the presence of volatile organic compounds were performed 4, 8, and 24 h after incubation, respectively. The detection of microbial growth was accomplished already after 8 h in cultures containing E. faecalis. After 24 h of incubation, characteristic mass spectra were obtained for all species. Processing these mass spectra by hierarchic clustering and principal component analysis (PCA) enabled us to differentiate between bacterial species. IMR-MS in conjunction with a cumulative end-point model provides the means for rapid growth detection and differentiation of Gram-positive bacteria on the species level, typically within an analysis time of less than 3 min per sample. PMID:22782437

Dolch, M E; Hornuss, C; Klocke, C; Praun, S; Villinger, J; Denzer, W; Schelling, G; Schubert, S

2012-11-01

43

Major ion toxicity in effluents: A review with permitting recommendations  

SciTech Connect

Effluent toxicity testing methods have been well defined, but for the most part, these methods do not attempt to segregate the effects of active ionic concentrations and ion imbalances upon test and species performances. The role of various total dissolved solids in effluents on regulatory compliance has emerged during the last few years and has caused confusion in technical assessment and in permitting and compliance issues. This paper assesses the issue of ionic strength and ion imbalance, provides a brief summary of applicable data, presents several case studies demonstrating successful tools to address toxicity resulting from salinity and ion imbalance, and provides recommendations for regulatory and compliance options to manage discharges with salinity/ion imbalance issues. Effluent toxicity resulting from inorganic ion imbalance and the ion concentration of the effluent is pervasive in permitted discharge from many industrial process and municipal discharges where process streams are concentrated, adjusted, or modified. This paper discusses procedures that use weight-of-evidence approaches to identify ion imbalance toxicity, including direct measurement, predictive toxicity models for freshwater, exchange resins, mock effluents, and ion imbalance toxicity with tolerant/susceptible test species. Cost-effective waste treatment control options for a facility whose effluent is toxic because of total dissolved solids (TDS) or because of specific ion(s) are scarce at best. Depending on the discharge situation, TDS toxicity may not be viewed with the same level of concern as other, more traditional, toxicants. These discharge situations often do not require the conservative safety factors required by other toxicants. Selection of the alternative regulatory solutions discussed in this paper may be beneficial, especially because they do not require potentially expensive or high-energy-using treatment options that may be ineffective control options. The information presented is intended to provide a better understanding of the role of ion imbalance in aquatic toxicity testing and to provide various recommendations that should be considered in addressing these issues.

Goodfellow, W.L.; Ausley, L.W.; Burton, D.T.; Denton, D.L.; Dorn, P.B.; Grothe, D.R.; Heber, M.A.; Norberg-King, T.J.; Rodgers, J.H. Jr.

2000-01-01

44

External electron ionization 7 T Fourier transform ion cyclotron resonance mass spectrometer for resolution and identification of volatile organic mixtures  

Microsoft Academic Search

An external electron ionization (EI) source has been interfaced to a 7 T Fourier transform ion cyclotron resonance mass spectrometer and tested for volatile complex mixture analysis. A new Sulfinert®-deactivated inlet system provides continuous stable sample flow to the EI source, leading to stable ion signal (±10% deviation) for 2 h from a 200 nL mixture of 15 n-alkylbenzenes. Ultrahigh-mass

Jinmei Fu; Jeremiah M Purcell; John P. Quinn; Tanner M. Schaub; Christopher L. Hendrickson; Ryan P. Rodgers; Alan G. Marshall

2006-01-01

45

External electron ionization 7 T Fourier transform ion cyclotron resonance mass spectrometer for resolution and identification of volatile organic mixtures  

Microsoft Academic Search

An external electron ionization (EI) source has been interfaced to a 7 T Fourier transform ion cyclotron resonance mass spectrometer and tested for volatile complex mixture analysis. A new Sulfinert®-deactivated inlet system provides continuous stable sample flow to the EI source, leading to stable ion signal (+\\/-10% deviation) for 2 h from a 200 nL mixture of 15 n-alkylbenzenes. Ultrahigh-mass

Jinmei Fu; Jeremiah M. Purcell; John P. Quinn; Tanner M. Schaub; Christopher L. Hendrickson; Ryan P. Rodgers; Alan G. Marshall

2006-01-01

46

Validation of selective ion flow tube mass spectrometry for fast quantification of volatile bases produced on Atlantic cod (Gadus morhua).  

PubMed

Selective ion flow tube mass spectrometry (SIFT-MS) is a direct mass spectrometric technique that allows qualitative and quantitative analysis of a large number of volatile organic compounds. Because of its speed and ease of use, this nondestructive technique could be considered as a practical tool for quality control. This research focuses on the possibilities of direct headspace sampling by SIFT-MS for the quantification of the volatile basic nitrogen content (TVB-N) of fish fillets. These volatile bases [trimethylamine (TMA), dimethylamine (DMA), and ammonia] give additional information in conjunction with the sensory scoring and microbiological analysis about the quality of the fish fillets. This research validates in a first part the SIFT-MS method for the quantification of the volatile bases in mixed cod samples. With regard to the investigated linearity, repeatability, reproducibility, recovery, limit of detection, and limit of quantification, SIFT-MS appeared to be an adequate technique for measuring volatile bases spiked on cod. In the second part of this research, the technique was validated for the analysis of volatile bases on cod fillets during a storage experiment under ice. A good correlation was obtained between the proposed direct headspace sampling and traditional methods. The sensitivity of the SIFT-MS method can be improved when cod fillets are made more alkaline (pH >11) during sampling. PMID:20387831

Noseda, Bert; Ragaert, Peter; Pauwels, Danny; Anthierens, Tom; Van Langenhove, Herman; Dewulf, Jo; Devlieghere, Frank

2010-05-12

47

Methionine metabolism: major pathways and enzymes involved and strategies for control and diversification of volatile sulfur compounds in cheese.  

PubMed

For economical reasons and to accommodate current market trends, cheese manufacturers and product developers are increasingly interested in controlling cheese flavor formation and developing new flavors. Due to their low detection threshold and diversity, volatile sulfur compounds (VSCs) are of prime importance in the overall flavor of cheese and make a significant contribution to their typical flavors. Thus, the control of VSCs formation offers considerable potential for industrial applications. This paper gives an overview of the main VSCs found in cheese, along with the major pathways and key enzymes leading to the formation of methanethiol from methionine, which is subsequently converted into other sulfur-bearing compounds. As these compounds arise primarily from methionine, the metabolism of this amino acid and its regulation is presented. Attention is focused in the enzymatic potential of lactic acid bacteria (LAB) that are widely used as starter and adjunct cultures in cheese-making. In view of industrial applications, different strategies such as the enhancement of the abilities of LAB to produce high amounts and diversity of VSCs are highlighted as the principal future research trend. PMID:23320908

Martínez-Cuesta, María Del Carmen; Peláez, Carmen; Requena, Teresa

2013-01-01

48

The major-ion composition of Carboniferous seawater  

NASA Astrophysics Data System (ADS)

The major-ion chemistry (Na+, Mg2+, Ca2+, K+, SO42-, and Cl-) of Carboniferous seawater was determined from chemical analyses of fluid inclusions in marine halites, using the cryo scanning electron microscopy (Cryo-SEM) X-ray energy-dispersive spectrometry (EDS) technique. Fluid inclusions in halite from the Mississippian Windsor and Mabou Groups, Shubenacadie Basin, Nova Scotia, Canada (Asbian and Pendleian Substages, 335.5-330 Ma), and from the Pennsylvanian Paradox Formation, Utah, USA, (Desmoinesian Stage 309-305 Ma) contain Na+-Mg2+-K+-Ca2+-Cl- brines, with no measurable SO42-, which shows that the Carboniferous ocean was a “CaCl2 sea”, relatively enriched in Ca2+ and low in SO42- with equivalents Ca2+ > SO42- + HCO3-. ?34S values from anhydrite in the Mississippian Shubenacadie Basin (13.2-14.0 ‰) and the Pennsylvanian Paradox Formation (11.2-12.6 ‰) support seawater sources. Br in halite from the Shubenacadie Basin (53-111 ppm) and the Paradox Basin (68-147 ppm) also indicate seawater parentages. Carboniferous seawater, modeled from fluid inclusions, contained ?22 mmol Ca2+/kg H2O (Mississippian) and ?24 mmol Ca2+/kg H2O (Pennsylvanian). Estimated sulfate concentrations are ?14 mmol SO42-/kg H2O (Mississippian), and ?12 mmol SO42-/kg H2O (Pennsylvanian). Calculated Mg2+/Ca2+ ratios are 2.5 (Mississippian) and 2.3 (Pennsylvanian), with an estimated range of 2.0-3.2. The fluid inclusion record of seawater chemistry shows a long period of CaCl2 seas in the Paleozoic, from the Early Cambrian through the Carboniferous, when seawater was enriched in Ca2+ and relatively depleted in SO42-. During this ?200 Myr interval, Ca2+ decreased and SO42- increased, but did not cross the Ca2+-SO42- chemical divide to become a MgSO4 sea (when SO42- in seawater became greater than Ca2+) until the latest Pennsylvanian or earliest Permian (?309-295 Ma). Seawater remained a MgSO4 sea during the Permian and Triassic, for ?100 Myr. Fluid inclusions also record a long interval, from the Early Cambrian to the Middle Devonian, when seawater had low Mg2+/Ca2+ ratios (<2) that coincide with calcite seas. The Mg2+/Ca2+ ratio of seawater rose from 0.9 in the Middle Devonian, to 2.5 in the Middle/Late Mississippian, 2.3 in the Middle Pennsylvanian, and 3.5 in the Early Permian. The transition from calcite seas to aragonite seas, established from the mineralogy of oölites and early marine cements, occurred in the Late Mississippian. Fluid inclusions show that seawater Mg2+/Ca2+ ratios rose above 2 by the Middle to Late Mississippian coinciding exactly with the shift to aragonite seas. Aragonite seas existed for ?100 Myr, from the Late Mississippian until the Late Triassic/Early Jurassic.

Holt, Nora M.; García-Veigas, Javier; Lowenstein, Tim K.; Giles, Peter S.; Williams-Stroud, Sherilyn

2014-06-01

49

Detection of volatile organic compounds in breath using thermal desorption electrospray ionization-ion mobility-mass spectrometry.  

PubMed

A thermal desorption unit has been interfaced to an electrospray ionization-ion mobility-time-of-flight mass spectrometer. The interface was evaluated using a mixture of six model volatile organic compounds which showed detection limits of <1 ng sample loaded onto a thermal desorption tube packed with Tenax, equivalent to sampled concentrations of 4 microg L(-1). Thermal desorption profiles were observed for all of the compounds, and ion mobility-mass spectrometry separations were used to resolve the probe compound responses from each other. The combination of temperature programmed thermal desorption and ion mobility improved the response of selected species against background ions. Analysis of breath samples resulted in the identification of breath metabolites, based on ion mobility and accurate mass measurement using siloxane peaks identified during the analysis as internal lockmasses. PMID:20143891

Reynolds, J C; Blackburn, G J; Guallar-Hoyas, C; Moll, V H; Bocos-Bintintan, V; Kaur-Atwal, G; Howdle, M D; Harry, E L; Brown, L J; Creaser, C S; Thomas, C L P

2010-03-01

50

Analysis of volatile components of drugs and explosives by solid phase microextraction-ion mobility spectrometry.  

PubMed

Current ion mobility spectrometry (IMS) devices are used to detect drugs and explosives in the form of particles and, in cases where the vapor pressure of the drugs or explosives is sufficiently high, the gas can be sampled and detected directly. The aim of this study is to demonstrate the use of solid phase microextraction (SPME) as a preconcentration technique coupled to an IMS for the detection of odor signature compounds of drugs and explosives. The reduced mobilities (K(o)) and IMS operating conditions for the odor signature compounds of cocaine, marijuana, and 3,4-methylenedioxy-N-methylamphetamine (MDMA) are reported for the first time. LODs, linear dynamic ranges (LDRs), and the precision of the analysis of these odor signature compounds, and the explosive taggant 2,3-dimethyl-2,3-dinitrobutane (DMNB) were obtained by SPME-IMS and normal IMS conditions. The systematic optimization of the IMS operating parameters for the detection of these odor compounds is also reported incorporating the use of genetic algorithms (GAs) for finding the optimal settings for the detection of these compounds of interest. These results support the case for targeting volatile components as a presumptive detection for the presence of the parent compounds of drugs and explosives. Furthermore, the IMS-specific GA developed can be used as an optimization tool for the detection of other compounds of interest in future work. PMID:18196520

Lai, Hanh; Guerra, Patricia; Joshi, Monica; Almirall, José R

2008-02-01

51

Volatile products and endpoint detection in reactive ion etching of III-V compounds with a broad beam ECR source  

NASA Astrophysics Data System (ADS)

A broad beam ECR plasma source has been applied to low pressure hydrocarbon reactive ion etching of III-V compounds. An additional RF bias is applied to the sample stage providing the means for independent control of current density and bombarding energy of ions on the sample surface. Chemical aspects of the etching process have been investigated with a differentially pumped energy selective Hiden quadrupole mass spectrometer. In particular, the dominant group III volatile species in InP and GaAs have been clearly identified for the first time as In(CH 3) 2+ and Ga(CH 3) 2+, respectively. Finally, we report the application of volatile product identification to endpoint detection and demonstrate resolution for multiple layers as thin as 50 Å. These results confirm that etch uniformity over the surface area of the sample is very good for these sources.

Melville, D. L.; Budinavicius, J.; Thompson, D. A.; Simmons, J. G.

52

Detection of volatile compounds produced by microbial growth in urine by selected ion flow tube mass spectrometry (SIFT-MS).  

PubMed

Selected ion flow tube-mass spectrometry has been used to measure the volatile compounds occurring in the headspace of urine samples inoculated with common urinary tract infection (UTI)-causing microbes Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumoniae, Enterococcus faecalis, or Candida albicans. This technique has the potential to offer rapid and simple diagnosis of the causative agent of UTIs. PMID:21741416

Storer, Malina K; Hibbard-Melles, Kim; Davis, Brett; Scotter, Jenny

2011-10-01

53

Major Ion Chemistry of Shark River Slough, Everglades National Park  

NASA Astrophysics Data System (ADS)

Shark River Slough (SRS) is the dominant surface water flow way in Everglades National Park and its water chemistry is currently being monitored at 6 sites as part of the Florida Coastal Everglades-Long Term Ecological Research program. In order to determine the sources of water, the interactions between the sources of water as well as to calculate residence times of different water source reservoirs and evaporative enrichment, surface water samples were analyzed for major anion and cation concentrations (i.e., Cl, SO2, Ca, K, Mg, and Na). Surface water samples were collected at each site using an ISCO 6172 autosampler, that was programmed to collect a 250-ml sample every 18 h and to composite four such samples into the same 1-liter bottle. Thus, each 1 liter sample represented a 3-day composite. Autosamplers were serviced monthly, and the collected 1 liter of water was split in the laboratory, with one half analyzed for major cations and anions at FIUs hydrogeology laboratory and the other analyzed for total nutrient concentrations at SERCs Nutrient Laboratory. Prior to being analyzed for major cations and anions, the sample was filtered and split again with one half acidified with 10% HCl for the cations analysis. This poster presents the results of the major cations and anions data collected in 2008 and 2009. Chloride and sulfate concentrations in the surface water of SRS tended to be lower and more variable at the most upstream freshwater site as compared to the downstream freshwater sites. The higher variability of the anion concentrations at the most upstream SRS site may be due to its proximity to the water discharge gates along Tamiami Trail that deliver water from the upstream water conservation areas into SRS. The higher concentration and less variability in chloride and sulfate concentrations at the more downstream freshwater sites may be related to greater exposure of the surface water to evaporation.

Neira, N. M.; Matthews, F. A.; Lagomasino, D.; Price, R. M.

2010-12-01

54

Ion-trap detection of volatile organic compounds in alveolar breath  

Microsoft Academic Search

We describe a method for the collection and microanalysis of the volatile organic compounds in human breath. A transportable apparatus supplies subjects with purified air and samples their alveolar breath; the volatile organic compounds are captured in an adsorptive trap containing activated carbon and molecular sieve. The sample is thermally desorbed from the trap in an automated microprocessor-controlled device, concentrated

M. Phillips; J. Greenberg

1992-01-01

55

Real-time detection of common microbial volatile organic compounds from medically important fungi by Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS)  

Microsoft Academic Search

We describe a new method, Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS) for the rapid and sensitive real-time detection and quantification of volatile organic compounds from medically important fungi, grown on a range of laboratory media.SIFT-MS utilises the chemical ionisation reactions of mass-selected ions to characterise volatile organic compounds (VOCs) that are produced as metabolites from fungi. This technique has the

Jennifer M. Scotter; Vaughan S. Langford; Paul F. Wilson; Murray J. McEwan; Stephen T. Chambers

2005-01-01

56

Occurrence, distribution, and trends of volatile organic compounds in the Ohio River and its major tributaries, 1987-96  

USGS Publications Warehouse

The Ohio River is a source of drinking water for more than 3 million people. Thus, it is important to monitor the water quality of this river to determine if contaminants are present, their concentrations, and if water quality is changing with time. This report presents an analysis of the occurrence, distribution, and trends of 21 volatile organic compounds (VOCs) along the main stem of the Ohio River and its major tributaries from 1987 through 1996. The data were collected by the Ohio River Valley Water Sanitation Commission's Organics Detection System, which monitors daily for VOCs at 15 stations. Various statistical methods were applied to basinwide data from all monitoring stations and to data from individual monitoring stations. For the basinwide data, one or more VOCs were detected in 45 percent of the 44,837 river-water samples. Trichloromethane, detected in 26 percent of the samples, was the most frequently detected VOC followed by benzene (11 percent), methylbenzene (6.4 percent), and the other 18 VOCs, which were detected in less than 4 percent of the samples. In samples from 8 of the 15 monitoring stations, trichloromethane was also the most frequently detected VOC. These stations were generally near large cities along the Ohio River. The median trichloromethane concentration was 0.3 microgram per liter (?g/L), and concentrations ranged from less than 0.1 to 125.3 ?g/L. Most of the VOCs had median detected concentrations that ranged from 0.1 to 0.4 ?g/L for the basinwide data and for samples from individual stations. Samples from stations in the upstream part of the basin and from the Kanawha River had the highest median concentrations. Ninety-nine percent of the detected VOC concentrations were within U.S. Environmental Protection Agency drinking-water regulations. Of the 268 exceedances of drinking-water regulations, 188 were due to the detection of 1,2-dichloroethane prior to 1993 in samples from the monitoring station near Paducah, Ky. Time trend analyses indicated that most VOCs had no trend in samples at most monitoring stations because they were detected infrequently. At one or more stations, 14 VOCs had decreasing trends in monthly mean concentrations that ranged from -0.01 to -0.42 ?/L per year. Nine VOCs had significant decreasing trends in percentage detection that ranged from -1.08 to -12.90 percent per year. These trends suggest that source-control efforts are working and that water quality is improving.

Lundgren, Robert F.; Lopes, Thomas J.

1999-01-01

57

Nucleation and growth of atmospheric particles: Contribution of ion-mediated nucleation and role of low volatile organics condensation  

NASA Astrophysics Data System (ADS)

Formation and subsequent growth of secondary particles is an important source of atmospheric aerosol and contributes significantly to climate effective aerosols. It is now generally accepted that H2SO4 and ions are involved in the nucleation process while low volatile organic gases (LV-SOG) and H2SO4 are involved in the growth process, although the relative contribution of ion versus neutral nucleation and possible involvement of species other than sulfuric acid in the nucleation process remain controversial. Here we study the particle formation and growth processes in the troposphere using a global chemical transport model (GEOS-Chem) with an advanced particle microphysics (APM) module incorporated. The widely used 2-product secondary organic aerosol (SOA) formation model has been extended to take into account the volatility changes of secondary organic gases (SOGs) arising from the aging process. In addition to semi-volatile SOG (SV-SOG) and medium-volatile SOG (MV-SOG), we add a third component representing low-volatile SOG (LV-SOG) and design a scheme to transfer MV-SOG to SV-SOG and SV-SOG to LV-SOG associated with oxidation aging. The co-condensation of H2SO4 and LV-SOG on particles is explicitly simulated in GEOS-Chem + APM. Our predicted LV-SOG concentrations are generally a factor of ~2-20 higher than those of [H2SO4], and LV-SOG condensation significantly enhances particle growth rates and SOA mass over many parts of the continents. We show that ion-mediated nucleation appears to be able to capture within a factor of ~ 2 the particle number concentrations measured around the globe. Comparisons of the simulated and observed evolution of particle size distributions at selected sites clearly show that LV-SOG condensation is critical in order to bring the simulations closer to the observations. Ion-mediated nucleation and LV-SOG condensation substantially increase the concentration of cloud condensation nuclei. The ability of GEOS-Chem +APM in explaining the seasonal and the diurnal variations of particle size distributions and number concentrations at a number of locations will be assessed and implications will be discussed.

Yu, F.; Luo, G.

2010-12-01

58

Identification of volatile chemical signatures from plastic explosives by SPME-GC/MS and detection by ion mobility spectrometry.  

PubMed

This study demonstrates the use of solid-phase microextraction (SPME) to extract and pre-concentrate volatile signatures from static air above plastic explosive samples followed by detection using ion mobility spectrometry (IMS) optimized to detect the volatile, non-energetic components rather than the energetic materials. Currently, sample collection for detection by commercial IMS analyzers is conducted through swiping of suspected surfaces for explosive particles and vapor sampling. The first method is not suitable for sampling inside large volume areas, and the latter method is not effective because the low vapor pressure of some explosives such as RDX and PETN make them not readily available in the air for headspace sampling under ambient conditions. For the first time, headspace sampling and detection of Detasheet, Semtex H, and C-4 is reported using SPME-IMS operating under one universal setting with limits of detection ranging from 1.5 to 2.5 ng for the target volatile signatures. The target signature compounds n-butyl acetate and the taggant DMNB are associated with untagged and tagged Detasheet explosives, respectively. Cyclohexanone and DMNB are associated with tagged C-4 explosives. DMNB is associated with tagged Semtex H explosives. Within 10 to 60 s of sampling, the headspace inside a glass vial containing 1 g of explosive, more than 20 ng of the target signatures can be extracted by the SPME fiber followed by IMS detection. PMID:20229010

Lai, Hanh; Leung, Alfred; Magee, Matthew; Almirall, José R

2010-04-01

59

Confined direct analysis in real time ion source and its applications in analysis of volatile organic compounds of Citrus limon (lemon) and Allium cepa (onion).  

PubMed

The DART (direct analysis in real time) ion source is a novel atmospheric pressure ionization technique that enables efficient ionization of gases, liquids and solids with high throughput. A major limit to its wider application in the analysis of gases is its poor detection sensitivity caused by open-air sampling. In this study, a confined interface between the DART ion source outlet and mass spectrometer sampling orifice was developed, where the plasma generated by the atmospheric pressure glow discharge collides and ionizes gas-phase molecules in a Tee-shaped flow tube instead of in open air. It leads to significant increase of collision reaction probability between high energy metastable molecules and analytes. The experimental results show that the ionization efficiency was increased at least by two orders of magnitude. This technique was then applied in the real time analysis of volatile organic compounds (VOCs) of Citrus Limon (lemon) and wounded Allium Cepa (onion). The confined DART ion source was proved to be a powerful tool for the studies of plant metabolomics. PMID:22499194

Li, Yue

2012-05-30

60

ANALYSIS OF AMBIENT POLAR VOLATILE ORGANIC COMPOUNDS USING CHEMICAL IONIZATION -- ION TRAP DETECTOR  

EPA Science Inventory

The current approach to measuring trace levels of volatile organic compounds (VOCs) in ambient air requires cryogenic trapping of the analytes, followed by thermal desorption and low-temperature refocussing onto a column for analysis by capillary gas chromatography/mass spectrome...

61

A method for measuring semi- and non-volatile organic halogens by combustion ion chromatography  

Microsoft Academic Search

Recent studies have shown that various semi- and non-volatile organohalogen compounds are ubiquitous in the environment: these include halogenated dioxins including chlorinated dioxins, other persistent organic pollutants (POPs), brominated flame retardants (BFRs), and perfluorooctane sulfonate (PFOS). However, monitoring and assessment of these compounds by the analyses of individual compounds and their isomers is onerous because of their low environmental concentrations

Yuichi Miyake; Mika Kato; Kohei Urano

2007-01-01

62

Development of a proton-transfer reaction-linear ion trap mass spectrometer for quantitative determination of volatile organic compounds.  

PubMed

Currently, proton-transfer reaction mass spectrometry (PTR-MS) allows for quantitative determination of volatile organic compounds in real time at concentrations in the low ppt range, but cannot differentiate isomers or isobaric molecules, using the conventional quadrupole mass filter. Here we pursue the application of linear quadrupole ion trap (LIT) mass spectrometry in combination with proton-transfer reaction chemical ionization to provide the advantages of specificity from MS/MS. A commercial PTR-MS platform composed of a quadrupole mass filter with the addition of end cap electrodes enabled the mass filter to operate as a linear ion trap. The rf drive electronics were adapted to enable the application of dipolar excitation to opposing rods, for collision-induced dissociation (CID) of trapped ions. This adaptation enabled ion isolation, ion activation, and mass analysis. The utility of the PTR-LIT was demonstrated by distinguishing between the isomeric isoprene oxidation pair, methyl vinyl ketone (MVK) and methacrolein (MACR). The CID voltage was adjusted to maximize the m/ z 41 to 43 fragment ratio of MACR while still maintaining adequate sensitivity. Linear calibration curves for MVK and MACR fragments at m/ z 41 and 43 were obtained with limits of detection of approximately 100 ppt, which should enable ambient measurements. Finally, the PTR-LIT method was compared to an established GC/MS method by quantifying MVK and MACR production during a smog chamber isoprene-NO x irradiation experiment. PMID:18841942

Mielke, Levi H; Erickson, David E; McLuckey, Scott A; Müller, Markus; Wisthaler, Armin; Hansel, Armin; Shepson, Paul B

2008-11-01

63

Quantitative Determination of Isobaric Volatile Organic Compounds Using Proton Transfer Reaction - Linear Ion Trap (PTR-LIT) Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Several low molecular weight isobaric volatile organic compounds (VOCs) occur in the atmosphere in the low ppb to ppt range. Proton transfer reaction mass spectrometry (PTR-MS) allows for quantitative determination of VOCs in real time at ppt concentrations, but cannot discern isobaric species. Although 3-D quadrupole ion traps are capable of MS/MS, they suffer from limited ion storage capacity and ion trapping efficiency. Here we pursue the application of a linear quadrupole ion trap in combination with proton transfer reaction chemical ionization to provide the advantages of specificity associated with MS/MS with improved performance characteristics relative to 3-D ion traps. In our application the LIT is operated at a drive frequency of 2.0 Mhz. Ions are sequentially ejected by ramping the rf voltage and then bent orthogonally to a secondary electron multiplier. The rf drive has been adapted to enable isolation of specific ions, collision induced dissociation (CID), and dipolar excitation. Two atmospherically important isomers, methyl vinyl ketone (MVK) and methacrolein, yield (M+H)+ parent ions at m/z 71. These isomers can be differentiated given that both species have a common CID fragment at m/z 43, while only methacrolein yields a CID fragment at m/z 41. Initial CID experiments of methacrolein in the PTR-LIT have focused on maximizing the m/z 41 to m/z 43 ratio to lower the limit of detection for discerning methacrolein from MVK. This presentation will describe the instrument, its modifications, and performance characteristics as a tandem mass spectrometer for the measurement of atmospheric isomers.

Mielke, L. H.; Erickson, D. E.; Doerge, C.; Wisthaler, A.; Hansel, A.; McLuckey, S. A.; Shepson, P. B.

2006-12-01

64

Evidence for deep pooling of low degree melts from volatile, major, and trace element chemistry of olivine-hosted melt inclusions and glasses from the ultra-slow spreading Gakkel Ridge  

Microsoft Academic Search

We present new analyses of volatiles and major elements for a suite of glasses and melt inclusions from ~85°E on the ultra-slow spreading Gakkel Ridge. The major element and volatile compositions of the melt inclusions are more variable and consistently more primitive than the glass data. CO2 contents in the melt inclusions extend to higher values (167-1596 ppm) than in

A. M. Shaw; M. D. Behn; S. E. Humphris; R. A. Reves-Sohn; P. M. Gregg

2009-01-01

65

Microbial Volatilization of Arsenic  

Microsoft Academic Search

Arsenic is a dangerous toxin and can be volatilized by many organisms, of which bacteria is a major source. We evaluated whether three common bacteria can volatilize immobile arsenic as well as evaluated a method used for measuring volatile arsenic in fungi can be used for bacteria. Bacillus cereus, Staphlococcus aureus, and Psuedomonas aeruginosa were incubated in media containing 10ppm,

Prince Amoako; Danny Aylwin; Sean O'Connor

66

Perturbations in major ion chemistry of Taylor Slough, Everglades National Park, Florida, USA  

NASA Astrophysics Data System (ADS)

Wetland ecosystems are influenced by perturbations in the cycling of water, nutrients, and other biogeochemically active elements. The purpose of this study was focused on identifying perturbations in major ion chemistry of Taylor Slough, Everglades National Park (ENP) Florida, and to attempt to identify the sources of the perturbations. Water samples were collected from 5 Florida Coastal Everglades-Long Term Ecological Research sites located along a freshwater upland to coastal transect. Composite samples were collected every three days using an ISCO sampler, and were analyzed for major cations and anions during a two-year period ranging from 2008-2010. As expected, the surface water chemistry at the upland sites contained lower ion concentrations than the coastal sites. However, a decrease in ion concentrations at the upland sites in a downstream direction varied from an increase in ion concentration at the coastal sites. This variation may be due to retardation of the ions by sediments and vegetation and proximity to Florida Bay respectively. Seasonal differences in the ion concentrations were observed as well as episodic changes in response to the passage of hurricanes.

Sandoval, E.; Price, R. M.

2010-12-01

67

Mercury and major ions in rainfall, throughfall, and foliage from the Florida Everglades  

Microsoft Academic Search

The deposition of Hg to the Everglades has been investigated using monthly integrated bulk and wet-only tower based precipitation samples, tower based aerosol Hg samples, and ground based throughfall samples. A small set of foliage samples was collected and analyzed for `reactive' and total Hg. There are large differences in the major ion chemistry of the wet and throughfall samples.

Jane L Guentzel; William M Landing; Gary A Gill; Curtis D Pollman

1998-01-01

68

The Major Outer Membrane Protein of Chlamydia psittaci Functions as a Porin-Like Ion Channel  

Microsoft Academic Search

The major outer membrane protein (MOMP) of Chlamydia species shares several biochemical properties with classical porin proteins. Secondary structure analysis by circular dichroism now reveals that MOMP purified from Chlamydia psittaci has a predominantly b-sheet content (62%), which is also typical of bacterial porins. Can MOMP form functional ion channels? To directly test the \\

SUSAN WYLLIE; RICHARD H. ASHLEY; DAVID LONGBOTTOM; ALAN J. HERRING

1998-01-01

69

MAJOR ION HYDROGEOCHEMICAL BUDGETS AND ELEVATED CHLORIDE CONCENTRATIONS IN SENECA LAKE, NEW YORK  

Microsoft Academic Search

Water samples were periodically collected from four lake sites (surface and 2 deep water samples) and seventeen streams within the Seneca Lake watershed from May 2000 through November 2004 and analyzed for the major ions (Cl - , Na + , SO4 2- , K + ,

John D. Halfman; Caterina M. Caiazza; Robert J. Stewart; Suzanne M. Opalka; Clare K. Morgan

70

Analysis of the volatile chemical markers of explosives using novel solid phase microextraction coupled to ion mobility spectrometry.  

PubMed

Ion mobility spectrometry (IMS) is routinely used in screening checkpoints for the detection of explosives and illicit drugs but it mainly relies on the capture of particles on a swab surface for the detection. Solid phase microextraction (SPME) has been coupled to IMS for the preconcentration of explosives and their volatile chemical markers and, although it has improved the LODs over a standalone IMS, it is limited to sampling in small vessels by the fiber geometry. Novel planar geometry SPME devices coated with PDMS and sol-gel PDMS that do not require an additional interface to IMS are now reported for the first time. The explosive, 2,4,6-trinitrotoluene (TNT), is sampled with the planar SPME reaching extraction equilibrium faster than with fiber SPME, concentrating detectable levels of TNT in a matter of minutes. The surface area, capacity, extraction efficiency, and LODs are also improved over fiber SPME allowing for sampling in larger volumes. The volatile chemical markers, 2,4-dinitrotoluene, cyclohexanone, and the taggant 4-nitrotoluene have also been successfully extracted by planar SPME and detected by IMS at mass loadings below 1 ng of extracted analyte on the planar device for TNT, for example. PMID:18666175

Guerra, Patricia; Lai, Hanh; Almirall, José R

2008-08-01

71

The major volatile compound 2-phenylethanol from the biocontrol yeast, Pichia anomala, inhibits growth and expression of aflatoxin biosynthetic genes of Aspergillus flavus.  

PubMed

Aspergillus flavus is a ubiquitous saprophyte that is able to produce the most potent natural carcinogenic compound known as aflatoxin B1 (AFB1). This toxin frequently contaminates crops including corn, cotton, peanuts, and tree nuts causing substantial economic loss worldwide. Consequently, more than 100 countries have strict regulations limiting AFB1 in foodstuffs and feedstuffs. Plants and microbes are able to produce volatile compounds that act as a defense mechanism against other organisms. Pichia anomala strain WRL-076 is a biocontrol yeast currently being tested to reduce AF contamination of tree nuts in California. We used the SPME-GC/MS analysis and identified the major volatile compound produced by this strain to be 2-phenylethanol (2-PE). It inhibited spore germination and AF production of A. flavus. Inhibition of AF formation by 2-PE was correlated with significant down regulation of clustering AF biosynthesis genes as evidenced by several to greater than 10,000-fold decrease in gene expression. In a time-course analysis we found that 2-PE also altered the expression patterns of chromatin modifying genes, MYST1, MYST2, MYST3, gcn5, hdaA and rpdA. The biocontrol capacity of P. anomala can be attributed to the production of 2-PE, which affects spore germination, growth, toxin production, and gene expression in A. flavus. PMID:24504634

Hua, Sui Sheng T; Beck, John J; Sarreal, Siov Bouy L; Gee, Wai

2014-05-01

72

DATA QUALIFICATION REPORT: MAJOR ION AND PH DATA FOR USE ON THE YUCCA MOUNTAIN PROJECT  

SciTech Connect

This data qualification report uses technical assessment and corroborating data methods according to Attachment 2 of AP-SIII.2Q, Rev. 0, ICN 2, ''Qualification of Unqualified Data and the Documentation of Rationale for Accepted Data'', to qualify major ion and pH data. This report was prepared in accordance with Data Qualification Plan TDP-NBS-GS-00003 1, Revision 2. Additional reports will be prepared to address isotopic and precipitation-related data. Most of the data considered in this report were acquired and developed by the U.S. Geological Survey (USGS). The data qualification team considers the sampling and analytical protocols employed by the USGS over the time period of data acquisition to be state-of-the-art. The sample collection methodologies have evolved with no significant change that could affect the quality of the data considered in this report into the currently used Hydrologic Procedures that support the Yucca Mountain Project-approved USGS Quality Assurance Program Plan. Consequently, for USGS data, the data collection methods, documentation, and results are reasonable and appropriate in view of standard practice at the time the data were collected. A small number of data sets were collected by organizations other than the USGS and were reviewed along with the other major ion and pH data using corroborating data methods. Hydrochemical studies reviewed in this qualification report indicate that the extent and quality of corroborating data are sufficient to support qualification of both USGS and non-USGS major ion and pH data for generalized hydrochemical studies. The corroborating data included other major ion and pH data, isotope data, and independent hydrological data. Additionally, the analytical adequacy of the major ion data was supported by a study of anion-cation charge balances. Charge balance errors for USGS and non-USGS data were under 10% and acceptable for all data. This qualification report addresses the specific major ion data sets selected to support the hydrochemical studies in Analysis/Model Report (AMR) S0040 and pH data used in AMRs U0100 and U0085. Based on a preponderance of evidence, these data are recommended to be qualified for inclusion in technical products in support of the Site Recommendation for generalized uses as described in this report.

C. WILSON; D.M. JENKINS; T. STEINBORN; R. WEMHEUER

2000-08-23

73

ICRH of JET and LHD Majority Ions at Their Fundamental Cyclotron Frequency  

NASA Astrophysics Data System (ADS)

Results of the experimental studies of ICRH at the fundamental cyclotron frequency of the majority deuterons in JET plasmas with near-tangential deuteron neutral beam injection (NBI) are presented. 1D, 2D and 3D ICRH modeling indicated that several ITER relevant mechanisms of heating may occur simultaneously in this heating scheme: fundamental ion cyclotron resonance heating of majority and beam D ions, impurity ion heating and electron heating due to Landau damping and TTMP. These mechanisms were studied in JET experiments with a ~90% D, 5% H plasma including traces of Be and Ar. Up to 2MW of ICRH power was applied at 25 MHz to NBI heated plasmas. In most of the discharges the toroidal magnetic field strength was 3.3T, but in one it was equal to 3.6T. The E+ component of the electric field governs the ion cyclotron heating of not too fast particles. The Doppler shifted RF absorption of the beam deuterons away from the cold resonance at which E+ is small was exploited to enhance the RF power absorption efficiency. Fundamental ICRH experiments were also carried out in LHD hydrogen plasma with high energy hydrogen NBI. ICRH was performed at 38MHz with injected power <1 MW. The effect of fundamental ICRH was clearly demonstrated in both machines.

Krasilnikov, A. V.; van Eester, D.; Lerche, E.; Ongena, J.; Mailloux, J.; Stamp, M.; Jachmich, S.; Leggate, H.; Vdovin, V.; Walden, A.; Mayoral, M.-L.; Bonheure, G.; Santala, M.; Kiptily, V.; Popovichev, S.; Biewer, T.; Crombe, K.; Esposito, B.; Marocco, D.; Riva, M.; Kaschuck, Yu. A.; Amosov, V. N.; Ericsson, G.; Giacomelli, L.; Hellesen, C.; Hjalmarsson, A.; Kallne, J.

2007-09-01

74

ICRH of JET and LHD Majority Ions at Their Fundamental Cyclotron Frequency  

SciTech Connect

Results of the experimental studies of ICRH at the fundamental cyclotron frequency of the majority deuterons in JET plasmas with near-tangential deuteron neutral beam injection (NBI) are presented. 1D, 2D and 3D ICRH modeling indicated that several ITER relevant mechanisms of heating may occur simultaneously in this heating scheme: fundamental ion cyclotron resonance heating of majority and beam D ions, impurity ion heating and electron heating due to Landau damping and TTMP. These mechanisms were studied in JET experiments with a {approx}90% D, 5% H plasma including traces of Be and Ar. Up to 2MW of ICRH power was applied at 25 MHz to NBI heated plasmas. In most of the discharges the toroidal magnetic field strength was 3.3T, but in one it was equal to 3.6T. The E{sub +} component of the electric field governs the ion cyclotron heating of not too fast particles. The Doppler shifted RF absorption of the beam deuterons away from the cold resonance at which E{sub +} is small was exploited to enhance the RF power absorption efficiency. Fundamental ICRH experiments were also carried out in LHD hydrogen plasma with high energy hydrogen NBI. ICRH was performed at 38MHz with injected power <1 MW. The effect of fundamental ICRH was clearly demonstrated in both machines.

Krasilnikov, A. V.; Kaschuck, Yu. A.; Amosov, V. N. [SRC RF Troitsk Institute for Innovating and Fusion Research, Troitsk (Russian Federation); Van Eester, D.; Lerche, E. [Laboratory for Plasma Physics--ERM/KMS, TEC partner, Brussels (Belgium); Ongena, J.; Bonheure, G. [Laboratory for Plasma Physics--ERM/KMS, TEC partner, Brussels (Belgium); Euratom-UKAEA Fus. Assoc., Culham Science Center (United Kingdom); Mailloux, J.; Stamp, M.; Jachmich, S.; Leggate, H.; Walden, A.; Mayoral, M.-L.; Santala, M.; Kiptily, V.; Popovichev, S. [Euratom-UKAEA Fus. Assoc., Culham Science Center (United Kingdom); Vdovin, V. [RNC Kurchatov Institute, Nuclear Fusion Institute, Moscow (Russian Federation); Biewer, T. [Euratom-UKAEA Fus. Assoc., Culham Science Center (United Kingdom); Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Crombe, K. [Euratom-UKAEA Fus. Assoc., Culham Science Center (United Kingdom); Department of Applied Physics, Ghent University, Gent (Belgium); Esposito, B. [ENEA, Frascati (Italy)] (and others)

2007-09-28

75

Atmospheric particle dry deposition of major ions to the South Atlantic coastal area observed at Baía de Todos os Santos, Brazil.  

PubMed

The coastal atmosphere adjacent to large urban areas can be strongly affected by the emission of air pollutants, among them, major ions species. In this study, the chemical composition and sources of carboxylates and other water-soluble ions in fine and coarse aerosols as well as estimates of particle dry deposition fluxes were studied at a tropical coastal site affected by an urban environment. The mean concentrations of the total carboxylates were 78 ng m-3 in fine fraction and 81 ng m-3 in coarse fraction of particulate matter (PM). The corresponding values for the total inorganic ions were 2143 ng m-3 and 4880 ng m-3 respectively. Main sources for fine particles were: (i) photochemical formation of carboxylic acids in vapor phase and a posterior gas-to-particle conversion onto sea salt particles; (ii) emissions from anthropic sources with long range transportation processes; and (iii) the interchanging of volatile species among atmospheric phases. In turn, for coarse particles, the predominant sources were: (i) gas-phase species and ab/adsorbed onto pre-existing particles afterwards; (ii) primary emission of coarse particles from anthropogenic sources; and (iii) sea salt spray and/or soil resuspension. Finally, particle dry deposition was a very important mechanism representing air-to-sea fluxes of major species. PMID:24676156

Mkoma, Stelyus L; da Rocha, Gisele O; Domingos, José S S; Santos, João V S; Cardoso, Manuela P; da Silva, Rogerio L; de Andrade, Jailson B

2014-03-01

76

[Major ion chemistry of surface water in the Xilin River Basin and the possible controls].  

PubMed

Under the increasing pressure of water shortage and steppe degradation, information on the hydrological cycle in the steppe region in Inner Mongolia is urgently needed. Major ions are widely used to identify the hydrological processes in a river basin. Based on the analysis results of 239 river water samples collected in 13 sections along the Xilin River system during 2006 to 2008, combined with data from groundwater and precipitation samples collected in the same period and the meteorological and hydrological data in the Xilin River Basin, hydrochemical characteristics and the chemistry of major ions of the Xilin River water have been studied by means of Piper triangle plots and Gibbs diagrams. The results showed that: (1) the total dissolved solid (TDS) in river water mainly ranged between 136.7 mg x L(-1) and 376.5 mg x L(-1), and (2) it had an increasing trend along the river flow path. (3) The major cations and anions of river water were Ca2+ and HCO3-, respectively, and the chemical type of the river water varied from HCO3- -Ca2+ in the headwater area to HCO(3-)-Ca2+ Mg2+ in the lower part. (4) The variation in the concentration of major irons in surface water was not significant at the temporal scale. Usually, the concentration values of major irons were much higher in May than those in other months during the runoff season, while the values were a bit lower in 2007 than those in 2006 and 2008. Except for SO4(2-), the concentrations of other ions such as Ca2+, Na+, Mg2+, K+, Cl- and HCO3- showed a upward trend along the river flow path. Comparing major ion concentrations of the river water with those of local groundwater and precipitation, the concentration in river water was between those of precipitation and groundwater but was much closer to the concentration of groundwater. This indicated that the surface water was recharged by a mixture of precipitation and groundwater, and groundwater showed a larger impact. The Gibbs plot revealed that the chemical compositions of the river water were mainly affected by rock weathering in the drainage area. PMID:24720196

Tang, Xi-Wen; Wu, Jin-Kui

2014-01-01

77

Major Ion concentrations in the new NEEM ice core in Greenland  

NASA Astrophysics Data System (ADS)

The drilling of the new deep ice core in NEEM (77.45°N 51.06°W) was terminated in 2010. Using a continuous flow analysis system (CFA), discrete samples were filled and analyzed for major ion concentrations (Na, K, Mg, Ca, Cl, SO_4 and NO_3) using Ion Chromatography (IC). The samples were measured at Alfred Wegener Institute for Polar and Marine Research (Germany) and National Institute of Polar Research (Japan). Here we present preliminary results of the major Ion concentrations. We found highest variations in concentrations of Calcium and Magnesium which are mainly originating from terrestrial sources with concentrations between 5-10 ppb and 4 ppb during the Holocene compared to 800 ppb and 80 ppb during the LGM. This is in line with measurements of particulate dust concentrations. Sulphate concentrations closely follow DO events and vary between 25 ppb during the Holocene and ~400 ppb during the LGM. Sodium concentrations vary between ~ 8 ppb during the Holocene and up to 100 ppb during the LGM. We discuss influences of changes in the source areas and atmospheric transport intensity on the different time scales.

Wegner, A.; Azuma, K. G.; Hirabayashi, M.; Schmidt, K.; Hansson, M.; Twarloh, B.

2012-12-01

78

Major ions in typical subterranean rivers and their anthropogenic impacts in southwest karst areas, China  

NASA Astrophysics Data System (ADS)

Subterranean rivers contain much of the groundwater in karst and supply many local people in southwest China. The quality of groundwater in subterranean rivers is of concern because of its sensitivity to anthropogenic activity. Groundwater samples in a rural catchment were collected at the discharge point, and the concentrations of major ions including potassium, sodium, calcium, magnesium, chloride, sulfate, nitrate and bicarbonate were analyzed in this study. Rainfall and discharge were also observed at the same time. It could be concluded from the data that the concentrations of sulfate and nitrate had a peak in the rainy season when the concentrations of sodium, calcium, magnesium and bicarbonate were low. The concentrations of potassium and chloride changed randomly throughout the year. The concentration of major ions in flood process was not completely controlled by discharge. Only the concentrations of nitrate and sulfate had obviously increased during the past two decades. It was believed that dilution, eluviation, karst erosion and anthropogenic activity can explain the ion variations and hence this study helps to understand environmental problem in karst.

Guo, Fang; Jiang, Guanghui; Yuan, Daoxian

2007-11-01

79

Detection of Volatile Vapors Emitted from Explosives with a Hand-held Ion Mobility Spectrometer  

SciTech Connect

Vapor detection of plastic explosives is difficult because of the low vapor pressures of explosive components (i.e. RDX and PETN) present in the complex elastomeric matrix. To facilitate vapor detection of plastic explosives, detection agents (taggants) with higher vapor pressures can be added to bulk explosives during manufacture. This paper investigates the detection of two of these taggants, ethyleneglycol dinitrate (EGDN) and 2,3-dimethyl-2,3-dinitrobutane (DMNB), using a handheld ion mobility spectrometer. These two taggants were detected both from neat vapor sources as well as from bulk explosives (nitroglycerin (NG)-dynamite and C-4 tagged with DMNB). EGDN was detected from NG-dynamite as EGDN·NO3- at a reduced mobility value of 1.45 cm2 V-1 s-1 with detection limits estimated to be about 10 ppbv. DMNB was identified from tagged C-4 as both negative and positive ions with reduced mobility values of 1.33 cm2 V-1 s-1 for DMNB·NO2- and 1.44 cm2 V-1s-1 for DMNB·NH4+. Positive ions for cyclohexanone were also apparent in the spectra from tagged C-4 producing three additional peaks.

Ewing, Robert Gordon; Miller, Carla Jean

2001-11-01

80

[Seasonal variation in the major ion chemistry and their sources in the Hubei Danjiangkou Reservoir, China].  

PubMed

Water temperature, pH, EC, TDS, ORP, Si and major anions (Cl- , NO3- and SO4(2-)) and major cations (Na+, K+, Ca2+ and Mg2+) in the Danjiangkou Reservoir, the water source area of the Middle Route of the South to North Water Transfer Project of China were monitored during the period of 2004-2006. Analysis of variance (ANOVA) and principal component analysis (PCA) were performed to explore their seasonal variations and origins. The results show that the water is slightly alkaline with an average pH ranging from 7.9 to 8.4. The water is HCO3- -Ca type with low mineralized degree, and its total dissolved solid ranges from 174.6-209.1 mg x L(-1). The major ions range are as follows: Cl-, from (4.0 +/- 0.5) mg x L(-1) to (6.9 +/- 1.8) mg x L(-1); NO3-, from (4.6 +/- 0.9) mg x L(-1) to (6.8 +/- 1.7) mg x L(-1); SO4(2-), from (24.3 +/- 2.7) mg x L(-1) to (35.4 +/- 6.9) mg x L(-1); HCO3-, from (133.0 +/- 11.7) mg x L(-1) to (153.5 +/- 29.6) mg x L(-1); Na+, from (2.0 +/- 0.3) mg x L(-1) to (5.3 +/- 1.0) mg x L(-1); K+, from (0.7 +/- 0.09) mg x L(-1) to (1.6 +/- 0.7) mg x L(-1); Ca2+, from (33.0 +/- 2.1) mg x L(-1) to (46.6 +/- 0.8) mg x L(-1); Mg2+, from (8.0 +/- 2.5) mg x L(-1) to (10.5 +/- 3.2) mg x L(-1). Statistical analyses indicate that the water quality variables display significant seasonal differences except HCO3 and Si. In general, major ion concentrations in flood season are relatively lower due to the dilution of precipitation. HCO3- accounts for 75%-88% of the total major anions, while Ca2+ and alkali-earth metals (Ca2+ + Mg2+) account for 60%-80% and 87%-96% of the total major cations respectively, reflecting that carbonic acid weathering is the main proton producer in the water. The major ions have no adverse effects on human according to water drinking quality guidelines of China and WHO. PMID:19256367

Li, Si-yue; Tan, Xiang; Xu, Zhi-fang; Zhang, Quan-fa

2008-12-01

81

Major-ion, nutrient, and trace-element concentrations in the Steamboat Creek Basin, Oregon, 1996  

SciTech Connect

This report presents the concentrations of major ions, nutrients, and trace elements in water and bottom sediments collected in the four-tributaries during the low-flow condition of September 9-13, 1996. Stream-water chemistry results are contrasted, and trace-element concentrations compared with US Environmental Protection Agency chronic aquatic life toxicity criteria. Bottom -sediment trace-element results also are constrasted and compared with concentrations considered to be enriched in streams of the nearby Willamette River Basin and to interim Canadian threshold effect level (TEL) concentrations established for the protection of aquatic life.

Rinella, F.A.

1998-11-01

82

Influence of extraction methodologies on the analysis of five major volatile aromatic compounds of citronella grass (Cymbopogon nardus) and lemongrass (Cymbopogon citratus) grown in Thailand.  

PubMed

This paper deals with the systematic comparison of extraction of major volatile aromatic compounds (VACs) of citronella grass and lemongrass by classical microhydrodistillation (MHD), as well as modern accelerated solvent extraction (ASE). Sixteen VACs were identified by GC/MS. GC-flame ionization detection was used for the quantification of five VACs (citronellal, citronellol, geraniol, citral, and eugenol) to compare the extraction efficiency of the two different methods. Linear range, LOD, and LOQ were calculated for the five VACs. Intraday and interday precisions for the analysis of VACs were determined for each sample. The extraction recovery, as calculated by a spiking experiment with known standards of VACs, by ASE and MHD ranged from 64.9 to 91.2% and 74.3 to 95.2%, respectively. The extraction efficiency of the VACs was compared for three solvents of varying polarities (hexane, dichloromethane, and methanol), seven different temperatures (ranging from 40 to 160 degrees C, with a gradual increment of 20 degrees C), five time periods (from 1 to 10 min), and three cycles (1, 2, and 3 repeated extractions). Optimum extraction yields of VACs were obtained when extractions were carried out for 7 min with dichloromethane and two extraction cycles at 120 degrees C. The results showed that the ASE technique is more efficient than MHD, as it results in improved yields and significant reduction in extraction time with automated extraction capabilities. PMID:22816268

Chanthai, Saksit; Prachakoll, Sujitra; Ruangviriyachai, Chalerm; Luthria, Devanand L

2012-01-01

83

PCBs and OCPs on a east-to-west transect: the importance of major currents and net volatilization for PCBs in the Atlantic Ocean.  

PubMed

Air-water exchange gradients of selected polychlorinated biphenyl (PCB) congeners across a large section of the tropical Atlantic suggested net volatilization of PCBs to the atmosphere. Only for the higher chlorinated PCB 153 and hexachlorobenzene (HCB) were gradients near equilibrium detected. The use of passive samplers also enabled the detection of dichlorodiphenyltrichloroethane (DDT) and its transformation products across the tropical Atlantic, indicating net deposition. There were clear differences between the southern and northern hemisphere apparent in terms of atmospheric concentrations: Once the ship moved from the southern into the northern hemisphere air, concentrations of HCB and other organochlorine pesticides increased several-fold. For large swaths of the tropical Atlantic Ocean, neither PCB nor organochlorine pesticide dissolved concentrations varied much longitudinally, probably due to efficient mixing by ocean currents. In selected samples, dissolved concentrations reflected the influence of river plumes and major ocean currents far away from the continents. Dissolved concentrations of PCBs 28, 52, 101, 118, and HCB increased in the Amazon plume and the Gulf Stream. While the Amazon plume flushed only a few kg of PCBs and HCB, the Gulf Stream is potentially delivering tons of PCBs into the North Atlantic annually. PMID:22303957

Lohmann, Rainer; Klanova, Jana; Kukucka, Petr; Yonis, Shifra; Bollinger, Kevyn

2012-10-01

84

Energy spectra of the major ion species in the ring current during geomagnetic storms  

NASA Technical Reports Server (NTRS)

Nearly equatorial storm time energy spectra of the four major magnetospheric ions, H(+), O(+), He(+), and He(2+), obtained for the August 1984-November 1985 period by the charge-energy-mass spectrometer aboard the AMPTE/CCE spacecraft during the main and early recovery phases of all geomagnetic storms with minimum Dst of less than -50 nT were examined. It was found that, in the dawn-to-noon sector, there was a dip in the a spectra of all ions at 5-20 keV/e, while in the noon-to-dusk sector, the proton phase space density dropped off sharply below 5 keV. These spectra were compared with those predicted by a model of ion drift and loss in the magnetosphere. It was found that the spectra are most consistent with a Volland-Stern electric field with gamma = 2 and with a rotation of the nominal dawn-to-dusk electric field eastward by 2 hrs local time.

Kistler, L. M.; Ipavich, F. M.; Hamilton, D. C.; Gloeckler, G.; Wilken, B.

1989-01-01

85

Mobilization of major inorganic ions during experimental diagenesis of characterized peats  

USGS Publications Warehouse

Laboratory experiments were undertaken to study changes in concentrations of major inorganic ions during simulated burial of peats to about 1.5 km. Cladium, Rhizophora, and Cyrilla peats were first analyzed to determine cation distributions among fractions of the initial materials and minerals in residues from wet oxidation. Subsamples of the peats (80 g) were then subjected to increasing temperatures and pressures in steps of 5??C and 300 psi at 2-day intervals and produced solutions collected. After six steps, starting from 30??C and 300 psi, a final temperature of 60??C and a final pressure of 2100 psi were achieved. The system was then allowed to stand for an additional 2 weeks at 60??C and 2100 psi. Treatments resulted in highly altered organic solids resembling lignite and expelled solutions of systematically varying compositions. Solutions from each step were analyzed for Na+, Ca2+, Mg2+, total dissolved Si (Si(T)), Cl-, SO42-, and organic acids and anions (OAAs). Some data on total dissolved Al (Al(T)) were also collected. Mobilization of major ions from peats during these experiments is controlled by at least three processes: (1) loss of dissolved ions in original porewater expelled during compaction, (2) loss of adsorbed cations as adsorption sites are lost during modification of organic solids, and (3) increased dissolution of inorganic phases at later steps due to increased temperatures (Si(T)) and increased complexing by OAAs (Al(T)). In general, results provide insight into early post-burial inorganic changes occurring during maturation of terrestrial organic matter. (C) 2000 Elsevier Science B.V. All rights reserved.

Bailey, A. M.; Cohen, A. D.; Orem, W. H.; Blackson, J. H.

2000-01-01

86

Major ion chemistry of groundwater in the extreme arid region northwest China  

NASA Astrophysics Data System (ADS)

The Ejina Basin, located in arid northwest China, is one of the most arid areas in the world. In recent years, rapid development has created a greater demand for water which is increasingly fulfilled by groundwater abstraction. Detailed knowledge of geochemical evolution of groundwater and water quality can improve the understanding of a hydrochemical system, and promote sustainable development and effective management of groundwater resources. To this end, a hydrochemical survey was conducted in the Ejina Basin in order to identify the major hydrochemical characteristics. The results of chemical analysis indicate that groundwater in the area is brackish. The major ions, TDS, and hydrochemical types of different areas are highly variable and show an obvious zonation from the recharge area to the discharge area. Saturation index (SI), calculated according to the ionic ration plot, indicates that the gypsum-halite dissolution reactions take place under the condition of the rock weathering to some extent, and evaporation is the dominant factor to determine the major ionic composition in the study area.

Jianhua, Si; Qi, Feng; Xiaohu, Wen; Yonghong, Su; Haiyang, Xi; Zongqiang, Chang

2009-05-01

87

Volatile (sulphur and chlorine), major, and trace element geochemistry of mafic to intermediate tephras from the Chilean Southern Volcanic Zone (33-43°S)  

NASA Astrophysics Data System (ADS)

Here we present the first systematic investigation of volatile geochemistry along the Southern Volcanic Zone (SVZ) of Chile. Holocene olivine-hosted melt inclusions in the most mafic tephras sampled from 16 volcanoes along the volcanic front of the SVZ between 33°S and 43°S were analysed for pre-eruptive sulphur, chlorine, and major element contents. These results are combined with trace element compositions of the host whole rocks. The highest fractionation-corrected gas contents occur in the least-degassed melt inclusions from small monogenetic cones of Los Hornitos, Cabeza de Vaca, and Apagado from both the transitional and the southern-central SVZ, reaching ~3,000 ?g/g S and 1,400 ?g/g Cl, while the lowest abundances of ~1,100 ?g/g S and ~600 ?g/g Cl were found in the central SVZ at Volcán Lonquimay, Volcán Llaima, and Volcán Villarrica. Chlorine co-varies with trace element indicators for the degree of melting and/or source enrichment, such that the lowest Cl contents are found in high-degree melts from the most depleted mantle sources. The size of the volcanic edifices correlates inversely with Cl abundances in the melt. This could reflect more extensive degassing during ascent through the complex magma plumbing systems beneath the stratovolcanoes or greater dilution during larger degrees of melting of more depleted sources, or a combination of these factors. Compared to other subduction zones, the SVZ melt inclusions exhibit Cl and S abundances in the same range as most of those from the Central American and those from the Marianas arcs.

Wehrmann, Heidi; Hoernle, Kaj; Jacques, Guillaume; Garbe-Schönberg, Dieter; Schumann, Kai; Mahlke, Julia; Lara, Luis E.

2014-03-01

88

Geochemical processes in the Onyx River, Wright Valley, Antarctica: Major ions, nutrients, trace metals  

NASA Astrophysics Data System (ADS)

We present data on major ions, nutrients and trace metals in an Antarctic stream. The Onyx River is located in Wright Valley (77-32 S; 161-34 E), one of a group of ancient river and glacier-carved landforms that comprise the McMurdo Dry Valleys of Antarctica. The river is more than 30 km long and is the largest of the glacial meltwater streams that characterize this relatively ice-free region near the Ross Sea. The complete absence of rainfall in the region and the usually small contributions of glacially derived tributaries to the main channel make this a comparatively simple system for geochemical investigation. Moreover, the lack of human impacts, past or present, provides an increasingly rare window onto a pristine aquatic system. For all major ions and silica, we observe increasing concentrations with distance from Lake Brownworth down to the recording weir near Lake Vanda. Chemical weathering rates are unexpectedly high and may be related to the rapid dissolution of ancient carbonate deposits and to the severe physical weathering associated with the harsh Antarctic winter. Of the nutrients, nitrate and dissolved reactive phosphate appear to have quite different sources. Nitrate is enriched in waters near the Lower Wright Glacier and may ultimately be derived from stratospheric sources; while phosphate is likely to be the product of chemical weathering of valley rocks and soils. We confirm the work of earlier investigations regarding the importance of the Boulder Pavement as a nutrient sink. Dissolved Mn, Fe, Ni, Cu, and Cd are present at nanomolar levels and, in all cases, the concentrations of these metals are lower than in average world river water. We hypothesize that metal uptake and exchange with particulate phases along the course of the river may serve as a buffer for the dissolved load. Concurrent study of these three solute classes points out significant differences in the mechanisms and sites of their removal from the Onyx River.

Green, William J.; Stage, Brian R.; Preston, Adam; Wagers, Shannon; Shacat, Joseph; Newell, Silvia

2005-02-01

89

Time study of trace elements and major ions during two cloud events at the Mt. Brocken  

NASA Astrophysics Data System (ADS)

Cloud water investigations have been performed at the highest elevation of Central Germany in 1997. Results of extensive trace element measurements are presented. Besides conductivity, pH, liquid water content and major ions the data set includes 49 minor and trace elements. Estimation of crustal enrichment factors (EFs) provides an indication of the anthropogenic contributions to the cloud water concentrations. The variation of cloud composition with time has been illustrated for two selected events with different air mass origins. The chemical composition of the cloud condensation nuclei on which the droplets grow mainly determines the cloud water chemistry. For a cloud event in June 1997 the concentrations of the crustally derived elements Si, Al, Fe, Ti, Ce, La and Nd follow each other closely. The fact that SO 42-, NO 3- and NH 4+ are only moderately correlated with the particular pollutants with high enrichment factors such as Cd, Sb, Pb, Zn, Cu, As, Bi, Sn, Mo, Ni, Tl and V indicates that their source regions are more widespread. During an event in October 1997 the time trends for most minor and trace elements follow rather closely those for the major ions NH 4+, SO 42- and NO 3-. Back trajectories show that the transport from continental and marine European sources was the likely cause of the sample concentrations. EFs of trace elements in cloud water samples during the June and October event show a strong correlation with those obtained for urban particulate matter. Although both events are influenced by air masses of different origin, there is a good agreement between the EF signatures.

Plessow, K.; Acker, K.; Heinrichs, H.; Möller, D.

90

Major Ion Chemistry and Mixing Proportions of Nitrate Sources in Urban Groundwater  

NASA Astrophysics Data System (ADS)

Working with Dr. Gilbert Hanson has allowed me to apply general mixing equations to identification of nonpoint sources of groundwater contamination. These methods have not commonly been used in hydrologic studies, as they involve a more classical petrologic approach, one which Dr. Hanson has pioneered. Our drinking water supplies are becoming more susceptible to contamination and knowing the chemistry of contaminate sources will yield precise determination of potential sources to groundwater and allow government agencies to adopt policies to reduce or prevent contamination. The geochemistry of soil water from below fertilized turfgrass sites and of sewage from septic tank/cesspools was used to place constraints on the sources of nitrate in groundwater of an unconsolidated aquifer in Suffolk County, Long Island, New York, USA. Twenty four sewage samples were acquired from Suffolk County Public Works. Soil water samples, from suction lysimeters, were acquired monthly during 2003, totaling 70 samples. We found that soil water concentrations were elevated in Ca, Mg and SO4 relative to sewage and sewage had higher concentrations of Cl, N-NO3, PO4, Na and K. This difference in the major ion chemistry allows identification of the source signatures in groundwater. We then compared the source signatures to 28 groundwater wells on binary ion diagrams of SO4, Cl and N- NO3 and created a cation sorption model for Na, Ca, Mg and K, in order to model cation concentrations on binary ion diagrams. These diagrams allow estimates of the relative contributions of each source to each well. Groundwater wells plotted according to their major land use and show that wells of similar land use have similar geochemistry and similar source contributions. The estimates of source contributions show that the proportions of soil water and sewage increase as residential land use increases. Although volumetric source proportions to groundwater wells are similar for soil water and sewage within a given land use, sewage contributes a greater proportion to the nitrate concentration in groundwater wells. For example, sewage contributes between 86-100% of the nitrate in wells sourced in medium density residential land use, even when accounting for a 50% reduction in nitrate concentrations from the septic tank/cesspool system. Our results indicate that to decrease the nitrate concentrations in groundwater one must reduce the load from septic tank/cesspool systems.

Munster, J.; Hanson, G. N.; Bokuniewicz, H.

2007-05-01

91

Solar Ion Processing of Major Element Surface Compositions of Mature Mare Soils: Insights from Combined XPS and Analytical TEM Observations  

NASA Technical Reports Server (NTRS)

Solar wind ions are capable of altering the sur-face chemistry of the lunar regolith by a number of mechanisms including preferential sputtering, radiation-enhanced diffusion and sputter erosion of space weathered surfaces containing pre-existing compositional profiles. We have previously reported in-situ ion irradiation experiments supported by X-ray photoelectron spectroscopy (XPS) and analytical TEM that show how solar ions potentially drive Fe and Ti reduction at the monolayer scale as well as the 10-100 nm depth scale in lunar soils [1]. Here we report experimental data on the effect of ion irradiation on the major element surface composition in a mature mare soil.

Christoffersen, R.; Dukes, C.; Keller, L. P.; Baragiola, R.

2012-01-01

92

Wet precipitation of major ions, polonium-210, and organic carbon in a metropolitan city, Seoul, Korea  

NASA Astrophysics Data System (ADS)

An extensive survey of chemical constituents in precipitation including dissolved organic carbon, dissolved nitrogen, major ions, trace elements, and radionuclides was conducted in a representative urban environment of Seoul over one-year period from 2009 to 2010. The sources for these chemical species were apportioned by applying principal component analysis (PCA) in association with commonly acknowledged key tracers, such as Na, K, Ca, and V. The fossil fuel combustion (especially coal) was shown to be the dominant source for most constituents being investigated, with biomass burning being recognized as another significant source. With the aid of air mass backward trajectory analyses, we concluded that the primary fraction of the chemical species in our precipitation samples originated locally in Korea, albeit the frequent long-range transport from the eastern and northeastern China might contribute substantially. Overall, our study suggests the significant role of human activities in altering the atmospheric environment of Seoul and presumably most urban areas around the world, highlighting its profound environmental implications, such as health risks posed by excessive polonium-210, enhanced rainwater acidity from organic acids, and radiative forcing by organic aerosols.

Yan, G.; Kim, G.

2011-12-01

93

Ion Channel-Forming Alamethicin Is a Potent Elicitor of Volatile Biosynthesis and Tendril Coiling. Cross Talk between Jasmonate and Salicylate Signaling in Lima Bean1  

PubMed Central

Alamethicin (ALA), a voltage-gated, ion channel-forming peptide mixture from Trichoderma viride, is a potent elicitor of the biosynthesis of volatile compounds in lima bean (Phaseolus lunatus). Unlike elicitation with jasmonic acid or herbivore damage, the blend of substances emitted comprises only the two homoterpenes, 4,11-dimethylnona-1,3,7-triene and 4,8,12-trimethyltrideca-1,3,7,11-tetraene, and methyl salicylate. Inhibition of octadecanoid signaling by aristolochic acid and phenidone as well as mass spectrometric analysis of endogenous jasmonate demonstrate that ALA induces the biosynthesis of volatile compounds principally via the octadecanoid-signaling pathway (20-fold increase of jasmonic acid). ALA also up-regulates salicylate biosynthesis, and the time course of the production of endogenous salicylate correlates well with the appearance of the methyl ester in the gas phase. The massive up-regulation of the SA-pathway (90-fold) interferes with steps in the biosynthetic pathway downstream of 12-oxophytodienoic acid and thereby reduces the pattern of emitted volatiles to compounds previously shown to be induced by early octadecanoids. ALA also induces tendril coiling in various species like Pisum, Lathyrus, and Bryonia, but the response appears to be independent from octadecanoid biosynthesis, because inhibitors of lipoxygenase and phospholipase A2 do not prevent the coiling reaction.

Engelberth, Jurgen; Koch, Thomas; Schuler, Gode; Bachmann, Nadine; Rechtenbach, Jana; Boland, Wilhelm

2001-01-01

94

Trading activity, realized volatility and jumps  

Microsoft Academic Search

This paper takes a new look at the relation between volume and realized volatility. In contrast to prior studies, we decompose realized volatility into two major components: a continuously varying component and a discontinuous jump component. Our results confirm that the number of trades is the dominant factor shaping the volume–volatility relation, whatever the volatility component considered. However, we also

Pierre Giot; Sébastien Laurent; Mikael Petitjean

2010-01-01

95

The general description of major ion concentrations in groundwater of Latvia  

NASA Astrophysics Data System (ADS)

Latvia is situated at the North central part of the Baltic sedimentary basin where the crystalline basement is found in depth between 0.6 to 2 km. Three large aquifer complexes with distinct chemical composition of groundwater are identified: the stagnant water exchange zone where Na-Ca-Cl brine is found; the slow water exchange zone where Na-Ca-Cl-SO4 brackish water is found and active water exchange zone where the freshwater resides. These are separated by distinct regional aquicludes. The composition of the Cl- dominated brines at the base of sedimentary basin is characterised by shift from Na+ towards Ca++ as dominant cation, partially associated with depth of the aquifer and the strength of the brine. The concentration of SO4-- here is inversely linked to the concentration of Ca++ and, according to geochemical modelling, often is close to the solubility limit of the gypsum. The major ion concentrations in the E and W part of the territory are rather different. Therefore two different initial sources of the formation brine were suggested. Alternatively the observations can be explained by different thermal histories of different parts of the basin, affecting the rate of albitization - exchange of the Na for Ca in the solution due to water-rock interaction. The groundwater composition in the slow exchange zone can be nicely explained by the mixing of freshwater and brine residing deeper in the presence of gypsum during some but no all stages of mixing. In some shallow parts of the zone still bound by the Narva regional aquiclude freshwater is found. The question is posted - could this be a paleogroundwater originating from the extensive continental glaciations that override the territory several times during the Pleistocene? Initial isotope studies presented elsewhere seems to give negative answer to this question. The active water exchange zone is characterised by fresh Ca-Mg-HCO3 water with exceptions in cases where gypsum are abundant in sedimentary rocks and sulphate ion prevails. The freshwater composition seems to be mostly controlled by three minerals - calcite, dolomite and gypsum. It is suggested that clay minerals can play a significant role in controlling the relative concentrations of cations, but this is not strictly proven jet. Well documented modern seawater intrusion induced by water abstraction is found in the territory of Liep?ja city. The upwelling of slat water from below can be spotted across the territory as well. These zones are usually associated with tectonic faults, enabling the upwelling of salty water across regional aquicludes. Particularly prominent is the saltwater body in the vicinity of the Riga city. Three major rives are discharging in the sea there making it a natural confluence zone of groundwater as well. The intensive groundwater abstraction in the city probably enhanced the upwelling of saltwater here, but primary it is a natural phenomenon. The interesting question is if there is any paleogroundwater trapped in the active or slow water exchange zone of the sedimentary basin that could be distinguished from modern infiltration water due to particular isotope signal originating in the quaternary cold stages or chemical composition - remains of relict sea water or sedimentation water. This study is supported by the ESF project No. 2009/0212/1DP/1.1.1.2.0/09/APIA/VIAA/060.

Kalv?ns, A.; Delina, A.

2012-04-01

96

Major ion and isotope geochemistry of fluids and gases from coalbed methane and shallow groundwater wells in Alberta, Canada  

Microsoft Academic Search

The production of coalbed methane (CBM) represents a vital new source of natural gas supply in Western Canada. There are, however, concerns over potential negative environmental impacts on shallow groundwater resources in the hypothetical case that leakage of fluids and gases from CBM operations occurs. This paper compares major ion and isotope geochemistry data for produced fluids or gases from

Katrina Cheung; Patrick Klassen; Bernhard Mayer; Fariborz Goodarzi; Ramon Aravena

2010-01-01

97

Major ion chemistry of the Ganga-Brahmaputra river system: Weathering processes and fluxes to the Bay of Bengal  

Microsoft Academic Search

The Ganga-Brahmaputra, one of the world's largest river systems, is first in terms of sediment transport and fourth in terms of water discharge. A detailed and systematic study of the major ion chemistry of these rivers and their tributaries, as well as the clay mineral composition of the bed sediments has been conducted. The chemistry of the highland rivers (upper

M. M. Sarin; S. Krishnaswami; K. Dilli; B. L. K. Somayajulu; W. S. Moore

1989-01-01

98

Major-ion, nutrient, and trace-element concentrations in the Steamboat Creek basin, Oregon, 1996  

USGS Publications Warehouse

In September 1996, a water-quality study was done by the U.S. Geological Survey, in coordination with the U.S. Forest Service, in headwater streams of Steamboat Creek, a tributary to the North Umpqua River Basin in southwestern Oregon. Field measurements were made in and surface-water and bottomsediment samples were collected from three tributaries of Steamboat Creek?Singe Creek, City Creek, and Horse Heaven Creek?and at one site in Steamboat Creek upstream from where the three tributaries flow into Steamboat Creek. Water samples collected in Singe Creek had larger concentrations of most major-ion constituents and smaller concentrations of most nutrient constituents than was observed in the other three creeks. City Creek, Horse Heaven Creek, and Steamboat Creek had primarily calcium bicarbonate water, whereas Singe Creek had primarily a calcium sulfate water; the calcium sulfate water detected in Singe Creek, along with the smallest observed alkalinity and pH values, suggests that Singe Creek may be receiving naturally occurring acidic water. Of the 18 trace elements analyzed in filtered water samples, only 6 were detected?aluminum, barium, cobalt, iron, manganese, and zinc. All six of the trace elements were detected in Singe Creek, at concentrations generally larger than those observed in the other three creeks. Of the detected trace elements, only iron and zinc have chronic toxicity criteria established by the U.S. Environmental Protection Agency (USEPA) for the protection of aquatic life; none exceeded the USEPA criterion. Bottom-sediment concentrations of antimony, arsenic, cadmium, copper, lead, mercury, zinc, and organic carbon were largest in City Creek. In City Creek and Horse Heaven Creek, concentrations for 11 constituents?antimony, arsenic, cadmium, copper, lead, manganese (Horse Heaven Creek only), mercury, selenium, silver, zinc, and organic carbon (City Creek only)?exceeded concentrations considered to be enriched in streams of the nearbyWillamette River Basin, whereas in Steamboat Creek only two trace elements ?antimony and nickel?exceeded Willamette River enriched concentrations. Bottom-sediment concentrations for six of these constituents in City Creek and Horse Heaven Creek?arsenic, cadmium, copper, lead, mercury, and zinc?also exceeded interim Canadian threshold effect level (TEL) concentrations established for the protection of aquatic life, whereas only four constituents between Singe Creek and Steamboat Creek?arsenic, chromium, copper (Singe Creek only), and nickel?exceeded the TEL concentrations.

Rinella, Frank A.

1998-01-01

99

The Volatility of Realized Volatility  

Microsoft Academic Search

Using unobservable conditional variance as measure, latent–variable approaches, such as GARCH and stochastic–volatility models, have traditionally been dominating the empirical finance literature. In recent years, with the availability of high–frequency financial market data modeling realized volatility has become a new and innovative research direction. By constructing “observable” or realized volatility series from intraday transaction data, the use of standard time

Fulvio Corsi; Uta Kretschmer; Stefan Mittnik; Christian Pigorsch

2005-01-01

100

The Volatility of Realized Volatility  

Microsoft Academic Search

In recent years, with the availability of high-frequency financial market data modeling realized volatility has become a new and innovative research direction. The construction of “observable” or realized volatility series from intra-day transaction data and the use of standard time-series techniques has lead to promising strategies for modeling and predicting (daily) volatility. In this article, we show that the residuals

Fulvio Corsi; Stefan Mittnik; Christian Pigorsch; Uta Pigorsch

2008-01-01

101

Volatility Jumps  

Microsoft Academic Search

The paper undertakes a non-parametric analysis of the very high frequency movements in stock market volatility using very finely sampled data on the S&P VIX index compiled by the CBOE. The data suggest that stock market volatility is best described as a pure jump process without a continuous component. The finding stands in contrast to nonparametric results, reported here and

Viktor Todorov; George Tauchen

2011-01-01

102

Relative potencies of volatile anesthetics in altering the kinetics of ion channels in BC3H1 cells.  

PubMed

Single channel recording techniques have been used to study effects of the volatile anesthetics enflurane, halothane, isoflurane and methoxyflurane, and the gaseous agent nitrous oxide, on the properties of nicotinic channels activated by acetylcholine. Single channel currents activated by 250 nM acetylcholine were recorded from cell-attached patches of BC3H1 mouse tumor cells grown in culture. All of the potent volatile agents shortened the duration of individual opening events and caused openings to appear grouped together in bursts. The slower time constant of channel open-time distributions was decreased 50% by approximately 0.22% enflurane (0.12 mM), 0.25% isoflurane (0.10 mM), 0.30% halothane (0.16 mM), 0.076% methoxyflurane (0.21 mM) or 80% nitrous oxide (20 mM) at room temperature. Even when values were corrected to 37 degrees C, the concentrations required to decrease channel open time are less than clinical dosages. Anesthetic potency in altering channel properties was directly related to both clinical potency and lipid solubility, although those agents with greater clinical potencies required relatively higher concentrations to reduce channel open time. Results are interpreted in terms of a simple sequential channel blocking model, a sequential blocking model in which anesthetics also enhance the rate at which open channels normally close, and a cyclic blocking model in which blocked channels may close directly without having to pass back through the open state. All of the agents appeared to act in a qualitatively similar fashion and no differences were found that could account for the differing clinical profiles of the volatile anesthetics. PMID:7562508

Wachtel, R E

1995-09-01

103

A Polymer-Rich Re-deposition Technique for Non-volatile Etching By-products in Reactive Ion Etching Systems  

NASA Astrophysics Data System (ADS)

Re-deposition is a non-volatile etching by-product in reactive ion etching systems that is well known to cause dirt on etching work. In this study, we propose a novel etching method called the polymer-rich re-deposition technique, used particularly for improving the etched sidewall where the re-deposition is able to accumulate. This technique works by allowing the accumulated re-deposition on the etched sidewall to have a higher polymer species than the new compounds in the non-volatile etching by-product. The polymer-rich re-deposition is easy to remove along with the photo-resist mask residual at the photo-resist strip step using an isopropyl alcohol-based solution. The traditional, additional cleaning process step used to remove the re-deposition material is not required anymore, so this reduces the overall processing time. The technique is demonstrated on an Al2O3-TiC substrate by C4F8 plasma, and the EDX spectrum confirms that the polymer re-deposition has C and F atoms as the dominant atoms, suggesting that it is a C—F polymer re-deposition.

Limcharoen, A.; Pakpum, C.; Limsuwan, P.

2013-07-01

104

DIRECT TRACE ANALYSIS OF VOLATILE ORGANIC COMPOUNDS IN AIR USING ION TRAP MASS SPECTROMETERS WITH FILTERED NOISE FIELDS  

EPA Science Inventory

Two ion trap mass spectrometers and direct air sampling interfaces are being evaluated in the laboratory for monitoring toxic air pollutants in real time. he mass spectrometers are the large, laboratory-based Finnigan MAT ion trap (ITMS) and the compact, field-deployable Teledyne...

105

Major ion chemistry, weathering processes and water quality assessment in upper catchment of Damodar River basin, India  

Microsoft Academic Search

The chemical characteristics of surface, groundwater and mine water of the upper catchment of the Damodar River basin were\\u000a studied to evaluate the major ion chemistry, geochemical processes controlling water composition and suitability of water\\u000a for domestic, industrial and irrigation uses. Water samples from ponds, lakes, rivers, reservoirs and groundwater were collected\\u000a and analysed for pH, EC, TDS, F, Cl,

Abhay Kumar Singh; G. C. Mondal; Suresh Kumar; T. B. Singh; B. K. Tewary; A. Sinha

2008-01-01

106

A new strategy to assess the quality of broccoli ( Brassica oleracea L. italica) based on enzymatic changes and volatile mass ion profile using Proton Transfer Reaction Mass Spectrometry (PTR-MS)  

Microsoft Academic Search

The shelf life of high quality horticultural products such as broccoli is relatively short, thereby limiting their potential for export and long distance trade. To assess the quality and the shelf life of vegetables, a reliable, accurate and high-throughput technique is required. In this study, an approach that profiled enzyme activities and volatile mass ions was used. The possible relationship

S. Raseetha; S. P. Heenan; I. Oey; D. J. Burritt; N. Hamid

2011-01-01

107

Volatile content and distribution in the Azorean mantle plume  

NASA Astrophysics Data System (ADS)

In order to assess pre-eruptive volatile contents of magmas in the central Azores, we have measured major element, trace element, and volatile contents of olivine hosted melt inclusions. Seventy tephra samples were collected from Sao Jorge, Pico and Faial islands. Three samples yielded naturally glassy melt inclusions, while five samples produced crystallized melt inclusions that were rehomogenized with either a one atmosphere furnace or a heating stage. The melt inclusions were analyzed for major elements, volatiles, and trace elements by electron microprobe, secondary ion mass spectrometry (SIMS), and laser ablation ICP-MS, respectively. Olivine host crystals for the melt inclusions are Fo77-88. Melt inclusions compositionally are alkali basalts with Mg #50-68, 40-51wt% SiO2, and 0.82-1.63wt% K2O (corrected for post-entrapment olivine crystallization), which is consistent with existing whole-rock data. They are trace element enriched with 19.3-49.9ppm La and 3.22-4.33 La/Sm. Volatile contents are 270-2509ppm CO2, 0.06-1.52wt% H2O, 120-1465ppm F, 30-2298ppm S, and 28-727ppm Cl. Volatile to trace element ratios are 8.4-46.5 CO2/Nb, 7-220 H2O/Ce, 2.1-42.4 F/Nd, 4-381 S/Dy, and 0.002-0.084 Cl/K. Correlation between Cl and F precludes seawater contamination as a source for the high volatile content. These data suggest that the HIMU component of the Azorean mantle plume is volatile rich, which is consistent with previously published volatile data from other HIMU sources, such as the Austral Islands plume (Lassiter et. al., 2002).

Costa, K.; Parman, S. W.; Saal, A. E.; Kelley, K. A.; Shimizu, N.; Nunes, J. C.; Rose-Koga, E. F.

2012-12-01

108

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)

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/?m) 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.

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

2012-04-01

109

Preliminary studies on the composition of major ions of some fish ponds of Malacca in Malaysia  

Microsoft Academic Search

This paper presents data on the ionic composition of tropical pond waters. The discussion is on the major cations calcium (6.58 p.p.m.) and sodium (3.79 p.p.m.) and the anions bicarbonate (20.24 p.p.m.) and sulphate (21.69 p.p.m.). Some ponds have extremely low alkalinity (10 to 27 p.p.m.) and most of the ponds have poor dissolved calcium content (2.5 to 9.9 p.p.m.).

Y. T. Tan

1971-01-01

110

Wet deposition of major ions in a rural area impacted by biomass burning emissions  

NASA Astrophysics Data System (ADS)

This work concerns the influence of industrialized agriculture in the tropics on precipitation chemistry. A total of 264 rain events were sampled using a wet-only collector in central São Paulo State, Brazil, between January 2003 and July 2007. Electroneutrality balance calculations (considering H +, K +, Na +, NH4+, Ca 2+, Mg 2+, Cl -, NO3-, SO42-, F -, PO43-, H 3CCOO -, HCOO -, CO42- and HCO3-) showed that there was an excess of cations (˜15%), which was attributed to the presence of unmeasured organic anion species originating from biomass burning and biogenic emissions. On average, the three ions NH4+, NO 3- and H + were responsible for >55% of the total ion concentrations in the rainwater samples. Concentrations (except of H +) were significantly higher ( t-test; P = 0.05), by between two to six-fold depending on species, during the winter sugar cane harvest period, due to the practice of pre-harvest burning of the crop. Principal component analysis showed that three components could explain 88% of the variance for measurements made throughout the year: PC1 (52%, biomass burning and soil dust resuspension); PC2 (26%, secondary aerosols); PC3 (10%, road transport emissions). Differences between harvest and non-harvest periods appeared to be mainly due to an increased relative importance of road transport/industrial emissions during the summer (non-harvest) period. The volume-weighted mean (VWM) concentrations of ammonium (23.4 ?mol L -1) and nitrate (17.5 ?mol L -1) in rainwater samples collected during the harvest period were similar to those found in rainwater from São Paulo city, which emphasizes the importance of including rural agro-industrial emissions in regional-scale atmospheric chemistry and transport models. Since there was evidence of a biomass burning source throughout the year, it appears that rainwater composition will continue to be affected by vegetation fires, even after sugar cane burning is phased out as envisaged by recent São Paulo State legislation.

Coelho, Cidelmara H.; Allen, Andrew G.; Fornaro, Adalgiza; Orlando, Eduardo A.; Grigoletto, Tahuana L. B.; Campos, M. Lucia A. M.

2011-09-01

111

Groundwater quality in Scotland: major ion chemistry of the key groundwater bodies.  

PubMed

Groundwater in Scotland is, for the most part, weakly to moderately mineralised and dominated by the Ca and HCO3 ions. The aquifer systems are almost entirely unconfined and most groundwater remains in contact with oxygen; some reducing groundwaters occur in deeper isolated cracks and joints within the many fractured bedrock aquifers such as Devonian sandstones. Groundwater depleted in oxygen is also common in the Coal Measures in the Midland Valley as a direct result of past coal and oil shale mining, when iron and other metals are taken into solution as the abandoned mine workings are allowed to flood. Low pH groundwaters are rare but do occur where calcite is absent in some basement rocks. Marine intrusion of coastal aquifers occurs locally in East Lothian and parts of Morayshire. Deeper circulating groundwaters are responsible for some of the more exotic spa waters, notably at Bridge of Earn near Perth. Nitrate contamination of groundwater is increasing in some areas, and is most prevalent in the south of Scotland. The Devonian aquifer in Fife and parts of the Permian sandstone aquifers of south-west Scotland are the worst affected. PMID:12169011

Robins, N S

2002-07-22

112

Major ion chemistry of groundwaters in the Damagh area, Hamadan, western Iran  

NASA Astrophysics Data System (ADS)

Hydrochemical investigations were carried out in Damagh area, Hamadan, western Iran, to assess chemical composition of groundwater. Forty representative groundwater samples were collected from different wells to monitor the water chemistry of various ions. Chemical analysis of the groundwater showed that the mean concentration of the cations is in the order Na+ > Ca2+ > Mg2+ > K+, while that for anions was HCO{3/-} > Cl- > SO{4/2 -} > NO{3/-}. All of the investigated groundwaters present two different chemical facies (Ca HCO3 and Na HCO3) which is in relation with their interaction with the geological formations of the basin, cation exchange between groundwater and clay minerals and anthropogenic activities. The principal component analysis (PCA) performed on groundwater identified three principal components controlling their variability in groundwater. Electrical conductivity, Mg2+, Na+, SO{4/2-}, and Cl- content were associated in the same component (PC1) (salinity), determined principally by anthropogenic activities. The pH, CO{3/2 -}, HCO{3/-}, and Ca2+ (PC2) content were related to the geogenic factor. Finally, the NO{3/-}, Cl- and K+ (PC3) were controlled by anthropogenic activity as a consequence of inorganic fertilizers.

Jalali, Mohsen; Khanlari, Zahra V.

2008-03-01

113

One-year observations of size distribution characteristics of major aerosol constituents at a coastal receptor site in Hong Kong - Part 1: Inorganic ions and oxalate  

NASA Astrophysics Data System (ADS)

Size distribution data of major aerosol constituents are essential in source apportioning of visibility degradation, testing and verification of air quality models incorporating aerosols. We report here one-year observations of mass size distributions of major inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, magnesium and calcium) and oxalate at a coastal suburban receptor site in Hong Kong, China. A total of 43 sets of size segregated samples in the size range of 0.056-18 ?m were collected from March 2011 to February 2012. The size distributions of sulfate, ammonium, potassium and oxalate were characterized by a dominant droplet mode with a mass mean aerodynamic diameter (MMAD) in the range of ~0.7-0.9 ?m. Oxalate had a slightly larger MMAD than sulfate on days with temperatures above 22 °C as a result of the process of volatilization and repartitioning. Nitrate was mostly dominated by the coarse mode but enhanced presence in fine mode was detected on winter days with lower temperature and lower concentrations of sea salt and soil particles. This data set reveals an inversely proportional relationship between the fraction of nitrate in the fine mode and product of the sum of sodium and calcium in equivalent concentrations and the dissociation constant of ammonium nitrate (i.e., (1/[Na+] + 2[Ca2+]) × (1/Ke')). The seasonal variation observed for sea salt aerosol abundance, with lower values in summer and winter, is possibly linked with the lower marine salinities in these two seasons. Positive matrix factorization was applied to estimate the relative contributions of local formation and transport to the observed ambient sulfate level through the use of the combined datasets of size-segregated sulfate and select gaseous air pollutants. On average, the regional/super-regional transport of air pollutants was the dominant source at this receptor site, especially on high sulfate days, while local formation processes contributed approximately 30% of the total sulfate. This work provides field measurement-based evidence for importance of understanding both local photochemistry and regional/super-regional transport in order to properly simulate sulfate aerosols in air quality models.

Bian, Q.; Huang, X. H. H.; Yu, J. Z.

2014-01-01

114

Analysis of Selected Volatile Organic Compounds in Split and Nonsplit Swiss Cheese Samples Using Selected-Ion Flow Tube Mass Spectrometry (SIFT-MS).  

PubMed

Splits/cracks are recurring product defects that negatively affect the Swiss cheese industry. Investigations to understand the biophysicochemical aspects of these defects, and thus determine preventive measures against their occurrence, are underway. In this study, selected-ion, flow tube mass spectrometry was employed to determine the volatile organic compound (VOC) profiles present in the headspace of split compared with nonsplit cheeses. Two sampling methodologies were employed: split compared with nonsplit cheese vat pair blocks; and comparison of blind, eye, and split segments within cheese blocks. The variability in VOC profiles was examined to evaluate the potential biochemical pathway chemistry differences within and between cheese samples. VOC profile inhomogeneity was most evident in cheeses between factories. Evaluation of biochemical pathways leading to the formation of key VOCs differentiating the split from the blind and eye segments within factories indicated release of additional carbon dioxide by-product. These results suggest a factory-dependent cause of split formation that could develop from varied fermentation pathways in the blind, eye, and split areas within a cheese block. The variability of VOC profiles within and between factories exhibit varied biochemical fermentation pathways that could conceivably be traced back in the making process to identify parameters responsible for split defect. PMID:24665988

Castada, Hardy Z; Wick, Cheryl; Taylor, Kaitlyn; Harper, W James

2014-04-01

115

Application of ion-implantation for improved non-volatile resistive random access memory (ReRAM)  

NASA Astrophysics Data System (ADS)

Resistive switching in transition metal oxides is believed to be controlled by the migration of oxygen vacancies and many interesting device structures employ substoichiometric oxide layers as a source of these active defects. However, the growth of thin (˜10 nm) oxide/suboxide heterostructures (e.g. HfO2/HfOx or Ta2O5/TaOx) is difficult using conventional film deposition techniques. In this study, ion-implantation is shown to provide an alternative means of synthesizing such structures, with results reported for Ta2O5/TaOx heterostructures fabricated by oxygen-implantation of Ta. The electrical properties of the fabricated heterostructures are discussed with reference to the physical structure of the samples determined from transmission electron microscopy and X-ray photoelectron spectroscopy.

Elliman, R. G.; Saleh, M. S.; Kim, T.-H.; Venkatachalam, D. K.; Belay, K.; Ruffell, S.; Kurunczi, P.; England, J.

2013-07-01

116

The Income Volatility See-Saw: Implications for School Lunch  

Microsoft Academic Search

Income volatility challenges the effectiveness of the safety net that USDA food assistance programs provide low-income families. This study examines income volatility among households with children and the implications of volatility for eligibility in the National School Lunch Program (NSLP). The results show that income volatility was higher for successively lower income groups and that the major determinants of changes

Constance Newman

2006-01-01

117

Landscape controls on dissolved nutrients, organic matter and major ions in a suburbanizing watershed  

NASA Astrophysics Data System (ADS)

Understanding the relative importance of anthropogenic and natural landscape features that drive spatial variability in water quality is a central challenge in studying the biogeochemistry of heterogeneous landscapes. We quantified the average annual flux and concentration of dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON), dissolved organic carbon (DOC), phosphate-P (PO4-P), sodium (Na+) and chloride (Cl-) at ~40 stream sites in three major (51 to 903 km2) NH basins. We used GIS to quantify anthropogenic (e.g. human population density, % impervious surface cover and % agriculture) and natural (e.g. % forest, % wetlands and soil C:N) landscape features for each sub-basin and then employed multiple-regression analysis to relate water quality parameters to landscape characteristics. Anthropogenic features were strong predictors of DIN flux and Na+ and Cl- concentrations, whereas wetland cover (a natural feature) was a significant, but weak predictor of DOC (r2=0.26, p<0.01) and DON (r2 = 0.14, p<0.05) flux. Anthropogenic features could not explain a significant amount of variance in DON or DOC flux. Mean PO4-P concentrations were surprisingly low (<0.015 mg P/L) when compared to the larger range in mean DIN concentrations (0.03 to 0.96 mg/L) and consequently no landscape characteristics could explain a significant amount of spatial variability in PO4-P flux or concentration. Human population density was the single best predictor of DIN flux (r2=0.76, p<0.01), and together with % impervious surface and % agriculture explained 86% (p<0.01) of the total variance. Among all sites, % road pavement was a strong predictor of stream Na+ and Cl- concentrations (r2 = 0.75 to 0.78, p<0.01) and % impervious surface was a stronger predictor (r2 = 0.86 to 0.92, p<0.01) among a subset of sites. Our results suggest that DIN and DON result from different sources in the landscape and although sources of DON and DOC are similar, DON and DOC concentrations respond differently to hydrologic events. Concentrations of DON were negatively correlated with discharge (r2= 0.06, p < 0.01), but DOC concentrations did not respond to discharge, suggesting there is much to learn about the decoupling of C and N rich dissolved organic matter (DOM). Our landscape models do not account for spatial variability in dissolved inorganic carbon (DIC), dissolved organic P (DOP) or particulate C, N and P; however, at our site with the longest record, the Lamprey River, DIC and particulate C account for only 25% and 5% respectively of the total C flux. Among three sites ranging from 3-16% development, particulate N only accounted for 12-18% of total N, but particulate P accounted for 30-50% and DOP accounted for an additional 40-50% of total P. Landscape characteristics may in fact be better predictors of spatial variability in particulate-P and DOP than PO4-P. Nonetheless, the landscape models that we have developed for DIN and DOM flux can be used by local watershed managers to predict changes in water quality in response to changes in land use.

Daley, M. L.; McDowell, W. H.

2010-12-01

118

Constraining groundwater recharge and the rate of geochemical processes using tritium and major ion geochemistry: Ovens catchment, southeast Australia  

NASA Astrophysics Data System (ADS)

SummaryConstraining recharge is essential for understanding and managing groundwater systems. This study uses high-precision Tritium (3H) concentrations together with major ion and environmental isotope (Sr, C, O, H) geochemistry to constrain rates of recharge and geochemical processes in the Ovens catchment of the southeast Murray Basin, Australia. 3H concentrations of groundwater in the Ovens catchment decline with depth but not with position in the catchment, implying that recharge occurs over broad areas. Recharge rates calculated using an exponential-piston flow model are 120-180 mm/yr in the coarse-grained alluvial gravels of the upper and middle Ovens and 30-45 mm/yr in the finer-grained sediments of lower Ovens. These recharge rates are similar to those calculated from the response of shallow bore hydrographs to rainfall. The geochemistry of groundwater with low (60-160 mg/L) total dissolved solids (TDS) from the upper and middle Ovens indicates that dissolution of both silicate minerals and calcite has occurred. Major ion geochemistry, 87Sr/86Sr ratios, and ?13C values in the upper and middle Ovens groundwater are correlated with groundwater residence times and constrain the progress of mineral reactions. Dissolution of silicates with high 87Sr/86Sr ratios (biotite and K-Feldspar) occurs prior to dissolution of silicates with low 87Sr/86Sr ratios (plagioclase) and calcite. Mineral dissolution mainly occurs in the upper 20 m of the aquifer system with relatively little change in geochemistry deeper in the flow system. Groundwater from the lower Ovens has higher TDS contents (600-9600 mg/L) due to higher degrees of evapotranspiration. Although a correlation between TDS and groundwater residence times exists, it is more likely to reflect differential recharge rates and not the rate of evapotranspiration. The conclusion that recharge occurs across the Ovens catchment indicates that protection of groundwater from surface contamination is dependent on the protection and management of large areas.

Cartwright, Ian; Morgenstern, Uwe

2012-12-01

119

Use of reconstituted waters to evaluate effects of elevated major ions associated with mountaintop coal mining on freshwater invertebrates  

USGS Publications Warehouse

In previous laboratory chronic 7-d toxicity tests conducted with the cladoceran Ceriodaphnia dubia, surface waters collected from Appalachian sites impacted by coal mining have shown toxic effects associated with elevated total dissolved solids (TDS). The objective of the present study was to evaluate the effects of elevated major ions in chronic laboratory tests with C. dubia (7-d exposure), a unionid mussel (Lampsilis siliquoidea; 28-d exposure), an amphipod (Hyalella azteca; 28-d exposure), and a mayfly (Centroptilum triangulifer; 35-d exposure) in 3 reconstituted waters designed to be representative of 3 Appalachian sites impacted by coal mining. Two of the reconstituted waters had ionic compositions representative of alkaline mine drainage associated with mountaintop removal and valley fill-impacted streams (Winding Shoals and Boardtree, with elevated Mg, Ca, K, SO4, HCO3), and a third reconstituted water had an ionic composition representative of neutralized mine drainage (Upper Dempsey, with elevated Na, K, SO4, and HCO3). The waters with similar conductivities but, with different ionic compositions had different effects on the test organisms. The Winding Shoals and Boardtree reconstituted waters were consistently toxic to the mussel, the amphipod, and the mayfly. In contrast, the Upper Dempsey reconstituted water was toxic to the mussel, the amphipod, and the cladoceran but was not toxic to the mayfly. These results indicate that, although elevated TDS can be correlated with toxicity, the specific major ion composition of the water is important. Moreover, the choice of test organism is critical, particularly if a test species is to be used as a surrogate for a range of faunal groups.

Kunz, James L.; Conley, Justin M.; Buchwalter, David B.; Norberg-King; Teresa J.; Kemble, Nile E.; Wang, Ning; Ingersoll, Christopher G.

2013-01-01

120

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC/MASS SPECTROMETRIC DETERMINATION OF VOLATILE CARBOXYLIC ACIDS USING ION-PAIR EXTRACTION AND THERMALLY INDUCED ALKYLATION  

EPA Science Inventory

Low molecular weight volatile carboxylic acids have been analyzed by high-performance liquid chromatography/mass spectrometry (HPLC/MS) using post-column derivatization and a moving belt interface. In order to prevent loss of the volatile solutes during transport to the mass spec...

121

Effect of cobalt ions on the metabolism of some volatile and polar compounds in the marine invertebrates Mytilus galloprovincialis and Actinia equina  

Microsoft Academic Search

The compositions of the volatile and polar fractions from two coexisting Black Sea invertebrates, the mussel Mytilus galloprovincialis and the beadlet anemone Actinia equina, were established. The main metabolites in the volatile fraction from the investigated animals appeared to be methyl esters of fatty acids and fatty aldehydes. In the polar fraction from both animals low concentrations of free acids

Jordan Nechev; Kamen Stefanov; Diana Nedelcheva; Simeon Popov

2007-01-01

122

Evidence for deep pooling of low degree melts from volatile, major, and trace element chemistry of olivine-hosted melt inclusions and glasses from the ultra-slow spreading Gakkel Ridge  

NASA Astrophysics Data System (ADS)

We present new analyses of volatiles and major elements for a suite of glasses and melt inclusions from ~85°E on the ultra-slow spreading Gakkel Ridge. The major element and volatile compositions of the melt inclusions are more variable and consistently more primitive than the glass data. CO2 contents in the melt inclusions extend to higher values (167-1596 ppm) than in the co-existing glasses (187-227 ppm), indicating that the melt inclusions were trapped at greater depths. Based on a vapor saturation model, we estimate that the melt inclusions were trapped between seafloor depths (~4 km) and ~9 km below seafloor, as compared to the glasses, which are all in equilibrium with their eruption depths. Melting conditions inferred from thermobarometry suggest relatively deep (25-40 km), cold (1240°-1325°C) melting conditions, consistent with the calculated thermal structure for the ultra-slow spreading Gakkel Ridge. The water contents and trace element compositions of the melt inclusions and glasses are remarkably homogeneous, an unexpected result for ultra-slow spreading environments where wide geochemical diversity is anticipated. Moreover, all melts can be described by a single liquid line of descent originating from a pooled melt composition that is consistent with the aggregate melt calculated from a thermal model for the Gakkel Ridge. These data suggest a model in which deep, low degree melts are efficiently pooled near the top of the melting column (9-20 km depth), after which crystallization commences and continues during ascent and eruption of the magma. Based on this melting model and the assumption that CO2 is perfectly incompatible, we show that the highest CO2 concentrations of the melt inclusions (~1600 ppm) are consistent with calculated CO2 concentrations of primary undegassed melts and yield a MORB source mantle CO2 content of ~90 ppm. This value is slightly lower than that inferred from the highest measured CO2/Nb ratio of Gakkel Ridge melt inclusions (443), which predicts a mantle CO2 content of 134 ppm and a global ridge flux of 2.0×1012 mol CO2/yr.

Shaw, A. M.; Behn, M. D.; Humphris, S. E.; Reves-Sohn, R. A.; Gregg, P. M.

2009-12-01

123

Characterizing interactions between surface water and groundwater in the Jialu River basin using major ion chemistry and stable isotopes  

NASA Astrophysics Data System (ADS)

The Jialu River, a secondary tributary of the Huaihe River, has been severely contaminated from major contaminant sources, such as a number of untreated or lightly treated sewage waste in some cities. Groundwater along the river is not an isolated component of the hydrologic system, but is instead connected with the surface water. This study aims to investigate temporal and spatial variations in water chemistry affected by humans and to characterize the relationships between surface water (e.g. reservoirs, lakes and rivers) and groundwater near the river in the shallow Quaternary aquifer. Concentration of Cl- in north Zhengzhou City increased prominently due to the discharge of a large amount of domestic water. Nitrate and potassium show maximum concentrations in groundwater in Fugou County. These high levels can be attributed to the use of a large quantity of fertilizer over this region. Most surface water appeared to be continuously recharged from the surrounding groundwater (regional wells) based on comparison surface water with groundwater levels, stable-isotopes and major ion signatures. However, the groundwater of a transitional well (location SY3) seemed to be recharged by river water via bank infiltration in September 2010. Fractional contributions of river water to the groundwater were calculated based on isotopic and chemical data using a mass-balance approach. Results show that the groundwater was approximately composed of 60-70% river water. These findings should be useful for a better understanding of hydrogeological processes at the river-aquifer interface and ultimately benefit water management in the future.

Yang, L.; Song, X.; Zhang, Y.; Han, D.; Zhang, B.; Long, D.

2012-11-01

124

Selected ion flow tube mass spectrometry analysis of volatile metabolites in urine headspace for the profiling of gastro-esophageal cancer.  

PubMed

Urine is considered an ideal biofluid for clinical investigation because it is obtained noninvasively and relatively large volumes are easily acquired. In this study, selected ion flow tube mass spectrometry (SIFT-MS) has been applied for the quantification of volatile organic compounds (VOCs) in the headspace vapor of urine samples, which were retrieved from three groups of patients with gastro-esophageal cancer, noncancer diseases of the upper gastro-intestinal tract, and a healthy cohort. Eleven VOCs have been investigated in this study. The concentrations of seven VOCs-acetaldehyde, acetone, acetic acid, hexanoic acid, hydrogen sulfide, methanol, and phenol-were found to be significantly different between cancer, positive control, and healthy groups using the Kruskal-Wallis test. The concentrations of acetaldehyde, acetone, acetic acid, hexanoic acid, hydrogen sulfide, and methanol were increased in the cancer cohort compared with healthy controls while the concentration of phenol decreased. The differences in the concentrations of ethanol, propanol, methyl phenol, and ethyl phenol were not significant between cancer and control groups. Receiver operating characteristics (ROC) analysis was applied for a combination of six VOCs (acetaldehyde, acetone, acetic acid, hexanoic acid, hydrogen sulfide, and methanol) to discriminate cancer patients from noncancer controls. The integrated area under ROC curve is 0.904. This result indicates that VOC profiling may be suitable in identifying those at high risk of gastro-esophageal cancer. Therefore, further investigations should be undertaken to assess the potential for VOC profiling as a new screening test in gastro-esophageal cancer. PMID:23421902

Huang, Juzheng; Kumar, Sacheen; Abbassi-Ghadi, Nima; Span?l, Patrik; Smith, David; Hanna, George B

2013-03-19

125

The volatile compound BinBase mass spectral database  

PubMed Central

Background Volatile compounds comprise diverse chemical groups with wide-ranging sources and functions. These compounds originate from major pathways of secondary metabolism in many organisms and play essential roles in chemical ecology in both plant and animal kingdoms. In past decades, sampling methods and instrumentation for the analysis of complex volatile mixtures have improved; however, design and implementation of database tools to process and store the complex datasets have lagged behind. Description The volatile compound BinBase (vocBinBase) is an automated peak annotation and database system developed for the analysis of GC-TOF-MS data derived from complex volatile mixtures. The vocBinBase DB is an extension of the previously reported metabolite BinBase software developed to track and identify derivatized metabolites. The BinBase algorithm uses deconvoluted spectra and peak metadata (retention index, unique ion, spectral similarity, peak signal-to-noise ratio, and peak purity) from the Leco ChromaTOF software, and annotates peaks using a multi-tiered filtering system with stringent thresholds. The vocBinBase algorithm assigns the identity of compounds existing in the database. Volatile compound assignments are supported by the Adams mass spectral-retention index library, which contains over 2,000 plant-derived volatile compounds. Novel molecules that are not found within vocBinBase are automatically added using strict mass spectral and experimental criteria. Users obtain fully annotated data sheets with quantitative information for all volatile compounds for studies that may consist of thousands of chromatograms. The vocBinBase database may also be queried across different studies, comprising currently 1,537 unique mass spectra generated from 1.7 million deconvoluted mass spectra of 3,435 samples (18 species). Mass spectra with retention indices and volatile profiles are available as free download under the CC-BY agreement (http://vocbinbase.fiehnlab.ucdavis.edu). Conclusions The BinBase database algorithms have been successfully modified to allow for tracking and identification of volatile compounds in complex mixtures. The database is capable of annotating large datasets (hundreds to thousands of samples) and is well-suited for between-study comparisons such as chemotaxonomy investigations. This novel volatile compound database tool is applicable to research fields spanning chemical ecology to human health. The BinBase source code is freely available at http://binbase.sourceforge.net/ under the LGPL 2.0 license agreement.

2011-01-01

126

The major-ion composition of Cenozoic seawater: the past 36 million years from fluid inclusions in marine halite  

USGS Publications Warehouse

Fluid inclusions from ten Cenozoic (Eocene-Miocene) marine halites are used to quantify the major-ion composition (Mg2+, Ca2+, K+, Na+, SO42?, and Cl?) of seawater over the past 36 My. Criteria used to determine a seawater origin of the halites include: (1) stratigraphic, sedimentologic, and paleontologic observations; (2) Br? in halite; (3) ?34S of sulfate minerals; (4) 87Sr/86Sr of carbonates and sulfates; and (5) fluid inclusion brine compositions and evaporation paths, which must overlap from geographically separated basins of the same age to confirm a “global” seawater chemical signal. Changes in the major-ion chemistry of Cenozoic seawater record the end of a systematic, long term (>150 My) shift from the Ca2+-rich, Mg2+- and SO42?-poor seawater of the Mesozoic (“CaCl2 seas”) to the “MgSO4 seas” (with higher Mg2+ and SO42?>Ca2+) of the Cenozoic. The major ion composition of Cenozoic seawater is calculated for the Eocene-Oligocene (36-34 Ma), Serravallian-Tortonian (13.5-11.8 Ma) and the Messinian (6-5 Ma), assuming chlorinity (565 mmolal), salinity, and the K+ concentration (11 mmolal) are constant and the same as in modern seawater. Fluid inclusions from Cenozoic marine halites show that the concentrations of Mg2+and SO42? have increased in seawater over the past 36 My and the concentration of Ca2+ has decreased. Mg2+ concentrations increased from 36 mmolal in Eocene-Oligocene seawater (36-34 Ma) to 55 mmolal in modern seawater. The Mg2+/Ca2+ ratio of seawater has risen from ?2.3 at the end of the Eocene, to 3.4 and 4.0, respectively, at 13.5 to 11.8 Ma and 6 to 5 Ma, and to 5 in modern seawater. Eocene-Oligocene seawater (36-34 Ma) has estimated ranges of SO42? = 14–23 mmolal and Ca2+ = 11–20 mmolal. If the (Ca2+)(SO42?) product is assumed to be the same as in modern seawater (?300 mmolal2), Eocene-Oligocene seawater had Ca2+ ?16 mmolal and SO42? ?19 mmolal. The same estimates of Ca2+ and SO42? for Serravallian-Tortonian seawater (13.5-11.8 Ma) are SO42? = 19–27 mmolal and Ca2+ = 8–16 mmolal and SO42? ?24 mmolal and Ca2+ ? 13 mmolal if the (Ca2+)(SO42?) product is equal to that in modern seawater. Messinian seawater has an estimated range of SO42? ?21–29 mmolal and Ca2+ ?7–15 mmolal with SO42? ?26 mmolal and Ca2+ ?12 mmolal assuming the (Ca2+)(SO42?) product is equal to that in modern seawater. Regardless of the estimation procedure, SO42? shows progressively increasing concentrations from 36 Ma to the present values, which are the highest of the Cenozoic.

Brennan, Sean T.;Lowenstein, Tim K.;Cendon, Dioni I.

2013-01-01

127

Chemical erosion in the eastern Himalaya: Major ion composition of the Brahmaputra and ? 13C of dissolved inorganic carbon  

NASA Astrophysics Data System (ADS)

Major ion composition of waters, ? 13C of its DIC (dissolved inorganic carbon), and the clay mineral composition of bank sediments in the Brahmaputra River System (draining India and Bangladesh) have been measured to understand chemical weathering and erosion and the factors controlling these processes in the eastern Himalaya. The time-series samples, collected biweekly at Guwahati, from the Brahmaputra mainstream, were also analyzed for the major ion composition. Clay mineralogy and chemical index of alteration (CIA) of sediments suggest that weathering intensity is relatively poor in comparison to that in the Ganga basin. This is attributed to higher runoff and associated physical erosion occurring in the Brahmaputra basin. The results of this study show, for the first time, spatial and temporal variations in chemical and silicate erosion rates in the Brahmaputra basin. The subbasins of the Brahmaputra watershed exhibit chemical erosion rates varying by about an order of magnitude. The Eastern Syntaxis basin dominates the erosion with a rate of ˜300 t km -2 y -1, one of the highest among the world river basins and comparable to those reported for some of the basaltic terrains. In contrast, the flat, cold, and relatively more arid Tibetan basin undergoes much slower chemical erosion (˜40 t km -2 y -1). The abundance of total dissolved solids (TDS, 102-203 mg/L) in the time-series samples collected over a period of one year shows variations in accordance with the annual discharge, except one of them, cause for which is attributable to flash floods. Na* (Na corrected for cyclic component) shows a strong positive correlation with Si, indicating their common source: silicate weathering. Estimates of silicate cations (Na sil+K sil+Ca sil+Mg sil) suggest that about half of the dissolved cations in the Brahmaputra are derived from silicates, a proportion higher than that for the Ganga system. The CO 2 consumption rate due to silicate weathering in the Brahmaputra watershed is ˜6 × 10 5 moles km -2 y -1; whereas that in the Eastern Syntaxis subbasin is ˜19 × 10 5 moles km -2 y -1, similar to the estimates for some of the basaltic terrains. This study suggests that the Eastern Syntaxis basin of the Brahmaputra is one of most intensely chemically eroding regions of the globe; and that runoff and physical erosion are the controlling factors of chemical erosion in the eastern Himalaya.

Singh, Sunil K.; Sarin, M. M.; France-Lanord, Christian

2005-07-01

128

Hexahydrated magnesium ions bind in the deep major groove and at the outer mouth of A-form nucleic acid duplexes.  

SciTech Connect

Magnesium ions play important roles in the structure and function of nucleic acids. Whereas the tertiary folding of RNA often requires magnesium ions binding to tight places where phosphates are clustered, the molecular basis of the interactions of magnesium ions with RNA helical regions is less well understood. We have refined the crystal structures of four decamer oligonucleotides, d(ACCGGCCGGT), r(GCG)d(TATACGC), r(GC)d(GTATACGC) and r(G)d(GCGTATACGC) with bound hexahydrated magnesium ions at high resolution. The structures reveal that A-form nucleic acid has characteristic [Mg(H2O)6]2+ binding modes. One mode has the ion binding in the deep major groove of a GpN step at the O6/N7 sites of guanine bases via hydrogen bonds. Our crystallographic observations are consistent with the recent NMR observations that in solution [Co(NH3)6]3+, a model ion of [Mg(H2O)6]2+, binds in an identical manner. The other mode involves the binding of the ion to phosphates, bridging across the outer mouth of the narrow major groove. These [Mg(H2O)6]2+ ions are found at the most negative electrostatic potential regions of A-form duplexes. We propose that these two binding modes are important in the global charge neutralization, and therefore stability, of A-form duplexes.

Robinson, H.; Gao, Y.-G.; Sanishvili, R.; Joachimiak, A.; Wang, A. H.-J.; Univ. of Illinois; Northwestern Univ.

2000-01-01

129

REDUCTION OF INGESTION EXPOSURE TO TRIHALOMETHANES DUE TO VOLATILIZATION. (R825362)  

EPA Science Inventory

Ingestion of tap water is one of the principal exposure pathways for disinfection byproducts (DBPs). One major class of DBPs, trihalomethanes (THM), are highly volatile, and volatilization will tend to lower ingestion exposures. This study quantifies volatilization...

130

Major ion chemistry, weathering processes and water quality assessment in upper catchment of Damodar River basin, India  

NASA Astrophysics Data System (ADS)

The chemical characteristics of surface, groundwater and mine water of the upper catchment of the Damodar River basin were studied to evaluate the major ion chemistry, geochemical processes controlling water composition and suitability of water for domestic, industrial and irrigation uses. Water samples from ponds, lakes, rivers, reservoirs and groundwater were collected and analysed for pH, EC, TDS, F, Cl, HCO3, SO4, NO3, Ca, Mg, Na and K. In general, Ca, Na, Mg, HCO3 and Cl dominate, except in samples from mining areas which have higher concentration of SO4. Water chemistry of the area reflects continental weathering, aided by mining and other anthropogenic impacts. Limiting groundwater use for domestic purposes are contents of TDS, F, Cl, SO4, NO3 and TH that exceed the desirable limits in water collected from mining and urban areas. The calculated values of SAR, RSC and %Na indicate good to permissible use of water for irrigation. High salinity, %Na, Mg-hazard and RSC values at some sites limit use for agricultural purposes.

Singh, Abhay Kumar; Mondal, G. C.; Kumar, Suresh; Singh, T. B.; Tewary, B. K.; Sinha, A.

2008-04-01

131

Principal Locations of Major-Ion, Trace-Element, Nitrate, and Escherichia coli Loading to Emigration Creek, Salt Lake County, Utah, October 2005  

USGS Publications Warehouse

Housing development and recreational activity in Emigration Canyon have increased substantially since 1980, perhaps causing an observed decrease in water quality of this northern Utah stream located near Salt Lake City. To identify reaches of the stream that contribute to water-quality degradation, a tracer-injection and synoptic-sampling study was done to quantify mass loading of major ions, trace elements, nitrate, and Escherichia coli (E. coli) to the stream. The resulting mass-loading profiles for major ions and trace elements indicate both geologic and anthropogenic inputs to the stream, principally from tributary and spring inflows to the stream at Brigham Fork, Burr Fork, Wagner Spring, Emigration Tunnel Spring, Blacksmith Hollow, and Killyon Canyon. The pattern of nitrate loading does not correspond to the major-ion and trace-element loading patterns. Nitrate levels in the stream did not exceed water-quality standards at the time of synoptic sampling. The majority of nitrate mass loading can be considered related to anthropogenic input, based on the field settings and trends in stable isotope ratios of nitrogen. The pattern of E. coli loading does not correspond to the major-ion, trace-element, or nitrate loading patterns. The majority of E. coli loading was related to anthropogenic sources based on field setting, but a considerable part of the loading also comes from possible animal sources in Killyon Canyon, in Perkins Flat, and in Rotary Park. In this late summer sampling, E. coli concentrations only exceeded water-quality standards in limited sections of the study reach. The mass-loading approach used in this study provides a means to design future studies and to evaluate the loading on a catchment scale.

Kimball, Briant A.; Runkel, Robert L.; Walton-Day, Katherine

2008-01-01

132

Identification of muscadine wine sulfur volatiles: pectinase versus skin-contact maceration.  

PubMed

Muscadine grapes ( Vitis rotundifolia ) are widely grown in the southern United States, as the more common Vitis vinifera cannot be cultivated due to Pierce's disease. There is interest to determine if certain cultivars can be used for good-quality wine production. This study compared the effect of pectolytic enzyme pretreatment with conventional skin-contact fermentation on Muscadine (Noble, Vitis rotundifolia ) wine major volatiles, aroma active volatiles, and volatile sulfur compounds (VSCs). Volatile composition, aroma activity, and VSCs in the initial juice and wine samples after 3 years were determined by gas chromatography in combination with mass spectrometry (GC-MS), olfactory detection (GC-O), and pulsed flame photometric detection (GC-PFPD). Forty-three nonethanol MS volatiles were common to all samples. Total ion chromatogram (TIC) MS peak area increased 91% in the skin-contact wines from the initial juice but only 24% in the enzyme-treated wine. Thirty-one VSCs were detected. Twenty-four sulfur volatiles were identified by matching their retention characteristics on polar and nonpolar columns with those of standards or MS spectrum matches. Six of these (sulfur dioxide, 1-propanethiol, 3-mercapto-2-pentanone, 3-mercapto-2-butanone, 2,8-epithio-cis-p-menthane, and 1-p-menthene-8-thiol) were reported for the first time in muscadine wine. Five additional VSCs were tentatively identified by matching standardized retention values with literature values, and two remain unidentified. Total sulfur peak areas increased 400% in the skin-contact wine and 560% in the enzyme-treated wine compared to the initial juice. There were 42 aroma-active volatiles in the initial juice, 48 in the skin-contact wine, and 66 in the enzyme-treated wine. Eleven aroma-active volatiles in the skin-contact wine and 16 aroma volatiles in the enzyme-treated wine appear to be due to sulfur volatiles. Pectolytic enzyme-treated wines contained less total volatiles but more sulfur and aroma-active volatiles than the traditional skin-contact wine. PMID:23289372

Gürbüz, Ozan; Rouseff, June; Talcott, Stephen T; Rouseff, Russell

2013-01-23

133

Comparisons between ion distributions retrieved from ENA images of the ring current and contemporaneous, multipoint ion measurements recorded in situ during the major magnetic storm of 15 May 2005  

Microsoft Academic Search

The Neutral Atom Detector Unit (NUADU) aboard the TC-2 spacecraft recorded energetic neutral atom (ENA) image data for >3 h during part of the main and recovery phases of a major magnetic storm on 15 May 2005. A custom designed, constrained linear inversion method was applied to retrieve ring current ion distributions in the ENA records out to L =

L. Lu; S. McKenna-Lawlor; S. Barabash; P. C. Brandt; J. Balaz; Z. X. Liu; Z. H. He; G. D. Reeves

2010-01-01

134

Location of the major barriers to water and ion movement in young roots of Zea mays L  

Microsoft Academic Search

The main barriers to the movement of water and ions in young roots of Zea mays were located by observing the effects of wounding various cell layers of the cortex on the roots' hydraulic conductivities and root pressures. These parameters were measured with a root pressure probe. Injury to the epidermis and cortex caused no significant change in hydraulic conductivity

Carol A. Peterson; Martina Murrmann; Ernst Steudle

1993-01-01

135

Soil volatile fungistasis and volatile fungistatic compounds  

Microsoft Academic Search

Fungistasis is a widespread phenomenon that can be mediated by soil microorganisms and volatile organic compounds (VOCs). The relationship between soil microorganisms and VOCs is still unclear, however, and many fungistatic compounds remain to be identified. We assessed the effects of soils (soil direct fungistasis) and VOCs produced by natural soils (soil volatile fungistasis) on the spore germination of several

Xu Chuankun; Mo Minghe; Zhang Leming; Zhang Keqin

2004-01-01

136

Quantify the loss of major ions induced by CO2 enrichment and nitrogen addition in subtropical model forest ecosystems  

NASA Astrophysics Data System (ADS)

studies have reported that atmospheric CO2 enrichment would increase the ion concentrations in the soil water. However, none of these studies could exactly quantify the amount of ion changes in the soil water induced by elevated CO2 and all of these experiments were carried out only in the temperate areas. Using an open-top chamber design, we studied the effects of CO2 enrichment alone and together with nitrogen (N) addition on soil water chemistry in the subtropics. Three years of exposure to an atmospheric CO2 concentration of 700 ppm resulted in accelerated base cation loss via leaching water below the 70 cm soil profile. The total of base cation (K+ + Na+ + Ca2+ + Mg2+) loss in the elevated CO2 treatment was higher than that of the control by 220%, 115%, and 106% in 2006, 2007, and 2008, respectively. The N treatment decreased the effect of high CO2 treatment on the base cation loss in the leachates. Compared to the control, N addition induced greater metal cation (Al3+ and Mn2+) leaching loss in 2008 and net Al3+ and Mn2+ loss in the high N treatment increased by 100% and 67%, respectively. However, the CO2 treatment decreased the effect of high N treatment on the metal cation loss. Changes of ion export followed by the exposure to the elevated CO2, and N treatments were related to both ion concentrations and leached water amount. We hypothesize that forests in subtropical China might suffer from nutrient limitation and some poisonous metal activation in plant biomass under future global change.

Liu, Juxiu; Zhang, Deqiang; Huang, Wenjuan; Zhou, Guoyi; Li, Yuelin; Liu, Shizhong

2014-04-01

137

The energy distributions of major ions in the cathode zone of a strongly abnormal nitrogen DC glow discharge  

Microsoft Academic Search

Energy distributions of N+ and N2+ ions bombarding the aluminium cathode of a glow discharge at high current densities (few mA cm?2) have been calculated and compared with experimentally determined values. The results show a high proportion of N+ compared to (N1+ + N2+) which are characteristic of a nitrogen discharge and arise from the small value of the cross-section

Z Wronski; H Murlak-Stachura

1998-01-01

138

Measurements of major ion concentration in settled coarse particles and aerosols at a semiarid rural site in India  

Microsoft Academic Search

Deposition rates and deposition velocities of water-soluble ions (F, Cl, NO3, SO4, NH4, Ca, Mg, Na and K) were measured at a rural site (Gopalpura, Agra). Dry deposition samples were collected throughout the year from December 1995 to August 1997, while the aerosol samples were collected only during the winter season of 1996. Surrogate technique was used to collect the

Gur Sumiran Satsangi; A Lakhani; P Khare; S. P Singh; K. M Kumari; S. S Srivastava

2002-01-01

139

Major ions, nutrients and primary productivity in volcanic neotropical streams draining rainforest and pasture catchments at Los Tuxtlas, Veracruz, Mexico  

Microsoft Academic Search

Six streams in the Los Tuxtlas region, a volcanic area in southeastern Mexico, were characterized chemically and biologically. Temperature, pH, conductivity, ions (Ca2+, Mg2+, Na+, K+, CaCO-3 and SO2-4), nutrients (NO-3, NH+4, total P and PO-34), and chlorophyll a from epilithon were measured every other month from September 1996 to July 1997. The streams studied had a consistent pattern of

Miriam G. Ramos-Escobedo; Gabriela Vázquez

2001-01-01

140

Conference on Planetary Volatiles  

NASA Technical Reports Server (NTRS)

Initial and present volatile inventories and distributions in the Earth, other planets, meteorites, and comets; observational evidence on the time history of volatile transfer among reservoirs; and volatiles in planetary bodies, their mechanisms of transport, and their relation to thermal, chemical, geological and biological evolution were addressed.

Hrametz, K.; Kofler, L.

1982-01-01

141

Conference on Planetary Volatiles  

NASA Technical Reports Server (NTRS)

Initial and present volatile inventories and distributions in the Earth, other planets, meteorites, and comets; observational evidence on the time history of volatile transfer among reservoirs; and volatiles in planetary bodies, their mechanisms of transport, and their relation to thermal, chemical, geological and biological evolution are addressed.

Pepin, R. O. (compiler); Oconnell, R. (compiler)

1982-01-01

142

Characterization of major water-soluble inorganic ions in size-fractionated particulate matters in Shanghai campus ambient air  

Microsoft Academic Search

The size-fractionated inhalable particles in ambient air were collected at the top of a lab building in a university campus of Shanghai; F?, Cl?, NO3?, SO42?, and NH4+ were extracted to determine the concentration. In every size, the concentration of the five ions followed the order of SO42?>NO3??NH4+?Cl?>F?. Their concentrations in PM1.6 were 5–7, 1–5, 3, 1–3, and ?0.1?g\\/m3, respectively,

Guangli Xiu; Danian Zhang; Jizhang Chen; Xuejuan Huang; Zhixiang Chen; Honglian Guo; Jinfang Pan

2004-01-01

143

Volatile Constituents of Montanoa tomentosa and Lippia graveolens.  

PubMed

The constituents of the volatile oils of MONTANOA TOMENTOSA and LIPPIA GRAVEOLENS, were investigated using capillary GC/MS. Borneol acetate, beta-cubebene, and beta-caryophyllene were found to be the major constituents of the volatile oil of M. TOMENTOSA, while P-cymene, 1,8-cineol, thymol, and carvacrol were the major volatile components of L. GRAVEOLENS. The possible correlation between the high concentration of monoterpenes and the alleged antifertility effect of the title plants is discussed. PMID:17269076

Compadre, C M; Hussain, R A; Leon, I; Enríquez, R G

1987-10-01

144

Establishing the occurrence of major and minor glucosinolates in Brassicaceae by LC-ESI-hybrid linear ion-trap and Fourier-transform ion cyclotron resonance mass spectrometry.  

PubMed

Glucosinolates (GLSs) are sulfur-rich plant secondary metabolites which occur in a variety of cruciferous vegetables and among various classes of them, genus Brassica exhibits a rich family of these phytochemicals at high, medium and low abundances. Liquid chromatography (LC) with electrospray ionization in negative ion mode (ESI-) coupled to a hybrid quadrupole linear ion trap (LTQ) and Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS) was employed for the selective and sensitive determination of intact GLSs in crude sample extracts of broccoli (Brassica oleracea L. Var. italica), cauliflower (B. oleracea L. Var. Botrytis) and rocket salad (Eruca sativa L.) with a wide range of contents. When LTQ and FTICR mass analyzers are compared, the magnitude of the limit of detection was ca. 5/6-fold lower with the FTICR MS. In addition, the separation and detection by LC-ESI-FTICR MS provides a highly selective assay platform for unambiguous identification of GLSs, which can be extended to lower abundance (minor) GLSs without significant interferences of other compounds in the sample extracts. The analysis of Brassicaceae species emphasized the presence of eight minor GLSs, viz. 1-methylpropyl-GLS, 2-methylpropyl-GLS, 2-methylbutyl-GLS, 3-methylbutyl-GLS, n-pentyl-GLS, 3-methylpentyl-GLS, 4-methylpentyl-GLS and n-hexyl-GLS. The occurrence of these GLSs belonging to the saturated aliphatic side chain families C(4), C(5) and C(6), presumably formed by chain elongation of leucine, homoleucine and dihomoleucine as primary amino acid precursors, is described. Based on their retention behavior and tandem MS spectra, all these minor compounds occurring in plant extracts of B. oleracea L. Var. italica, B. oleracea L. Var. Botrytis and E. sativa L. were tentatively identified. PMID:22030302

Lelario, Filomena; Bianco, Giuliana; Bufo, Sabino A; Cataldi, Tommaso R I

2012-01-01

145

The Volatile Content of the Lunar Volcanic Glasses and the Presence of Water in the Moon's Interior  

NASA Astrophysics Data System (ADS)

The composition and origin of the lunar volatiles has been the subject of considerable interest and is one of the most important unsolved questions regarding the formation of the Moon. The general consensus today is that the Moon formed and evolved through a single or a series of catastrophic heating events, during which most of the highly volatile elements were lost. Hydrogen, being the lightest element, is thought to have been completely lost during this period. Here we report, by virtue of major advances in secondary ion mass spectrometry, improved limits on the indigenous volatile (CO2, H2O, F, S, Cl) contents of the most primitive basalts in the Moon, the lunar volcanic glasses from Apollo 15. Three outstanding features of the data are: 1) the significant correlation among H2O, Cl, F and S contents, 2) the clear relationship between the volatile and the major element contents, and 3) the volatiles concentration profiles within a single selected glass bead with decreasing contents from the core to the rim. The new data indicate that H2O and the other volatiles are indigenous to the Moon and that the volatile contents in the volcanic glasses were affected by degassing processes during the fire-fountain style of eruption. Although the pre-eruptive water content of the lunar volcanic glasses cannot be precisely constrained, numerical modeling of diffusive degassing of the very-low-Ti glasses provides a best estimate of 745 ppm water, with a minimum of 260 ppm at the 95% confidence level. Our results indicate that, contrary to prevailing ideas, the bulk Moon might not be entirely depleted in highly volatile elements, including water. Thus, the presence of water must be considered in models constraining the Moon's formation and its thermal and chemical evolution. Acknowledgement: Funding for our research came from NASA Cosmochemistry Program.

Saal, Alberto E.; Hauri, E. H.; LoCascio, M.; Van Orman, J.; Rutherford, M. J.; Cooper, R. F.

2008-09-01

146

Analysis of secondary organic aerosol using a Micro-Orifice Volatilization Impactor (MOVI) coupled to an ion trap mass spectrometer with atmospheric pressure chemical ionization (APCI-IT/MS)  

NASA Astrophysics Data System (ADS)

We describe the development and characterization of a Micro-Orifice Volatilization Impactor (MOVI) which is coupled to an ion trap mass spectrometer with atmospheric pressure chemical ionization (APCI-IT/MS), and its application in laboratory and field measurements. The MOVI-APCI-IT/MS allows the quantification of organic acids and other oxidation products of volatile organic compounds (VOCs) in secondary organic aerosols (SOA) on a semi-continuous basis. Furthermore, the vapor pressure and saturation concentration of the particle components can be estimated. The MOVI was first described in 2010 by Yatavelli and Thornton (Yatavelli and Thornton, 2010). It is a single stage, multi-nozzle impactor with 100 nozzles, each having a diameter of 150 ?m. At a flow-rate of 10 L·min-1 air is drawn through the MOVI and particles are collected on a deposition plate. The cut-point diameter (d50, diameter of 50% collection efficiency) is at 130 nm. A low pressure-drop of only 5.3% of atmospheric pressure behind the nozzles allows collecting not only low-volatile but even semi-volatile compounds, which are an important part of SOA. After collecting particles hydrocarbon-free synthetic air is led over the collection surface into the APCI-IT/MS and the collection surface is heated up to 120 ° C in less than 200 s, volatilizing the sampled SOA. The vaporized compounds are transferred into the ion source and subsequently analyzed by mass spectrometry. Due to the soft ionization at atmospheric pressure the obtained mass spectra show only low fragmentations and can easily be interpreted. In laboratory experiments the MOVI-APCI-IT/MS was used for the chemical analysis of SOA generated from ?-pinene-ozonolysis in a smog chamber. The limit of detection was found at 7.3 ng for pinic acid. The vapor pressure log p0 and the saturation concentration C25* for pinic acid were calculated from the desorption temperature using the method presented by Faulhaber et al. (Faulhaber et al., 2009). Furthermore, in summer 2011 the MOVI-APCI-IT/MS was successfully tested in field measurements during the "Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen - Rocky Mountain Biogenic Aerosol Study" (BEACHON-RoMBAS) in a ponderosa pine woodland in the southern Rocky Mountains of North America. The study was focused on understanding the formation, growth and properties of biogenic organic aerosol. We measured the composition of the aerosol particles and determined the concentration of pinic acid and isobaric substances. By means of intercomparison studies with other instruments like an aerosol mass spectrometer (AMS) and a MOVI coupled to a chemical ionization mass spectrometer (CIMS) we could validate our measurements.

Brueggemann, M.; Vogel, A.; Hoffmann, T.

2012-04-01

147

CHARACTERIZATION OF CORIANDER (CORIANDRUM SATIVUM L.) SEEDS AND LEAVES: VOLATILE AND NON VOLATILE EXTRACTS  

Microsoft Academic Search

The main aim of this study was the characterization of coriander essential oil. The major volatile compounds in coriander seed essential oil were linalool, ?-terpinene, ?-pinene, camphor, decanal geranyl acetate, limonene, geraniol, camphene and D- limonene. While the major volatile compounds identified in coriander leaves essential oil (CLEO) were (E)-2-decenal, linalool, (E)-2-dodecenal, (E)-2-tetradecenal, 2-decen-1-ol, (E)-2-undecenal, dodecanal, (E)-2-tridecenal, (E)-2-hexadecenal, pentadecenal, ?-pinene.

Muhammad Khuram Shahwar; Ahmed Hassan El-Ghorab; Faqir Muhammad Anjum; Masood Sadiq Butt; Shahzad Hussain; Muhammad Nadeem

2011-01-01

148

Characterization of Coriander (Coriandrum sativum L.) Seeds and Leaves: Volatile and Non Volatile Extracts  

Microsoft Academic Search

The main aim of this study was the characterization of coriander essential oil. The major volatile compounds in coriander seed essential oil were linalool, ?-terpinene, ?-pinene, camphor, decanal geranyl acetate, limonene, geraniol, camphene, and D-limonene, while the major volatile compounds identified in coriander leaves essential oil were (E)-2-decenal, linalool, (E)-2-dodecenal, (E)-2-tetradecenal, 2-decen-1-ol, (E)-2-undecenal, dodecanal, (E)-2-tridecenal, (E)-2-hexadecenal, pentadecenal, and ?-pinene. The

Muhammad Khuram Shahwar; Ahmed Hassan El-Ghorab; Faqir Muhammad Anjum; Masood Sadiq Butt; Shahzad Hussain; Muhammad Nadeem

2012-01-01

149

Spatial and seasonal variability of water-soluble ions in PM2.5 aerosols in 14 major cities in China  

NASA Astrophysics Data System (ADS)

We analyzed PM2.5 aerosols from 14 major cities in China for concentrations of water-soluble (WS) major and trace elements (Na, Mg, Ca, K, Fe, Mn, Zn, Rb, Sr, Ba, Pb, S and Cl). The main focus was to examine patterns in spatial distribution and seasonal variability. Using principal component analysis, we identified three general sources for WS-elements in aerosols as anthropogenic, seasalts and fine dust particles originating from soils. The spatial patterns identified show that anthropogenic activity is the most important factor influencing the concentration of heavy metals in aerosols. Concentrations of WS-S, Zn and Pb were correlated with the locations of major industrial zones, and regulated by topography and seasonal weather patterns. We found higher WS-metals concentrations during the winter season, probably related to coal combustion in northern China. Moderate correlations of WS-S, Zn, Pb and Cl suggest that coal combustion releases. The seasonal pattern in WS-Fe concentrations shows the importance of acid precipitation events where coal combustion contributes to additional Fe (II) deposition. The findings of this study support the argument that WS-S in fine particles enhanced the production of hydrogen ions act to reduce the pH values of precipitation. Our interpretation of these spatial and seasonal patterns in WS-major and trace elements in aerosols highlights the need for continued research on trends in acidic deposition in major industrial cities in China.

Cheng, Miao-Ching; You, Chen-Feng; Cao, Junji; Jin, Zhangdong

2012-12-01

150

Volatile monoterpenes inhibit potato tuber sprouting  

Microsoft Academic Search

Several volatile monoterpenes, which are among the major constituents of several easily obtainable essential oils, were phytotoxic\\u000a in the gaseous phase to emerged potato tuber sprouts. Analyses of the more phytotoxic monoterpenes were conducted using a\\u000a continuous-flow system in which the compounds were released as volatiles into the headspace surrounding the tubers. Several\\u000a of these compounds, which have low mammalian

Steven F. Vaughn; Gayland F. Spencer

1991-01-01

151

Biogeochemical processes controlling the mobility of major ions and trace metals in aquitard sediments beneath an oil sand tailing pond: laboratory studies and reactive transport modeling.  

PubMed

Increased production and expansion of the oil sand industry in Alberta are of great benefit to the economy, but they carry major environmental challenges. The volume of fluid fine tailings requiring storage is 840×10(6) m(3) and growing, making it imperative that we better understand the fate and transport of oil sand process-affected water (OSPW) seepage from these facilities. Accordingly, the current study seeks to characterize both a) the potential for major ion and trace element release, and b) the principal biogeochemical processes involved, as tailing pond OSPW infiltrates into, and interacts with, underlying glacial till sediments prior to reaching down gradient aquifers or surface waters. Objectives were addressed through a series of aqueous and solid phase experiments, including radial diffusion cells, an isotope analysis, X-ray diffraction, and sequential extractions. The diffusion cells were also simulated in a reactive transport framework to elucidate key reaction processes. The experiments indicate that the ingress and interaction of OSPW with the glacial till sediment-pore water system will result in: a mitigation of ingressing Na (retardation), displacement and then limited precipitation of exchangeable Ca and Mg (as carbonates), sulfate reduction and subsequent precipitation of the produced sulfides, as well as biodegradation of organic carbon. High concentrations of ingressing Cl (~375 mg L(-1)) and Na (~575 mg L(-1)) (even though the latter is delayed, or retarded) are expected to migrate through the till and into the underlying sand channel. Trace element mobility was influenced by ion exchange, oxidation-reduction, and mineral phase reactions including reductive dissolution of metal oxyhydroxides - in accordance with previous observations within sandy aquifer settings. Furthermore, although several trace elements showed the potential for release (Al, B, Ba, Cd, Mn, Pb, Si, Sr), large-scale mobilization is not supported. Thus, the present results suggest that in addition to the commonly cited naphthenic acids, remediation of OSPW-impacted groundwater will need to address high concentrations of major ions contributing to salinization. PMID:23727691

Holden, A A; Haque, S E; Mayer, K U; Ulrich, A C

2013-08-01

152

Biogeochemical processes controlling the mobility of major ions and trace metals in aquitard sediments beneath an oil sand tailing pond: Laboratory studies and reactive transport modeling  

NASA Astrophysics Data System (ADS)

Increased production and expansion of the oil sand industry in Alberta are of great benefit to the economy, but they carry major environmental challenges. The volume of fluid fine tailings requiring storage is 840 × 106 m3 and growing, making it imperative that we better understand the fate and transport of oil sand process-affected water (OSPW) seepage from these facilities. Accordingly, the current study seeks to characterize both a) the potential for major ion and trace element release, and b) the principal biogeochemical processes involved, as tailing pond OSPW infiltrates into, and interacts with, underlying glacial till sediments prior to reaching down gradient aquifers or surface waters. Objectives were addressed through a series of aqueous and solid phase experiments, including radial diffusion cells, an isotope analysis, X-ray diffraction, and sequential extractions. The diffusion cells were also simulated in a reactive transport framework to elucidate key reaction processes. The experiments indicate that the ingress and interaction of OSPW with the glacial till sediment-pore water system will result in: a mitigation of ingressing Na (retardation), displacement and then limited precipitation of exchangeable Ca and Mg (as carbonates), sulfate reduction and subsequent precipitation of the produced sulfides, as well as biodegradation of organic carbon. High concentrations of ingressing Cl (~ 375 mg L- 1) and Na (~ 575 mg L- 1) (even though the latter is delayed, or retarded) are expected to migrate through the till and into the underlying sand channel. Trace element mobility was influenced by ion exchange, oxidation-reduction, and mineral phase reactions including reductive dissolution of metal oxyhydroxides — in accordance with previous observations within sandy aquifer settings. Furthermore, although several trace elements showed the potential for release (Al, B, Ba, Cd, Mn, Pb, Si, Sr), large-scale mobilization is not supported. Thus, the present results suggest that in addition to the commonly cited naphthenic acids, remediation of OSPW-impacted groundwater will need to address high concentrations of major ions contributing to salinization.

Holden, A. A.; Haque, S. E.; Mayer, K. U.; Ulrich, A. C.

2013-08-01

153

Evaluation of fast volatile analysis for detection of Botrytis cinerea infections in strawberry.  

PubMed

Grey mold (Botrytis cinerea) is one of the major phytopathogens causing serious losses during strawberry postharvest and storage. B. cinerea-host interaction affect emissions of volatile compounds during infection resulting in a characteristic earthy, mushroom odor. Therefore, the objective of this study was to evaluate two analytical techniques based on fast volatile analysis on their performance for monitoring evolution and early detection of B. cinerea infections in strawberry. In a first experiment headspace multi-capillary column-ion mobility spectrometry (HS MCC-IMS) has been successfully used to evaluate development of strawberry aroma during shelflife. In a second experiment the same technique has been used to detect the degree of B. cinerea infection through changes in the volatile profile. Additionally, these samples were analyzed with headspace solid-phase-microextraction fast GC-MS (HS SPME fast GC-MS). Both HS MCC-IMS and HS SPME fast GC-MS could determine the changes in volatile composition as a function of the degree of B. cinerea infection as determined by an enzyme-linked immunosorbent assay (ELISA) and could be used to follow the evolution of infection. According to the ELISA data, some fruit were infected even without any symptoms and volatiles produced by the fungus may be overshadowed by the fruit volatiles. Therefore, both analytical techniques could not be used for early detection of B. cinerea infections. After identification of the volatile compounds and multivariate data analysis, potential biomarkers specific for B. cinerea were highlighted, being 3-methylbutanal, cis-4-decenal, 2-methyl-1-butanol, 2-methyl-1-propanol, 1-octen-3-one and 1-octen-3-ol. PMID:22986207

Vandendriessche, Thomas; Keulemans, Johan; Geeraerd, Annemie; Nicolai, Bart M; Hertog, Maarten L A T M

2012-12-01

154

Wet deposition and related atmospheric chemistry in the São Paulo metropolis, Brazil: Part 1. Major inorganic ions in rainwater as evaluated by capillary electrophoresis with contactless conductivity detection  

NASA Astrophysics Data System (ADS)

The metropolitan region of São Paulo (17.8 million inhabitants) presents serious air quality problems. An official network monitors key air pollutants, however, there is no regular program of evaluation of the wet deposition and data about rainwater composition is scarce. Opening a series of articles on this subject, capillary zone electrophoresis with contactless conductivity detection (CZE-CCD) is proposed and applied as a quick and inexpensive alternative to ion chromatography for the determination of the ionic composition of rainwater. Excellent resolution of the peaks and sufficient sensitivity were obtained for major ions. Switching from anion to cation determination is fast (30 min) and as simple as inverting the polarity of the voltage supply and changing the modifier added to the buffer solution. CZE-CCD was applied to the study of wet-only deposition collected in São Paulo during the period from May l997 to March 1998. The volume weighted means of the anions, sulfate, nitrate and chloride, were, respectively, 17, 22 and 29 ?mol l -1. Among the cations, ammonium was the dominating one, with 28 ?mol l -1, followed by calcium, 23 ?mol l -1, sodium, 12 ?mol l -1, and potassium, 5.8 ?mol l -1. The wet flux of these anions and cations were, respectively, 2.5, 2.2, 1.6, 0.78, 1.4, 0.43 and 0.35 g m -2 yr -1. By attributing all sodium to marine origin, half of the chloride and more than 90% of all other ions are ascribable to continental/anthropogenic sources. Literature data for rainwater from inland regions (˜200 km apart from São Paulo) reveals lower deposition of all ions but H +. Absorption of NH 3 and incorporation of calcium carbonate, mainly in the metropolitan region itself, accounts for decreased acidity. The enrichment in all other ions during the studied period indicates the prevalence of the anthropogenic emissions from the metropolis over continental sources and explains the high correlation between the ions NO 3-, SO 42-, and NH 4+; the same ions responsible for a factor that, alone, explains 42% of the variability in the PCA.

Rocha, Flávio R.; Fracassi da Silva, José A.; Lago, Claudimir L.; Fornaro, Adalgiza; Gutz, Ivano G. R.

155

Air concentrations and wet deposition of major inorganic ions at five non-urban sites in China, 2001-2003  

NASA Astrophysics Data System (ADS)

Air and precipitation measurements at five sites were undertaken from 2001 to 2003 in four different provinces in China, as part of the acid rain monitoring program IMPACTS. The sites were located in Tie Shan Ping (TSP) in Chongqing, Cai Jia Tang (CJT) in Hunan, Lei Gong Shan (LGS) and Liu Chong Guan (LCG) in Guizhou and Li Xi He (LXH) in Guangdong. The site characteristics are quite varied with TSP and LCG located relatively near big cites while the three others are situated in more regionally representative areas. The distances to urban centres are reflected in the air pollution concentrations, with annual average concentrations of SO 2 ranging from 0.5 to above 40 ?g S m -3. The main components in the airborne particles are (NH 4) 2SO 4 and CaSO 4. Reduced nitrogen has a considerably higher concentration level than oxidised nitrogen, reflecting the high ammonia emissions from agriculture. The gas/particle ratio for the nitrogen compounds is about 1:1 at all the three intensive measurement sites, while for sulphur it varies from 2.5 to 0.5 depending on the distance to the emission sources. As in air, the predominant ions in precipitation are sulphate, calcium and ammonium. The volume weighted annual concentration of sulphate ranges from about 70 ?eq l -1 at the most rural site (LGS) to about 200 ?eq l -1 at TSP and LCG. The calcium concentration ranges from 25 to 250 ?eq l -1, while the total nitrogen concentration is between 30 and 150 ?eq l -1; ammonium is generally twice as high as nitrate. China's acid rain research has traditionally been focused on urban sites, but these measurements show a significant influence of long range transported air pollutants to rural areas in China. The concentration levels are significantly higher than seen in most other parts of the world.

Aas, Wenche; Shao, Min; Jin, Lei; Larssen, Thorjørn; Zhao, Dawei; Xiang, Renjun; Zhang, Jinhong; Xiao, Jinsong; Duan, Lei

156

The effect of H2O gas on volatilities of planet-forming major elements. I - Experimental determination of thermodynamic properties of Ca-, Al-, and Si-hydroxide gas molecules and its application to the solar nebula  

NASA Technical Reports Server (NTRS)

The vapor pressures of Ca(OH)2(g), Al(OH)3(g), and Si(OH)4(g) molecules in equilibrium with solid calcium-, aluminum, and silicon-oxides, respectively, were determined, and were used to derive the heats of formation and entropies of these species, which are expected to be abundant under the currently postulated physical conditions in the primordial solar nebula. These data, in conjunction with thermodynamic data from literature, were used to calculate the relative abundances of M, MO(x), and M(OH)n gas species and relative volatilities of Fe, Mg, Si, Ca, and Al for ranges of temperature, total pressure, and H/O abundance ratio corresponding to the plausible ranges of physical conditions in the solar nebula. The results are used to explain how Ca and Al could have evaporated from Ca,Al-rich inclusions in carbonaceous chondrites, while Si, Mg, and Fe condensed onto them during the preaccretion alteration of CAIs.

Hashimoto, Akihiko

1992-01-01

157

Chemical characteristics of aerosols at coastal station in Hong Kong. I. Seasonal variation of major ions, halogens and mineral dusts between 1995 and 1996  

NASA Astrophysics Data System (ADS)

Aerosols samples (total suspended particulate "TSP" and PM 10 particulate) were collected at coastal monitoring station in Hong Kong between 1995 and 1996. They were analyzed to investigate the seasonal cycle among major ions (Na +, NH 4+-N, K +, Mg 2+, Ca 2+, Cl -, NO 3-, and SO 42-), halogen elements (Br, I) and mineral dusts. The concentration of major ions showed a summer minimum and a winter maximum in a coastal region of Hong Kong. Halogen (Br, I) and dust concentrations exhibited a very similar variation. From the molar equivalence of Na + and Cl -, it was found that the Cl - in TSP or PM 10 was deviated from sea-salt (NaCl) component. Bromine (Br) in aerosols evidently originated from marine source but iodine (I) in aerosols may have been generated from natural and anthropogenic sources including possible biomass emission. The ratios of nonsea-salt sulfate (nss-SO 42-) to nitrate (NO 3-) and trace elements (As, Sb, Se, Pb, V and Zn) were used to explain the different pollution emissions.

Cheng, Z. L.; Lam, K. S.; Chan, L. Y.; Wang, T.; Cheng, K. K.

158

Deterministic implied volatility models  

Microsoft Academic Search

In this paper, we characterize two deterministic implied volatility models, defined by assuming that either the per-delta or the per-strike implied volatility surface has a deterministic evolution. Practitioners have recently proposed these two models to describe two regimes of implied volatility (see Derman (1999 Risk4 55–9)). In an arbitrage-free sticky-delta model, we show that the underlying asset price is the

P. Balland

2002-01-01

159

Characterizing interactions between surface water and groundwater in the Jialu River basin using major ion chemistry and stable isotopes  

NASA Astrophysics Data System (ADS)

The Jialu River, a secondary tributary of the Huaihe River, has been severely contaminated for the major contaminant sources, such as a number of untreated or lightly treated sewage wastes in some cities. Groundwater along the river is not an isolated component of the hydrologic system, but instead connected with the surface water. This study aims to characterize the relationships between surface water (e.g. reservoirs, lakes and rivers) and groundwater near the river in the shallow Quaternary aquifer. The concentration of Cl- in North Zhengzhou City increased prominently due to the discharge of a large amount of domestic water. Nitrate and potassium show maximum concentrations in groundwater in Fugou County. These high levels can be attributed to the use of a large quantity of fertilizer over this region. The regional well had water with a constant stable isotopic signature, which illustrates that the groundwater never or rarely receive recharge from surface water. However, the groundwater of transitional well (location SY3) seemed to be recharged by river water via bank infiltration in September 2010. Fractional contributions of river water to the groundwater were calculated based on isotopic and chemical data using a mass-balance approach. Results show that the groundwater was approximately composed of 60-70% river water. These findings would be useful for a better understanding of hydrogeological processes at the river-aquifer interface and ultimately benefit water management in the future.

Yang, L.; Song, X.; Zhang, Y.; Han, D.; Zhang, B.; Long, D.

2012-05-01

160

Lunar apatite with terrestrial volatile abundances.  

PubMed

The Moon is thought to be depleted relative to the Earth in volatile elements such as H, Cl and the alkalis. Nevertheless, evidence for lunar explosive volcanism has been used to infer that some lunar magmas exsolved a CO-rich and CO(2)-rich vapour phase before or during eruption. Although there is also evidence for other volatile species on glass spherules, until recently there had been no unambiguous reports of indigenous H in lunar rocks. Here we report quantitative ion microprobe measurements of late-stage apatite from lunar basalt 14053 that document concentrations of H, Cl and S that are indistinguishable from apatites in common terrestrial igneous rocks. These volatile contents could reflect post-magmatic metamorphic volatile addition or growth from a late-stage, interstitial, sulphide-saturated melt that contained approximately 1,600 parts per million H(2)O and approximately 3,500 parts per million Cl. Both metamorphic and igneous models of apatite formation suggest a volatile inventory for at least some lunar materials that is similar to comparable terrestrial materials. One possible implication is that portions of the lunar mantle or crust are more volatile-rich than previously thought. PMID:20651686

Boyce, Jeremy W; Liu, Yang; Rossman, George R; Guan, Yunbin; Eiler, John M; Stolper, Edward M; Taylor, Lawrence A

2010-07-22

161

A BENCH SCALE STUDY ON BIODEGRADATION AND VOLATILIZATION OF ETHYLBENZOATE IN AQUIFERS. (R825549C039)  

EPA Science Inventory

Experiments were conducted to investigate the fate of ethylbenzoate and soil microorganisms in shallow aquifers. Biodegradation and volatilization have been identified as the major mechanisms in attenuating ethylbenzoate in contaminated soils. The rate of volatilization was ex...

162

An exploratory comparative study of volatile compounds in exhaled breath and emitted by skin using selected ion flow tube mass spectrometry  

Microsoft Academic Search

Selected ion flow tube mass spectrometry (SIFT-MS) has been used to carry out a pilot parallel study on five volunteers to determine changes occurring in several trace compounds present in exhaled breath and emitted from skin into a collection bag surrounding part of the arm, before and after ingesting 75 g of glucose in the fasting state. SIFT-MS enabled real-time

Claire Turner; Bhavin Parekh; Christopher Walton; Patrik S?pane?l; David Smith; Mark Evans

2008-01-01

163

Fluoride volatility method for reprocessing of LWR and FR fuels  

Microsoft Academic Search

Fluoride volatility method is based on direct fluorination of powdered spent fuel with fluorine gas in a flame fluorination reactor, where the volatile fluorides (represented mainly by UF6, partially NpF6) are separated from the non-volatile ones (e.g. PuF4, AmF3, CmF3, fluorides of majority of fission products), the objective being to separate a maximum fraction of uranium component from plutonium, minor

Jan Uhlí?; Martin Mare?ek

2009-01-01

164

Volatile liquid storage system  

Microsoft Academic Search

This patent describes a method of collecting and abating emission from a volatile liquid in an above ground storage tank. It comprises the liquid storage tank having a bottom, a vertical cylindrical circular wall having a lower edge portion joined to the bottom, and an external fixed roof, the tank having an internal floating roof floating on a volatile liquid

R. J. Laverman; P. J. Winters; J. K. Rinehart

1992-01-01

165

Volatiles in Chainpur chondrules  

NASA Technical Reports Server (NTRS)

A study of volatile element concentrations in individual chondrules in the Chainpur LL3 chondrite is presented. Volatile elements differing in geochemical behavior tended to vary randomly and correlated variations were observed only for those elements inferred to occupy similar mineral sites. Variations in Co and Ni in kamacite show that metal in chondrule interiors has not approached equilibrium, and that postformational element distribution has mainly altered siderophile concentrations in surface metal grains, and has probably left ionic species unaltered. Etching to remove 3 to 5% of the chondrule dissolved siderophiles, enhanced Zn and Na volatiles relative to nonvolatile Cr in the etch, and produced a large Cd enhancement. If metamorphic redistribution of nonsiderophile volatiles was neglible, their high concentrations are inconsistent with chondrule formation by direct condensation, and models involving sudden melting of preexisting solids can explain the observations but require rapid cooling to prevent volatile loss.

Grossman, J. N.; Kracher, A.; Wasson, J. T.

1979-01-01

166

Semi-continuous mass closure of the major components of fine particulate matter in Riverside, CA  

NASA Astrophysics Data System (ADS)

The application of newly developed semi-continuous aerosol monitors allows for the measurement of all the major species of PM 2.5 on a 1-h time basis. Temporal resolution of both non-volatile and semi-volatile species is possible. A suite of instruments to measure the major chemical species of PM 2.5 allows for semi-continuous mass closure. A newly developed dual-oven Sunset carbon monitor is used to measure non-volatile organic carbon, semi-volatile organic carbon and elemental carbon. Inorganic species, including sulfate and nitrate, can be measured with an ion chromatograph based sampler. Comparison of the sum of the major chemical species in an urban aerosol with mass measured by an FDMS resulted in excellent agreement. Linear regression analysis resulted in a zero-intercept slope of 0.98±0.01 with an R2=0.86. One-hour temporal resolution of the major species of PM 2.5 may reduce the uncertainty in receptor based source apportionment modeling, will allow for better forecasting of PM 2.5 episodes, and may lead to increased understanding of related health effects.

Grover, Brett D.; Eatough, Norman L.; Woolwine, Woods R.; Cannon, Justin P.; Eatough, Delbert J.; Long, Russell W.

167

Major-ion chemistry, ?13C and 87Sr/86Sr as indicators of hydrochemical evolution and sources of salinity in groundwater in the Yuncheng Basin, China  

NASA Astrophysics Data System (ADS)

Processes controlling hydrogeochemistry in the Yuncheng Basin, China, were characterised using major-ion chemistry, 87Sr/86Sr ratios and ?13C values. Evapotranspiration during recharge increased solute concentrations by factors of ˜5-50 in deep palaeowaters, while higher degrees of evapotranspiration have occurred in shallow, modern groundwater. Aquifer sediments (loess) contain approximately 15 weight% calcite; trends in groundwater HCO3 concentrations and ?13C values (ranging from -16.4 to -8.2‰) indicate that carbonate weathering is a significant source of DIC. Groundwater 87Sr/86Sr ratios (0.7110-0.7162, median of 0.7116) are similar to those in both loess carbonate (0.7109-0.7116) and local rainfall (0.7112), and are significantly lower than Sr in aquifer silicates (0.7184-0.7251). Despite evidence for substantial carbonate dissolution, groundwater is generally Ca-poor (< 10% of total cations) and Na-rich, due to cation exchange. Saturation with respect to carbonate minerals occurs during or soon after recharge (all calcite and dolomite saturation indices are positive). Subsequent carbonate dissolution in the deep aquifer must occur as a second-stage process, in response to Ca loss (by ion exchange) and/or via incongruent dissolution of dolomite and impure calcite. The latter is consistent with positive correlations between ?13C values and Mg/Ca and Sr/Ca ratios ( r 2 = 0.32 and 0.34).

Currell, Matthew J.; Cartwright, Ian

2011-06-01

168

First Identification of 5,11-Dideoxytetrodotoxin in Marine Animals, and Characterization of Major Fragment Ions of Tetrodotoxin and Its Analogs by High Resolution ESI-MS/MS  

PubMed Central

Even though tetrodotoxin (TTX) is a widespread toxin in marine and terrestrial organisms, very little is known about the biosynthetic pathway used to produce it. By describing chemical structures of natural analogs of TTX, we can start to identify some of the precursors that might be important for TTX biosynthesis. In the present study, an analog of TTX, 5,11-dideoxyTTX, was identified for the first time in natural sources, the ovary of the pufferfish and the pharynx of a flatworm (planocerid sp. 1), by comparison with totally synthesized (?)-5,11-dideoxyTTX, using high resolution ESI-LC-MS. Based on the presence of 5,11-dideoxyTTX together with a series of known deoxy analogs, 5,6,11-trideoxyTTX, 6,11-dideoxyTTX, 11-deoxyTTX, and 5-deoxyTTX, in these animals, we predicted two routes of stepwise oxidation pathways in the late stages of biosynthesis of TTX. Furthermore, high resolution masses of the major fragment ions of TTX, 6,11-dideoxyTTX, and 5,6,11-trideoxyTTX were also measured, and their molecular formulas and structures were predicted to compare them with each other. Although both TTX and 5,6,11-trideoxyTTX give major fragment ions that are very close, m/z 162.0660 and 162.1020, respectively, they are distinguishable and predicted to be different molecular formulas. These data will be useful for identification of TTXs using high resolution LC-MS/MS.

Yotsu-Yamashita, Mari; Abe, Yuka; Kudo, Yuta; Ritson-Williams, Raphael; Paul, Valerie J.; Konoki, Keiichi; Cho, Yuko; Adachi, Masaatsu; Imazu, Takuya; Nishikawa, Toshio; Isobe, Minoru

2013-01-01

169

First identification of 5,11-dideoxytetrodotoxin in marine animals, and characterization of major fragment ions of tetrodotoxin and its analogs by high resolution ESI-MS/MS.  

PubMed

Even though tetrodotoxin (TTX) is a widespread toxin in marine and terrestrial organisms, very little is known about the biosynthetic pathway used to produce it. By describing chemical structures of natural analogs of TTX, we can start to identify some of the precursors that might be important for TTX biosynthesis. In the present study, an analog of TTX, 5,11-dideoxyTTX, was identified for the first time in natural sources, the ovary of the pufferfish and the pharynx of a flatworm (planocerid sp. 1), by comparison with totally synthesized (-)-5,11-dideoxyTTX, using high resolution ESI-LC-MS. Based on the presence of 5,11-dideoxyTTX together with a series of known deoxy analogs, 5,6, 11-trideoxyTTX, 6,11-dideoxyTTX, 11-deoxyTTX, and 5-deoxyTTX, in these animals, we predicted two routes of stepwise oxidation pathways in the late stages of biosynthesis of TTX. Furthermore, high resolution masses of the major fragment ions of TTX, 6,11-dideoxyTTX, and 5,6,11-trideoxyTTX were also measured, and their molecular formulas and structures were predicted to compare them with each other. Although both TTX and 5,6,11-trideoxyTTX give major fragment ions that are very close, m/z 162.0660 and 162.1020, respectively, they are distinguishable and predicted to be different molecular formulas. These data will be useful for identification of TTXs using high resolution LC-MS/MS. PMID:23924959

Yotsu-Yamashita, Mari; Abe, Yuka; Kudo, Yuta; Ritson-Williams, Raphael; Paul, Valerie J; Konoki, Keiichi; Cho, Yuko; Adachi, Masaatsu; Imazu, Takuya; Nishikawa, Toshio; Isobe, Minoru

2013-01-01

170

Integrated Chemical and Microorganism Monitoring of Air Using Gas Chromatography/Ion Mobility Spectometry: Toward an Expanded-Use Volatile Organic Analyzer (VOA)  

NASA Technical Reports Server (NTRS)

The work described in this research program originated with the choice by NASA of an ion mobility spectrometer for air quality monitoring on-board the international spacestation. Though the gas chromatograph-ion mobility spectrometer analyzer known as VOA met or exceeded expectations, limitations in the basic understanding of response and the utilization of foundational principles into usable technology was considered unacceptable. In this research program, a comprehensive model for the origins of mobility spectra was proposed, tested and verified. The principles considered responsible for the appearance of mobility spectra have now been elucidated through this project. This understanding has been applied in automated identification of mobility spectra using neural networks and routine procedures for this now exist. Finally, the limitation on linear range has been shown to be a technical limitation and not a fundamental limitation so that a hardware component was crafted to extend the linear range of a mobility spectrometer by 10X. This project has led to one Ph.D. dissertation and one MS thesis. In addition, over ten public presentations at professional meetings and six journal publications have resulted from this program of research. The findings are so plentiful that total analysis of the findings may require four to six years or more. The findings confirm that the decision to use VOA was sound and that the chemical and physical principles of mobility spectrometry are both understandable and predictable.

Eiceman, G. A.

1999-01-01

171

Kinetics of the reactions of acetone and glyoxal with O2+ and NO+ ions and application to the detection of oxygenated volatile organic compounds in the atmosphere by chemical ionization mass spectrometry  

NASA Astrophysics Data System (ADS)

In situ measurements of oxygenated volatile organic compounds (OVOC) in the upper troposphere-lower stratosphere (UTLS) have gained strong interest because these compounds may be transported during convective events to the UTLS, where they may contribute to the HOx budget thus influencing the chemistry of ozone. With the aim to quantify OVOC of similar mass (58 u) by chemical ionization mass spectrometry (CIMS), ion-molecule reactions of acetone and glyoxal with O2+ and NO+ have been studied. O2+ reacts at the theoretical collision rate with acetone and glyoxal, with room-temperature rate constant values of (3.1 ± 0.7) × 10-9 and (1.8 ± 0.4) × 10-9 cm3 molecule-1 s-1, respectively, independent of pressure. The charge transfer product ion (m/z 58) and a specific fragment product ion are formed for each reaction. NO+ reacts with acetone and glyoxal with a rate constant lower than the collision rate in N2 buffer gas at 1.7 hPa, leading to the formation of the association product in both cases as single reaction productE The rate constants increase with pressure at 295 K for both ranges of 1.2-19.2 hPa N2 and 1.3-2.6 hPa He, indicating a falloff kinetic regime. These results are analysed using conventional statistical calculations. Consistency of the rate constants is obtained for both buffer gases and pressure ranges employed, and high-pressure limits are in agreement with the collision rate constants. Troe analytical expressions of the rate constants are derived for use under any pressure and temperature. From the reaction kinetics and mechanisms obtained in this study and others, a scheme is discussed to quantify separately acetone, glyoxal, and propanal in the UTLS by CIMS, using NO+, O2+, and H3O+ as reagent ions, taking into account potential interferences from other important OVOC such as acetaldehyde and from non-methane hydrocarbons such as n-propane, butane and 2-methyl propane.

Guimbaud, C.; Catoire, V.; Bergeat, A.; Michel, E.; Schoon, N.; Amelynck, C.; Labonnette, D.; Poulet, G.

2007-06-01

172

Pluto's Volatile Transport  

NASA Astrophysics Data System (ADS)

Pluto's varying subsolar latitude and heliocentric distance leads to large variations in the surface volatile distribution and surface pressure. I present results of new volatile transport models (Young 2012a, b). The models include insolation, thermal emission, subsurface conduction, heating of a volatile slab, internal heat flux, latent heat of sublimation, and strict global mass balance. Numeric advances include initial conditions that allow for rapid convergence, efficient computation with matrix arithmetic, and stable Crank-Nicholson timesteps for both bare and volatile-covered areas. Runs of the model show six distinct seasons on Pluto. (1) As Pluto approaches perihelion, the volatiles on the old winter pole (the Rotational North Pole, RNP) becomes more directly illuminated , and the pressure and albedo rise rapidly. (2) When a new ice cap forms on the Rotational South Pole, RSP, volatiles are exchanged between poles. The pressure and albedo change more slowly. (3) When all volatiles have sublimed from the RNP, the albedo and pressure drop rapidly. (4-6) A similar pattern is repeated near aphelion with a reversal of the roles and the poles. I will compare results with earlier Pluto models of Hansen and Paige (1996), show the dependence on parameters such as substrate inertia, and make predictions for the New Horizons flyby of Pluto in 2015. This work was supported, in part, by funding from NASA Planetary Atmospheres Grant NNG06GF32G and the Spitzer project (JPL research support Agreement 1368573). Hansen, C. J. and D. A. Paige 1996. Seasonal Nitrogen Cycles on Pluto. Icarus 120, 247-265. Young, L. A. 2012a. Volatile transport on inhomogeneous surfaces: I - Analytic expressions, with application to Pluto’s day. Icarus, in press Young, L. A. 2012b. Volatile transport on inhomogeneous surfaces: II. Numerical calculations, with application to Pluto's season. In preparation.

Young, Leslie

2012-10-01

173

Volatile organic compounds (VOCs) in urban atmosphere of Hong Kong  

Microsoft Academic Search

The assessment of volatile organic compounds (VOCs) has become a major issue of air quality network monitoring in Hong Kong. This study is aimed to identify, quantify and characterize volatile organic compounds (VOCs) in different urban areas in Hong Kong. The spatial distribution, temporal variation as well as correlations of VOCs at five roadside sampling sites were discussed. Twelve VOCs

S. C. Lee; M. Y. Chiu; K. F. Ho; S. C. Zou; Xinming Wang

2002-01-01

174

DYNAMIC ANALYSIS OF SORPTION OF VOLATILE ORGANIC COMPOUNDS IN WATER  

Microsoft Academic Search

Chlorinated and brominated volatile organic compounds are among the groundwater pollutants creating major environmental problems. In this study, dynamic behavior of certain volatile organic compounds in water was investigated by using a novel moment technique. Adsorption equilibrium constant and the penetration length of tracers were evaluated by the first absolute and the second central moment expressions derived for a pulse-response

Nail Yasyerli; Ugur Harbili

2008-01-01

175

Volatile anesthetics-induced neuroinflammatory and anti-inflammatory responses  

PubMed Central

Volatile anesthetics have been the major anesthetics used clinically for more than 150 years. They provide all components of general anesthesia and are easy to be applied and monitored with modern equipment and technology. In addition to having anesthetic property, volatile anesthetics have multiple other effects. Many studies have clearly shown that volatile anesthetics can reduce systemic and local inflammatory responses induced by various stimuli in humans and animals. On the other hand, recent animal studies have shown that volatile anesthetics may induce mild neuroinflammation. These dual effects on inflammation may have significant biological implications and are briefly reviewed here.

2013-01-01

176

An exploratory comparative study of volatile compounds in exhaled breath and emitted by skin using selected ion flow tube mass spectrometry.  

PubMed

Selected ion flow tube mass spectrometry (SIFT-MS) has been used to carry out a pilot parallel study on five volunteers to determine changes occurring in several trace compounds present in exhaled breath and emitted from skin into a collection bag surrounding part of the arm, before and after ingesting 75 g of glucose in the fasting state. SIFT-MS enabled real-time quantification of ammonia, methanol, ethanol, propanol, formaldehyde, acetaldehyde, isoprene and acetone. Following glucose ingestion, blood glucose and trace compound levels were measured every 30 min for 2 h. All the above compounds, except formaldehyde, were detected at the expected levels in exhaled breath of all volunteers; all the above compounds, except isoprene, were detected in the collection bag. Ammonia, methanol and ethanol were present at lower levels in the bag than in the breath. The aldehydes were present at higher levels in the bag than in breath. The blood glucose increased to a peak about 1 h post-ingestion, but this change was not obviously correlated with temporal changes in any of the compounds in breath or emitted by skin, except for acetone. The decrease in breath acetone was closely mirrored by skin-emitted acetone in three volunteers. Breath and skin acetone also clearly change with blood glucose and further work may ultimately enable inferences to be drawn of the blood glucose concentration from skin or breath measurements in type 1 diabetes. PMID:18215004

Turner, Claire; Parekh, Bhavin; Walton, Christopher; Spanel, Patrik; Smith, David; Evans, Mark

2008-01-01

177

Sodium channels as targets for volatile anesthetics.  

PubMed

The molecular mechanisms of modern inhaled anesthetics are still poorly understood although they are widely used in clinical settings. Considerable evidence supports effects on membrane proteins including ligand- and voltage-gated ion channels of excitable cells. Na(+) channels are crucial to action potential initiation and propagation, and represent potential targets for volatile anesthetic effects on central nervous system depression. Inhibition of presynaptic Na(+) channels leads to reduced neurotransmitter release at the synapse and could therefore contribute to the mechanisms by which volatile anesthetics produce their characteristic end points: amnesia, unconsciousness, and immobility. Early studies on crayfish and squid giant axon showed inhibition of Na(+) currents by volatile anesthetics at high concentrations. Subsequent studies using native neuronal preparations and heterologous expression systems with various mammalian Na(+) channel isoforms implicated inhibition of presynaptic Na(+) channels in anesthetic actions at clinical concentrations. Volatile anesthetics reduce peak Na(+) current (I(Na)) and shift the voltage of half-maximal steady-state inactivation (h(?)) toward more negative potentials, thus stabilizing the fast-inactivated state. Furthermore recovery from fast-inactivation is slowed, together with enhanced use-dependent block during pulse train protocols. These effects can depress presynaptic excitability, depolarization and Ca(2+) entry, and ultimately reduce transmitter release. This reduction in transmitter release is more potent for glutamatergic compared to GABAergic terminals. Involvement of Na(+) channel inhibition in mediating the immobility caused by volatile anesthetics has been demonstrated in animal studies, in which intrathecal infusion of the Na(+) channel blocker tetrodotoxin increases volatile anesthetic potency, whereas infusion of the Na(+) channels agonist veratridine reduces anesthetic potency. These studies indicate that inhibition of presynaptic Na(+) channels by volatile anesthetics is involved in mediating some of their effects. PMID:22479247

Herold, Karl F; Hemmings, Hugh C

2012-01-01

178

Sodium Channels as Targets for Volatile Anesthetics  

PubMed Central

The molecular mechanisms of modern inhaled anesthetics are still poorly understood although they are widely used in clinical settings. Considerable evidence supports effects on membrane proteins including ligand- and voltage-gated ion channels of excitable cells. Na+ channels are crucial to action potential initiation and propagation, and represent potential targets for volatile anesthetic effects on central nervous system depression. Inhibition of presynaptic Na+ channels leads to reduced neurotransmitter release at the synapse and could therefore contribute to the mechanisms by which volatile anesthetics produce their characteristic end points: amnesia, unconsciousness, and immobility. Early studies on crayfish and squid giant axon showed inhibition of Na+ currents by volatile anesthetics at high concentrations. Subsequent studies using native neuronal preparations and heterologous expression systems with various mammalian Na+ channel isoforms implicated inhibition of presynaptic Na+ channels in anesthetic actions at clinical concentrations. Volatile anesthetics reduce peak Na+ current (INa) and shift the voltage of half-maximal steady-state inactivation (h?) toward more negative potentials, thus stabilizing the fast-inactivated state. Furthermore recovery from fast-inactivation is slowed, together with enhanced use-dependent block during pulse train protocols. These effects can depress presynaptic excitability, depolarization and Ca2+ entry, and ultimately reduce transmitter release. This reduction in transmitter release is more potent for glutamatergic compared to GABAergic terminals. Involvement of Na+ channel inhibition in mediating the immobility caused by volatile anesthetics has been demonstrated in animal studies, in which intrathecal infusion of the Na+ channel blocker tetrodotoxin increases volatile anesthetic potency, whereas infusion of the Na+ channels agonist veratridine reduces anesthetic potency. These studies indicate that inhibition of presynaptic Na+ channels by volatile anesthetics is involved in mediating some of their effects.

Herold, Karl F.; Hemmings Jr., Hugh C.

2012-01-01

179

Volatile terpenoids from aeciospores of Cronartium fusiforme.  

NASA Technical Reports Server (NTRS)

Identification of the terpenoids present in the volatile fraction from aeciospores of the gall rust fungus Cronartium fusiforme. The major monoterpenoid hydrocarbons found to be present with only traces of camphene include alpha-pinene, beta-pinene, delta(3)-carene, myrcene, linonene, beta-phellandrene, and delta-terpinene. A number of monoterpenoid alcohols, acyclic sesquiterpenes, and aromatic compounds were also present.

Laseter, J. L.; Weete, J. D.; Walkinshaw, C. H.

1973-01-01

180

Complete Models with Stochastic Volatility  

Microsoft Academic Search

The paper proposes an original class of models for the continuous-time price process of a financial security with nonconstant volatility. The idea is to define instantaneous volatility in terms of exponentially weighted moments of historic log-price. The instantaneous volatility is therefore driven by the same stochastic factors as the price process, so that, unlike many other models of nonconstant volatility,

David G. Hobson; L. C. G. Rogers

1998-01-01

181

Martian Volatiles and Isotopic Signatures  

NASA Technical Reports Server (NTRS)

Data on martian volatiles gathered from Viking atmosphere measurements, modest groundbased spectra, shock-implanted atmospheric gases in martian (SNC) meteorites, trapped mantle gases in martian meteorites, and volatile-rich solid phases in martian meteorites, are presented. Atmospheric volatiles, surface volatiles, and isotopic chronologies are discussed, along with energetic particle interactions.

Bogard, Donald D.

1997-01-01

182

Nonparametric Stochastic Volatility  

Microsoft Academic Search

Using recent advances in the nonparametric estimation of continuous-time processes under mild statistical assumptions as well as recent developments on nonparametric volatility estimation by virtue of market microstructure noise-contaminated high-frequency asset price data, we provide (i) a theory of spot variance estimation and (ii) functional methods for stochastic volatility modelling. Our methods allow for the joint evaluation of return and

Federico M. Bandi; Roberto Reno

2009-01-01

183

Metabolomics of plant volatiles.  

PubMed

Plants communicate with their surrounding ecosystems using a diverse array of volatile metabolites that are indicative of the physiological status of the emitter. A variety of systems have been adapted to capture, analyze, identify, and quantify airborne metabolites released by plants. Metabolomic experiments typically involve four steps: sample collection, preparation, product separation, and data analysis. To date, two different types of headspace sampling, static and dynamic, are widely used for volatile metabolome investigation. For static headspace analysis, solid-phase microextraction (SPME) is used to sample volatiles while push and pull as well as closed-loop stripping methods are used for dynamic headspace sampling. After collection, volatile blends are most efficiently and routinely separated prior to analysis using gas chromatography (GC). Sample preparation is simplified because derivatization is not needed with volatile metabolites. GC coupled to detection by electron impact mass spectrometry (EI-MS) provides high chromatographic resolution, sensitivity, compound-specific detection, quantitation, and the potential to identify unknowns by characteristic and reproducible fragmentation spectra in addition to retention time. A variety of resources can be used to identify unknown compounds in a given volatile sample including >600,000 compounds with known mass spectra catalogued in searchable mass spectral libraries. PMID:19588114

Qualley, Anthony V; Dudareva, Natalia

2009-01-01

184

Theoretical predictions of volatile bearing phases and volatile resources in some carbonaceous chondrites  

NASA Technical Reports Server (NTRS)

Carbonaceous chondrites are usually believed to be the primary constituents of near-Earth asteroids and Phobos and Diemos, and are potential resources of fuels which may be exploited for future planetary missions. The nature and abundances are calculated of the major volatile bearing and other phases, including the vapor phase that should form in C1 and C2 type carbonaceous chondrites as functions of pressure and temperature. The results suggest that talc, antigorite plus or minus magnesite are the major volatile bearing phases and are stable below 400 C at 1 bar in these chondritic compositions. Simulated heating of a kilogram of C2 chondrite at fixed bulk composition between 400 and 800 C at 1 bar yields about 135 gm of volatile, which is made primarily of H2O, H2, CH4, CO2 and CO. The relative abundances of these volatile species change as functions of temperature, and on a molar basis, H2 becomes the most dominant species above 500 C. In contrast, Cl chondrites yield about 306 gm of volatile under the same condition, which consist almost completely of 60 wt percent H2O and 40 wt percent CO2. Preliminary kinetic considerations suggest that equilibrium dehydration of hydrous phyllosilicates should be attainable within a few hours at 600 C. These results provide the framework for further analyses of the volatile and economic resource potentials of carbonaceous chondrites.

Ganguly, Jibamitra; Saxena, Surendra K.

1989-01-01

185

Evaluation of ?-radiation on green tea odor volatiles  

NASA Astrophysics Data System (ADS)

The aim of this study was to evaluate the gamma radiation effects on green tea odor volatiles in green tea at doses of 0, 5, 10, 15 and 20 kGy. The volatile organic compounds were extracted by hydrodistillation and analyzed by GC/MS. The green tea had a large influence on radiation effects, increasing the identified volatiles in relation to control samples. The dose of 10 kGy was responsible to form the majority of new odor compounds following by 5 and 20 kGy. However, the dose of 5 kGy was the dose that degraded the majority of volatiles in non-irradiated samples, following by 20 kGy. The dose of 15 kGy showed has no effect on odor volatiles. The gamma radiation, at dose up to 20 kGy, showed statistically no difference between irradiated and non irradiated green tea on odors compounds.

Fanaro, G. B.; Duarte, R. C.; Araújo, M. M.; Purgatto, E.; Villavicencio, A. L. C. H.

2011-01-01

186

Quality of major ion and total dissolved solids data from groundwater sampled by the National Water-Quality Assessment Program, 1992–2010  

USGS Publications Warehouse

Field blank samples help determine the frequency and magnitude of contamination bias, and replicate samples help determine the sampling variability (error) of measured analyte concentrations. Quality control data were evaluated for calcium, magnesium, sodium, potassium, chloride, sulfate, fluoride, silica, and total dissolved solids. A 99-percent upper confidence limit is calculated from field blanks to assess the potential for contamination bias. For magnesium, potassium, chloride, sulfate, and fluoride, potential contamination in more than 95 percent of environmental samples is less than or equal to the common maximum reporting level. Contamination bias has little effect on measured concentrations greater than 4.74 mg/L (milligrams per liter) for calcium, 14.98 mg/L for silica, 4.9 mg/L for sodium, and 120 mg/L for total dissolved solids. Estimates of sampling variability are calculated for high and low ranges of concentration for major ions and total dissolved solids. Examples showing the calculation of confidence intervals and how to determine whether measured differences between two water samples are significant are presented.

Gross, Eliza L.; Lindsey, Bruce D.; Rupert, Michael G.

2012-01-01

187

Assessment of spatial variability of major-ion concentrations and del oxygen-18 values in surface snow, Upper Fremont Glacier, Wyoming, USA  

USGS Publications Warehouse

One hundred samples were collected from the surface of the Upper Fremont Glacier at equally spaced intervals defined by an 8100m2 snow grid to asesss the significance of lateral variability in major-ion concentrations and del oxygen-18 values. Comparison of the observed variability of each chemical constituent to the variability expected by measurement error indicated substantial lateral variability with the surface-snow layer. Results of the nested ANOVA indicate most of the variance for every constituent is in the values grouped at the two smaller geographic scales (between 506m2 and within 506m2 sections). The variance data from the snow grid were used to develop equations to evaluate the significance of both positive and negative concentration/value peaks of nitrate and del oxygen-18 with depth, in a 160m ice core. Values of del oxygen-18 in the section from 110-150m below the surface consistently vary outside the expected limits and possibly represents cooler temperatures during the Little Ice Age from about 1810 to 1725 A.D. -from Authors

Naftz, D. L.; Schuster, P. F.; Reddy, M. M.

1994-01-01

188

Apoptosis-mediated proliferation inhibition of human colon cancer cells by volatile principles of Citrus aurantifolia  

Microsoft Academic Search

Fruits of Citrus aurantifolia were subjected to hydro-distillation using Clevenger type apparatus to obtain volatile oil. Chemical composition of volatile oil was analysed by GC–MS. Twenty-two compounds representing more than 89.5% of the volatile oil were identified. d-limonene (30.13%) and d-dihydrocarvone (30.47%) were found to be the major compounds in the lime volatile oil. This oil showed 78% inhibition of

Jaiprakash R. Patil; G. K. Jayaprakasha; K. N. Chidambara Murthy; Shane E. Tichy; Mahadev B. Chetti; Bhimanagouda S. Patil

2009-01-01

189

Volatiles of Chrysanthemum zawadskii var. latilobum K  

PubMed Central

The volatile aroma constituents of Chrysanthemum zawadskii var. latilobum K. were separated by hydro distillation extraction (HDE) method using a Clevenger-type apparatus, and analyzed by gas chromatography-mass spectrometry (GC/MS). The yield of C. zawadskii var. latilobum K. flower essential oil (FEO) was 0.12% (w/w) and the color was light green. Fifty-five volatile chemical components, which make up 88.38% of the total aroma composition, were tentatively characterized. C. zawadskii var. latilobum K. FEOs contained 27 hydrocarbons, 12 alcohols, 7 ketones, 4 esters, 1 aldehyde, 1 amine, and 3 miscellaneous components. The major functional groups were terpene alcohol and ketone. Borneol (12.96), (±)-7-epi-amiteol (12.60), and camphor (10.54%) were the predominant volatiles. These compounds can be used in food and pharmaceutical industries due to their active bio-functional properties.

Chang, Kyung-Mi; Kim, Gun-Hee

2012-01-01

190

Biogenic volatile emissions from the soil.  

PubMed

Volatile compounds are usually associated with an appearance/presence in the atmosphere. Recent advances, however, indicated that the soil is a huge reservoir and source of biogenic volatile organic compounds (bVOCs), which are formed from decomposing litter and dead organic material or are synthesized by underground living organism or organs and tissues of plants. This review summarizes the scarce available data on the exchange of VOCs between soil and atmosphere and the features of the soil and particle structure allowing diffusion of volatiles in the soil, which is the prerequisite for biological VOC-based interactions. In fact, soil may function either as a sink or as a source of bVOCs. Soil VOC emissions to the atmosphere are often 1-2 (0-3) orders of magnitude lower than those from aboveground vegetation. Microorganisms and the plant root system are the major sources for bVOCs. The current methodology to detect belowground volatiles is described as well as the metabolic capabilities resulting in the wealth of microbial and root VOC emissions. Furthermore, VOC profiles are discussed as non-destructive fingerprints for the detection of organisms. In the last chapter, belowground volatile-based bi- and multi-trophic interactions between microorganisms, plants and invertebrates in the soil are discussed. PMID:24689847

Peñuelas, J; Asensio, D; Tholl, D; Wenke, K; Rosenkranz, M; Piechulla, B; Schnitzler, J P

2014-08-01

191

Volatile aldehydes in libraries and archives  

NASA Astrophysics Data System (ADS)

Volatile aldehydes are produced during degradation of paper-based materials. This may result in their accumulation in archival and library repositories. However, no systematic study has been performed so far. In the frame of this study, passive sampling was carried out at ten locations in four libraries and archives. Despite the very variable sampling locations, no major differences were found, although air-filtered repositories were found to have lower concentrations while a non-ventilated newspaper repository exhibited the highest concentrations of volatile aldehydes (formaldehyde, acetaldehyde, furfural and hexanal). Five employees in one institution were also provided with personal passive samplers to investigate employees' exposure to volatile aldehydes. All values were lower than the presently valid exposure limits. The concentration of volatile aldehydes, acetic acid, and volatile organic compounds (VOCs) in general was also compared with that of outdoor-generated pollutants. It was evident that inside the repository and particularly inside archival boxes, the concentration of VOCs and acetic acid was much higher than the concentration of outdoor-generated pollutants, which are otherwise more routinely studied in connection with heritage materials. This indicates that further work on the pro-degradative effect of VOCs on heritage materials is necessary and that monitoring of VOCs in heritage institutions should become more widespread.

Fenech, Ann; Strli?, Matija; Kralj Cigi?, Irena; Levart, Alenka; Gibson, Lorraine T.; de Bruin, Gerrit; Ntanos, Konstantinos; Kolar, Jana; Cassar, May

2010-06-01

192

Volatile liquid storage system  

SciTech Connect

This patent describes a method of collecting and abating emission from a volatile liquid in an above ground storage tank. It comprises the liquid storage tank having a bottom, a vertical cylindrical circular wall having a lower edge portion joined to the bottom, and an external fixed roof, the tank having an internal floating roof floating on a volatile liquid stored in the tank, and air vent means in the tank in communication with a vapor space in the tank constituting at least the space above the floating roof when the floating roof floats on a predetermined maximum volume of volatile liquid in the tank; permitting ambient air; pumping emission laden air from the tank vapor space above the floating roof; and by means of the emissions abatement apparatus eliminating most of the emission from the emissions laden air with formation of a gaseous effluent and then discharging the resulting gaseous effluent to the atmosphere.

Laverman, R.J.; Winters, P.J.; Rinehart, J.K.

1992-09-15

193

Sources of Terrestrial Volatiles  

NASA Technical Reports Server (NTRS)

Atmospheres are found enveloping those planets and satellites best able to hold them. The obvious conclusion is that volatile escape must have played nearly as great a role as volatile supply. A consequence of this view is that volatile supplies were probably much greater than the atmospheres that remain. The likeliest candidates are sources associated with the main events of planetary accretion itself such as volatile-rich planetesimals, or direct gravitational capture of nebular gases. Late asteroidal or cometary volatile-rich veneers are attractive, but they present quantitative difficulties. Comets in particular are inadequate, because the associated mass of stray comets that would have been scattered to the Oort Cloud or beyond is excessive. This difficulty applies to Uranus-Neptune planetesimals as well as to a putative massive early Kuiper Belt. Another potential problem with comets is that the D/H ratio in the three comets for which this has been measured is about twice that of Earth's oceans. Objects falling from a much augmented ancient asteroid belt remain a viable option, but timing is an issue: Can the depopulation of the asteroid belt be delayed long enough that it makes sense to talk of asteroids as a late veneer? Early accretion of asteroids as objects scattered into the maw of infant Earth makes more sense. Another appealing candidate population of volatile-rich objects for the inner solar system would be scattered planetesimals associated with the accretion of Jupiter, for two reasons: (1) Before there was Jupiter, there was no object in the solar system capable of expelling comets efficiently, and (2) the cross section of the inner solar system to stray objects was Greater when there were m many planetesimals.

Zahnle, K. J.; Dones, L.

1998-01-01

194

Polycyclic aromatic hydrocarbons (PAHs) in ambient aerosols from Beijing: characterization of low volatile PAHs by positive-ion atmospheric pressure photoionization (APPI) coupled with Fourier transform ion cyclotron resonance.  

PubMed

Aromatic fractions derived from aerosol samples were characterized by gas chromatography and mass spectrometry (GC-MS), high temperature simulated distillation (SIMDIS), and positive-ion atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), respectively. It was found that about 27 wt % compounds in aromatic fractions could not be eluted from a GC column and some large molecule PAHs were neglected in GC-MS analysis. APPI FT-ICR MS was proven to be a powerful approach for characterizing the molecular composition of aromatics, especially for the large molecular species. An aromatic sample from Beijing urban aerosol was successfully characterized by APPI FT-ICR MS. Results showed that most abundant aromatic compounds in PM2.5 (particles with aerodynamic diameter ? 2.5 ?m) were highly condensed hydrocarbons with 4-8 aromatic rings and their homologues with very short alkyl chains. Furthermore, heteroatom-containing hydrocarbons were found as the significant components of the aromatic fractions: O1, O2, N1, and S1 class species with 10-28 DBEs (double bond equivalents) and 14-38 carbon numbers were identified by APPI FT-ICR MS. The heteroatom PAHs had similar DBEs and carbon number distribution as regular PAHs. PMID:24702199

Jiang, Bin; Liang, Yongmei; Xu, Chunming; Zhang, Jingyi; Hu, Miao; Shi, Quan

2014-05-01

195

Major ion chemistry in the headwaters of the Yamuna river system:. Chemical weathering, its temperature dependence and CO 2 consumption in the Himalaya  

NASA Astrophysics Data System (ADS)

The Yamuna river and its tributaries in the Himalaya constitute the Yamuna River System (YRS). The YRS basin has a drainage area and discharge comparable in magnitude to those of the Bhagirathi and the Alaknanda rivers, which merge to form the Ganga at the foothills of the Himalaya. A detailed geochemical study of the YRS was carried out to determine: (i) the relative significance of silicate, carbonate and evaporite weathering in contributing to its major ion composition; (ii) CO 2 consumption via silicate weathering; and (iii) the factors regulating chemical weathering of silicates in the basin. The results show that the YRS waters are mildly alkaline, with a wide range of TDS, ˜32 to ˜620 mg l-1. In these waters, the abundances of Ca, Mg and alkalinity, which account for most of TDS, are derived mainly from carbonates. Many of the tributaries in the lower reaches of the Yamuna basin are supersaturated with calcite. In addition to carbonic acid, sulphuric acid generated by oxidation of pyrites also seems to be supplying protons for chemical weathering. Silicate weathering in YRS basin contributes, on average, ˜25% (molar basis) of total cations on a basin wide scale. Silicate weathering, however, does not seem to be intense in the basin as evident from low Si/(Na*+K) in the waters, ˜1.2 and low values of chemical index of alteration (CIA) in bed sediments, ˜60. CO 2 drawdown resulting from silicate weathering in the YRS basin in the Himalaya during monsoon ranges between (4 to 7) × 10 5 moles km -2 y -1. This is higher than that estimated for the Ganga at Rishikesh for the same season. The CO 2 consumption rates in the Yamuna and the Ganga basins in the Himalaya are higher than the global average value, suggesting enhanced CO 2 drawdown in the southern slopes of the Himalaya. The impact of this enhanced drawdown on the global CO 2 budget may not be pronounced, as the drainage area of the YRS and the Ganga in the Himalaya is small. The CO 2 drawdown by silicates in the YRS basin is marginally higher than the reported values of CO 2 release from oxidation of organic rich sediments, estimated using Re as a proxy. This comparison shows the need to constrain CO 2 sources and sinks better to balance its budget in a regional scale. The results also show that silicate weathering rate in the YRS basin is ˜10 mm ky -1 and on the Ganga basin, it is ˜5 mm ky -1, which are several times lower than the carbonate weathering rates. The significantly higher silicate weathering rate observed in the YRS basin seems to be governed by rapid physical erosion in this region. The apparent activation energy for overall silicate weathering in the YRS basin, derived from Na* and Si concentrations and water temperature, ranges from ˜50 to 80 kJ mol -1. These values are comparable to those reported for granitoid weathering in natural watersheds and feldspar weathering in laboratory experiments. This study brings to light the sources contributing to major ions, enhanced chemical weathering rates in the Yamuna River Basin and interdependence of silicate weathering on physical erosion and temperature.

Dalai, T. K.; Krishnaswami, S.; Sarin, M. M.

2002-10-01

196

Declining Temporal Variability of Major Ions Concentrations but not Arsenic Concentration as Function of Groundwater age in the Ganges-Brahmaputra-Meghna Delta of Bangladesh  

NASA Astrophysics Data System (ADS)

Elevated arsenic concentrations in groundwater of the Ganges-Brahmaputra-Meghna (GBM) delta region pose a devastating health threat. One issue of considerable uncertainty is the magnitude of temporal variations in groundwater As concentrations. Despite the importance of the issue, there are very few high quality, long-term, time series data for groundwater As from the region. This presentation addresses the issue with a series of samples from Araihazar, Bangladesh, that were collected biweekly or monthly between 2001 and 2004 and analyzed by high resolution inductively-coupled plasma mass spectrometry. The method is precise (better than 5 percent long-term reproducibility for As and generates data for 32 other elements. Our study site comprises six nests of monitoring wells installed in an area where the hydrology and geochemistry have been carefully studied. Dissolved As concentrations range from < 1 ug/L to 600 ug/L in the shallow Holocene aquifer (upper 30 m) and mostly < 1 ug/L (As < 1-6.6 ug/L) in the deep Pleistocene aquifer (> 30 m depth). Dating of shallow aquifer water resulted in tritium-helium ages ranging from < 1 yr to > 40 yr. Deep Pleistocene aquifer water was 14C-dated and found to be up to thousands of years old. In the shallow aquifers, variations in groundwater As concentrations in all but 2 out of 28 wells did not display any discernable pattern linked to seasonal water table fluctuations. In addition, As concentration fluctuations were limited (0-15 percent) in all 28 wells. The two wells displayed seasonal pattern of As variations (10-15 percent) were particularly shallow (depths 6 m and 9 m). Redox-sensitive indicators such as Fe and Mn in both wells also displayed seasonal pattern. In contrast to As, most of wells with tritium-helium ages <21 years showed much larger variations in dissolved Cl- concentrations (10-43 percent) and total dissolved cations (5-31 percent) concentrations. Temporal variability was considerably reduced for groundwater >21 years old: 6-7 percent and 10-14 percent, major cations and anions, respectively. This suggests that despite the apparent influence of recharge on major ion concentrations, dissolved As concentrations in most shallow aquifers are relatively well buffered. No notable variability (<2 percent) in As concentrations was observed in groundwaters from the Pleistocene aquifer.

Dhar, R. K.; Zheng, Y.; Stute, M.; Cheng, Z.; Vangeen, A.; Shamsudduha, M.; Hoque, M. A.; Shanewaz, M.; Ahmed, K.

2004-12-01

197

Headspace Volatiles of Marijuana  

Microsoft Academic Search

THE sweet odour of Cannabis sativa, L. is of special interest as a possible means for the detection of illicit marijuana traffic. US Customs dogs, trained to alert to the odour of marijuana and hashish, are successfully used to find concealed contraband. An electronic ``sniffer'' that employs a portable quadrupole mass spectrometer to detect volatile vapours of drugs, including marijuana,

L. V. S. Hood; M. E. Dames; G. T. Barry

1973-01-01

198

SIMPLIFIED VOLATILE ORGANICS SAMPLER  

EPA Science Inventory

The report describes the results of a task supporting EPA in its efforts to license hazardous waste incinerators. The study provided a design for a simplified sampling system for medium levels of volatile organic compounds (VOCs). Most of the study involved evaluation of sorbents...

199

Stochastic Volatility, Smile Asymptotics  

Microsoft Academic Search

We consider the pricing and hedging problem for options on stocks whose volatility is arandom process. Traditional approaches, such as that of Hull & White, have been successful inaccounting for the much observed smile curve, and the success of a large class of such models inthis respect is guaranteed by a theorem of Renault & Touzi, for which we present

George C. Papanicolaou; K. Ronnie Sircar

1998-01-01

200

PREDICTING THE TOXICITY OF MAJOR IONS IN SEAWATER TO MYSID SHRIMP (MYSIDOPSIS BAHIA), SHEEPSHEAD MINNOW (CYPRINODON VARIEGATUS), AND INLAND SILVERSIDE MINNOW (MENIDIA BERYLLINA)  

EPA Science Inventory

Although marine organisms are naturally adapted to salinities well above those of freshwater, elevated concentrations of specific ions have been shown to cause adverse effects on some saltwater species. Because some ions are also physiologically essential, a deficiency of these i...

201

Volatile Selenium Flux in the Great Salt Lake  

NASA Astrophysics Data System (ADS)

Volatilization of selenium has been proven to be the major source of selenium vapor from oceans and estuaries and it may be the major mechanism of permanent selenium removal from the Great Salt Lake (other than brine shrimp harvest). However, the volatilization flux of selenium from the Great Salt Lake has not been previously measured due to challenges of analysis in this hyper-saline environment. This work presents results from recent field studies examining the spatial distribution of volatile selenium (geographical and with depth) in the South Arm (main body) of the Great Salt Lake. The analyses involved collection of volatile selenium in a cryo-focusing trap system via sparging with helium. The cryo-trapped volatile selenium was digested with nitric acid and analyzed by ICP-MS. The results show concentrations of volatile selenium that are much greater than values reported for marine estuaries and oceans. Volatile selenium flux to the atmosphere was determined using mass transport equations corrected to simulate the highly saline environment of the South Arm of the Great Salt Lake.

Diaz, X.; Johnson, W. P.

2006-12-01

202

Analysis of volatile organic compounds from illicit cocaine samples  

SciTech Connect

Detection of illicit cocaine hydrochloride shipments can be improved if there is a greater understanding of the identity and quantity of volatile compounds present. This study provides preliminary data concerning the volatile organic compounds detected in a limited Set of cocaine hydrochloride samples. In all cases, cocaine was one of the major volatile compounds detected. Other tropeines were detected in almost all samples. Low concentrations of compounds that may be residues of processing solvents were observed in some samples. The equilibrium emissivity of. cocaine from cocaine hydrochloride was investigated and a value of 83 parts-per-trillion was determined.

Robins, W.H.; Wright, B.W.

1994-07-01

203

Coyote estrous urine volatiles.  

PubMed

Samples of female coyote urine were taken once or twice each week during the winter and spring for two years. Headspace analysis was employed with Tenax GC trapping and GC-MS. Tenax trapping was started in less than 1 hr after sampling, and mild conditions were used to minimize losses of highly volatile and labile compounds. Thirty-four compounds were identified. They include sulfur compounds, aldehydes and ketones, hydrocarbons, and one alcohol. The principal constituent is methyl 3-methylbut-3-enyl sulfide, which usually comprised 50% or more of the total volatiles observed. The concentration of many constituents varied widely. This appeared to be quasiperiodic for five of the constituents, with a period of a few weeks, and with pronounced maxima at the peak of estrus. Apparently these compounds are 3-methyltetrahydrothiophene, methyl 3-methylbutyl sulfide, octanal, dodecanal, and bis(3-methylbut-3-enyl) disulfide. One or more of these compounds may have pheromonal activity in coyote relationships. PMID:24276012

Schultz, T H; Flath, R A; Stern, D J; Mon, T R; Teranishi, R; Kruse, S M; Butler, B; Howard, W E

1988-02-01

204

Volatiles of the Jobo Fruit (Spondias mombin L.)  

Microsoft Academic Search

The volatile fraction of the fruit of Spondias mombin was investigated by GC and GC\\/MS. Forty-eight compounds were identified, accounting for 82% of the volatiles. The major components were ethyl acetate (14.4%), ethyl butyrate (14.4%), ethyl hexanoate (8.8%), hexyl butyrate (7.9%) and linalool (6.1%). The esters and linalool are responsible for the fruity topnote of the aroma.

Lorenzo Sagrero-Nieves; Herman L. De Pooter

1992-01-01

205

The role of volatiles in the reduction of iron oxides  

Microsoft Academic Search

With iron ore reduction processes using coal-ore pellets or mixtures, it is possible that volatiles from the coals can contribute to the overall reduction. By identifying the possible reducing species in the volatiles as H2\\/CO and simulating these constituents, the rates for H2 and CO were investigated in the temperature and reduction range of interest where hydrogen was the major

Il Sohn

2005-01-01

206

Volatile components of green walnut husks.  

PubMed

Volatiles were isolated from whole green mature walnuts (Hartley variety) with husks still intact using dynamic headspace sweeping with trapping on Tenax. A total of 45 volatile compounds were identified by GC-MS. Major volatiles identified included (E)-4, 8-dimethyl-1,3,7-nonatriene, pinocarvone, pinocarveol, myrtenal, myrtenol, (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, caryophyllene epoxide, verbenol, verbenone, and terpinolene. Green walnuts that had been infested with codling moth showed appreciably higher amounts emitted for (E)-4,8-dimethyl-1,3,7-nonatriene, (E, E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, alpha- and beta-pinenes, sabinene, (E)-beta-ocimene, (E,E)-alpha-farnesene, and linalool. The infested nuts also emitted benzyl methyl ether, isobutyl cyanide, and 1-nitro-3-methylbutane, compounds not found with the healthy nuts. Volatiles from uninfested green walnuts at the maturity stage where the husk was just beginning to split were also analyzed and compared. PMID:10898636

Buttery, R G; Light, D M; Nam, Y; Merrill, G B; Roitman, J N

2000-07-01

207

Plant volatiles: production, function and pharmacology.  

PubMed

Plant volatiles typically occur as a complex mixture of low-molecular weight lipophilic compounds derived from different biosynthetic pathways, and are seemingly produced as part of a defense strategy against biotic and abiotic stress, as well as contributing to various physiological functions of the producer organism. The biochemistry and molecular biology of plant volatiles is complex, and involves the interplay of several biochemical pathways and hundreds of genes. All plants are able to store and emit volatile organic compounds (VOCs), but the process shows remarkable genotypic variation and phenotypic plasticity. From a physiological standpoint, plant volatiles are involved in three critical processes, namely plant–plant interaction, the signaling between symbiotic organisms, and the attraction of pollinating insects. Their role in these ‘‘housekeeping’’ activities underlies agricultural applications that range from the search for sustainable methods for pest control to the production of flavors and fragrances. On the other hand, there is also growing evidence that VOCs are endowed with a range of biological activities in mammals, and that they represent a substantially under-exploited and still largely untapped source of novel drugs and drug leads. This review summarizes recent major developments in the study of biosynthesis, ecological functions and medicinal applications of plant VOCs. PMID:21670801

Maffei, Massimo E; Gertsch, Jürg; Appendino, Giovanni

2011-08-01

208

Headspace sampling and detection of cocaine, MDMA, and marijuana via volatile markers in the presence of potential interferences by solid phase microextraction-ion mobility spectrometry (SPME-IMS).  

PubMed

The successful air sampling and detection of cocaine, methylenedioxymethylamphetamine (MDMA), and marijuana using SPME-IMS achieved by targeting their volatile markers (methyl benzoate, piperonal, and terpenes, respectively) is presented. Conventional methods of direct air sampling for drugs are ineffective because the parent compounds of these drugs have very low vapor pressures, making them unavailable for headspace sampling. Instead of targeting the parent drugs, IMS was set at the optimal operating conditions (determined in previous work) in order to detect their volatile chemical markers. SPME is an effective and rapid air sampling technique for the preconcentration of analytes which is especially useful in confined spaces such as cargo containers, where the volatile marker compounds of drugs can be found in sufficient concentrations. By sampling the air using a 100 microm polydimethyl siloxane (PDMS) SPME fiber for as little as one minute, enough mass of the targeted volatile markers in the headspace of a quart-sized metal paint can (gallon, approximately 1101 cm(3)) which contained sub-gram quantities of the drug samples was recovered for IMS detection. Additionally, several potentially interfering compounds found in goods commonly shipped in cargo containers were tested individually as well as in mixtures with the drugs. No peak interferences were observed for MDMA or marijuana, and minimal peak interferences were found for cocaine. PMID:18600317

Lai, Hanh; Corbin, Inge; Almirall, José R

2008-09-01

209

Mechanism of formation of the major estradiol product ions following collisional activation of the molecular anion in a tandem quadrupole mass spectrometer.  

PubMed

The importance of the mass spectral product ion structure is highlighted in quantitative assays, which typically use multiple reaction monitoring (MRM), and in the discovery of novel metabolites. Estradiol is an important sex steroid whose quantitation and metabolite identification using tandem mass spectrometry has been widely employed in numerous clinical studies. Negative electrospray ionization tandem mass spectrometry of estradiol (E2) results in several product ions, including the abundant m/z 183 and 169. Although m/z 183 is one of the most abundant product ions used in many quantitative assays, the structure of m/z 183 has not been rigorously examined. We suggest a structure for m/z 183 and a mechanism of formation consistent with collision induced dissociation (CID) of E2 and several stable isotopes ([D4]-E2, [(13)C6]-E2, and [D1]-E2). An additional product ion from E2, namely m/z 169, has also been examined. MS(3) experiments indicated that both m/z 183 and m/z 169 originate from only E2 [M - H](-) m/z 271. These ions, m/z 183 and m/z 169, were also present in the collision induced decomposition mass spectra of other prominent estrogens, estrone (E1) and estriol (E3), indicating that these two product ions could be used to elucidate the estrogenic origin of novel metabolites. We propose two fragmentation schemes to explain the CID data and suggest a structure of m/z 183 and m/z 169 consistent with several isotopic variants and high resolution mass spectrometric measurements. PMID:23955001

Wooding, Kerry M; Barkley, Robert M; Hankin, Joseph A; Johnson, Christopher A; Bradford, Andrew P; Santoro, Nanette; Murphy, Robert C

2013-10-01

210

Quantification of Art v 1 and Act c 1 being major allergens of mugwort pollen and kiwi fruit extracts in mass-units by ion-exchange HPLC-UV method.  

PubMed

A simple ion-exchange HPLC-UV method was developed for determination of major allergens from mugwort pollen and kiwi fruit extracts in mass-units. The separation of Art v 1 and Act c 1 from other components in the extracts was achieved in one step. The extinction coefficients used in the study were theoretically determined and compared to the extinction coefficients determined by gravimetry. We also reported a close correlation of the major allergen contents with the overall allergenic potency of the extracts determined by inhibition ELISA. This method could be a useful tool for standardization of allergenic extracts for clinical use. PMID:17652037

Blanusa, Milan; Perovic, Iva; Popovic, Milica; Polovic, Natalija; Burazer, Lidija; Milovanovic, Mina; Gavrovic-Jankulovic, Marija; Jankov, Ratko; Cirkovic Velickovic, Tanja

2007-10-01

211

Major Programs  

Cancer.gov

The Division of Cancer Prevention supports major scientific collaborations and research networks at more than100 sites across the United States; investigator-initiated grants; postdoctoral training; and specialized resources for researchers.

212

VOLATILE ORGANIC COMPOUNDS INHIBIT HUMAN AND RAT NEURONAL NICOTINIC ACETYLCHOLINE RECEPTORS EXPRESSED IN XENOPUS OOCYTES.  

EPA Science Inventory

This manuscript provides evidence to indicate that rats and humans are equally sensitive at the pharmacodynamic level to effects of volatile organic compounds. ? This manuscript also presents novel data that provides a plausible mechanism, disruption of ion channel functi...

213

PERTURBATION OF VOLTAGE-SENSITIVE Ca2+ CHANNEL FUNCTION BY VOLATILE ORGANIC SOLVENTS.  

EPA Science Inventory

The mechanisms underlying the acute neurophysiological and behavioral effects of volatile organic compounds (VOCs) remain to be elucidated. However, the function of neuronal ion channels is perturbed by VOCs. The present study examined effects of toluene (TOL), trichloroethylene ...

214

Majors Exploration  

NSDL National Science Digital Library

Put on your safari hat, open your mind and get ready to enter the world of majors explorations. If you ever wondered about a field of study and whether it is right for you, you are about to find out. You will also learn where majors and fields lead for careers that may interest you. All you need for the journey is the mind of the explorer and a commitment to thoroughly investigating the options which await you.

Prentice Hall (Prentice Hall)

2012-01-05

215

Volatiles released from bean plants in response to agromyzid flies.  

PubMed

Liriomyza sativae Blanchard and Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) are two invasive flies in China that have caused economical damage on vegetables and ornamental plants. In this article, we report the profiles of emitted volatiles from healthy, mechanically damaged, and leafminer-damaged bean, Phaseolus vulgaris L., plants. Among 25 emitted volatiles identified, (E)-2-hexen-1-al, (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), (Z)-3-hexenyl acetate, (Z)-3-hexen-1-ol, (syn)- and (anti)-2-methylpropanal oxime, (syn)-2-methylbutanal oxime, linalool, and (E,E)-alpha-farnesene were consistently released from damaged bean plants. Combined amounts of these nine compounds made up more than 70% of the total volatiles emitted from each treatment. No qualitative differences in volatile emission were found between bean plants damaged by the two fly species; however, amounts of several major compounds induced by L. huidobrensis damage were significantly higher than those from plants damaged by L. sativae. The mechanically damaged plants released a higher proportion of green leaf volatiles than plants in the other treatments, whereas leafminer-damaged plants produced more terpenoids and oximes. Furthermore, the volatile profiles emitted from plants, damaged by adult leafminers, by second instar larvae, and even the plants with empty mines left by leafminer larvae (the pupal stage) were significantly different. The identification of volatile oximes released from damaged plants was confirmed and is discussed in a behavioral and biological control context. PMID:16404576

Wei, Jia-Ning; Zhu, Junwei; Kang, Le

2006-07-01

216

Impact of particle size on distribution of major ions in acid- and water-soluble components of PM 10 atmospheric aerosols in the coastal region of Mumbai  

NASA Astrophysics Data System (ADS)

In this study, the concentration of acid and water-soluble ions (Na +, K +, Mg++, Ca ++, F -, Cl -, NO 3- and SO 4- -) in different particle size range (> 1.1-<2.0 ?m, > 2.0-<3.3 ?m, > 3.3-<4.7 ?m, > 4.7-<5.8 ?m, > 5.8-<9.0 ?m and > 9 ?m-<10 ?m) of PM 10 atmospheric aerosols collected by six stages Anderson Cascade Impactor were determined using conductivity suppressed ion-chromatography system. Suspended particulate matters in the form of respirable (PM 10) aerosols were collected on the roof of a three storied building at a height of 20 m above the ground, at Bhabha Atomic Research Centre (BARC), Mumbai using Hi-Volume Sampler (HVS) with Whatman glass fiber filter paper during the period of March-June 2009. The sequence of solubility of ions in both extractants (acid + water) of PM 10 aerosols from greatest to least was found to be Na + > Ca ++ > K + > Cl - > F - > Mg ++ > NO 3- ? SO 4--. The average concentration of Na +, K +, Mg++, Ca ++, F -, Cl -, NO 3- and SO 4-- in PM 10 aerosols was estimated to be 13.36 g/kg, 3.76 g/kg,0.251 g/kg,3.771 g/kg,0.833 g/kg,1.17 g/kg, 81 ?g/kg and 290 ?g/kg respectively. The enrichment of particular ion in soluble components may be due to its high abundance in PM 10 aerosols, less sorptivity with the tiny solid particles of atmospheric dust, high extractability and leachability, high solubility and mobility. By classifying the PM 10 aerosols into two categories viz fine particle (< 2.5 ?m) and coarse particle (> 2.5 ?m-<10 ?m), it was found that generally, in the fine particle, the geometric mean concentration of total soluble ions in acid and water components was found to be higher than coarse particle. Overall, it was also observed that generally as particle size increases, the geometric mean concentration of soluble ions in both extractants of PM 10 aerosols decreases.

Kumar, Ajay; Mishra, Manish K.; Divkar, J. K.; Rout, Sabyasachi; Narayanan, Usha; Hegde, A. G.

2010-11-01

217

Headspace sampling and detection of cocaine, MDMA, and marijuana via volatile markers in the presence of potential interferences by solid phase microextraction–ion mobility spectrometry (SPME-IMS)  

Microsoft Academic Search

The successful air sampling and detection of cocaine, methylenedioxymethylamphetamine (MDMA), and marijuana using SPME-IMS\\u000a achieved by targeting their volatile markers (methyl benzoate, piperonal, and terpenes, respectively) is presented. Conventional\\u000a methods of direct air sampling for drugs are ineffective because the parent compounds of these drugs have very low vapor pressures,\\u000a making them unavailable for headspace sampling. Instead of targeting the

Hanh Lai; Inge Corbin; José R. Almirall

2008-01-01

218

THE ECONOMIC VALUE OF USING REALIZED VOLATILITY IN FORECASTING FUTURE IMPLIED VOLATILITY  

Microsoft Academic Search

We examine the economic benefits of using realized volatility to forecast future implied volatility for pricing, trading, and hedging in the S&P 500 index options market. We propose an encompassing regression approach to forecast future implied volatility, and hence future option prices, by combining historical realized volatility and current implied volatility. Although the use of realized volatility results in superior

Wing Hong Chan; Ranjini Jha; Madhu Kalimipalli

2009-01-01

219

Major Andre  

ERIC Educational Resources Information Center

If most Revolutionary era people seem two-dimensional their lives simpler to understand than ours, it may be only that history, with the benefit of hindsight, clarifies. Examines a profile of Major John Andre, the British liaison officer in Benedict Arnold's plan to surrender West Point, as both hero and villain to show the complexity of early…

Henisch, B. A.; Henisch, H. K.

1976-01-01

220

VOLATILIZATION OF ORGANIC POLLUTANTS FROM WATER  

EPA Science Inventory

The volatilization of organic environmental contaminants from water bodies to the atmosphere was investigated. The general aim was to elucidate the factors that control the volatilization process and develop predictive methods for calculating volatilization rates for various comp...

221

Subduction and volatile recycling in Earth's mantle  

NASA Technical Reports Server (NTRS)

The subduction of water and other volatiles into the mantle from oceanic sediments and altered oceanic crust is the major source of volatile recycling in the mantle. Until now, the geotherms that have been used to estimate the amount of volatiles that are recycled at subduction zones have been produced using the hypothesis that the slab is rigid and undergoes no internal deformation. On the other hand, most fluid dynamical mantle flow calculations assume that the slab has no greater strength than the surrounding mantle. Both of these views are inconsistent with laboratory work on the deformation of mantle minerals at high pressures. We consider the effects of the strength of the slab using two-dimensional calculations of a slab-like thermal downwelling with an endothermic phase change. Because the rheology and composition of subducting slabs are uncertain, we consider a range of Clapeyron slopes which bound current laboratory estimates of the spinel to perovskite plus magnesiowustite phase transition and simple temperature-dependent rheologies based on an Arrhenius law diffusion mechanism. In uniform viscosity convection models, subducted material piles up above the phase change until the pile becomes gravitationally unstable and sinks into the lower mantle (the avalanche). Strong slabs moderate the 'catastrophic' effects of the instabilities seen in many constant-viscosity convection calculations; however, even in the strongest slabs we consider, there is some retardation of the slab descent due to the presence of the phase change.

King, S. D.; Ita, J. J.; Staudigel, H.

1994-01-01

222

Analysis of free and bound volatiles by gas chromatography and gas chromatography-mass spectrometry in uncased and cased tobaccos.  

PubMed

The free and bound volatiles of tobaccos were analyzed by capillary GC and GC-MS. Bound volatiles were isolated by dichloromethane extraction followed by stream distillation continuous extraction (SDE) at pH 2.5 acid hydrolysis. The bound aromatic compounds were hydrolyzed by acid at pH 2.5, and the bound volatiles were liberated and extracted into dichloromethane by SDE simultaneously. In total, 23 volatiles were identified, with neophytadiene, 2-ethyl hexanol, damascenone, benzene ethanol, palmitic acid, stearic acid, linoleic acid, farnesyl acetone, 3-oxo-ionol, and megastigmatrienone being the major components. They consisted mainly of compounds exhibiting aromatic characteristics. The quality and quantity of free and bound volatiles exhibited different distributions in uncased or cased tobaccos. The volatiles existed in higher amounts in bound form than in free form. Compared with uncased tobaccos, free form volatiles showed a decrease after the casing process, while bound volatiles showed an increase. PMID:11883660

Cai, Jibao; Liu, Baizhan; Ling, Ping; Su, Qingde

2002-02-22

223

Plant volatile analogues strengthen attractiveness to insect.  

PubMed

Green leaf bug Apolygus lucorum (Meyer-Dür) is one of the major pests in agriculture. Management of A. lucorum was largely achieved by using pesticides. However, the increasing population of A. lucorum since growing Bt cotton widely and the increased awareness of ecoenvironment and agricultural product safety makes their population-control very challenging. Therefore this study was conducted to explore a novel ecological approach, synthetic plant volatile analogues, to manage the pest. Here, plant volatile analogues were first designed and synthesized by combining the bioactive components of ?-ionone and benzaldehyde. The stabilities of ?-ionone, benzaldehyde and analogue 3 g were tested. The electroantennogram (EAG) responses of A. lucorum adult antennae to the analogues were recorded. And the behavior assay and filed experiment were also conducted. In this study, thirteen analogues were acquired. The analogue 3 g was demonstrated to be more stable than ?-ionone and benzaldehyde in the environment. Many of the analogues elicited EAG responses, and the EAG response values to 3 g remained unchanged during seven-day period. 3 g was also demonstrated to be attractive to A. lucorum adults in the laboratory behavior experiment and in the field. Its attractiveness persisted longer than ?-ionone and benzaldehyde. This indicated that 3 g can strengthen attractiveness to insect and has potential as an attractant. Our results suggest that synthetic plant volatile analogues can strengthen attractiveness to insect. This is the first published study about synthetic plant volatile analogues that have the potential to be used in pest control. Our results will support a new ecological approach to pest control and it will be helpful to ecoenvironment and agricultural product safety. PMID:24911460

Sun, Yufeng; Yu, Hao; Zhou, Jing-Jiang; Pickett, John A; Wu, Kongming

2014-01-01

224

Plant Volatile Analogues Strengthen Attractiveness to Insect  

PubMed Central

Green leaf bug Apolygus lucorum (Meyer-Dür) is one of the major pests in agriculture. Management of A. lucorum was largely achieved by using pesticides. However, the increasing population of A. lucorum since growing Bt cotton widely and the increased awareness of ecoenvironment and agricultural product safety makes their population-control very challenging. Therefore this study was conducted to explore a novel ecological approach, synthetic plant volatile analogues, to manage the pest. Here, plant volatile analogues were first designed and synthesized by combining the bioactive components of ?-ionone and benzaldehyde. The stabilities of ?-ionone, benzaldehyde and analogue 3 g were tested. The electroantennogram (EAG) responses of A. lucorum adult antennae to the analogues were recorded. And the behavior assay and filed experiment were also conducted. In this study, thirteen analogues were acquired. The analogue 3 g was demonstrated to be more stable than ?-ionone and benzaldehyde in the environment. Many of the analogues elicited EAG responses, and the EAG response values to 3 g remained unchanged during seven-day period. 3 g was also demonstrated to be attractive to A. lucorum adults in the laboratory behavior experiment and in the field. Its attractiveness persisted longer than ?-ionone and benzaldehyde. This indicated that 3 g can strengthen attractiveness to insect and has potential as an attractant. Our results suggest that synthetic plant volatile analogues can strengthen attractiveness to insect. This is the first published study about synthetic plant volatile analogues that have the potential to be used in pest control. Our results will support a new ecological approach to pest control and it will be helpful to ecoenvironment and agricultural product safety.

Sun, Yufeng; Yu, Hao; Zhou, Jing-Jiang; Pickett, John A.; Wu, Kongming

2014-01-01

225

Closed cycle cooler for VOC preconcentration. Final report. [VOC (volatile organic compound)  

Microsoft Academic Search

The use of automated gas chromatographs at air quality network monitoring stations to obtain measurements of ambient concentrations of volatile organic compounds (VOCs) has been a goal of EPA's Atmospheric Research and Exposure Assessment Laboratory. Presently, instrument designs require excessive amounts of cryogen to preconcentrate and resolve the more volatile organic compounds. The large consumption of cryogen becomes a major

1993-01-01

226

Volatiles from Hawaiian submarine basalts determined by dynamic high temperature mass spectrometry  

Microsoft Academic Search

Quantitative measurements of volatiles from Hawaiian submarine basalts have been made using a Knudsen cell dynamic-mass spectrometer system. The principal advantage of the technique is the ability to determine simultaneously the absolute amounts of more than one volatile released from the same sample. From mass pyrograms it was observed that the release of water was bimodal, with the major release

John S. Killingley; David W. Muenow

1975-01-01

227

Efficient estimation of stochastic volatility using noisy observations: a multi-scale approach  

Microsoft Academic Search

With the availability of high-frequency financial data, nonparametric estimation of the volatility of an asset return process becomes feasible. A major problem is how to estimate the volatility consistently and efficiently, when the observed asset returns contain error or noise, for example, in the form of microstructure noise. The issue of consistency has been addressed in the recent literature. However,

Lan Zhang

2006-01-01

228

Volatile production by Aspergillus versicolor as a possible cause of odor in houses affected by fungi  

Microsoft Academic Search

Aspergillus versicolor, which has been isolated from several mould affected houses was shown by laboratory studies under axenic conditions to produce several specific volatile compounds on water agar. These compounds were not produced by the fungus when grown on a rich malt extract medium or on several synthetic media. The volatile compounds were analysed by GC-MS. The majority of the

Jonny Bjurman; Jan Kristensson

1992-01-01

229

Chemically-resolved aerosol volatility measurements from two megacity field studies  

NASA Astrophysics Data System (ADS)

The volatilities of different chemical species in ambient aerosols are important but remain poorly characterized. The coupling of a recently developed rapid temperature-stepping thermodenuder (TD, operated in the range 54-230°C) with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) during field studies in two polluted megacities has enabled the first direct characterization of chemically-resolved urban particle volatility. Measurements in Riverside, CA and Mexico City are generally consistent and show ambient nitrate as having the highest volatility of any AMS standard aerosol species while sulfate showed the lowest volatility. Total organic aerosol (OA) showed volatility intermediate between nitrate and sulfate, with an evaporation rate of 0.6%·K-1 near ambient temperature, although OA dominates the residual species at the highest temperatures. Different types of OA were characterized with marker ions, diurnal cycles, and positive matrix factorization (PMF) and show significant differences in volatility. Reduced hydrocarbon-like OA (HOA, a surrogate for primary OA, POA), oxygenated OA (OOA, a surrogate for secondary OA, SOA), and biomass-burning OA (BBOA) separated with PMF were all determined to be semi-volatile. The most aged OOA-1 and its dominant ion, CO2+, consistently exhibited the lowest volatility, with HOA, BBOA, and associated ions for each among the highest. The similar or higher volatility of HOA/POA compared to OOA/SOA contradicts the current representations of OA volatility in most atmospheric models and has important implications for aerosol growth and lifetime. A new technique using the AMS background signal was demonstrated to quantify the fraction of species up to four orders-of-magnitude less volatile than those detectable in the MS mode, which for OA represent ~5% of the non-refractory (NR) OA signal. Our results strongly imply that all OA types should be considered semivolatile in models. The study in Riverside identified organosulfur species (e.g. CH3HSO3+ ion, likely from methanesulfonic acid), while both studies identified ions indicative of amines (e.g. C5H12N+) with very different volatility behaviors than inorganic-dominated ions. The oxygen-to-carbon ratio of OA in each ambient study was shown to increase both with TD temperature and from morning to afternoon, while the hydrogen-to-carbon ratio showed the opposite trend.

Huffman, J. A.; Docherty, K. S.; Aiken, A. C.; Cubison, M. J.; Ulbrich, I. M.; Decarlo, P. F.; Sueper, D.; Jayne, J. T.; Worsnop, D. R.; Ziemann, P. J.; Jimenez, J. L.

2009-09-01

230

Evaluation of microchip capillary electrophoresis with external contactless conductivity detection for the determination of major inorganic ions and lithium in serum and urine samples.  

PubMed

The determination of inorganic ions in clinical samples in less than 90 seconds was demonstrated for microchip capillary electrophoresis using capacitively coupled contactless conductivity detection (C(4)D). Bare electrophoresis chips were used in combination with external electrodes which were part of the chip holder. In order to achieve the required selectivity and sensitivity, an optimization of the electrode layout was carried out. Limits of detection (LOD) of 1 microM for K(+), 1.5 microM for Ca(2+), 3 microM for Na(+), 1.75 microM for Mg(2+) and 7.5 microM for Li(+) were achieved. The determination of inorganic cations (NH(4)(+), K(+), Na(+), Ca(2+), Mg(2+)) and anions (Cl(-), NO(3)(-), SO(4)(2-), phosphate) in blood serum and urine samples was possible in one common electrolyte solution containing 15 mM L-arginine, 10.75 mM maleic acid and 1.5 mM 18-crown-6 at pH 5.90 by simply switching the separation voltage from positive to negative polarity. Lithium, present at significant levels when used for therapeutic purposes, can also be determined in blood serum using a slightly modified background electrolyte solution. PMID:18941681

Kubán, Pavel; Hauser, Peter C

2008-11-01

231

Volatile compounds in samples of cork and also produced by selected fungi.  

PubMed

The production of volatile compounds by microbial communities of cork samples taken during the cork manufacturing process was investigated. The majority of volatiles were found in samples collected at two stages: resting after the first boiling and nontreated cork disks. Volatile profiles produced by microbiota in both stages are similar. The releasable volatile compounds and 2,4,6-trichloroanisole (TCA) produced in cork-based culture medium by five isolated fungal species in pure and mixed cultures were also analyzed by gas chromatography coupled with mass spectrometry (GC-MS).The results showed that 1-octen-3-ol and esters of fatty acids (medium chain length C8-C20) were the main volatile compounds produced by either pure fungal species or their mixture. Apparently, Penicillium glabrum is the main contributor to the overall volatile composition observed in the mixed culture. The production of releasable TCA on cork cannot be attributed to any of the assayed fungal isolates. PMID:21574572

Barreto, M C; Vilas Boas, L; Carneiro, L C; San Romão, M V

2011-06-22

232

Syrtis Major  

NASA Technical Reports Server (NTRS)

(Released 6 June 2002) The Science This image, located near the equator and 288W (72E), is near the southern edge of a low, broad volcanic feature called Syrtis Major. A close look at this image reveals a wrinkly texture that indicates a very rough surface that is associated with the lava flows that cover this region. On a larger scale, there are numerous bright streaks that trail topographic features such as craters. These bright streaks are in the wind shadows of the craters where dust that settles onto the surface is not as easily scoured away. It is important to note that these streaks are only bright in a relative sense to the surrounding image. Syrtis Major is one of the darkest regions on Mars and it is as dark as fresh basalt flows or dunes are on Earth. The Story Cool! It almost looks as if nature has 'painted' comets on the surface of Mars, using craters as comet cores and dust as streaky tails. Of course, that's just an illusion. As in many areas of Mars, the wind is behind the creation of such fantastic landforms. The natural phenomenon seen here gives this particular surface of Mars a very dynamic, fast-moving, almost luminous 'cosmic personality.' The bright, powdery-looking streaks of dust are in the 'wind shadows' of craters, where dust that settles onto the surface is not as easily scoured away. That's because the wind moves across the land in a particular direction, and a raised surface like the rim of a crater 'protects' dust from being completely blown away on the other side. The raised landforms basically act as a buffer. From the streaks seen above, you can tell the wind was blowing in a northeast to southwest direction. Why are the streaks so bright? Because they contrast with the really dark underlying terrain in this volcanic area of Mars. Syrtis Major is one of the darkest regions on Mars because it is made of basalt. Basalt is typically dark gray or black, and forms when a certain type of molten lava cools. The meaning of the word basalt has been traced back to an ancient Ethiopian word 'basal,' which means 'a rock from which you can obtain iron.' That must have made it a very desired material with ancient Earth civilizations long ago. Basalt is actually one of the most abundant types of rock found on Earth. Most of the volcanic islands in the ocean are made of basalt, including the large shield volcano of Mauna Loa, Hawaii, which is often compared to Martian shield volcanoes. Shield volcanoes don't have high, steep, mountain-like sides, but are instead low and broad humps upon the surface. They're created when highly fluid, molten-basalt flows spread out over wide areas. Over several millennia of basaltic layering upon layering, these volcanoes can reach massive sizes like the ones seen on Mars. You can see the wrinkly texture of dark lava flows (now hard and cool) in the above image beneath the brighter dust.

2002-01-01

233

High Consumption Volatility: The Impact of Natural Disasters?  

Microsoft Academic Search

A history of repeated external and domestic shocks has made economic insecurity a major concern across the Caribbean region. Of particular concern to all households, especially the poorest segments of the population, is the exposure to shocks that are generated by catastrophic events or natural disasters.Auffret shows that despite high consumption growth, the Caribbean region suffers from a high volatility

Philippe Auffret

2003-01-01

234

Source apportionment of volatile organic compounds in Hong Kong homes  

Microsoft Academic Search

Indoor volatile organic compound (VOC) data obtained in 100 Hong Kong homes were analyzed to investigate the nature of emission sources and their contributions to indoor concentrations. A principal component analysis (PCA) showed that off-gassing of building materials, household products, painted wood products, room freshener, mothballs and consumer products were the major sources of VOCs in Hong Kong homes. The

H. Guo

2011-01-01

235

Assessment of volatile organic compound emissions from ecosystems of China  

Microsoft Academic Search

Isoprene, monoterpene, and other volatile organic compound (VOC) emissions from grasslands, shrublands, forests, and peatlands in China were characterized to estimate their regional magnitudes and to compare these emissions with those from landscapes of North America, Europe, and Africa. Ecological and VOC emission sampling was conducted at 52 sites centered in and around major research stations located in seven different

L. F. Klinger; Q.-J. Li; A. B. Guenther; J. P. Greenberg; B. Baker; J.-H. Bai

2002-01-01

236

Volatile organic compounds in ambient air of Mumbai—India  

Microsoft Academic Search

Volatile organic compounds (VOCs) are a major group of air pollutants which play a critical role in atmospheric chemistry. These contribute to toxic oxidants which are harmful to ecosystem, human health and atmosphere. The variability of pollutants is an important factor in determining human exposure to these chemicals. Data on levels of VOCs in developing countries, including India, are lacking.The

Anjali Srivastava; A. E. Joseph; S. Devotta

2006-01-01

237

Does Insider Trading Raise Market Volatility? &ast  

Microsoft Academic Search

This paper studies the role of insider trading in explaining cross-country differences in stock market volatility. It introduces a new measure of insider trading. The central finding is that countries with more prevalent insider trading have more volatile stock markets, even after one controls for liquidity\\/maturity of the market, and the volatility of the underlying fundamentals (volatility of real output

Julan Du; Shang-Jin Wei

2004-01-01

238

Does Insider Trading Raise Market Volatility?  

Microsoft Academic Search

This paper studies the role of insider trading in explaining cross-country differences in stock market volatility. It introduces a new measure of insider trading. The central finding is that countries with more prevalent insider trading have more volatile stock markets, even after one controls for liquidity\\/maturity of the market, and the volatility of the underlying fundamentals (volatility of real output

Julan Du; Shang-Jin Wei

2003-01-01

239

Does Insider Trading Raise Market Volatility?  

Microsoft Academic Search

This paper studies the role of insider trading in explaining cross-country differences in stock market volatility. The central finding is that countries with more prevalent insider trading have more volatile stock markets, even after one controls for liquidity\\/maturity of the market and the volatility of the underlying fundamentals (volatility of real output and of monetary and fiscal policies). Moreover, the

Julan Du; Shang-Jin Wei

2003-01-01

240

Volatile Compounds in Spanish Paprika  

Microsoft Academic Search

The volatile compounds extracted from both sweet and hot samples of commercial Spanish paprika were analyzed by gas chromatography\\/mass spectrometry (GC-MS). Sixty-one peaks were detected in the volatile extracts of which 55 were identified, only 24 were present in all four samples. The substances identified belonged to several chemical classes: phenols, aldehydes, acids, ketones, alcohols, ethers, nitrogen compounds, aromatic hydrocarbons,

Javier Mateo; Mercedes Aguirrezábal; Concepción Dom??nguez; José Mar??a Zumalacárregui

1997-01-01

241

Complete Models with Stochastic Volatility  

Microsoft Academic Search

The paper proposes an original class of models for the continuous time price processof a financial security with non-constant volatility. The idea is to define instantaneousvolatility in terms of exponentially-weighted moments of historic log-price. The instantaneousvolatility is therefore driven by the same stochastic factors as the price process, sothat unlike many other models of non-constant volatility, it is not necessary

David G. Hobson; L. c. g. Rogers

1996-01-01

242

Trends in volatile substance abuse.  

PubMed

The purpose of this article is to evaluate whether social, geographic, and demographic factors have a relationship to trends in volatile substance abuse. Two datasets were obtained. Dataset 1 was all patients reported to U.S. poison centers with inhalation abuse of a non-pharmaceutical substance between 2000 and 2005. Dataset 2 was annual data from the U.S. Dept of Labor and U.S. Census Bureau for each of the 50 states for the years 2000 through 2005 for unemployment rate, population density, poverty rate, high school graduation rate and percentage of population with bachelor degree. The two datasets were compared for geographic (by state) and temporal (by year) relationships using U.S. government demographic categories. The U.S. poison centers state that 12,428 patients with volatile substance abuse have been reported over the 6 year period of 2000-2005, with a mean of 2,071 patients annually. A strong negative trend was found between volatile substance abuse and population density, with volatile substance abuse increasing as population density decreased. This trend remained consistent over the 6 years of evaluation. A negative trend was found with percentage of population with a bachelor's degree and volatile substance abuse. No trend was found when comparing volatile substance abuse and poverty rate, unemployment rate, or high school graduation rate. Volatile substance abuse appears to increase as population density decreases, following a previously suggested relationship with a rural setting. Volatile substance abuse appears to increase as percentage of population with a bachelor's degree decreases. PMID:19340679

Spiller, Henry; Lorenz, Douglas J

2009-01-01

243

Inflation Volatility and Forecast Accuracy  

Microsoft Academic Search

This paper examines the statistical properties of inflation in a sample of inflation-targeting and non-inflation-targeting countries. First, it analyses the time-varying volatility of a measure of the persistent component of inflation. Based on this measure, inflation-targeting countries (Australia, Canada, New Zealand, Sweden and the United Kingdom) have experienced a relatively more pronounced fall in the volatility of inflation than non-inflation-targeting

Jamie Hall; Jarkko Jääskelä

2009-01-01

244

Evolution of Triton's volatile budget  

NASA Technical Reports Server (NTRS)

Triton's volatile budget provides important links to planetary formation processes in the cold outer solar nebula. However, the budget has been modified by processes subsequent to the accretion of this body. It is of interest to assess whether certain formation environments can be ruled out for Triton on the basis of its current volatile abundances, and also to quantify some of the post-accretional processes by which the abundances have been modified.

Lunine, J. I.

1993-01-01

245

Areal distribution of selected trace elements, salinity, and major ions in shallow ground water, Tulare Basin, Southern San Joaquin Valley, California  

USGS Publications Warehouse

The distribution of salinity and selected trace elements in shallow ground water in the Tulare Basin, California, was assessed to evaluate potential problems related to disposal in evaporation ponds of irrigation drain water containing elevated concentrations of selenium and other trace elements. The constituents of primary concern were selenium, arsenic, and salinity; uranium, boron, and molybdenum also were evaluated. Samples from 117 shallow wells were analyzed, and the results for samples from 110 of the wells were interpreted in relation to surficial geology, sediment depositional environment, soil characteristics, and hydrologic processes to determine the geochemical and hydrologic factors affecting the distribution of these constituents in ground water. In general, shallow ground water in areas where concentrations of salinity and most trace elements are elevated is influenced primarily by sediments derived from marine sedimentary rocks originating in the Coast Range, San Emigdio Mountains, and Tehachapi Mountains, and probably by unusual exposures of similar marine formations in the Sierra Nevada. Ground water in areas where concentrations of salinity and trace elements are significantly lower generally is influenced by igneous and metamorphic rocks exposed in the Sierra Nevada. In addition to sources of sediments, evaporation of shallow ground water, as indicated by isotopic enrichment of oxygen-18 and deuterium, increases salinity and concentrations of conservative trace elements such as selenium (under oxidizing conditions) and boron. Redox conditions affect the oxidation state of all trace elements of concern, except boron, and were found to be a major influence on trace-element solubility. Under oxidized conditions, selenate predominates and behaves conservatively, and arsenate predominates and is affected by sorption reactions that can limit arsenic solubility. Under reduced conditions, selenium is reduced to insoluble elemental selenium and arsenite predominates and generally is more soluble than arsenate. Elevated concentrations of uranium in shallow ground water probably are associated with uranium deposits in Kern County and other parts of the basin where oxidized conditions cause the more solubleuranyl species to predominate. Boron was correlated with salinity and behaved conservatively, whereas adsorption and precipitation of molybdenum minerals probably limited molybdenum solubility. Inter- relations among constituents were examined with principal component analysis. The first two principal components explained 50.7 percent of the variance in the data. The first principal component was related to salinity, and the second principal component was related to redox conditions, reflecting two of the major influences on shallow ground-water quality found in this study.

Fujii, Roger; Swain, W. C.

1995-01-01

246

Fruit volatile analysis using an electronic nose.  

PubMed

Numerous and diverse physiological changes occur during fruit ripening, including the development of a specific volatile blend that characterizes fruit aroma. Maturity at harvest is one of the key factors influencing the flavor quality of fruits and vegetables. The validation of robust methods that rapidly assess fruit maturity and aroma quality would allow improved management of advanced breeding programs, production practices and postharvest handling. Over the last three decades, much research has been conducted to develop so-called electronic noses, which are devices able to rapidly detect odors and flavors. Currently there are several commercially available electronic noses able to perform volatile analysis, based on different technologies. The electronic nose used in our work (zNose, EST, Newbury Park, CA, USA), consists of ultra-fast gas chromatography coupled with a surface acoustic wave sensor (UFGC-SAW). This technology has already been tested for its ability to monitor quality of various commodities, including detection of deterioration in apple; ripeness and rot evaluation in mango; aroma profiling of thymus species; C(6) volatile compounds in grape berries; characterization of vegetable oil and detection of adulterants in virgin coconut oil. This system can perform the three major steps of aroma analysis: headspace sampling, separation of volatile compounds, and detection. In about one minute, the output, a chromatogram, is produced and, after a purging cycle, the instrument is ready for further analysis. The results obtained with the zNose can be compared to those of other gas-chromatographic systems by calculation of Kovats Indices (KI). Once the instrument has been tuned with an alkane standard solution, the retention times are automatically converted into KIs. However, slight changes in temperature and flow rate are expected to occur over time, causing retention times to drift. Also, depending on the polarity of the column stationary phase, the reproducibility of KI calculations can vary by several index units. A series of programs and graphical interfaces were therefore developed to compare calculated KIs among samples in a semi-automated fashion. These programs reduce the time required for chromatogram analysis of large data sets and minimize the potential for misinterpretation of the data when chromatograms are not perfectly aligned. We present a method for rapid volatile compound analysis in fruit. Sample preparation, data acquisition and handling procedures are also discussed. PMID:22491160

Vallone, Simona; Lloyd, Nathan W; Ebeler, Susan E; Zakharov, Florence

2012-01-01

247

Fruit Volatile Analysis Using an Electronic Nose  

PubMed Central

Numerous and diverse physiological changes occur during fruit ripening, including the development of a specific volatile blend that characterizes fruit aroma. Maturity at harvest is one of the key factors influencing the flavor quality of fruits and vegetables1. The validation of robust methods that rapidly assess fruit maturity and aroma quality would allow improved management of advanced breeding programs, production practices and postharvest handling. Over the last three decades, much research has been conducted to develop so-called electronic noses, which are devices able to rapidly detect odors and flavors2-4. Currently there are several commercially available electronic noses able to perform volatile analysis, based on different technologies. The electronic nose used in our work (zNose, EST, Newbury Park, CA, USA), consists of ultra-fast gas chromatography coupled with a surface acoustic wave sensor (UFGC-SAW). This technology has already been tested for its ability to monitor quality of various commodities, including detection of deterioration in apple5; ripeness and rot evaluation in mango6; aroma profiling of thymus species7; C6 volatile compounds in grape berries8; characterization of vegetable oil9 and detection of adulterants in virgin coconut oil10. This system can perform the three major steps of aroma analysis: headspace sampling, separation of volatile compounds, and detection. In about one minute, the output, a chromatogram, is produced and, after a purging cycle, the instrument is ready for further analysis. The results obtained with the zNose can be compared to those of other gas-chromatographic systems by calculation of Kovats Indices (KI). Once the instrument has been tuned with an alkane standard solution, the retention times are automatically converted into KIs. However, slight changes in temperature and flow rate are expected to occur over time, causing retention times to drift. Also, depending on the polarity of the column stationary phase, the reproducibility of KI calculations can vary by several index units11. A series of programs and graphical interfaces were therefore developed to compare calculated KIs among samples in a semi-automated fashion. These programs reduce the time required for chromatogram analysis of large data sets and minimize the potential for misinterpretation of the data when chromatograms are not perfectly aligned. We present a method for rapid volatile compound analysis in fruit. Sample preparation, data acquisition and handling procedures are also discussed.

Vallone, Simona; Lloyd, Nathan W.; Ebeler, Susan E.; Zakharov, Florence

2012-01-01

248

Arsenic(III, V) adsorption on a goethite-based adsorbent in the presence of major co-existing ions: Modeling competitive adsorption consistent with spectroscopic and molecular evidence  

NASA Astrophysics Data System (ADS)

Adsorption of the two oxyanions, arsenate (As(V)) and arsenite (As(III)), on a common goethite-based granular porous adsorbent is studied in the presence of major co-existing ions in groundwater (i.e., phosphate, silicic acid, sulfate, carbonate, magnesium, and calcium) and predicted using the extended triple layer model (ETLM), a dipole modified single-site triple layer surface complexation model consistent with spectroscopic and molecular evidence. Surface species of all ions were selected according to the previous ETLM studies and published experimental spectroscopic/theoretical molecular information. The adsorption equilibrium constants for all ions were determined using adsorption data obtained in single-solute systems. The adsorption equilibrium constants referenced to the site-occupancy standard state (indicated by K?) were compared with those for goethite in the literature if available. The values of these constants for the goethite-based adsorbent are found to be close to the values for goethite previously studied. These "constrained" adsorption equilibrium constants determined in single-solute systems were used in the ETLM to predict the competitive interactions of As(III, V) with the co-existing ions in binary-solute systems. The ETLM is capable of predicting As(III, V) adsorption in the presence of oxyanions (phosphate, silicic acid, sulfate, and carbonate). This study presents the first successful and systematic prediction of the competitive interactions of As(III, V) with these oxyanions using the ETLM. The ETLM prediction of surface (and aqueous) speciation also provides insights into the distinct adsorption behavior of As(III, V) in the presence of the oxyanions. Magnesium and calcium significantly enhanced As(V) adsorption at higher pH values, while they had little effect on As(III) adsorption. The enhanced adsorption of As(V), however, could not be predicted by the ETLM using the surface species proposed in previous ETLM studies. Further studies are necessary to identify ternary complexes, especially at high pH. Adsorption isotherms of As(V), a dominant form of arsenic in adsorptive water treatment systems, in the presence of the co-existing ions under relevant conditions of water treatment systems are also obtained and predicted by the ETLM to study and compare the effect of the co-existing ions on As(V) removal.

Kanematsu, Masakazu; Young, Thomas M.; Fukushi, Keisuke; Green, Peter G.; Darby, Jeannie L.

2013-04-01

249

Volatile metabolites from indoor molds grown on media containing wood constituents.  

PubMed

Since volatile mold metabolites are used for the detection of mold growth in buildings, it was interesting to determine whether different indoor mold species show different affinity for the major components of wood, a common building material. Growth and volatile metabolites were studied when Aspergillus versicolor, Penicillium chrysogenum, and P. palitans were grown on laboratory substrates containing the major wood constituents cellulose, xylan and lignin. Microbial volatile organic compounds (MVOCs) were characterized by thermal desorption/gas chromatography/mass spectroscopy. Growth and volatile metabolites varied considerably and there appeared to be complementary substrate specificities for P. chrysogenum, and P. palitans grown on cellulose and xylan. The failure of A. versicolor to produce characteristic MVOCs when grown on media containing wood constituents suggests that systems using volatile metabolites to detect microbial growth in buildings may be fundamentally unreliable for the detection of this species. PMID:12943002

Wilkins, Ken; Larsen, Kjeld; Simkus, Mirella

2003-01-01

250

Volatile flux from subduction zone volcanoes: Insights from a detailed evaluation of the fluxes from volcanoes in Japan  

NASA Astrophysics Data System (ADS)

Global volatile fluxes from subaerial volcanoes at subduction zones were estimated based on a compilation of fluxes from various sources, including persistent degassing, hot and cold springs, soil degassing, and eruptions. Because worldwide comprehensive datasets are not available, especially for diffuse volatile discharges, volatile fluxes from Japan arcs were estimated based on detailed datasets, and the regional fluxes were extrapolated to the global flux with consideration of the regional characteristics of volcanic volatile compositions, which were estimated based on volcanic gas compositions of persistent degassing. The estimated global fluxes indicate that persistent degassing is the major source of volatiles, especially for S with a contribution of 80%. Diffuse discharges and persistent degassing are similarly important sources of H2O, CO2, and Cl, but the contribution of explosive eruptions is less than 15% for all the volatiles. The estimates of diffuse degassing fluxes include large errors due to limited data. However, the potential impact of these sources on the global flux indicates the importance of further studies to quantify these fluxes. The volatile budget of subduction zone volcanism was evaluated by comparing the estimated volatile fluxes, the volatile contents in the crust, and the primitive magma volatile contents. The contribution of volatiles remaining in the crust are not significant; however, consideration of lower crust foundering significantly alters the volatile budget estimate because the primitive magma supply rate should be significantly increased to account for the lower crust foundering.

Shinohara, Hiroshi

2013-12-01

251

The distillation and volatility of ionic liquids  

NASA Astrophysics Data System (ADS)

It is widely believed that a defining characteristic of ionic liquids (or low-temperature molten salts) is that they exert no measurable vapour pressure, and hence cannot be distilled. Here we demonstrate that this is unfounded, and that many ionic liquids can be distilled at low pressure without decomposition. Ionic liquids represent matter solely composed of ions, and so are perceived as non-volatile substances. During the last decade, interest in the field of ionic liquids has burgeoned, producing a wealth of intellectual and technological challenges and opportunities for the production of new chemical and extractive processes, fuel cells and batteries, and new composite materials. Much of this potential is underpinned by their presumed involatility. This characteristic, however, can severely restrict the attainability of high purity levels for ionic liquids (when they contain poorly volatile components) in recycling schemes, as well as excluding their use in gas-phase processes. We anticipate that our demonstration that some selected families of commonly used aprotic ionic liquids can be distilled at 200-300°C and low pressure, with concomitant recovery of significant amounts of pure substance, will permit these currently excluded applications to be realized.

Earle, Martyn J.; Esperança, José M. S. S.; Gilea, Manuela A.; Canongia Lopes, José N.; Rebelo, Luís P. N.; Magee, Joseph W.; Seddon, Kenneth R.; Widegren, Jason A.

2006-02-01

252

Volatile organic compounds released by the entomopathogenic fungus Beauveria bassiana.  

PubMed

The composition of volatile organic compounds (VOC) released by the entomopathogenic fungus Beauveria bassiana (Hyphomycete: Deuteromycotina) utilizing two different carbon sources was investigated. Analyses were performed by solid-phase microextraction (SPME) coupled to capillary gas chromatography (CGC) and CGC-mass spectrometry (MS). Major components in glucose-grown cultures were diisopropyl naphthalenes, ethanol, and sesquiterpenes. Alkane-grown fungal VOC switched to a fingerprint with prevalence of n-decane. This is the first report on the volatiles released by entomopathogenic fungi. PMID:16733086

Crespo, R; Pedrini, N; Juárez, M P; Dal Bello, G M

2008-01-01

253

Volatile components of ethanolic extract from broccolini leaves.  

PubMed

Broccolini (Brassica oleracea Italica?×?Alboglabra) is a hybrid of broccoli and kai-lan, Chinese broccoli. To date, no study has been reported on the chemical composition of the volatile fractions of this raw material. In this study, the volatile constituents from the ethanolic extract of broccolini leaves were analysed by gas chromatography-mass spectrometry (GC-MS). Sixteen compounds were identified. The major components include 5-phenyl-undecane (11%), n-hexadecanoic acid (9.34%), octadecanoic acid (6.39%), 1,1,3-trimethyl-3-phenyl-indan (4.0%), 3-(2-phenylethyl)benzonitrile (3.48%) and phytol (3.37%). PMID:21859369

Wang, Xiaoqin; Zhang, Bochao; Wang, Bingfang; Zhang, Xuewu

2012-01-01

254

TREATMENT OF CHLORINATED VOLATILE ORGANIC COMPOUNDS IN UPFLOW WETLAND MESOCOSMS. (R828773C003)  

EPA Science Inventory

Sorption, biodegradation and hydraulic parameters were determined in the laboratory for two candidate soil substrate mixtures for construction of an upflow treatment wetland for volatile organic compounds (VOCs) at a Superfund site. The major parent contaminants in the groundw...

255

Volatilization of mercury by resting mercury-resistant bacterial cells  

SciTech Connect

The mercuric ion reduction systems encoded by the Hg{sup 2+}inducible mer operon confers bacterial resistance to mercuric ion. The mer A gene product which is a FAD-containing enzyme catalyzes the reduction of Hg{sup 2+} to volatile elemental mercury with the helo of intracellular thiols and NADP as a cofactor Our earlier studies have shown that growing cells of different mercury-resistant bacteria reduce Hg{sup 2+} compounds to Ha(O). We have also shown the effect of thiol compounds and flavins on mercury-degrading enzyme activities in mercury-resistant bacteria. Here we report that resting cells of mercury-resistant bacteria survive in a buffer system for several hours, synthesize inducible mercury-degrading enzymes and volatilize mercury from a mercury-containing buffer system. We know of no information regarding studies of mercury-degrading enzymes in resting mercury-resistant bacterial cells.

Ghosh, S.; Sadhukhan, P.C.; Ghosh, D.K. [Univ. College of Science, Calcutta (India)] [and others] [Univ. College of Science, Calcutta (India); and others

1996-02-01

256

Modeling the influence of precursor volatility and molecular structure on secondary organic aerosol formation using evaporated fuel experiments  

NASA Astrophysics Data System (ADS)

We use SOA production data from an ensemble of evaporated fuels to test various SOA formation models. Except for gasoline, traditional SOA models focusing exclusively on volatile species in the fuels under-predict the observed SOA formation. These models can be improved dramatically by accounting for lower volatility species, but at the cost of a large set of free parameters. In contrast, a SOA model based only on the volatility of the precursor, starting with the volatility distribution of the evaporated fuels and optimized for the volatility reduction of first-generation products, reasonably reproduces the observed SOA formation with relatively few free parameters. The exceptions are exotic fuels such as Fischer-Tropsch fuels that expose the central assumption of the volatility based model that most emissions consist of complex mixtures displaying reasonably average behavior. However, for the vast majority of fuels, the volatility based model performs well.

Jathar, S. H.; Donahue, N. M.; Adams, P. J.; Robinson, A. L.

2013-09-01

257

Volatility from copper and tungsten alloys for fusion reactor applications  

SciTech Connect

Accident scenarios for fusion power plants present the potential for release and transport of activated constituents volatilized from first wall and structural materials. The extent of possible mobilization and transport of these activated species, many of which are oxidation driven'', is being addressed by the Fusion Safety Program at the Idaho National Engineering Laboratory (INEL). This report presents experimental measurements of volatilization from a copper alloy in air and steam and from a tungsten alloy in air. The major elements released included zinc from the copper alloy and rhenium and tungsten from the tungsten alloy. Volatilization rates of several constituents of these alloys over temperatures ranging from 400 to 1200{degree}C are presented. These values represent release rates recommended for use in accident assessment calculations. 8 refs., 3 figs., 5 tabs.

Smolik, G.R.; Neilson, R.M. Jr.; Piet, S.J. (EG and G Idaho, Inc., Idaho Falls, ID (USA))

1989-01-01

258

Spiral mining for lunar volatiles  

NASA Astrophysics Data System (ADS)

Lunar spiral mining, extending outward from a periodically mobile central power and processing station represents an alternative for comparison with more traditional mining schemes. In this concept, a mining machine would separate regolith fines and extract the contained volatiles. Volatiles then would be pumped along the miner's support arm to the central station for refining and for export or storage. The basic architecture of the central processing station would be cylindrical. A central core area could house the power subsystem of hydrogen-oxygen engines or fuel cells. Habitat sections and other crew occupied areas could be arranged around the power generation core. The outer cylinder could include all volatile refining subsystems. Solar thermal power collectors and reflectors would be positioned on top of the central station. Long term exploitation of a volatile resource region would begin with establishment of a support base at the center of a long boundary of the region. The mining tract for each spiral mining system would extend orthogonal to this boundary. New spiral mining systems would be activated along parallel tracts as demand for lunar He-3 and other solar wind volatiles increased.

Schmitt, H. H.; Kulcinski, G. L.; Sviatoslavsky, I. N.; Carrier, W. D., III

259

Comparative volatile profiles in soy sauce according to inoculated microorganisms.  

PubMed

We compared the volatile profiles in soy sauce according to inoculation with Tetragenococcus halophilus and/or Zygosaccharomyces rouxii. Totals of 107 and 81 volatiles were respectively identified by using solid-phase microextraction and solvent extraction. The various volatile compounds identified included acids, aldehydes, esters, ketones, furans and furan derivatives, and phenols. The major volatiles in the samples treated with T. halophilus were acetic acid, formic acid, benzaldehyde, methyl acetate, ethyl 2-hydroxypropanoate, 2-hydroxy-3-methyl-2-cyclopenten-1-one, and 4-hydroxy-3-methoxybenzaldehyde, while those in the samples inoculated with Z. rouxii were mainly ethanol, acetaldehyde, ethyl propanoate, 2/3-methylbutanol, 1-butanol, 2-phenylethanol, ethyl 2-methylpropanoate, and 4-hydroxy-2-ethyl-5-methyl-3(2H)-furanone. The results indicate that T. halophilus produced significant acid compounds and could affect the Z. rouxii activity, supporting the notion that yeasts and lactic acid bacteria respectively have different metabolic pathways of alcoholic fermentation and lactic acid fermentation, and produce different dominant volatile compounds in soy sauce. PMID:24200796

Lee, Kyung Eun; Lee, Sang Mi; Choi, Yong Ho; Hurh, Byung Serk; Kim, Young-Suk

2013-01-01

260

[Allelopathy and chemical constituents of Ligularia virgaurea volatile].  

PubMed

Ligularia virgaurea is a noxious weed widely distributed on the psychro-grasslands of east Qinghai-Tibet Plateau of China, but the allelopathic effects of its volatile is less known. In this study, the allelopathy of L. virgaurea volatile to 5 kinds of grasses was examined, and its chemical constituents were analyzed by GC-MS. The results demonstrated that the volatile of growing L. virgaurea could inhibit the seed germination speed and germination rate of all tested grasses. The inhibitory effects on Elymus nutans and Bromus magnus were significant, while Poa annua and Festuca ovin were not very sensitive. 18 major constituents were identified from the essential oil of L. virgaurea, accounted for 68.24% of the total. The main chemical components were 2-methylheptane (9.84%), 3-methyl-heptane (8.25%), heptane (7.93%), 4-methyl-1-(methylethyl)-bicyclo [3, 1, 0] hex-2-ene (7.79%), 3-methyl-hexane (6.38%), 2-methyl-hexane (5.54%), and D-limonene (4.70%). Monoterpenoids accounted for 16.58% of the total, indicating that volatilization was one of the ways by which L. virgaurea released allelochemicals. The allelopathy of the volatile may play an important role in enhancing the competitive ability of the species, and be one of reasons of grassland degeneration. PMID:16422498

Ma, Ruijun; Wang, Mingli; Zhu, Xuetai; Lu, Xianwen; Sun, Kun

2005-10-01

261

Study of cesium volatility from sodium carbonate based melts  

SciTech Connect

Purpose of this study was to obtain thermodynamic data on cesium volatility from sodium carbonate-based molten salts for application to the Rockwell-ETEC molten salt oxidation process. At 1073 to 1373 K, volatility tests were conducted on a horizontal and a vertical transpiration apparatus using a carrier gas composed of CO{sub 2}(g) and H{sub 2}O(g) which was passed over or bubbled through a sodium carbonate bath containing cesium carbonate and various additives. The major vapor species was identified to be CsOH(g) except when greater than 3% chloride is present in the melt, then the major vapor species is CsCl(g). The decrease in volatility of cesium as a function of cesium concentration in Cs{sub 2}CO{sub 3{minus}}Na{sub 2}CO{sub 3} mixtures follows Raoult`s law very closely. Thus, this system exhibits close to ideal solution behavior. Addition of 22.5 wt % sodium sulfate decreases the cesium volatility by just under a factor of 2, and the addition of 10.0 wt % sodium chloride increases the cesium volatility about an order of magnitude. The addition of 2.0 wt % ash, molecular sieve, or silica show little or no effect. However, the data indicate that higher concentrations of ash will decrease the cesium volatility. For the addition of 22.5 wt % sodium sulfate the activity coefficient, {gamma}(Cs{sub 2}CO{sub 3}){sup {1/2}}, is calculated to be 0.720 {plus_minus} 0.068, and for the addition of 10.0 wt % sodium chloride, the activity coefficient, {gamma}(CsCl), is calculated to be 8.118 {plus_minus} 2.317. Assuming that Henry`s law applies, these activity coefficients are used to extrapolate the effect on cesium retention in the molten salt oxidizer of sulfate and chloride at lower cesium concentrations.

Ebbinghaus, B.B.; Krikorian, O.H.; Adamson, M.G.; Fleming, D.L.

1993-12-01

262

The Relationship Between Molybdenum Oxidation State and Iodine Volatility in Nuclear Fuel  

SciTech Connect

The relationship between molybdenum oxidation state and iodine volatility in nuclear fuel was investigated using high-temperature Knudsen cell-mass spectroscopy. It was observed that the ratio of the intensities of molecular iodine ions I{sub 2}{sup +} and CsI{sup +} in the Knudsen cell-mass spectroscopic experiments can be used to investigate the iodine volatility in fuel under different conditions. The experiments show that the iodine volatility is similar in systems consisting of CsI alone, CsI/UO{sub 2}, and CsI/UO{sub 2}/MoO{sub x} (with molybdenum in oxidation states 0, 2, and 4). The iodine volatility is much higher, however, in CsI/UO{sub 2}/MoO{sub 3} systems (with molybdenum in oxidation state = 6). The iodine volatility in the fuel increases significantly if oxidation of the molybdenum goes to the MoO{sub 3} stage. The increase in the iodine volatility is caused by the formation of elemental iodine from cesium iodide. It is concluded from these measurements that the oxidation of the fuel to the UO{sub 2.2} will substantially increase the volatilization of fission product iodine. An analysis of the literature data suggests that the enhanced iodine volatilization process may be initiated when the fuel is oxidized to UO{sub 2.02}.

Sunder, S. [Atomic Energy of Canada Limited (Canada)

2003-11-15

263

The reduction of iron oxides by volatiles in a rotary hearth furnace process: Part III. The simulation of volatile reduction in a multi-layer rotary hearth furnace process  

Microsoft Academic Search

For reduction of iron oxides by volatiles from coal, the major reductant was found to be H2, and it can affect the overall reduction of iron oxides. In this study, the reduction by actual volatiles of composite pellets\\u000a at 1000 ?C was studied. The volatile reduction of the hand-packed Fe2O3\\/coal composite pellet as it is devolatilizing out of the pellet

I. Sohn; R. J. Fruehan

2006-01-01

264

Volatiles from Ficus hispida and their attractiveness to fig wasps.  

PubMed

Volatile compositions of receptive (ready to be pollinated), postpollinated, and postparasitized figs. and leaves of Ficus hispida were analyzed. Differences among them were examined, and the specificity of fig wasp attractiveness was investigated. Linalool was the major constituent of steam-distilled oil of either male or female receptive figs, while dibutyl phthalate was the major compound of the oils of postparasitized and postpollinated figs. In petroleum ether extracts, palmitic oil, and 9,12-octadecadienoic acid were the main constituents of male and female receptive figs, while hexadecanoic acid ethyl ester was the major compound of postparasitized and postpollinated figs. In dichloromethane extracts, linalool was the major constituent of male and female receptive figs, 1-hydroxylinalool was the major component of male postparasitized figs, and 1-hydroxylinalool and benzyl alcohol were the major constituents of female postpollinated figs. Bioassays with sticky traps showed that Ceratosolen solmsimarchal was attracted to dichloromethane extracts of male and female receptive figs and to petroleum ether extracts of female receptive figs, but was not attracted to dichloromethane and petroleum ether extracts of male postparasitized and female postpollinated figs. Figs were attractive to pollinating wasps only at the receptive stage. The volatile constituents of receptive figs were different from those of postpollinated or postparasitized figs. From a receptive to a postpollinated state, figs changed in their volatile composition. Some compounds disappeared or decreased in amount. These include linalool, linalool oxide, alpha-terpeneol, and 2,6-dimethyl-1,7-octadiene-3,6-diol, which may act as the attractants of the wasps. Others increased in amount, or several additional chemicals appeared. These include dibutyl phthalate, 1-hydroxylinalool, and benzyl alcohol, which may be repellents of the wasps. That dichloromethane extracts of male and female receptive figs showed similar activities in attracting fig wasps indicates that receptive figs of both sexes are similarly attractive to fig wasps, which is further supported by their similar volatile composition. Leaf extract was not attractive to the wasps. PMID:11710602

Song, Q; Yang, D; Zhang, G; Yang, C

2001-10-01

265

Chemical composition and antioxidant effect of glycosidically bound volatile compounds from oregano ( Origanum vulgare L. ssp. hirtum)  

Microsoft Academic Search

The present work examines the content and chemical composition of the glycosidically bound volatiles from oregano as well as their antioxidative properties. The glycosidically bound volatiles amounted to 20 mg kg?1 in dried leaves and flowers of oregano. Fourteen volatile aglycones were identified with thymoquinone as the major component. Other important aglycones were benzyl alcohol, eugenol, 2-phenyl-ethanol, thymol, 3-hexen-1-ol and

M Milos; J Mastelic; I Jerkovic

2000-01-01

266

Identification of a volatile phytotoxin from algae  

NASA Technical Reports Server (NTRS)

The objectives were to develop a trap system for isolating fractions of volatile algal phytotoxin and to characterize the major components of the isolated phytotoxin fractions. A bioassay using Phaseolus vulgaris seedlings was developed to aid in investigating the properties of the phytotoxin produced by cultures of Euglena gracilis var. bacillaris and Chlorella vulgaris. Two traps were found, 1.0 M hydrochloric acid and 0 C, which removed the phytotoxin from the algal effluent and which could be treated to release that phytotoxin as judged with the bioassay procedure. It was also determined that pretraps of 1.0 M sodium hydroxide and 1.0 M potassium biocarbonate could be used without lowering the phytotoxin effect. Ammonia was identified in trap solutions by ninhydrin reaction, indophenol reaction and derivatization with dansyl chloride and phenylisothiocyanate. Ammonia at the gaseous concentrations detected was found to have the same effects in the bioassay system as the volatile phytotoxin. It is possible that other basic, nitrogen containing compounds which augment the effects of ammonia were present at lower concentrations in the algal effluent.

Garavelli, J. S.; Fong, F.; Funkhouser, E. A.

1984-01-01

267

Magmatic volatiles and the weathering of Mars  

NASA Technical Reports Server (NTRS)

The sources for volatiles on Mars have been the subject of many hypotheses for exogenous influences including late accretion of volatile-enriched material, impact devolatilization to create massive early atmospheres, and even major bombardment by comets. However, the inventory of chemically active volatiles observable at the contemporary surface of Mars is consistent with domination by endogenous, subsequent planetary processes, viz., persistent magmatic outgassing. Volcanism on Mars has been widespread in both space and time. Notwithstanding important specific differences between the mantles of Earth and Mars, the geochemical similarities are such that the suite of gases emitted from Martian volcanic activity should include H2O, CO2, S-containing gases (e.g. H2S and/or SO2), and Cl-containing gases (e.g., Cl2 and/or HCl). H2O and CO2 exist in the atmosphere of Mars. Both are also present as surface condensates. However, spectroscopic observations of the Martian atmosphere clearly show that the S- and Cl-containing gases are severely depleted, with upper limits of less than or equal to 10(exp -7) the abundance of CO2. Likewise, there is no evidence of polar condensates of compounds of these elements as there is for CO2 and H2O. Within the soil, on the other hand, there has been direct measurement of incorporated H2O and abundant compounds containing S and Cl. Barring some as yet implausible geochemical sequestering process, the S/Cl ratio of about 6:1 in Martian soils implies a limit of 5% on the contribution of matter of solarlike composition (e.g., carbonaceous chondrite or cometary material) to these volatiles. Hence, exogenous sources are minor or not yet observed. From analysis of elemental trends in Martian soils, it has been recently shown that a simple two-component model can satisfy the Viking in situ measurements. Component A includes Si and most or all the Al, Ca, Ti, and Fe. Component B, taken as 16 +/- 3% by weight of the total, contains S and most or all the Cl and Mg. These results constrain several models of Martian soil mineralogy but are consistent with a mixture of silicates (such as Fe-rich clays and accessory minerals and soluble salts). The overall element profile is notably like shergottites, with significant incorporation of chemically reactive atmospheric gases from magmatic degassing.

Clark, B. C.

1993-01-01

268

Low volatile organic compound paints  

Microsoft Academic Search

Increasingly stringent air emission standards in various states has dictated the elimination of engineering finishes which are derived from high volatile organic compound (VOC) paint chemistries. In July 1989, Allied-Signal, Inc., Kansas City Division, Kansas City, Missouri, voluntarily closed its paint facility, due to non-compliance with local air emission standards. The following details the materials selection and evaluations which led

1991-01-01

269

Possible Sources of Polar Volatiles  

NASA Astrophysics Data System (ADS)

Extensive analyses of returned Apollo samples demonstrated that the Moon is extremely volatile poor. While this conclusion remains true, various measurements since the late 90's implicated the presence of water: e.g., enhanced reflection of circularly polarized radar signals and suppression of epithermal neutrons near the poles. More recently, traces of H2O have been discovered inside volcanic glass, along with more significant amounts residing in hydrous minerals (apatite) returned from both highland and mare landing sites. Three recent lunar missions (DIXI, M3, Cassini) identified hydrous phases on/near the lunar surface, whereas the LCROSS probe detected significant quantities of volatiles (OH, H2O and other volatiles) excavated by the Centaur impact. These new mission results and sample studies, however, now allow testing different hypotheses for the generation, trapping, and replenishment of these volatiles. Solar-proton implantation must contribute to the hydrous phases in the lunar regolith in order to account for the observed time-varying abundances and occurrence near the lunar equator. This also cannot be the entire story. The relatively low speed LCROSS-Centaur impact (2.5km/s) could not vaporize such hydrous minerals, yet emissions lines of OH (from the thermal disassociation of H2O), along with other compounds (CO2, NH2) were detected within the first second, before ejecta could reach sunlight. Telescopic observations by Potter and Morgan (1985) discovered a tenuous lunar atmosphere of Na, but the LCROSS UV/Vis spectrometer did not detect the Na-D line until after the ejecta reached sunlight (along with a line pair attributed to Ag). With time, other volatile species emerged (OH, CO). The LAMP instrument on the Lunar Reconnaissance Orbiter had a different viewpoint from the side (rather than from above) and detected many other atomic species release by the LCROSS-Centaur impact. Consequently, it appears that there is a stratigraphy for trapped species: surface layer of atomic/molecules over a regolith containing an assortment of cold-trapped elements (Na/Ca/Mg/K/Ag/Hg) and compounds (OH, CO, H2). In addition to the solar flux, cometary dust dominates the impact flux for particles less than 1g and dominates impact flashes observed telescopically (Cooke, pers. comm.). While large, volatile-rich impactors may be less frequent, they have the potential for injecting significant quantities (10-15%) into impact melts (Harris and Schultz, 2011). In addition, laboratory impact experiments at the NASA Ames Vertical Gun Range used high-speed spectroscopy to illustrate the capture of volatile fractions below the surface during hypervelocity impacts. On the Moon, melt-trapped volatiles comprising the regolith would be gradually recycled during each lunation during impact gardening, thereby titrating the supply of volatiles to the polar deep freeze. Consequently, diverse sources likely contributed this potpourri of trapped cold-trapped volatile

Schultz, P. H.

2011-12-01

270

Changes in streamflow and summary of major-ion chemistry and loads in the North Fork Red River basin upstream from Lake Altus, northwestern Texas and western Oklahoma, 1945-1999  

USGS Publications Warehouse

Upstream from Lake Altus, the North Fork Red River drains an area of 2,515 square miles. The quantity and quality of surface water are major concerns at Lake Altus, and water-resource managers and consumers need historical information to make informed decisions about future development. The Lugert-Altus Irrigation District relies on withdrawals from the lake to sustain nearly 46,000 acres of agricultural land. Kendall's tau tests of precipitation data indicated no statistically significant trend over the entire 100 years of available record. However, a significant increase in precipitation occurred in the last 51 years. Four streamflow-gaging stations with more than 10 years of record were maintained in the basin. These stations recorded no significant trends in annual streamflow volume. Two stations, however, had significant increasing trends in the base-flow index, and three had significant decreasing trends in annual peak flows. Major-ion chemistry in the North Fork Red River is closely related to the chemical composition of the underlying bedrock. Two main lithologies are represented in the basin upstream from Lake Altus. In the upper reaches, young and poorly consolidated sediments include a range of sizes from coarse gravel to silt and clay. Nearsurface horizons commonly are cemented as calcium carbonate caliche. Finer-grained gypsiferous sandstones and shales dominate the lower reaches of the basin. A distinct increase in dissolved solids, specifically sodium, chloride, calcium, and sulfate, occurs as the river flows over rocks that contain substantial quantities of gypsum, anhydrite, and dolomite. These natural salts are the major dissolved constituents in the North Fork Red River.

Smith, S. Jerrod; Wahl, Kenneth L.

2003-01-01

271

Pyrolysis and volatilization of cocaine  

SciTech Connect

The increasing popularity of inhaling cocaine vapor prompted the present study, to determine cocaine's fate during this process. The free base of (3H)cocaine (1 microCi/50 mg) was added to a glass pipe, which was then heated in a furnace to simulate freebasing. Negative pressure was used to draw the vapor through a series of glass wool, ethanol, acidic, and basic traps. Air flow rate and temperature were found to have profound effects on the volatilization and pyrolysis of cocaine. At a temperature of 260 degrees C and a flow rate of 400 mL/min, 37% of the radioactivity remained in the pipe, 39% was found in the glass wool trap, and less than 1% in the remainder of the volatilization apparatus after a 10-min volatilization. Reducing the air flow rate to 100 mL/min reduced the amount of radioactivity collected in the glass wool trap to less than 10% of the starting material and increased the amount that remained in the pipe to 58%. GC/MS analysis of the contents of the glass wool trap after volatilization at 260 degrees C and a flow rate of 400 mL/min revealed that 60% of the cocaine remained intact, while approximately 6 and 2% of the starting material was recovered as benzoic acid and methylecgonidine, respectively. As the temperature was increased to 650 degrees C, benzoic acid and methylecgonidine accounted for 83 and 89% of the starting material, respectively, whereas only 2% of the cocaine remained intact. Quantitation of cocaine in the vapor during the course of volatilization revealed high concentrations during the first two min and low concentrations for the remaining time.

Martin, B.R.; Lue, L.P.; Boni, J.P. (Virginia Commonwealth Univ., Richmond (USA))

1989-05-01

272

Volatility Forecasting: The Jumps Do Matter  

Microsoft Academic Search

This study reconsiders the role of jumps for volatility forecasting by showing that jumps have a positive and mostly significant impact on future volatility. This result becomes apparent once volatility is correctly separated into its continuous and discontinuous component. To this purpose, we introduce the concept of threshold multipower variation (TMPV), which is based on the joint use of bipower

Fulvio Corsi; Davide Pirino; Roberto Reno

2009-01-01

273

Spray Drying: Retention of Volatile Compounds Revisited  

Microsoft Academic Search

Retention or loss of trace volatile compounds during spray drying can be vital for product quality. Examples of cases where loss or retentions of volatile substances are important include retention of balanced flavor and aroma in food products, removal of odiferous substances, and control of the release of volatile organic compounds to the atmosphere. Factors and mechanisms determining losses of

C. Judson King

1995-01-01

274

Does Insider Trading Raise Market Volatility?  

Microsoft Academic Search

This paper studies the role of insider trading in explaining cross-country difference in stock market volatility. It introduces a new (albeit imperfect) measure of insider trading for 50 or so countries. The central finding is that countries with more prevalent insider trading do have more volatile stock markets, even after one controls for liquidity\\/maturity of the market, and the volatility

Julan Du; Shang-Jin Wei

2002-01-01

275

Volatiles in interplanetary dust particles: a review.  

PubMed

The paper presents a review of the volatiles found within interplanetary dust particles. These particles have been shown to represent primitive material from early in the solar system's formation and also may contain records of stellar processes. The organogenic elements (i.e., H, C, N, O, and S) are among the most abundant elements in our solar system, and their abundances, distributions, and isotopic compositions in early solar system materials permit workers to better understand the processes operating early in the evolutionary history of solar system materials. Interplanetary dust particles have a range of elemental compositions, but generally they have been shown to be similar to carbonaceous chondrites, the solar photosphere, Comet Halley's chondritic cores, and matrix materials of chondritic chondrites. Recovery and analysis of interplanetary dust particles have opened new opportunities for analysis of primitive materials, although interplanetary dust particles represent major challenges to the analyst because of their small size. PMID:11537855

Gibson, E K

1992-03-25

276

Alkaline dechlorination of chlorinated volatile organic compounds  

SciTech Connect

The vast majority of contaminated sites in the United States and abroad are contaminated with chlorinated volatile organic compounds (VOCs) such as trichloroethylene (TCE), trichloroethane (TCA), and chloroform. These VOCs are mobile and persistent in the subsurface and present serious health risks at trace concentrations. The goal of this project was to develop a new chemical treatment system that can rapidly and effectively degrade chlorinated VOCs. The system is based on our preliminary findings that strong alkalis such as sodium hydroxide (NaOH) can absorb and degrade TCE. The main objectives of this study were to determine the reaction rates between chlorinated VOCs, particularly TCE, and strong alkalis, to elucidate the reaction mechanisms and by-products, to optimize the chemical reactions under various experimental conditions, and to develop a laboratory bench- scale alkaline destruction column that can be used to destroy vapor- phase TCE.

Gu, B.; Siegrist, R.L.

1996-06-01

277

Volatile fraction of lavender and bitter fennel infusion extracts.  

PubMed

The relative proportions of chemical classes (hydrocarbons, oxides, alcohols/ethers, aldehydes/ketones, acids/esters/lactones) in the essential oil of lavender (Lavendula angustifolia Mill., family Lamiaceae) and bitter fennel (Foeniculum vulgare Mill. subsp. vulgare var. vulgare (Mill.) Thellung, family Apiaceae) and in the volatile fraction of infusion extracts were examined and showed remarkable differences. The volatile compounds of infusions were isolated by hydrodistillation and solid phase extraction (SPE). Their qualitative and semiquantitative compositions were compared with the essential oil isolated by hydrodistillation directly from the plant material and analyzed by GC-MS. Furthermore, quantification of the major constituents of lavender oil and of the volatile fraction obtained by hydrodistillation of the infusion was performed. Comparison of the total essential oil yield quantified by hydrodistillation of the lavender infusion (0.7% v/w, corresponding to plant material) with the essential oil yield of the blossoms (5.1% v/w) revealed that only 13.9% of the initial oil could be extracted by infusion. The main constituents of the volatile fraction of the lavender infusion were (hydrodistillation/SPE): linalool (39.3%/28.2%), 1,8 cineole (24.8%/18.9%), cis-linalool oxide (furanoid) (5.8%/8.0%), trans-linalool oxide (furanoid) (4.1%/7.1%), camphor (5.3%/4.0%) and alpha-terpineol (4.0%/3.0%). The major constituents of lavender essential oil were linalool (28.8%), 1,8-cineole (18.05%), linalyl acetate (13.9%) and alpha-terpineol (4.0%). Most intriguing, in the volatile fraction of lavender infusion a significant proportional decrease of linalyl acetate and an increase of linalool oxides was recognized. The essential oil yield of fennel fruits was 12.5% v/w, whereas 1.8% v/w volatile fraction (corresponding to plant material) was obtained by hydrodistillation of the fennel infusion, which is equivalent to 14.5% of the initial fennel essential oil. The main constituents of the volatile fraction of the fennel infusion were (hydrodistillation/SPE): trans-anethole (56.4%/54.8%), fenchone (36.2%/39.5%) and estragole (2.5%/2.2%), which were also the major compounds of the genuine bitter fennel essential oil. In infusions, the proportion of ethers vs. ketones was shifted significantly towards a higher proportion of the latter compared with the essential oil obtained from the fruits. PMID:20923003

Tschiggerl, Christine; Bucar, Franz

2010-09-01

278

Implications of low SOA volatility and fragmentation reactions on the evolution of SOA in the atmosphere  

NASA Astrophysics Data System (ADS)

We investigate the issues of low SOA volatility and gas-phase fragmentation reactions using both box and 3D model simulations. Analyzing both the laboratory and field data, we show that the observed slow evaporation behavior of SOA implies very low "effective volatility", under any realistic assumptions of mass accommodation coefficient. This analysis suggests that models may need to use different parameters to represent SOA formation versus its atmospheric evolution. A 5-product volatility basis set fit of ambient SOA evaporation rate measurements during the CARES field campaign show that a major fraction of the ambient SOA could be considered to be non-volatile under most atmospheric conditions. Accordingly, we revise our models to transform SOA "after formation" to a non-volatile non-absorbing organic aerosol (OA). We also develop simplified parameterizations to capture the first order effects of gas-phase fragmentation reactions. Using the box model, we show that, regardless of the fragmentation scheme, all multigenerational chemistry parameterizations predict one to two orders of magnitude higher SOA compared to models based on fixed smog chamber SOA yields. Increasing the amount of fragmentation reduces SOA loadings as expected. In addition, the box model shows that in our non-volatile SOA approach too, similar to the semi-volatile approach, the SOA is comprised of multi-generational oxidation products. But peak values of simulated O/C ratio are lower in the semi-volatile as compared to the non-volatile approach. Using the 3D model, we demonstrate complex variations in spatial and temporal distribution of SOA with varying degrees of fragmentation and the treatment of SOA as semi-volatile or non-volatile.

Shrivastava, M.; Zelenyuk, A.; Imre, D. G.; Easter, R. C.; Beranek, J.; Zaveri, R. A.; Fast, J. D.

2012-12-01

279

Ion Trap Mass Spectrometry  

SciTech Connect

This chapter describes research conducted in a few research groups in the 1990s in which RF quadrupole ion trap mass spectrometers were coupled to a powerful atomic ion source, the inductively coupled plasma used in conventional ICP-MS instruments. Major section titles for this chapter are: RF Quadrupole Ion Traps Features of RF Quadrupole Ion Trap Mass Spectrometers Selective Ion Trapping methods Inductively Coupled Plasma Source Ion Trap Mass Spectrometers

Eiden, Greg C.

2005-09-01

280

Development of a PTR-TOFMS instrument for real-time measurements of volatile organic compounds in air  

Microsoft Academic Search

A proton transfer reaction-time-of-flight mass spectrometer (PTR-TOFMS) has been developed for real-time measurements of volatile organic compounds in air. The instrument is designed to be operated with a hollow cathode discharge ion source and an ion drift tube at relatively high pressures. Each component of the system, an ion source, a drift tube, an ion transfer region, and a time-of-flight

Hiroshi Tanimoto; Nobuyuki Aoki; Satoshi Inomata; Jun Hirokawa; Yasuhiro Sadanaga

2007-01-01

281

Source characteristics of oxygenated volatile organic compounds and hydrogen cyanide  

Microsoft Academic Search

Airborne trace gas measurements from Transport and Chemical Evolution over the Pacific (TRACE-P), Pacific Exploratory Mission (PEM)-Tropics B, and Intercontinental Chemical Transport Experiment-North America (INTEX-NA) experiments are analyzed to examine the major source factors contributing to the observed variabilities of oxygenated volatile organic compounds and cyanides. The positive matrix factorization method is applied to coincident measurements of 11 chemicals including

Changsub Shim; Yuhang Wang; Hanwant B. Singh; Donald R. Blake; Alex B. Guenther

2007-01-01

282

Formation of volatile branched chain esters in bananas (Musa sapientum L.).  

PubMed

Substrates controlling the formation of branched chain volatile esters in ripening bananas were investigated by the application of alcohol and amino acid precursors to whole fruit and tissue samples. The resulting changes in the profile of the volatile esters were determined using SPME and GC. These changes revealed the selectivity characteristics of the esterification enzyme AAT, the availability of acyl CoA's for ester formation, and the role of substrate supply on volatile production. The results obtained suggest that substrate supply is a major determinant of the quantitative and qualitative composition of the resulting aroma profile. PMID:10956138

Wyllie, S G; Fellman, J K

2000-08-01

283

The effects of volatile oils on in vitro potato sprout growth  

Microsoft Academic Search

Summary  The effects of 10 volatile oils and their main compounds on potato sprout growth were investigated in vitro. Sprout growth\\u000a was inhibited especially by the volatile oils fromOriganum onites, Rosa damascena, Carum carvi, Mentha piperita, Echinophora tuneifolia andCoriandrum sativum. The major compound of volatile oils was carvacrol (78.2%) inO. onites, citronellol (46.7%) inR. damascena, S-(+)-carvone (54.9%) inC. carvi, menthol (44.1%)

H. Baydar; T. Karado?an

2003-01-01

284

Effect of gamma irradiation on curcuminoids and volatile oils of fresh turmeric ( Curcuma longa)  

NASA Astrophysics Data System (ADS)

In our earlier study a radiation dose of 5 kGy was reported to be suitable for microbial decontamination and shelf life extension of fresh turmeric ( Curcuma longa), while maintaining its quality attributes. In continuation of that work, the effect of gamma radiation on curcuminoids and volatile oil constituents in fresh turmeric was studied. Fresh peeled turmeric rhizomes were gamma irradiated at doses of 1, 3 and 5 kGy. Curcuminoid content and volatile oils were analyzed by reverse phase HPLC and GC-MS, respectively. The curcuminoid content was slightly increased by gamma irradiation. No statistically significant changes were observed due to irradiation in majority of the volatile oil constituents.

Dhanya, R.; Mishra, B. B.; Khaleel, K. M.

2011-11-01

285

Chemical composition of the fixed and volatile oils of Nigella sativa L. from Iran.  

PubMed

The chemical composition of the extracted fixed oil (total fatty acid composition) and volatile oil of Nigella sativa L. seeds grown in Iran were determined by GC and GC/MS. Eight fatty acids (99.5%) and thirty-two compounds (86.7%) have been identified in the fixed and volatile oils, respectively. The main fatty acids of the fixed oil were linoleic acid (55.6%), oleic acid (23.4%), and palmitic acid (12.5%). The major compounds of the volatile oil were trans-anethole (38.3%), p-cymene (14.8%), limonene (4.3%), and carvone (4.0%). PMID:14577620

Nickavar, Bahman; Mojab, Faraz; Javidnia, Katayoun; Amoli, Mohammad Ali Roodgar

2003-01-01

286

Trends in Volatile Substance Abuse  

Microsoft Academic Search

The purpose of this article is to evaluate whether social, geographic, and demographic factors have a relationship to trends in volatile substance abuse. Two datasets were obtained. Dataset 1 was all patients reported to U.S. poison centers with inhalation abuse of a non-pharmaceutical substance between 2000 and 2005. Dataset 2 was annual data from the U.S. Dept of Labor and

Henry Spiller; Douglas J. Lorenz

2009-01-01

287

Volatiles in Earths interior (Invited)  

NASA Astrophysics Data System (ADS)

Water is certainly the most important volatile. Recycling of water into the mantle occurs in subduction zones where water also triggers melting in the mantle wedge above the subducted slab. However, both the flux of water into the zone of melting as well as the composition of the fluids are poorly constrained. Moreover, it is uncertain whether fluids percolate through the mantle wedge primarily by channelized flow or by pervasive flow, with major implications for the relative contributions of subducted slab and the mantle wedge to the trace element budget of island arc volcanics. To constrain the composition and the flux of fluids in subduction zones, we have measured the solubilities of UO2, ThSiO4, MoOx and WOx in fluids of variable salinity and over a range of oxygen fugacities (Bali et al., in prep). In separate sets of experiments, we measured the solubility of U, Th, Mo, and W in mantle minerals coexisting with the corresponding phases in order to determine fluid/mineral partition coefficients. Our data show that the U/Th ratio in calcalkaline volcanics is a sensitive indicator of redox state and salinity and observed enrichments of U over Th require transport by oxidizing and moderately saline fluids. W, on the other hand, is always very incompatible in mantle minerals and strongly partitioned into aqueous fluids, irrespective of oxidation state and salinity. W contents in magmas can therefore be used to constrain the amount of fluids involved in melting. To distinguish between channelized and pervasive flow in subduction zones, we also looked at the partitioning of halogens, particularly chlorine between aqueous fluids and mantle minerals (Bernini et al., in prep.). Chlorine is highly incompatible in upper mantle minerals, with concentrations below 1 ppm in mantle minerals in equilibrium with fluids containing several wt. % of NaCl. Since water solubility in mantle minerals is much higher than Cl solubility, fluids percolating through the mantle will loose much more water than chlorine and therefore become concentrated. From available data on the salinities of fluids released from the slab and the Cl/H2O ratio in primitive melt inclusions from arc volcanoes, we can estimate that the ratio of rock to fluid that must have reached chemical equilibrium must exceed 1000, implying that fluids percolate by pervasive flow through the mantle wedge. The relative abundance of noble gases on Earth, particularly the depletion of Xe relative to Ar must be due to some process occurring very early in Earth history. We show new experimental results (Shcheka & Keppler, in prep.) that demonstrate that argon is highly compatible in MgSiO3 perowskite, with concentrations reaching more than 1 wt. % at 24 GPa and 1600 C, while xenon solubility is negligible. We therefore suggest that during the crystallization of a magma ocean, argon was preferentially incorporated into perovskite, while most noble gases from the atmosphere were lost to space. Mantle convection later released argon, but not xenon from the deep mantle to the surface and therefore produced the high Ar/Xe ratio in Earths atmosphere. The depletion of Xe relative to Ar is therefore likely to be characteristic for a planet that underwent fractionation of silicate perovskite from a magma ocean.

Keppler, H.

2010-12-01

288

Investigation of Volatile Compounds and Characterization of Flavor Profiles of Fresh Pistachio Nuts (Pistacia vera L.)  

Microsoft Academic Search

Volatile compounds and flavor characteristics of Uzun, Kirmizi, Halebi, Siirt ve Ohadi varieties of fresh pistachio nuts cultivated in the Pistachionut Research Institute located in Gaziantep, Turkey were investigated by using Solid Phase Micro Extraction\\/Gas Chromatography\\/Mass Spectroscopy (SPME\\/GC\\/MS) and sensory flavor profile analysis techniques. Major volatile compounds of the fresh pistachio nuts were detected as ?-pinene (15.53–48.57%), ?-terpinolene (1.66–23.06%), limonene

Perihan Kendirci; Tomris Altu? Ono?ur

2011-01-01

289

Volatile 1-octen-3-ol induces a defensive response in Arabidopsis thaliana  

Microsoft Academic Search

1-Octen-3-ol is a major volatile metabolite produced by mold fungi. When Arabidopsis plants were treated with 1-octen-3-ol,\\u000a some defense genes that are turned on by wounding or ethylene\\/jasmonic acid signaling were induced. The treatment also enhanced\\u000a resistance of the plant against Botrytis cinerea. When the induction of defense genes with 1-octen-3-ol was compared with that by volatile methyl jasmonate (MeJA)

Kyutaro Kishimoto; Kenji Matsui; Rika Ozawa; Junji Takabayashi

2007-01-01

290

Chemical characterization and allelopathic potential of volatile oil of Eucalyptus tereticornis against Amaranthus viridis  

Microsoft Academic Search

The present study investigated the chemical composition and allelopathic potential of volatile oil from Eucalyptus tereticornis on growth and establishment of Amaranthus viridis, a wasteland weed. The volatile oil was rich in monoterpenoids and a total of 34 components were identified by gas chromatography\\/gas chromatography–mass spectroscopy analyses, constituting 98.52%. ?-Pinene (32.5%) and 1,8-cineole (22.4%) were the two major constituents. The

Shalinder Kaur; Harminder Pal Singh; Daizy Rani Batish; Ravinder Kumar Kohli

2011-01-01

291

Field sampling method for quantifying volatile sulfur compounds from animal feeding operations  

Microsoft Academic Search

Volatile sulfur compounds (VSCs) are a major class of chemicals associated with odor from animal feeding operations (AFOs). Identifying and quantifying VSCs in air is challenging due to their volatility, reactivity, and low concentrations. In the present study, a canister-based method collected whole air in fused silica-lined (FSL) mini-canister (1.4L) following passage through a calcium chloride drying tube. Sampled air

Steven Trabue; Kenwood Scoggin; Frank Mitloehner; Hong Li; Robert Burns; Hongwei Xin

2008-01-01

292

Investigation of the Volatile Fraction of Rosemary Infusion Extracts  

PubMed Central

The relative proportions of chemical classes (hydrocarbons, oxides, alcohols, ketones, esters) in the essential oil of rosemary (Rosmarinus officinalis L., Lamicaeae) and in the volatile fraction of the infusion extracts were examined and showed remarkable differences. The volatile compounds of the infusion were isolated by two different methods, hydrodistillation and solid phase extraction (SPE). The main constituents of the volatile fraction of the infusion were (hydrodistillation/SPE): 1,8-cineole (42.4%/44.7%), camphor (31.4%/31.8%), ?-terpineol (8.6%/8.1%) and borneol (8.3%/7.8%). The qualitative and quantitative composition of the volatile compounds of the infusion was compared to the essential oil isolated by hydrodistillation directly from the leaves. The major constituents of the essential oil of the leaves were 1,8-cineole (41.6%), camphor (17.0%), ?-pinene (9.9%), ?-terpineol (4.9%) and borneol (4.8%). Comparison of the total essential oil yield quantified by hydrodistillation of the infusion (0.36% v/w) with the essential oil yield of the leaves (1.84% v/w) revealed that only 19.6% of the initial oil could be extracted by infusion.

Tschiggerl, Christine; Bucar, Franz

2010-01-01

293

Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5  

PubMed Central

Summary Streptomyces sp. FORM5 is a bacterium that is known to produce the antibiotic streptazolin and related compounds. We investigated the strain for the production of volatiles using the CLSA (closed-loop stripping analysis) method. Liquid and agar plate cultures revealed the formation of new 2-alkylpyridines (streptopyridines), structurally closely related to the already known 2-pentadienylpiperidines. The structures of the streptopyridines A to E were confirmed by total synthesis. The analysis of the liquid phase by solvent extraction or extraction with an Oasis adsorbent showed that streptazolin and 2-pentadienylpiperidine are the major compounds, while the streptopyridines are only minor components. In the gas phase, only the streptopyridines could be detected. Therefore, an orthogonal set of analysis is needed to assess the metabolic profile of bacteria, because volatile compounds are obviously overlooked by traditional analytical methods. The streptopyridines are strain specific volatiles that are accompanied by a broad range of headspace constituents that occur in many actinomycetes. Volatiles might be of ecological importance for the producing organism, and, as biosynthetic intermediates or shunt products, they can be useful as indicators of antibiotic production in a bacterium.

Groenhagen, Ulrike; Maczka, Michael; Dickschat, Jeroen S

2014-01-01

294

Ion mobility studies of electronically excited states of atomic transition metal cations: Development of an ion mobility source for guided ion beam experiments  

Microsoft Academic Search

The design of an ion mobility source developed to couple to a guided ion beam tandem mass spectrometer is presented. In these\\u000a exploratory studies, metal ions are created continuously by electron ionization of the volatile hexacarbonyls of the three\\u000a group 6 transition metals. These ions are focused into a linear hexapole ion trap, which collects the ions and then creates

Christopher Iceman; Chad Rue; Robert M. Moision; Barun K. Chatterjee; P. B. Armentrout

2007-01-01

295

Trends in major-ion constituents and properties for selected sampling sites in the Tongue and Powder River watersheds, Montana and Wyoming, based on data collected during water years 1980-2010  

USGS Publications Warehouse

The primary purpose of this report is to present information relating to flow-adjusted temporal trends in major-ion constituents and properties for 16 sampling sites in the Tongue and Powder River watersheds based on data collected during 1980–2010. In association with this primary purpose, the report presents background information on major-ion characteristics (including specific conductance, calcium, magnesium, potassium, sodium adsorption ratio, sodium, alkalinity, chloride, fluoride, dissolved sulfate, and dissolved solids) of the sampling sites and coal-bed methane (CBM) produced water (groundwater pumped from coal seams) in the site watersheds, trend analysis methods, streamflow conditions, and factors that affect trend results. The Tongue and Powder River watersheds overlie the Powder River structural basin (PRB) in northeastern Wyoming and southeastern Montana. Limited extraction of coal-bed methane (CBM) from the PRB began in the early 1990’s, and increased dramatically during the late 1990’s and early 2000’s. CBM-extraction activities produce discharges of water with high concentrations of dissolved solids (particularly sodium and bicarbonate ions) relative to most stream water in the Tongue and Powder River watersheds. Water-quality of CBM produced water is of concern because of potential effects of sodium on agricultural soils and potential effects of bicarbonate on aquatic biota. Two parametric trend-analysis methods were used in this study: the time-series model (TSM) and ordinary least squares regression (OLS) on time, streamflow, and season. The TSM was used to analyze trends for 11 of the 16 study sites. For five sites, data requirements of the TSM were not met and OLS was used to analyze trends. Two primary 10-year trend-analysis periods were selected. Trend-analysis period 1 (water years 1986–95; hereinafter referred to as period 1) was selected to represent variability in major-ion concentrations in the Tongue and Powder River watersheds before potential effects of CBM-extraction activities. Trend analysis period 2 (water years 2001–10; hereinafter referred to as period 2) was selected because it encompassed substantial CBM-extraction activities and therefore might indicate potential effects of CBM-extraction activities on water quality of receiving streams in the Tongue and Powder River watersheds. For sites that did not satisfy data requirements for the TSM, OLS was used to analyze trends for period 2 (if complete data were available) or a 6-year period (2005–10). Flow-rate characteristics of CBM-produced water were estimated to allow general comparisons with streamflow characteristics of the sampling sites. The information on flow-rate characteristics of CBM-produced water in relation to streamflow does not account for effects of disposal, treatment, or other remediation activities on the potential quantitative effects of CBM-produced water on receiving streams. In many places, CBM-produced water is discharged into impoundments or channels in upper reaches of tributary watersheds where water infiltrates and does not directly contribute to streamflow. For Tongue River at State line (site 4) mean annual pumping rate of CBM-produced water during water years 2001–10 (hereinafter referred to as mean CBM pumping rate) was 6 percent of the mean of annual median streamflows during water years 2001–10 (hereinafter referred to as 2001–10 median streamflow). For main-stem Tongue River sites 5, 7, and 10, mean CBM pumping rate was 8–12 percent of 2001–10 median streamflow. For main-stem Powder River sites (sites 12, 13, and 16), mean CBM pumping rates were 26, 28, and 34 percent of 2001–10 median streamflows, respectively. For main-stem Tongue River sites analyzed by using the TSM and downstream from substantial CBM-extraction activities [Tongue River at State line (site 4), Tongue River at Tongue River Dam (site 5), Tongue River at Birney Day School (site 7), and Tongue River at Miles City (site 10)], generally small significant or nonsignificant decreases in most constituents are in

Sando, Steven K.; Vecchia, Aldo V.; Barnhart, Elliott P.; Sando, Thomas R.; Clark, Melanie L.; Lorenz, David L.

2014-01-01

296

NATURAL EMISSIONS OF NON-METHANE VOLATILE ORGANIC COMPOUNDS, CARBON MONOXIDE, AND OXIDES OF NITROGEN FROM NORTH AMERICA. (R825259)  

EPA Science Inventory

Abstract The magnitudes, distributions, controlling processes and uncertainties associated with North American natural emissions of oxidant precursors are reviewed. Natural emissions are responsible for a major portion of the compounds, including non-methane volatile o...

297

NATURAL EMISSIONS OF NON-METHANE VOLATILE ORGANIC COMPOUNDS, CARBON MONOXIDE, AND OXIDES OF NITROGEN FROM NORTH AMERICA  

EPA Science Inventory

The magnitudes, distributions, controlling processes and uncertainties associated with North American natural emissions of oxidant precursors are reviewed. Natural emissions are repsonsible for a major portion of the compounds, including non-methane volatile organic compounds (N...

298

Production of volatile organic compounds by mycobacteria.  

PubMed

The need for improved rapid diagnostic tests for tuberculosis disease has prompted interest in the volatile organic compounds (VOCs) emitted by Mycobacterium tuberculosis complex bacteria. We have investigated VOCs emitted by Mycobacterium bovis BCG grown on Lowenstein-Jensen media using selected ion flow tube mass spectrometry and thermal desorption-gas chromatography-mass spectrometry. Compounds observed included dimethyl sulphide, 3-methyl-1-butanol, 2-methyl-1-propanol, butanone, 2-methyl-1-butanol, methyl 2-methylbutanoate, 2-phenylethanol and hydrogen sulphide. Changes in levels of acetaldehyde, methanol and ammonia were also observed. The compounds identified are not unique to M. bovis BCG, and further studies are needed to validate their diagnostic value. Investigations using an ultra-rapid gas chromatograph with a surface acoustic wave sensor (zNose) demonstrated the presence of 2-phenylethanol (PEA) in the headspace of cultures of M. bovis BCG and Mycobacterium smegmatis, when grown on Lowenstein-Jensen supplemented with glycerol. PEA is a reversible inhibitor of DNA synthesis. It is used during selective isolation of gram-positive bacteria and may also be used to inhibit mycobacterial growth. PEA production was observed to be dependent on growth of mycobacteria. Further study is required to elucidate the metabolic pathways involved and assess whether this compound is produced during in vivo growth of mycobacteria. PMID:22224870

McNerney, Ruth; Mallard, Kim; Okolo, Phyllis Ifeoma; Turner, Claire

2012-03-01

299

Localization of volatile isotopes on a cryotrap  

NASA Astrophysics Data System (ADS)

Neutron-induced fission of uranium allows for the production of high-intensity neutron-rich radioactive ion beams. However, also large quantities of unwanted volatile radioactive species are produced that have to be hindered from contaminating the beamline and vacuum system of the facility. In the framework of radioprotection studies within the MAFF project at the FRM II in Garching with 10 14 fission events/s [D. Habs et al., The Munich accelerator for fission fragments MAFF, Nucl. Instr. and Meth. B 204 (2003) 739], the performance of a cryotrap system has been studied, designed to localize gaseous radioactivity close to its origin. These studies provide important radioprotection information for the planned EURISOL facility with 10 15 fission events/s. Design considerations of a compact cryotrap operated with cold helium gas at a saturation temperature around 18 K will be presented. Activity distribution calculations of the fission source, the cryotrap and the subsequent vacuum system result in a prediction of the retention capability of the cryotrap system of 99.98%. These design calculations have been experimentally verified with three cryotrap prototypes differing in cold surface area as well as in their internal helium gas flow characteristics. Retention capabilities have been measured with and without passive shielding of the external thermal load (300 K) using different tracer gases and an inclusive pressure-related diagnostics as well as mass-spectroscopic measurements.

Thirolf, P. G.; Gross, M.; Habs, D.; Kohlhund, A.; Nebel, F.; Neumayr, J. B.; Stoepler, R.; Szerypo, J.

2008-10-01

300

Pre-eruptive volatile content and degassing history of an evolving peralkaline volcano  

Microsoft Academic Search

The volatile contents of melt inclusions trapped within phenocrysts of quartz and feldspar in peralkaline rhyolites from Mayor Island, New Zealand, have been studied using Fourier transform infrared spectroscopy and ion microprobe analyses. The glass inclusions analyzed span the ~ 130 ka subaerial eruptive history of the island and come from volcanic deposits representing a wide range of eruptive styles

J. Barclay; M. R. Carroll; B. F. Houghton; C. J. N. Wilson

1996-01-01

301

AMBIENT LEVEL VOLATILE ORGANIC COMPOUND (VOC) MONITORING USING SOLID ADSORBANTS - RECENT U.S. EPA STUDIES  

EPA Science Inventory

Ambient air spiked with 1-10 ppbv concentrations of 41 toxic volatile organic compounds (VOCs) listed in U.S. Environmental Protection Agency (EPA) Compendium Method TO-14A was monitored using solid sorbents for sample collection and a Varian Saturn 2000 ion trap mass spectrome...

302

Volatile organic compounds in industrial, urban, and suburban areas: Sources and exposures  

Microsoft Academic Search

This research was aimed at evaluating and refining sampling and analytical methods for airborne volatile organic compounds (VOCs), and at characterizing concentrations and potential exposures of VOCs found in indoor and ambient air in industrial, urban and suburban communities. A new analytical strategy of combining selective ion monitoring (SIM) and scan mode mass spectrometer analyses was developed and evaluated. This

Chunrong Jia

2007-01-01

303

Volatility in the Foreign Currency Futures Market  

Microsoft Academic Search

We examine the volatility implications of around-the-clock foreign exchange trading with transaction data on futures contracts from the Chicago Mercantile Exchange and the London International Financial Futures Exchange. We find higher U.S.-European and U.S.-Japanese exchange-rate volatilities during U.S. trading hours and higher European cross-rate volatilities during European trading hours. While the diclosure of private information through trading may partly explain

Campbell R. Harvey; Roger D. Huang

1991-01-01

304

Bacterial volatiles and their action potential  

Microsoft Academic Search

During the past few years, an increasing awareness concerning the emission of an unexpected high number of bacterial volatiles\\u000a has been registered. Humans sense, intensively and continuously, microbial volatiles that are released during food transformation\\u000a and fermentation, e.g., the aroma of wine and cheese. Recent investigations have clearly demonstrated that bacteria also employ\\u000a their volatiles during interactions with other organisms

Marco Kai; Maria Haustein; Francia Molina; Anja Petri; Birte Scholz; Birgit Piechulla

2009-01-01

305

Fatty Acid Composition and Volatile Constituents of Protaetia brevitarsis Larvae  

PubMed Central

A total of 48 different volatile oils were identified form P. brevitarsis larvae by gas chromatography/mass spectrometry (GC/MS). Acids (48.67%) were detected as the major group in P. brevitarsis larvae comprising the largest proportion of the volatile compounds, followed by esters (19.84%), hydrocarbons (18.90%), alcohols (8.37%), miscellaneous (1.71%), aldehydes (1.35%) and terpenes (1.16%). The major volatile constituents were 9-hexadecenoic acid (16.75%), 6-octadecenoic acid (14.88%) and n-hexadecanoic acid (11.06%). The composition of fatty acid was also determined by GC analysis and 16 fatty acids were identified. The predominant fatty acids were oleic acid (C18:1, 64.24%) followed by palmitic acid (C16:0, 15.89%), palmitoleic acid (C16:1, 10.43%) and linoleic acid (C18:2, 4.69%) constituting more than 95% of total fatty acids. The distinguished characteristic of the fatty acid profile of P. brevitarsis larvae was the high proportion of unsaturated fatty acid (80.54% of total fatty acids) versus saturated fatty acids (19.46% of total fatty acids). Furthermore, small but significant amounts of linoleic, linolenic and ?-linolenic acids bestow P. brevitarsis larvae with considerable nutritional value. The novel findings of the present study provide a scientific basis for the comprehensive utilization of the insect as a nutritionally promising food source and a possibility for more effective utilization.

Yeo, Hyelim; Youn, Kumju; Kim, Minji; Yun, Eun-Young; Hwang, Jae-Sam; Jeong, Woo-Sik; Jun, Mira

2013-01-01

306

Volatile organic compound sensor system  

DOEpatents

Generally, this invention relates to the development of field monitoring methodology for new substances and sensing chemical warfare agents (CWAs) and terrorist substances. It also relates to a portable test kit which may be utilized to measure concentrations of halogenated volatile organic compounds (VOCs) in the field. Specifically it relates to systems for reliably field sensing the potential presence of such items while also distinguishing them from other elements potentially present. It also relates to overall systems and processes for sensing, reacting, and responding to an indicated presence of such substance, including modifications of existing halogenated sensors and arrayed sensing systems and methods.

Schabron, John F. (Laramie, WY); Rovani, Jr., Joseph F. (Laramie, WY); Bomstad, Theresa M. (Waxahachie, TX); Sorini-Wong, Susan S. (Laramie, WY); Wong, Gregory K. (Laramie, WY)

2011-03-01

307

Volatile organic compound sensor system  

DOEpatents

Generally, this invention relates to the development of field monitoring methodology for new substances and sensing chemical warfare agents (CWAs) and terrorist substances. It also relates to a portable test kit which may be utilized to measure concentrations of halogenated volatile organic compounds (VOCs) in the field. Specifically it relates to systems for reliably field sensing the potential presence of such items while also distinguishing them from other elements potentially present. It also relates to overall systems and processes for sensing, reacting, and responding to an indicated presence of such substance, including modifications of existing halogenated sensors and arrayed sensing systems and methods.

Schabron, John F. (Laramie, WY) [Laramie, WY; Rovani, Jr., Joseph F. (Laramie, WY); Bomstad, Theresa M. (Laramie, WY) [Laramie, WY; Sorini-Wong, Susan S. (Laramie, WY) [Laramie, WY

2009-02-10

308

Volatile Release from the Siberian Traps Inferred from Melt Inclusions  

NASA Astrophysics Data System (ADS)

The Siberian Traps Large Igneous Province is one of the largest known continental flood volcanic provinces in the Phanerozoic. The quantification of volatile degassing is particularly important because the Siberian Traps have often been invoked as a possible trigger for the end-Permian mass extinction (e.g. Campbell et al., 1992; Wignall, 2001). Volatile degassing provides a crucial mechanism to link mafic volcanic eruption to global environmental change. Mafic flood basalt magmas are expected to have low volatile contents (similar to mid-ocean ridge basalts). However, Siberian Traps magmas were chambered in and erupted through a thick sedimentary basin and may have interacted with, and obtained volatiles from, sedimentary lithologies such as limestone, coal, and evaporite. Melt inclusions from the Siberian Traps provide insight into the potential total volatile budget throughout the evolution of the large igneous province. These droplets of trapped melt may preserve volatile species that would otherwise have degassed at the time of eruption (Thordarson et al., 1996). Mafic pyroclastic deposits from the lowermost Arydzhangsky suite (basal Siberian Traps) contain clinopyroxene phenocrysts hosting melt inclusions. Electron microprobe analysis of clinopyroxene-hosted re-homogenized melt inclusions indicates maximum measured concentrations of up to 1500 - 2000 ppm sulfur, 500 - 760 ppm chlorine, and 1900 - 2400 ppm fluorine. Olivines from the Maymechinsky suite, recognized as the last extrusive products of Siberian Traps volcanism, contain melt inclusions with maximum sulfur concentrations in the range of 5000 ppm, and less substantial concentrations of chlorine and fluorine. Intrusive igneous rocks from the province also display significant volatile contents. A sill from the Ust-Ilimsk region yielded plagioclase-hosted melt inclusions which contain chlorine and fluorine concentrations nearing one weight percent. Visscher et al. (2004) proposed that chlorofluorocarbon compounds (CFCs) may have played a major role in the terrestrial end-Permian extinction. These CFCs are powerful catalysts for the breakdown of ozone, a process which can expose the biosphere to increased ultraviolet radiation. Measurements of elevated chlorine and fluorine from the Siberian Traps may thus provide a concrete source for CFCs that could have triggered this kill mechanism.

Black, B. A.; Elkins-Tanton, L. T.; Rowe, M. C.; Ukstins Peate, I.

2009-12-01

309

THEORETICAL EVALUATION OF STABILITY OF VOLATILE ORGANIC CHEMICALS AND POLAR VOLATILE ORGANIC CHEMICALS IN CANISTERS  

EPA Science Inventory

A mathematical model was developed for describing loss by physical adsorption of volatile organic chemicals (VOCs) and polar volatile organic chemicals (PVOCs) in stainless steel canisters. he model incorporates compound specific properties such as polarizability, vapor concentra...

310

EOBII, a gene encoding a flower-specific regulator of phenylpropanoid volatiles' biosynthesis in petunia.  

PubMed

Floral scent, which is determined by a complex mixture of low molecular weight volatile molecules, plays a major role in the plant's life cycle. Phenylpropanoid volatiles are the main determinants of floral scent in petunia (Petunia hybrida). A screen using virus-induced gene silencing for regulators of scent production in petunia flowers yielded a novel R2R3-MYB-like regulatory factor of phenylpropanoid volatile biosynthesis, EMISSION OF BENZENOIDS II (EOBII). This factor was localized to the nucleus and its expression was found to be flower specific and temporally and spatially associated with scent production/emission. Suppression of EOBII expression led to significant reduction in the levels of volatiles accumulating in and emitted by flowers, such as benzaldehyde, phenylethyl alcohol, benzylbenzoate, and isoeugenol. Up/downregulation of EOBII affected transcript levels of several biosynthetic floral scent-related genes encoding enzymes from the phenylpropanoid pathway that are directly involved in the production of these volatiles and enzymes from the shikimate pathway that determine substrate availability. Due to its coordinated wide-ranging effect on the production of floral volatiles, and its lack of effect on anthocyanin production, a central regulatory role is proposed for EOBII in the biosynthesis of phenylpropanoid volatiles. PMID:20543029

Spitzer-Rimon, Ben; Marhevka, Elena; Barkai, Oren; Marton, Ira; Edelbaum, Orit; Masci, Tania; Prathapani, Naveen-Kumar; Shklarman, Elena; Ovadis, Marianna; Vainstein, Alexander

2010-06-01

311

Dynamic modeling of biodegradation and volatilization of hazardous aromatic substances in aerobic bioreactor.  

PubMed

The aerobic biological process is one of the best technologies available for removing hazardous organic substances from industrial wastewaters. But in the case of volatile organic compounds (benzene, toluene, ethylbenzene, p-xylene, naphthalene), volatilization can contribute significantly to their removal from the liquid phase. One major issue is to predict the competition between volatilization and biodegradation in biological process depending on the target molecule. The aim of this study was to develop an integrated dynamic model to evaluate the influence of operating conditions, kinetic parameters and physical properties of the molecule on the main pathways (biodegradation and volatilization) for the removal of Volatile Organic Compounds (VOC). After a comparison with experimental data, sensitivity studies were carried out in order to optimize the aerated biological process. Acclimatized biomass growth is limited by volatilization, which reduces the bioavailability of the substrate. Moreover, the amount of biodegraded substrate is directly proportional to the amount of active biomass stabilized in the process. Model outputs predict that biodegradation is enhanced at high SRT for molecules with low H and with a high growth rate population. Air flow rate should be optimized to meet the oxygen demand and to minimize VOC stripping. Finally, the feeding strategy was found to be the most influential operating parameter that should be adjusted in order to enhance VOC biodegradation and to limit their volatilization in sequencing batch reactors (SBR). PMID:22877879

Mozo, I; Lesage, G; Yin, J; Bessiere, Y; Barna, L; Sperandio, M

2012-10-15

312

Flavour compounds in tomato fruits: identification of loci and potential pathways affecting volatile composition  

PubMed Central

The unique flavour of a tomato fruit is the sum of a complex interaction among sugars, acids, and a large set of volatile compounds. While it is generally acknowledged that the flavour of commercially produced tomatoes is inferior, the biochemical and genetic complexity of the trait has made breeding for improved flavour extremely difficult. The volatiles, in particular, present a major challenge for flavour improvement, being generated from a diverse set of lipid, amino acid, and carotenoid precursors. Very few genes controlling their biosynthesis have been identified. New quantitative trait loci (QTLs) that affect the volatile emissions of red-ripe fruits are described here. A population of introgression lines derived from a cross between the cultivated tomato Solanum lycopersicum and its wild relative, S. habrochaites, was characterized over multiple seasons and locations. A total of 30 QTLs affecting the emission of one or more volatiles were mapped. The data from this mapping project, combined with previously collected data on an IL population derived from a cross between S. lycopersicum and S. pennellii populations, were used to construct a correlational database. A metabolite tree derived from these data provides new insights into the pathways for the synthesis of several of these volatiles. One QTL is a novel locus affecting fruit carotenoid content on chromosome 2. Volatile emissions from this and other lines indicate that the linear and cyclic apocarotenoid volatiles are probably derived from separate carotenoid pools.

Mathieu, Sandrine; Cin, Valeriano Dal; Fei, Zhangjun; Li, Hua; Bliss, Peter; Taylor, Mark G.; Klee, Harry J.; Tieman, Denise M.

2009-01-01

313

Study of the volatile compounds produced by Debaryomyces hansenii NRRL Y-7426 during the fermentation of detoxified concentrated distilled grape marc hemicellulosic hydrolysates.  

PubMed

The volatile compounds produced by Debaryomyces hansenii NRRL Y-7426 during the fermentation of detoxified concentrated distilled grape marc hemicellulosic hydrolysates was analysed by GC-MS. Thirty-five compounds corresponding to ten groups of volatile compounds: terpenes, higher alcohols, C? alcohols, aldehydes, volatile acids, acetates, ethyl esters, volatile phenols, sulphur compounds and hydrocarbons were identified. The supplementation with commercial nutrients increased the concentration of 2-phenylethanol, a commercial flavour and fragrance compound, with a rose-like odour, employed in cosmetics and food industries; and other positive compounds to the aroma such as terpenes and ethyl esters. Non-supplemented media produced the highest content in higher alcohols, volatile acids, sulphur compounds and in the majority of hydrocarbons detected, meanwhile supplementation with vinasses hardly produced volatile compounds. Only four volatile compounds contributed directly to the aroma according to the OAVs values higher than 1. Finally, a PCA analysis allowed accounting for 100 % of the variance. PMID:22806750

Salgado, José Manuel; González-Barreiro, Carmen; Rodríguez-Solana, Raquel; Simal-Gándara, Jesús; Domínguez, José Manuel; Cortés, Sandra

2012-11-01

314

Conference on Deep Earth and Planetary Volatiles  

NASA Technical Reports Server (NTRS)

The following topics are covered in the presented papers: (1) rare gases systematics and mantle structure; (2) volatiles in the earth; (3) impact degassing of water and noble gases from silicates; (4) D/H ratios and H2O contents of mantle-derived amphibole megacrysts; (5) thermochemistry of dense hydrous magnesium silicates; (6) modeling of the effect of water on mantle rheology; (7) noble gas isotopes and halogens in volatile-rich inclusions in diamonds; (8) origin and loss of the volatiles of the terrestrial planets; (9) structure and the stability of hydrous minerals at high pressure; (10) recycling of volatiles at subduction zones and various other topics.

1994-01-01

315

Deodorization of garlic breath volatiles by food and food components.  

PubMed

The ability of foods and beverages to reduce allyl methyl disulfide, diallyl disulfide, allyl mercaptan, and allyl methyl sulfide on human breath after consumption of raw garlic was examined. The treatments were consumed immediately following raw garlic consumption for breath measurements, or were blended with garlic prior to headspace measurements. Measurements were done using a selected ion flow tube-mass spectrometer. Chlorophyllin treatment demonstrated no deodorization in comparison to the control. Successful treatments may be due to enzymatic, polyphenolic, or acid deodorization. Enzymatic deodorization involved oxidation of polyphenolic compounds by enzymes, with the oxidized polyphenols causing deodorization. This was the probable mechanism in raw apple, parsley, spinach, and mint treatments. Polyphenolic deodorization involved deodorization by polyphenolic compounds without enzymatic activity. This probably occurred for microwaved apple, green tea, and lemon juice treatments. When pH is below 3.6, the enzyme alliinase is inactivated, which causes a reduction in volatile formation. This was demonstrated in pH-adjusted headspace measurements. However, the mechanism for volatile reduction on human breath (after volatile formation) is unclear, and may have occurred in soft drink and lemon juice breath treatments. Whey protein was not an effective garlic breath deodorant and had no enzymatic activity, polyphenolic compounds, or acidity. Headspace concentrations did not correlate well to breath treatments. PMID:24592995

Munch, Ryan; Barringer, Sheryl A

2014-04-01

316

Volatile and non-volatile compounds in irradiated semi-rigid crystalline poly(ethylene terephthalate) polymers.  

PubMed

In this study two different semi-rigid crystalline and oriented polyethylene terephthalate materials were used and were irradiated at 25-kGy dose at room temperature by using a caesium137 radiator. Volatile and non-volatile compounds present in the irradiated materials were identified and quantified. The qualitative results obtained from HS/GC/TCD/FID analysis at room temperature showed volatiles could not be identified. The HS/GC/MSD analysis performed at 106 degrees C showed that the irradiation generated 668-742 micrograms/kg formic acid, 868-922 micrograms/kg acetic acid, 17-32 micrograms/kg 1,3-dioxolane, and 47-71 micrograms/kg 2-methyl-1, 3-dioxolane based on PET weight. The results obtained from the thermal desorption and GC/MSD performed at 200 degrees C showed that 10-12 mg/kg acetaldehyde, 479-975 micrograms/kg 1,3-dioxolane, and 6.6-11.2 mg/kg methyl-1, 3-dioxolane were detected after irradiation. The concentrations of the two dioxolanes found from thermal desorption were much higher than those observed in the HS, although formic and acetic acids were not detected. It is possible that the formic and acetic acids produced by irradiation underwent further reactions with ethylene glycol during thermal desorption to form the dioxolanes. The soluble solid extracted from various PET specimens before and after irradiation were in a range of 0.67-0.78%. PET cyclic trimer is the major component and is present at 0.41-0.50%, accounting for more than 50% of the percent total solid in PET. Statistically, irradiation did not increase the soluble solid and cyclic trimer. The overall results suggest that 25-kGy irradiation had a significant effect on increasing the volatile but not the non-volatile compounds detected in the PET specimens. PMID:11212551

Komolprasert, V; McNeal, T P; Agrawal, A; Adhikari, C; Thayer, D W

2001-01-01

317

Econometric analysis of realized volatility and its use in estimating stochastic volatility models  

Microsoft Academic Search

The availability of intraday data on the prices of speculative assets means that we can use quadratic variation-like measures of activity in financial markets, called realized volatility, to study the stochastic properties of returns. Here, under the assumption of a rather general stochastic volatility model, we derive the moments and the asymptotic distribution of the realized volatility error-the difference between

Ole E. Barndorff-Nielsen; Neil Shephard

2002-01-01

318

Comparative study of volatile oil content and antimicrobial activity of pecan cultivars growing in Egypt.  

PubMed

The volatile oils obtained from the leaves of four pecan cultivars growing in Egypt were evaluated for their chemical composition and antimicrobial activity. The selected cultivars (cv.) were Carya illinoinensis (Wangneh.) K. Koch. cv. Wichita, C. illinoinensis cv. Western Schley, C. illinoinensis cv. Cherokee, and C. illinoinensis cv. Sioux. The gas chromatography-mass spectrometry analyses revealed that the volatile oils from samples of the different cultivars differ in composition and percentage of their components. ?-Curcumene was found as the major constituent of the cv. Wichita oil, whereas germacrene D was the major component of cv. Sioux, cv. Cherokee, and cv. Western Schley. The antimicrobial activity was assayed using the Kirby-Bauer Method by measuring the zone of inhibition of growth. All volatile oils displayed an antimicrobial activity against the tested bacterial strains. On the other hand, only the volatile oil of cv. Wichita showed an antifungal effect on Aspergillus flavus. This work has identified candidates of volatile oils for future in vivo studies to develop antibiotic substitutes for the diminution of human and animal pathogenic bacteria. Nevertheless, the variations of the volatile oil components and antimicrobial potencies of the different studied cultivars, necessitate identifying the cultivars used in future studies. PMID:24180553

El Hawary, Seham S; Zaghloul, Soumaya S; El Halawany, Ali M; El Bishbishy, Mahitab H

2013-11-01

319

Citrus Leaf Volatiles as Affected by Developmental Stage and Genetic Type  

PubMed Central

Major volatiles from young and mature leaves of different citrus types were analyzed by headspace-solid phase microextraction (HS-SPME)-GC-MS. A total of 123 components were identified form nine citrus cultivars, including nine aldehydes, 19 monoterpene hydrocarbons, 27 oxygenated monoterpenes, 43 sesquiterpene hydrocarbons, eight oxygenated sesquiterpenes, two ketones, six esters and nine miscellaneous. Young leaves produced higher amounts of volatiles than mature leaves in most cultivars. The percentage of aldehyde and monoterpene hydrocarbons increased, whilst oxygenated monoterpenes and sesquiterpenes compounds decreased during leaf development. Linalool was the most abundant compound in young leaves, whereas limonene was the chief component in mature ones. Notably, linalool content decreased, while limonene increased, during leaf development in most cultivars. Leaf volatiles were also affected by genetic types. A most abundant volatile in one or several genotypes can be absent in another one(s), such as limonene in young leaves of lemon vs. Satsuma mandarin and ?-terpinene in mature leaves of three genotypes vs. the other four. Compositional data was subjected to multivariate statistical analysis, and variations in leaf volatiles were identified and clustered into six groups. This research determining the relationship between production of major volatiles from different citrus varieties and leaf stages could be of use for industrial and culinary purposes.

Azam, Muhammad; Jiang, Qian; Zhang, Bo; Xu, Changjie; Chen, Kunsong

2013-01-01

320

Antimicrobial activity of volatile components and various extracts of the red alga Jania rubens.  

PubMed

The methanol, dichloromethane, hexane, chloroform and volatile oil extracts of the red alga Jania rubens were tested in vitro for their antimicrobial activity (five Gram-positive, four Gram-negative bacteria and Candida albicans ATCC 10239). GC-MS analysis of the volatile components of J. rubens identified 40 compounds which constituted 77.53% of the total. The volatile components of J. rubens consisted of n-docosane (6.35%), n-eicosane (5.77%) and n-tetratriacontane (5.58%) as major components. The methanol and chloroform extracts (4 mg/disc) showed more potent antimicrobial activity than the hexane and dichloromethane extracts and the volatile oil of J. rubens. PMID:17128433

Karabay-Yavasoglu, N Ulku; Sukatar, Atakan; Ozdemir, Guven; Horzum, Zerrin

2007-02-01

321

Volatile compounds in the skin and pulp of Queen Anne's pocket melon.  

PubMed

The quantitative distribution of volatile compounds in the skin and pulp of Queen Anne's pocket melon [Cucumis melo var. dudaim (L.) Naudin] has been investigated. Volatile compounds were extracted by liquid-liquid microextraction (LLME) using chloroform and analyzed by GC-FID and GC-MS. Sixty volatiles, including 20 esters, 15 alcohols, 7 lactones, 7 aldehydes and ketones, 6 sulfur compounds, and 5 C(6) compounds, have been identified. Among them, 38 were reported for the first time in pocket melon, 10 of them have been, however, labeled "tentatively identified". The results showed that the levels of volatiles in skin were significantly higher than those observed in pulp. Eugenol, the major constituent in skin (15.3%), thioether esters, and lactones were thought to contribute significantly to the unique aroma of the pocket melon. Finally, the distribution of lactones was also found to be different in skin and pulp according to their carbon chain length. PMID:17032026

Aubert, Christophe; Pitrat, Michel

2006-10-18

322

The role of volatiles in the reduction of iron oxides  

NASA Astrophysics Data System (ADS)

With iron ore reduction processes using coal-ore pellets or mixtures, it is possible that volatiles from the coals can contribute to the overall reduction. By identifying the possible reducing species in the volatiles as H2/CO and simulating these constituents, the rates for H2 and CO were investigated in the temperature and reduction range of interest where hydrogen was the major reductant and studied in detail. In the initial stages of the present study, the fundamentals of hydrogen reduction of fine powder were found to be a complex mechanism of chemical kinetics and mass transfer. Complete uniform reduction for porous and dense iron ores were not observed contrary to existing work regarding this subject. Morphological observations of iron ores reduced at low and high temperatures showed a topochemical receding interface to be dominating with an intermediate region developing for higher temperature samples indicating the importance of pore mass transfer at the later stages of reduction. Although the activation energy of 50˜56 kJ/mole for these powder samples were comparable to the literature values for solely chemical kinetics controlled reactions, the reaction rates were not proportional to sample weight and also did not exhibit complete uniform internal reduction. The calculated mass transfer rates were comparable to the observed rate which suggested that bulk mass transfer is important to the mixed-control. The reaction rate at the mixed control regime was found to be first order with respect to hydrogen partial pressure. Results of reducing iron oxide powders in a mixture of He-40%H2 -5%CO and H2-1%H2S showed that H2S and CO which is involved with the volatiles does not affect the rate at the reduction range of interest indicating the role of volatiles is dominated by the hydrogen reduction. The single composite pellet experiments at 900 and 1000°C showed significant fixed carbon reduction to occur above 1000°C. Depending upon the type of carbon reductant in the composite pellet, secondary reactions with carbon and H2O was possible. Sintering of the pellets did not occur until a significant amount of reduction was obtained and thus for volatile reduction it is likely that the effects of sintering was negligible. To determine the possibility of volatile reduction, a layer of Fe 2O3 powders were spread over HV coals resulting in the reduction of the top layer by about 20% at 1000°C after 1000 seconds. The morphology of the reduced Fe2O3 layer indicated that the reduction is higher near the interface of Coal/Fe2O3. The volatile reduction of a single layer of composite pellet was found to be negligible. However, the reduction of Fe2O3 pellets at the top layer by the volatiles from the bottom layers of a three-layer pellet geometry was observed to be about 15%. From the morphological observations and the computed rates of bulk mass transfer, volatile reduction seems to be controlled by a mixed-controlled mechanism of bulk mass transfer and the limited-mixed control. Using the reduction information obtained from the single pellet experiments reduced in hydrogen, an empirical relationship was obtained to approximately predict the amount of volatile reduction up to 20%.

Sohn, Il

323

Non-volatile memory based on transition metal perovskite oxide resistance switching  

NASA Astrophysics Data System (ADS)

Driven by the non-volatile memory market looking for new advanced materials, this dissertation focuses on the study of non-volatile resistive random access memory (RRAM) based on transition metal perovskite oxides. Pr0.7Ca0.3MnO3 (PCMO), one of the representative materials in this family, has demonstrated a large range of resistance change when short electrical pulses with different polarity are applied. Such electrical-pulse-induced resistance (EPIR), with attractive features such as fast response, low power, high-density and non-volatility, makes PCMO and related materials promising candidates for non-volatile RRAM application. The objective of this work is to investigate, optimize and understand the properties of this universal EPIR behavior in transition metal perovskite oxide, represented by PCMO thin film devices. The research work includes fabrication of PCMO thin film devices, characterization of these EPIR devices as non-volatile memories, and investigation of their resistive switching mechanisms. The functionality of this perovskite oxide RRAM, including pulse magnitude/width dependence, power consumption, retention, endurance and radiation-hardness has been investigated. By studying the "shuttle tail" in hysteresis switching loops of oxygen deficient devices, a diffusion model with oxygen ions/vacancies as active agents at the metal/oxide interface is proposed for the non-volatile resistance switching effect in transition metal perovskite oxide thin films. The change of EPIR switching behavior after oxygen/argon ion implantation also shows experiment support for the proposed model. Furthermore, the universality, scalability and comparison with other non-volatile memories are discussed for future application.

Nian, Yibo

324

IN-HOUSE REFORMULATION AND EVALUATION OF MAJOR MANUFACTURER'S VEHICLE REFINISHING COATINGS  

EPA Science Inventory

The goal is to develop high quality vehicle refinishing paint formulations that contain much less toxi and volatile solvents than the major manufacturer's Federal compliant and California complaint coatings. The reformulated coatings being developed will maintain or improve upo...

325

Volatile exchange between undamaged plants - a new mechanism affecting insect orientation in intercropping.  

PubMed

Changes in plant volatile emission can be induced by exposure to volatiles from neighbouring insect-attacked plants. However, plants are also exposed to volatiles from unattacked neighbours, and the consequences of this have not been explored. We investigated whether volatile exchange between undamaged plants affects volatile emission and plant-insect interaction. Consistently greater quantities of two terpenoids were found in the headspace of potato previously exposed to volatiles from undamaged onion plants identified by mass spectrometry. Using live plants and synthetic blends mimicking exposed and unexposed potato, we tested the olfactory response of winged aphids, Myzus persicae. The altered potato volatile profile deterred aphids in laboratory experiments. Further, we show that growing potato together with onion in the field reduces the abundance of winged, host-seeking aphids. Our study broadens the ecological significance of the phenomenon; volatiles carry not only information on whether or not neighbouring plants are under attack, but also information on the emitter plants themselves. In this way responding plants could obtain information on whether the neighbouring plant is a competitive threat and can accordingly adjust their growth towards it. We interpret this as a response in the process of adaptation towards neighbouring plants. Furthermore, these physiological changes in the responding plants have significant ecological impact, as behaviour of aphids was affected. Since herbivore host plants are potentially under constant exposure to these volatiles, our study has major implications for the understanding of how mechanisms within plant communities affect insects. This knowledge could be used to improve plant protection and increase scientific understanding of communication between plants and its impact on other organisms. PMID:23922710

Ninkovic, Velemir; Dahlin, Iris; Vucetic, Andja; Petrovic-Obradovic, Olivera; Glinwood, Robert; Webster, Ben

2013-01-01

326

Neonatal withdrawal from maternal volatile substance abuse  

Microsoft Academic Search

AIM: To determine whether neonates born to mothers who are volatile substance abusers are at risk for an abstinence syndrome. METHODS: A consecutive sample of infants born to volatile substance abusing mothers was studied over four years, in a university affiliated medical centre with a variable mix of primary, secondary, and tertiary care patients. Infants were clinically scored with the

M. Tenenbein; O. G. Casiro; M. M. Seshia; V. D. Debooy

1996-01-01

327

Lunar Volatiles: An Earth-Moon Perspective.  

National Technical Information Service (NTIS)

It has generally been accepted that the Moon is depleted in volatile elements. However, the recent discovery of measurable water in lunar glasses and apatites suggests that volatiles are not as depleted as was once thought. And, in fact, some authors have...

J. H. Jones

2011-01-01

328

Volatility Determinants: Heterogeneity, Leverage, and Jumps  

Microsoft Academic Search

We identify three main endogenous determinants in the dynamics of asset price volatility, namely heterogeneity, leverage, and jumps. We find that each of the three components plays a significant role in volatility forecasting and neglecting one of them is detrimental to the forecasting performance. Importantly, we find remarkable forecasting power for the negative past returns at all the considered frequencies,

Fulvio Corsi; Roberto Reno

329

Aggregation and Model Construction for Volatility Models  

Microsoft Academic Search

In this paper we will rigourously study some of the properties of continuous time stochastic volatility models. We have five main results, including: the stochastic volatility class can be linked to Cox process based models of tick-by-tick financial data; we characterise the moments, autocorrelation function and spectrum of squared returns; based only on discrete time returns, we give a simple

O. E. Barndorf-Nielsen; Neil Shephard

1998-01-01

330

Oil price volatility and the macroeconomy  

Microsoft Academic Search

Recent theoretical work suggests that oil price shocks may have an adverse impact on the macroeconomy, not only because they increase the level of oil prices, but also because they raise oil price volatility. This paper provides empirical support for this proposition by showing that oil price volatility, measured by monthly standard deviations of daily oil prices, helps to forecast

J. Peter Ferderer

1996-01-01

331

Volatility transmission patterns and terrorist attacks  

Microsoft Academic Search

The objective of this study is to analyse volatility transmission between the US and Eurozone stock markets considering the financial market responses to the September 11, March 11 and July 7 terrorist attacks. In order to do this, we use a multivariate GARCH model and take into account the asymmetric volatility phenomenon, the non-synchronous trading problem and the turmoil periods

Helena Chuliá; Francisco Climent; Pilar Soriano; Hipòlit Torró

2009-01-01

332

Non-volatile, solid state bistable electrical switch  

NASA Technical Reports Server (NTRS)

A bistable switching element is made of a material whose electrical resistance reversibly decreases in response to intercalation by positive ions. Flow of positive ions between the bistable switching element and a positive ion source is controlled by means of an electrical potential applied across a thermal switching element. The material of the thermal switching element generates heat in response to electrical current flow therethrough, which in turn causes the material to undergo a thermal phase transition from a high electrical resistance state to a low electrical resistance state as the temperature increases above a predetermined value. Application of the electrical potential in one direction renders the thermal switching element conductive to pass electron current out of the ion source. This causes positive ions to flow from the source into the bistable switching element and intercalate the same to produce a non-volatile, low resistance logic state. Application of the electrical potential in the opposite direction causes reverse current flow which de-intercalates the bistable logic switching element and produces a high resistance logic state.

Williams, Roger M. (inventor)

1994-01-01

333

Lunar Volatiles: An Earth-Moon Perspective  

NASA Technical Reports Server (NTRS)

It has generally been accepted that the Moon is depleted in volatile elements. However, the recent discovery of measurable water in lunar glasses and apatites suggests that volatiles are not as depleted as was once thought. And, in fact, some authors have claimed that water contents of the lunar and terrestrial mantles are similar. Moderately volatile alkali elements may have a bearing on this issue. In general, bulk Moon alkalis are depleted relative to the bulk silicate Earth. Although the bulk lunar chemical composition is difficult to reconstruct, good correlations of alkali elements with refractory lithophile incompatible trace elements make this conclusion robust. These observations have been taken to mean that the Moon overall is depleted in volatiles relative to the Earth. Since water is more volatile than any of the alkali elements, presumably this conclusion is true for water, or even more so.

Jones, John H.

2011-01-01

334

Volatile organic compound sensing devices  

DOEpatents

Apparatus employing vapochromic materials in the form of inorganic double complex salts which change color reversibly when exposed to volatile organic compound (VOC) vapors is adapted for VOC vapor detection, VOC aqueous matrix detection, and selective VOC vapor detection. The basic VOC vapochromic sensor is incorporated in various devices such as a ground probe sensor, a wristband sensor, a periodic sampling monitor, a soil/water penetrometer, an evaporative purge sensor, and various vacuum-based sensors which are particularly adapted for reversible/reusable detection, remote detection, continuous monitoring, or rapid screening of environmental remediation and waste management sites. The vapochromic sensor is used in combination with various fiber optic arrangements to provide a calibrated qualitative and/or quantitative indication of the presence of VOCs.

Lancaster, Gregory D. (Idaho Falls, ID); Moore, Glenn A. (Idaho Falls, ID); Stone, Mark L. (Idaho Falls, ID); Reagen, William K. (Stillwater, MN)

1995-01-01

335

Volatile organic compound sensing devices  

DOEpatents

Apparatus employing vapochromic materials in the form of inorganic double complex salts which change color reversibly when exposed to volatile organic compound (VOC) vapors is adapted for VOC vapor detection, VOC aqueous matrix detection, and selective VOC vapor detection. The basic VOC vapochromic sensor is incorporated in various devices such as a ground probe sensor, a wristband sensor, a periodic sampling monitor, a soil/water penetrometer, an evaporative purge sensor, and various vacuum-based sensors which are particularly adapted for reversible/reusable detection, remote detection, continuous monitoring, or rapid screening of environmental remediation and waste management sites. The vapochromic sensor is used in combination with various fiber optic arrangements to provide a calibrated qualitative and/or quantitative indication of the presence of VOCs. 15 figs.

Lancaster, G.D.; Moore, G.A.; Stone, M.L.; Reagen, W.K.

1995-08-29

336

Kinetics of volatile extraction from carbonaceous chondrites: Dehydration of talc  

NASA Technical Reports Server (NTRS)

Carbonaceous chondrites are believed to be the primary constituents of near-Earth asteroids and Phobos and Deimos, and are potential resources of fuels that may be exploited for future planetary missions. Calculations of equilibrium phase relations suggest that talc (Ta) and antigorite (Ant) are likely to be the major hydrous phases in the C1 and C2 meteorites (Ganguly and Saxena, 1989), which constitute the most volatile rich classes of carbonaceous chondrites. The dehydration kinetics of talc are studied as a function of temperature, grain size, composition and fluid fugacity, as part of a systematic study of the reaction kinetics of the volatile bearing phases that are either known or likely to be present in carbonaceous chondrites. The dehydration kinetics were investigated at 1 bar, 775 to 875 C by monitoring the in-situ weight loss as a function of time of a natural talc. The talc platelets had a dimension of 0.8 to 1 micron. The run durations varied from 233.3 hours at 775 C (48 percent dehydration) to 20.8 hours at 875 C (80 pct. dehydration). The results can be adequately represented by a given rate equation. Theoretical analysis suggests that the reduction in the concentration of H2O in the environment of dehydrating talc, as would be encountered in processing chondritic materials, will have negligible effect on the rate of dehydration, unless there is a change of reaction mechanism owing to the presence of other volatile species.

Bose, Kunal; Ganguly, Jibamitra

1991-01-01

337

Volatile organic compound losses from sewage sludge-amended soils  

SciTech Connect

Volatile organic compounds (VOCs) applied to soil in sludge have been assumed to disappear quickly and completely. The VOC behavior in sludge-amended soils has been studied previously only in laboratory systems where the sludged soil has been spiked with compounds of interest. Behavior in these systems may not necessarily represent compound behavior in field soils to which contaminated sludge is added. A series of laboratory microcosm experiments were designed therefore to investigate the behavior of toluene, ethyl benzene, o-, m-, and p-xylene applied to soil in contaminated sludge, and factors influencing loss processes. The VOC loss from sludge-amended soil was well described by a simple one step pseudo-first-order model but in certain soils was better described by a two step first-order model. Volatilization was the predominant loss process. Rates of loss depended on sludge application rate, method of sludge application, soil properties, and on compound characteristics. Experiments indicated that spiking sludge-amended soils gave a reasonable indication of VOC loss rates from systems amended with contaminated sludge at least over a period of 23 d. The majority of VOCs applied to soils in sludge volatilizes quickly to the atmosphere over a few to 10s of days with a small fraction lost more slowly. Potential for VOC crop uptake, livestock ingestion, and contamination of ground water is low under routine, managed applications of sewage sludge to agricultural land.

Wilson, S.C.; Jones, K.C.

1999-08-01

338

Mercury Polar Volatiles: Complex Hydrocarbons vs Water Ice  

NASA Astrophysics Data System (ADS)

Radiometric measurements by MLA elucidate the emplacement and sequestration of volatiles on Mercury, repeatedly imaged by Earth-based radar. We have reported [Neumann et al., 2012, LPSC, #2651] the presence of MLA-dark deposits coinciding with many of the radar-bright regions thought to indicate the presence of subsurface ice. Thermal models [Paige et al., 2012, LPSC, #2875] suggest that at certain latitudes, maximum temperatures exceed the regime of stability of surface water ice, but average subsurface temperatures allow its persistence there against sublimation. At the highest latitudes, where radar signatures fill large portions of polar craters, measurements by MLA are at the noise limit for measuring reflectance; however, several profiles have been obtained with useful energy data. We explore the working hypothesis that dark, complex organics (common in asteroids & comets) overly water ice, providing an important constraint on thermal models of polar regions. Repeated profiles are being acquired in the extended mission in order to more clearly delineate the boundaries of volatile deposits. A good sampling of craters over the appropriate latitude range will further constrain the composition of volatiles. We will report on further mapping in the MESSENGER Extended Mission to the coldest north polar regions, where the majority of ices lie.

Neumann, G. A.; Mazarico, E.; Zuber, M. T.; Smith, D. E.; Paige, D. A.; Solomon, S. C.; Ernst, C. M.; Barnouin, O. S.; Mao, D.

2012-12-01

339

The ESA Lunar Lander and the search for Lunar Volatiles  

NASA Astrophysics Data System (ADS)

Following the Apollo era the moon was considered a volatile poor body. Samples collected from the Apollo missions contained only ppm levels of water formed by the interaction of the solar wind with the lunar regolith [1]. However more recent orbiter observations have indicated that water may exist as water ice in cold polar regions buried within craters at concentrations of a few wt. % [2]. Infrared images from M3 on Chandrayaan-1 have been interpreted as showing the presence of hydrated surface minerals with the ongoing hydroxyl/water process feeding cold polar traps. This has been supported by observation of ephemeral features termed "space dew" [3]. Meanwhile laboratory studies indicate that water could be present in appreciable quantities in lunar rocks [4] and could also have a cometary source [5]. The presence of sufficient quantities of volatiles could provide a resource which would simplify logistics for long term lunar missions. The European Space Agency (ESA's Directorate of Human Spaceflight and Operations) have provisionally scheduled a robotic mission to demonstrate key technologies to enable later human exploration. Planned for launch in 2018, the primary aim is for precise automated landing, with hazard avoidance, in zones which are almost constantly illuminated (e.g. at the edge of the Shackleton crater at the lunar south pole). These regions would enable the solar powered Lander to survive for long periods > 6 months, but require accurate navigation to within 200m. Although landing in an illuminated area, these regions are close to permanently shadowed volatile rich regions and the analysis of volatiles is a major science objective of the mission. The straw man payload includes provision for a Lunar Volatile and Resources Analysis Package (LVRAP). The authors have been commissioned by ESA to conduct an evaluation of possible technologies to be included in L-VRAP which can be included within the Lander payload. Scientific aims are to demonstrate the extraction of volatiles and determine the volatile inventory of the moon with a view for future In-Situ Resource Utilization (ISRU). Surface samples will be collected by a robotic arm with the possibility of a rover to collect more distant samples. The concentration, chemical and accurate isotopic ratios (D/H, 12C/13C, 15N/14N, 18O/16O and noble gases) of liberated volatiles will be determined, possibly using similar technology to the Philae comet lander of the Rosetta mission [6]. An additional aim is the monitoring of the chemical and isotopic composition of the tenuous lunar atmosphere [7] which will become contaminated by active human exploration. The lunar atmosphere will provide information on the processes involved in forming lunar volatiles and their concentration mechanisms. Modelling the effects of contamination from the Lander is an essential part of this study so that these can be recognized and minimized.

Morse, A. D.; Barber, S. J.; Pillinger, J. M.; Sheridan, S.; Wright, I. P.; Gibson, E. K.; Merrifield, J. A.; Waltham, N. R.; Waugh, L. J.; Pillinger, C. T.

2011-10-01

340

Breath measurements as volatile organic compound biomarkers.  

PubMed Central

A brief review of the uses of breath analysis in studies of environmental exposure to volatile organic compounds (VOCs) is provided. The U.S. Environmental Protection Agency's large-scale Total Exposure Assessment Methodology Studies have measured concentrations of 32 target VOCs in the exhaled breath of about 800 residents of various U.S. cities. Since the previous 12-hr integrated personal air exposures to the same chemicals were also measured, the relation between exposure and body burden is illuminated. Another major use of the breath measurements has been to detect unmeasured pathways of exposure; the major impact of active smoking on exposure to benzene and styrene was detected in this way. Following the earlier field studies, a series of chamber studies have provided estimates of several important physiological parameters. Among these are the fraction, f, of the inhaled chemical that is exhaled under steady-state conditions and the residence times. tau i in several body compartments, which may be associated with the blood (or liver), organs, muscle, and fat. Most of the targeted VOCs appear to have similar residence times of a few minutes, 30 min, several hours, and several days in the respective tissue groups. Knowledge of these parameters can be helpful in estimating body burden from exposure or vice versa and in planning environmental studies, particularly in setting times to monitor breath in studies of the variation with time of body burden. Improvements in breath methods have made it possible to study short-term peak exposure situations such as filling a gas tank or taking a shower in contaminated water.

Wallace, L; Buckley, T; Pellizzari, E; Gordon, S

1996-01-01

341

Improved Ambient Pressure Pyroelectric Ion Source  

NASA Technical Reports Server (NTRS)

The detection of volatile vapors of unknown species in a complex field environment is required in many different applications. Mass spectroscopic techniques require subsystems including an ionization unit and sample transport mechanism. All of these subsystems must have low mass, small volume, low power, and be rugged. A volatile molecular detector, an ambient pressure pyroelectric ion source (APPIS) that met these requirements, was recently reported by Caltech researchers to be used in in situ environments.

Beegle, Luther W.; Kim, Hugh I.; Kanik, Isik; Ryu, Ernest K.; Beckett, Brett

2011-01-01

342

Volatiles in lunar regolith samples: A survey  

NASA Astrophysics Data System (ADS)

A summary is given of the literature data on the content of volatiles in the lunar regolith, the characterization of the likely sources of the volatiles, and the possible processes of their migration and burial. The main sources of volatiles in the regolith are the solar wind, small Solar System bodies (comets and meteorites), and the lunar interior. Different sources are the leading ones for different volatiles. Water and other volatiles can accumulate on the surface and in the near-surface layers of the Moon only in the so-called cold traps in polar basins, where other volatiles, as well as water ice, including highly toxic elements such as mercury and cadmium must be accumulated. The content of volatiles in the lunar interior is comparable to that in terrestrial rocks. Water could have played an important role in the early stages of the Moon's history, e.g., in the formation of mare basalts. The isotopic composition of the lunar juvenile water is similar to that on the Earth, which suggests a common origin of the terrestrial and lunar water.

Ivanov, A. V.

2014-03-01

343

Chemical composition and biological activity of the volatiles of Anthemis melampodina and Pluchea dioscoridis.  

PubMed

The volatile fractions obtained by hydrodistillation of the fresh leaves of Anthemis melampodina and Pluchea dioscoridis were analysed by GC-MS technique. Of 38 components identified in the volatile oil of A. melampodina, santolinatriene was the major component (27.33%). The oil was characterized by a high percentage of monoterpene hydrocarbons (49.94%) while sesquiterpene hydrocarbons and oxygenated sesquiterpenes represented only 7.41% and 11.43% of the oil. 36 components were identified in the volatile oil of P. dioscoridis. Farnesol was the major component (16.50%) accompanied by a high percentage of sesquiterpene alcohols. Oxygenated sesquiterpenes (26.43%) and sesquiterpene hydrocarbons (39.43%) represented the main constituents in the oil. P. dioscoridis showed a marked mosquito larvicidal activity against Culex pipiens (LC(50) 71.86 ppm), while A. melampodina was moderately active (LC(50) 139.42 ppm). PMID:11933125

Grace, Mary H

2002-03-01

344

Characterization of volatiles in strawberry guava (Psidium cattleianum Sabine) fruit.  

PubMed

Volatile compounds were isolated from strawberry guava fruit by simultaneous steam distillation-solvent extraction according to Likens-Nickerson. Compounds were identified by capillary GC-MS and sensorially characterized by sniffing GC. Two hundred and four compounds were identified in the aroma concentrate, of which ethanol, alpha-pinene, (Z)-3-hexenol, (E)-beta-caryophyllene, and hexadecanoic acid were found to be the major constituents. The presence of many aliphatic esters and terpenic compounds is thought to contribute to the unique flavor of the strawberry guava fruit. PMID:11743779

Pino, J A; Marbot, R; Vázquez, C

2001-12-01

345

The Volatile Constituents of Ziziphora taurica subsp. cleonioides.  

PubMed

The volatile constituents of ZIZIPHORA TAURICA subsp. CLEONIOIDES (Boiss.) P. H. Davis (Lamiaceae) were studied for the first time by analysis of the essential oil. 33 compounds, from the 44 consisting the total of the fraction, are identified by means of capillary GC and GC-MS. The identified components represent about 96% of the oil. Major constituents found are pulegone (62%) and isomenthone (8%). In addition the presence of 13% hydrocarbons, 9% alcohols, 73% ketones, and, finally, 1% phenols, oxides, ethers, and one ester, was demonstrated. PMID:17265230

Kokkalou, E

1988-04-01

346

Measurement of non-enteric emission fluxes of volatile fatty acids from a California dairy by solid phase micro-extraction with gas chromatography\\/mass spectrometry  

Microsoft Academic Search

Dairies are a major source of volatile organic compounds (VOCs) in California's San Joaquin Valley; a region that experiences high ozone levels during summer. Short-chain carboxylic acids, or volatile fatty acids (VFAs), are believed to make up a large fraction of VOC emissions from these facilities, although there are few studies to substantiate this. In this work, a method using

Phillip Alanis; Mark Sorenson; Matt Beene; Charles Krauter; Brian Shamp; Alam S. Hasson

2008-01-01

347

Volatile-Mediated Killing of Arabidopsis thaliana by Bacteria Is Mainly Due to Hydrogen Cyanide? †  

PubMed Central

The volatile-mediated impact of bacteria on plant growth is well documented, and contrasting effects have been reported ranging from 6-fold plant promotion to plant killing. However, very little is known about the identity of the compounds responsible for these effects or the mechanisms involved in plant growth alteration. We hypothesized that hydrogen cyanide (HCN) is a major factor accounting for the observed volatile-mediated toxicity of some strains. Using a collection of environmental and clinical strains differing in cyanogenesis, as well as a defined HCN-negative mutant, we demonstrate that bacterial HCN accounts to a significant extent for the deleterious effects observed when growing Arabidopsis thaliana in the presence of certain bacterial volatiles. The environmental strain Pseudomonas aeruginosa PUPa3 was less cyanogenic and less plant growth inhibiting than the clinical strain P. aeruginosa PAO1. Quorum-sensing deficient mutants of C. violaceum CV0, P. aeruginosa PAO1, and P. aeruginosa PUPa3 showed not only diminished HCN production but also strongly reduced volatile-mediated phytotoxicity. The double treatment of providing plants with reactive oxygen species scavenging compounds and overexpressing the alternative oxidase AOX1a led to a significant reduction of volatile-mediated toxicity. This indicates that oxidative stress is a key process in the physiological changes leading to plant death upon exposure to toxic bacterial volatiles.

Blom, Dirk; Fabbri, Carlotta; Eberl, Leo; Weisskopf, Laure

2011-01-01

348

Prey and Non-prey Arthropods Sharing a Host Plant: Effects on Induced Volatile Emission and Predator Attraction  

PubMed Central

It is well established that plants infested with a single herbivore species can attract specific natural enemies through the emission of herbivore-induced volatiles. However, it is less clear what happens when plants are simultaneously attacked by more than one species. We analyzed volatile emissions of lima bean and cucumber plants upon multi-species herbivory by spider mites (Tetranychus urticae) and caterpillars (Spodoptera exigua) in comparison to single-species herbivory. Upon herbivory by single or multiple species, lima bean and cucumber plants emitted volatile blends that comprised mostly the same compounds. To detect additive, synergistic, or antagonistic effects, we compared the multi-species herbivory volatile blend with the sum of the volatile blends induced by each of the herbivore species feeding alone. In lima bean, the majority of compounds were more strongly induced by multi-species herbivory than expected based on the sum of volatile emissions by each of the herbivores separately, potentially caused by synergistic effects. In contrast, in cucumber, two compounds were suppressed by multi-species herbivory, suggesting the potential for antagonistic effects. We also studied the behavioral responses of the predatory mite Phytoseiulus persimilis, a specialized natural enemy of spider mites. Olfactometer experiments showed that P. persimilis preferred volatiles induced by multi-species herbivory to volatiles induced by S. exigua alone or by prey mites alone. We conclude that both lima bean and cucumber plants effectively attract predatory mites upon multi-species herbivory, but the underlying mechanisms appear different between these species.

Hordijk, Cornelis A.; Posthumus, Maarten A.; Dicke, Marcel

2008-01-01

349

Ion-Ion Neutralization.  

National Technical Information Service (NTIS)

This work is part of a larger programme of ionic reaction studies at thermal energies, conducted by the authors of this report, which includes determinations of ion-molecule reaction rate coefficients and product ion distributions, electron-ion recombinat...

D. Smith N. G. Adams

1979-01-01

350

Securing non-volatile memory regions  

DOEpatents

Methods, apparatus and articles of manufacture to secure non-volatile memory regions are disclosed. An example method disclosed herein comprises associating a first key pair and a second key pair different than the first key pair with a process, using the first key pair to secure a first region of a non-volatile memory for the process, and using the second key pair to secure a second region of the non-volatile memory for the same process, the second region being different than the first region.

Faraboschi, Paolo; Ranganathan, Parthasarathy; Muralimanohar, Naveen

2013-08-20

351

Identification of Major Histocompatibility Complex-Regulated Body Odorants by Statistical Analysis of a Comparative Gas Chromatography/Mass Spectrometry Experiment  

SciTech Connect

Gas chromatography (GC), combined with mass spectrometry (MS) detection, is a powerful analytical technique that can be used to separate, quantify, and identify volatile compounds in complex mixtures. This paper examines the application of GC-MS in a comparative experiment to identify volatiles that differ in concentration between two groups. A complex mixture might comprise several hundred or even thousands of volatile compounds. Because their number and location in a chromatogram generally are unknown, and because components overlap in populous chromatograms, the statistical problems offer significant challenges beyond traditional two-group screening procedures. We describe a statistical procedure to compare two-dimensional GC-MS profiles between groups, which entails (1) signal processing: baseline correction and peak detection in single ion chromatograms; (2) aligning chromatograms in time; (3) normalizing differences in overall signal intensities; and (4) detecting chromatographic regions that differ between groups. Compared to existing approaches, the proposed method is robust to errors made at earlier stages of analysis, such as missed peaks or slightly misaligned chromatograms. To illustrate the method, we identify differences in GC-MS chromatograms of ether-extracted urine collected from two nearly identical inbred groups of mice, to investigate the relationship between odor and genetics of the major histocompatibility complex.

Willse, Alan R.; Belcher, Ann; Preti, George; Wahl, Jon H.; Thresher, Miranda; Yang, Peter; Yamazaki, Kunio; Beauchamp, Gary

2005-04-15

352

Simultaneous determination of non-volatile, semi-volatile, and volatile organic acids in tobacco by SIM-Scan mode GC-MS.  

PubMed

A method for simultaneous determination of seven nonvolatile organic acids (NVOAs), five semivolatile organic acids (SVOAs), and twelve volatile organic acids (VOAs) in tobacco by synchronous SIM (Selected Ion Monitoring)-scan mode GC-MS was developed. The collection of NVOAs and SVOAs data was performed in full-scan mode, and that of VOAs data was carried out with SIM. Recoveries of NVOAs and SVOAs varied from 90.0 to 103.0%, and RSDs were less than 4.0%; recoveries of VOAs ranged from 89.5 to 99.3%, and their RSDs were less than 3.0%. Twelve tobacco samples were analyzed by the described method, and the results show that the method is applicable for the simultaneous determination of VOAs, NVOAs, and SVOAs in tobacco. PMID:18307165

Wang, Baoxing; Yang, Shihua; Chen, Guohui; Wu, Yi; Hou, Ying; Xu, Guowang

2008-03-01

353

Reduction of volatile acidity of acidic wines by immobilized Saccharomyces cerevisiae cells.  

PubMed

Excessive volatile acidity in wines is a major problem and is still prevalent because available solutions are nevertheless unsatisfactory, namely, blending the filter-sterilized acidic wine with other wines of lower volatile acidity or using reverse osmosis. We have previously explored the use of an empirical biological deacidification procedure to lower the acetic acid content of wines. This winemaker's enological practice, which consists in refermentation associated with acetic acid consumption by yeasts, is performed by mixing the acidic wine with freshly crushed grapes, musts, or marc from a finished wine fermentation. We have shown that the commercial strain Saccharomyces cerevisiae S26 is able to decrease the volatile acidity of acidic wines with a volatile acidity higher than 1.44 g?L(-1) acetic acid, with no detrimental impact on wine aroma. In this study, we aimed to optimize the immobilization of S26 cells in alginate beads for the bioreduction of volatile acidity of acidic wines. We found that S26 cells immobilized in double-layer alginate-chitosan beads could reduce the volatile acidity of an acidic wine (1.1 g?L(-1) acetic acid, 12.5 % (v/v) ethanol, pH 3.12) by 28 and 62 % within 72 and 168 h, respectively, associated with a slight decrease in ethanol concentration (0.7 %). Similar volatile acidity removal efficiencies were obtained in medium with high glucose concentration (20 % w/v), indicating that this process may also be useful in the deacidification of grape musts. We, therefore, show that immobilized S. cerevisiae S26 cells in double-layer beads are an efficient alternative to improve the quality of wines with excessive volatile acidity. PMID:23361840

Vilela, A; Schuller, D; Mendes-Faia, A; Côrte-Real, M

2013-06-01

354

Realized Volatility and Absolute Return Volatility: A Comparison Indicating Market Risk  

PubMed Central

Measuring volatility in financial markets is a primary challenge in the theory and practice of risk management and is essential when developing investment strategies. Although the vast literature on the topic describes many different models, two nonparametric measurements have emerged and received wide use over the past decade: realized volatility and absolute return volatility. The former is strongly favored in the financial sector and the latter by econophysicists. We examine the memory and clustering features of these two methods and find that both enable strong predictions. We compare the two in detail and find that although realized volatility has a better short-term effect that allows predictions of near-future market behavior, absolute return volatility is easier to calculate and, as a risk indicator, has approximately the same sensitivity as realized volatility. Our detailed empirical analysis yields valuable guidelines for both researchers and market participants because it provides a significantly clearer comparison of the strengths and weaknesses of the two methods.

Takaishi, Tetsuya; Stanley, H. Eugene; Li, Baowen

2014-01-01

355

Muscodor albus Volatiles Control Toxigenic Fungi under Controlled Atmosphere (CA) Storage Conditions  

PubMed Central

Muscodor albus, a biofumigant fungus, has the potential to control post-harvest pathogens in storage. It has been shown to produce over 20 volatile compounds with fungicidal, bactericidal and insecticidal properties. However, M. albus is a warm climate endophyte, and its biofumigant activity is significantly inhibited at temperatures below 5 °C. Conidia of seven mycotoxin producing fungi, Aspergillus carbonarius, A. flavus, A. niger, A. ochraceus, Penicillium verrucosum, Fusarium culmorum and F. graminearum, were killed or prevented from germinating by exposure to volatiles from 2 g M. albus-colonized rye grain per L of headspace in sealed glass jars for 24 h at 20 °C. Two major volatiles of M. albus, isobutyric acid (IBA) and 2-methyl-1-butanol (2MB) at 50 ?L/L and 100 ?L/L, respectively, gave differential control of the seven fungi when applied individually at 20 °C. When the fungi were exposed to both IBA and 2MB together, an average of 94% of the conidia were killed or suppressed. In a factorial experiment with controlled atmosphere storage (CA) at 3 °C and 72 h exposure to four concentrations of IBA and 2MB combinations, 50 ?L/L IBA plus 100 ?L/L 2MB killed or suppressed germination of the conidia of all seven fungi. Controlled atmosphere had no significant effect on conidial viability or volatile efficacy. Major volatiles of M. albus may have significant potential to control plant pathogens in either ambient air or CA storage at temperatures below 5 °C. However, combinations of volatiles may be required to provide a broader spectrum of control than individual volatiles.

Braun, Gordon; Vailati, Matteo; Prange, Robert; Bevis, Eric

2012-01-01

356

Volatile Evolution of Magma Associated with the Solchiaro Eruption in the Phlegrean Volcanic District (Italy)  

NASA Astrophysics Data System (ADS)

The Phlegrean volcanic district (PVD) in southern Italy is one of the best known volcanic hazard areas in the world. More than 1.5 million people live in close proximity to the volcanic centers. The PVD comprises three volcanic fields: the Campi Flegrei caldera and the islands of Ischia and Procida. The area contains many volcanic centers (cinder cones, tuff rings, calderas) and has been the site of episodic volcanic activity for more than 60 ka. Some of these eruptions have been extremely violent. We studied volatiles in the magma associated with the Solchiaro eruption on the Island of Procida, Italy, to gain a better understanding of the relationship between eruptive style and intensity and the volatile content of the magma. The Solchiaro eruption is one of the more primitive products erupted in the PVD and provides information on the source of later more evolved magmas associated with this volcanic system. The composition of the magma before eruption was determined by analyzing melt inclusions (MIs) in forsteritic olivine and diopside. Several different types of MIs were observed in both phases. Some MI contained only glass, others contained glass plus one or more bubbles, and some contained glass plus bubbles plus crystals. We analyzed MIs containing only glass and those containing one or two bubbles. The composition of MIs ranges from basaltic to trachy-basaltic. Among major elements potassium shows the highest variability, from 1.48 to 3.73 wt %. Laser ablation-inductively coupled plasma mass spectroscopy (LA-ICPMS) analysis of MIs combined with major element analysis suggest assimilation of LILE and halogens from wallrock. Diopside-hosted MI have a higher H2O content than olivine-hosted MI, based on Secondary Ion Mass Spectrometric (SIMS) analysis. MI in olivine contain from 1.13 to 1.38 wt % H2O. F, Cl, S, CO2 contents are highly variable in both olivine and diopside-hosted MIs. The trend in H2O versus CO2 suggests emplacement of an originally CO2-saturated magma at >5 km that rises through the crust as it is undergoing crystallization. The magma eventually ponds at shallow depths (<1 km) before eruption. The inferred emplacement and crystallization history of magma at Campi Flegrei is similar to what was observed at Mt. St. Helens in the months immediately preceding the May 1980 eruption.

Esposito, R.; Bodnar, R. J.; de Vivo, B.; Lima, A.; Fedele, L.; Shimizu, N.; Belkin, H.

2008-12-01

357

Volatile Trapping in Martian Clathrates  

NASA Astrophysics Data System (ADS)

Thermodynamic conditions suggest that clathrates might exist on Mars. Despite observations which show that the dominant condensed phases on the surface of Mars are solid carbon dioxide and water ice, clathrates have been repeatedly proposed to play an important role in the distribution and total inventory of the planet's volatiles. Here we review the potential consequences of the presence of clathrates on Mars. We investigate how clathrates could be a potential source for the claimed existence of atmospheric methane. In this context, plausible clathrate formation processes, either in the close subsurface or at the base of the cryosphere, are reviewed. Mechanisms that would allow for methane release into the atmosphere from an existing clathrate layer are addressed as well. We also discuss the proposed relationship between clathrate formation/dissociation cycles and how potential seasonal variations influence the atmospheric abundances of argon, krypton and xenon. Moreover, we examine several Martian geomorphologic features that could have been generated by the dissociation of extended subsurface clathrate layers. Finally we investigate the future in situ measurements, as well as the theoretical and experimental improvements that will be needed to better understand the influence of clathrates on the evolution of Mars and its atmosphere.

Mousis, Olivier; Chassefière, Eric; Lasue, Jérémie; Chevrier, Vincent; Elwood Madden, Megan E.; Lakhlifi, Azzedine; Lunine, Jonathan I.; Montmessin, Franck; Picaud, Sylvain; Schmidt, Frédéric; Swindle, Timothy D.

2013-01-01

358

Two terpene synthases are responsible for the major sesquiterpenes emitted from the flowers of kiwifruit (Actinidia deliciosa)  

Microsoft Academic Search

Kiwifruit vines rely on bees for pollen transfer between spatially separated male and female individuals and require synchronized flowering to ensure pollination. Volatile terpene compounds, which are important cues for insect pollinator attraction, were studied by dynamic headspace sampling in the major green-fleshed kiwifruit (Actinidia deliciosa) cultivar 'Hayward' and its male pollinator 'Chieftain'. Terpene volatile levels showed a profile dominated

Niels J. Nieuwenhuizen; Mindy Y. Wang; Adam J. Matich; Sol A. Green; Xiuyin Chen; Yar-Khing Yauk; Lesley L. Beuning; Dinesh A. Nagegowda; Natalia Dudareva; Ross G. Atkinson

2009-01-01

359

The information content of implied volatility indexes for forecasting volatility and market risk  

Microsoft Academic Search

In this paper, we assess the efficiency, information content and unbiasedness of volatility forecasts based on the VIX\\/VXN implied volatility indexes, RiskMetrics and GARCHtype models at the 5-, 10- and 22-day time horizon. Our empirical application focuses on the S&P100 and NASDAQ100 indexes. We also deal with the information content of the competing volatility forecasts in a market risk (VaR

Pierre GIOT

2003-01-01

360

Serratia odorifera : analysis of volatile emission and biological impact of volatile compounds on Arabidopsis thaliana  

Microsoft Academic Search

Bacteria emit a wealth of volatiles. The combination of coupled gas chromatography\\/mass spectrometry (GC\\/MS) and proton-transfer-reaction\\u000a mass spectrometry (PTR-MS) analyses provided a most comprehensive profile of volatiles of the rhizobacterium Serratia odorifera 4Rx13. An array of compounds, highly dominated by sodorifen (approximately 50%), a bicyclic oligomethyl octadiene, could\\u000a be detected. Other volatiles included components of the biogeochemical sulfur cycle such

Marco Kai; Elena Crespo; Simona M. Cristescu; Frans J. M. Harren; Wittko Francke; Birgit Piechulla

2010-01-01

361

Semi-volatile secondary organic aerosol in urban atmospheres: meeting a measurement challenge  

NASA Astrophysics Data System (ADS)

Ammonium nitrate and semi-volatile organic compounds are significant components of fine particles in urban atmospheres. These components, however, are not properly determined with current US EPA accepted methods such as the PM 2.5 FRM or other single filter samplers due to significant losses of semi-volatile material (SVM) from particles collected on the filter during sampling. Continuous PM 2.5 mass measurements are attempted using methods such as the R&P TEOM monitor. This method, however, heats the sample to remove particle-bound water which also results in evaporation of SVM. Research at Brigham Young University has resulted in samplers for both the integrated and continuous measurement of total PM 2.5, including the SVM. The PC-BOSS is a charcoal diffusion denuder based sampler for the determination of fine particulate chemical composition including the semi-volatile organic material. The RAMS is a modified TEOM monitor which includes diffusion denuders and Nafion dryers to remove gas phase material which can be absorbed by a charcoal sorbent filter. The RAMS then uses a "sandwich filter" consisting of a conventional particle collecting Teflon coated TX40 filter, followed by an activated charcoal sorbent filter which retains any semi-volatile ammonium nitrate or organic material lost from the particles collected on the TEOM monitor Teflon coated filter, thus allowing for determination of total PM 2.5 mass including the SVM. Recent research conducted by Brigham Young University using these two samplers has indicated the following about semi-volatile organic aerosol: The majority of semi-volatile fine particulate organic material is secondary organic aerosol. This semi-volatile organic aerosol is not retained on the heated filter of a regular TEOM monitor and hence is not measured by this sampling technique. In addition, secondary ammonium nitrate is also lost. Much of the semi-volatile organic aerosol is also lost during sampling from single filter samplers such as the PM 2.5 FRM sampler. The amount of semi-volatile organic aerosol lost from single filter samplers can vary from less than 1/3 that lost from heated TEOM filters during cold winter conditions to essentially all during warm summer conditions. Semi-volatile organic aerosol can only be reliably collected using an appropriate denuder sampler. Either a PM 2.5 FRM sampler or the IMPROVE sampler can be easily modified to a denuder sampler with filters which can be analyzed for semi-volatile OC, nonvolatile OC and EC using existing OC/EC analytical techniques. The research upon which these statements are based is summarized in this document.

Eatough, Delbert J.; Long, Russell W.; Modey, William K.; Eatough, Norman L.

362

Reactive flash volatilization of fluid fuels  

DOEpatents

The invention provides methods for the production of synthesis gas. More particularly, various embodiments of the invention relate to systems and methods for volatilizing fluid fuel to produce synthesis gas by using a metal catalyst on a solid support matrix.

Schmidt, Lanny D.; Dauenhauer, Paul J.; Dreyer, Bradon J.; Salge, James R.

2013-01-08

363

Laboratory Investigations of Volatile Trapping in Comets  

NASA Technical Reports Server (NTRS)

This grant supports research on the formation of comets and their role in delivering volatiles to the early Earth. The volatile delivery system is of special importance because of the fundamental role played by these volatiles in the origin and early evolution of life. Our work during the period under review focussed on a test of the way in which amorphous ice forming at temperatures below 75 K traps noble gases, and the use of the resulting data to interpret noble gas abundances found in planetary atmospheres. We have found that these experiments support the idea that comets were indeed significant contributors of volatiles to the Earth's inventory. The results of our research to date are summarized in the accompanying paper "From the Interstellar Medium to Planetary Atmospheres via Comets". Other papers published on this subject or using the results of our analyses are listed in the bibliography. Copies of currently available reprints are attached as part of this report.

Owen, Tobias C.

1997-01-01

364

Volatile Solvent Use among Western Australian Adolescents.  

ERIC Educational Resources Information Center

Semistructured interviews were conducted with 40 adolescents who reported inhaling volatile solvents. All were aware of the short-term health risks involved in use, and most reported experiencing ill effects. Offers suggestions for intervention. (Author/GCP)

Carroll, Annemaree; Houghton, Stephen; Odgers, Peta

1998-01-01

365

Volatile Losses from Aged Field Sediments.  

National Technical Information Service (NTIS)

The purpose of this technical note is to describes laboratory investigations conducted to obtain flux data from contaminated aged field sediments and a laboratory spiked sediment for the emission of volatile organic chemicals (VOCs) from sediment exposed ...

1999-01-01

366

Release of volatile mercury from vascular plants  

NASA Technical Reports Server (NTRS)

Volatile, organic solvent soluble mercury has been found in leaves and seeds of several angiosperms. Leaves of garlic vine, avocado, and haole-koa release mercury in volatile form rapidly at room temperature. In garlic vine, the most active release is temperature dependent, but does not parallel the vapor-pressure temperature relationship for mercury. Mercury can be trapped in nitric-perchloric acid digestion fluid, or n-hexane, but is lost from the hexane unless the acid mixture is present. Seeds of haole-koa also contain extractable mercury but volatility declines in the series n-hexane (90%), methanol (50%), water (10%). This suggests that reduced volatility may accompany solvolysis in the more polar media.

Siegel, S. M.; Puerner, N. J.; Speitel, T. W.

1974-01-01

367

VOLATILE ORGANIC ANALYSIS BY DIRECT AQUEOUS INJECTION  

EPA Science Inventory

Gas chromatographic environmental analysis by direct aqueous injection (DAI) was studied for 24 volatile organic analytes (VOAs). Internal standardization was used to determine the precision of analyzing these compounds by DAI. Aequous samples were directly introduced to a gas ch...

368

Volatile Organic Carbon Emissions. Phase 2.  

National Technical Information Service (NTIS)

Engineering studies evaluated bisulfite (HS03) absorbent solutions in a bench-scale absorption unit for the control of volatile organic compounds (VOCs) emitted from the manufacture of multi-base propellent at Radford Army Ammunition Plant. An optimizatio...

C. A. Jake

1987-01-01

369

Microwave spectra of some volatile organic compounds  

NASA Technical Reports Server (NTRS)

A computer-controlled microwave (MRR) spectrometer was used to catalog reference spectra for chemical analysis. Tables of absorption frequency, peak absorption intensity, and integrated intensity are included for 26 volatile organic compounds, all but one of which contain oxygen.

White, W. F.

1975-01-01

370

Levels and composition of volatile organic compounds on commuting routes in Detroit, Michigan  

Microsoft Academic Search

Vehicle emissions can constitute a major share of ambient concentrations of many volatile organic compounds (VOCs) and other air pollutants in urban areas. Especially high concentrations may occur at curbsides, vehicle cabins, and other microenvironments. Such levels are not reflected by monitoring at fixed sites. This study reports on measurements of VOCs made from buses and cars in Detroit, MI.

Stuart A Batterman; Chung-Yu Peng; James Braun

2002-01-01

371

Functional characterization of enzymes forming volatile esters from strawberry and banana  

Microsoft Academic Search

Volatile esters are flavor components of the majority of fruits. The last step in their biosynthesis is catalyzed by alcohol acyltransferases (AATs), which link alcohols to acyl moieties. Full-length cDNAs putatively encoding AATs were isolated from fruit of wild strawberry (Fragaria vesca) and banana (Musa sapientum) and compared to the previously isolated SAAT gene from the cultivated strawberry (Fragaria x

M. J. Beekwilder; Mayte Alvarez-Huerta; Evert Neef; Francel W. A. Verstappen; Harro J. Bouwmeester; A. Aharoni

2004-01-01

372

Volatile Components of Banana Fruit (Musa sapientum L.) “Indio” from Cuba  

Microsoft Academic Search

Volatile components of banana fruit “Indio” were isolated by simultaneous steam distillation\\/solvent extraction. Thirty-nine components were identified (42 mg\\/kg), of which the major ones were 2-heptyl acetate, isoamyl acetate, 2-methylbutyl acetate and 2-heptyl acetate.

Jorge A. Pino; Ariel Ortega; Rolando Marbot; Juan Aguero

2003-01-01

373

Deciphering the History of Martian Volatiles: A MultiComponent Space Exploration Program  

Microsoft Academic Search

To characterize Mars climate evolution requires to trace back the history of volatile species, including water. Indeed, atmospheric gases control, through UV-visible absorption and IR radiative transfer, the thermal structure of the atmosphere, the surface temperature, and ultimately the global hydrological system, which is a major component of the present Earth climate system. The composition and mass of the atmosphere

E. Chassefiere

2000-01-01

374

Improvement of volatile composition of wines by controlled addition of malolactic bacteria  

Microsoft Academic Search

The effect of malolactic fermentation (MLF) on the volatile composition of red wines was studied by inoculation with selected lactic acid bacteria. Four wines were inoculated with different Oenococcus oeni (syn. Leuconostoc oenos) strains, the major malolactic species found in wines, and one was inoculated with a Lactobacillus sp. strain. A non inoculated wine was also analyzed to act as

Sergi Maicas; José-Vicente Gil; Isabel Pardo; Sergi Ferrer

1999-01-01

375

A biochemical model describing volatile fatty acid metabolism in thermophilic aerobic digestion of wastewater sludge  

Microsoft Academic Search

A biochemical model was developed to explain the mechanism of volatile fatty acid (VFA) metabolism in Thermophilic Aerobic Digestion (TAD). The effects of substrate addition on the metabolic behavioral patterns of TAD biomass, from a pilot scale system, were examined. The majority of the substrates examined under batch test conditions, with TAD process biomass, under microaerobic conditions, were oxidized to

A. Chu; D. S. Mavinic; W. D. Ramey; H. G. Kelly

1996-01-01

376

Volatile Nanoparticle Formation and Growth within a Diluting Diesel Car Exhaust  

Microsoft Academic Search

A major source of particle number emissions is road traffic. However, scientific knowledge concerning secondary particle formation and growth of ultrafine particles within vehicle exhaust plumes is still very limited. Volatile nanoparticle formation and subsequent growth conditions were analyzed here to gain a better understanding of “real-world” dilution conditions. Coupled computational fluid dynamics and aerosol microphysics models together with measured

Ulrich Uhrner; Michael Zallinger; Sibylle von Löwis; Hanna Vehkamäki; Birgit Wehner; Frank Stratmann; Alfred Wiedensohler

2011-01-01

377

Volatile organic compounds in snow in the Quebec-Windsor Corridor  

Microsoft Academic Search

Volatile organic compounds (VOC) were determined in snow to investigate the role of the snowpack as an exchange medium for atmospherically active compounds of anthropogenic and biogenic origin. The major question was which VOC species occur in snow and how the species identity and selected concentrations are related to the sampling area and environmental conditions. Samples were collected using a

G. Kos; P. A. Ariya

2010-01-01

378

Clinoptilolite zeolite and cellulose amendments to reduce ammonia volatilization in a calcareous sandy soil  

Microsoft Academic Search

Leaching of nitrate (NO3-) below the root zone and gaseous losses of nitrogen (N) such as ammonia (NH3) volatilization, are major mechanisms of N loss from agricultural soils. New techniques to minimize such losses are needed to maximize N uptake efficiency and minimize production costs and the risk of potential N contamination of ground and surface waters. The effects of

Z. L. He; D. V. Calvert; A. K. Alva; Y. C. Li; D. J. Banks

2002-01-01

379

Oral malodor in children and volatile sulfur compound- producing bacteria in saliva: preliminary microbiological investigation  

Microsoft Academic Search

Purpose: This study examined and compared levels of salivary bacteria which produced volatile sulfur compounds (VSC) in young children with and without oral malodor. Methods: Clinic populations of children aged two to seven years, whose parents presented with an unsolicited major complaint of oral malodor in their child (OM+), or aged-matched controls in whom oral malodor was not detected by

Fariba Paryavi-Gholami; Glenn E. Minah; Foo Turng

1999-01-01

380

Role of Volatility in the Development of JP-8 Surrogates for Diesel Engine Application.  

National Technical Information Service (NTIS)

Surrogates for JP-8 have been developed in the high temperature gas phase environment of gas turbines. In diesel engines, the fuel is introduced in the liquid phase where volatility plays a major role in the formation of the combustible mixture and autoig...

N. Henein P. Lee Z. Zheng

2014-01-01

381

Volatile Hydrocarbon Exposure During In Situ Burning of Crude Oil at Sea  

Microsoft Academic Search

Personal exposure of response workers (and other personnel) to volatile hydrocarbons and benzene was monitored as part of the Newfoundland Offshore Burn Experiment (NOBE), a major oil spill combustion trial organized by Environment Canada and sponsored by over 25 governmental and private organizations from Canada and the United States. Benzene and total petroleum hydrocarbons were monitored using organic vapor monitors

Stephen M. Bowes III

1996-01-01

382

Volatility: A hidden Markov process in financial time series  

Microsoft Academic Search

Volatility characterizes the amplitude of price return fluctuations. It is a central magnitude in finance closely related to the risk of holding a certain asset. Despite its popularity on trading floors, volatility is unobservable and only the price is known. Diffusion theory has many common points with the research on volatility, the key of the analogy being that volatility is

Zoltán Eisler; Josep Perelló; Jaume Masoliver

2007-01-01

383

The Distribution of Exchange Rate Volatility  

Microsoft Academic Search

Using high-frequency data on Deutschemark and Yen returns against the dollar, we construct model-free estimates of daily exchange rate volatility and correlation, covering an entire decade. In addition to being model-free, our estimates are also approximately free of measurement error under general conditions, which we delineate. Hence, for all practical purposes, we can treat the exchange rate volatilities and correlations

Torben G. Andersen; Tim Bollerslev; Francis X. Diebold; Paul Labys

384

Alternative Models For Conditional Stock Volatility  

Microsoft Academic Search

This paper compares several statistical models for monthly stock return volatility. The focus is on U.S. data from 1834-19:5 because the post-1926 data have been analyzed in more detail by others. Also, the Great Depression had levels of stock volatility that are inconsistent with stationary models for conditional heteroskedasticity, We show the importance of nonlinearities in stock return behavior that

Adrian R. Pagan; G. William Schwert

1990-01-01

385

Mercury volatilization from salt marsh sediments  

Microsoft Academic Search

In situ volatilization fluxes of gaseous elemental mercury, Hg(0), were estimated for tidally exposed salt marsh sediments in the summer at the urban\\/industrial Secaucus High School Marsh, New Jersey Meadowlands (Secaucus, New Jersey) and in the early autumn at a regional background site in the Great Bay estuary (Tuckerton, New Jersey). Estimated daytime sediment-air mercury volatilization fluxes at the Secaucus

Lora M. Smith; John R. Reinfelder

2009-01-01

386

Long-memory volatility in derivative hedging  

NASA Astrophysics Data System (ADS)

The aim of this work is to take into account the effects of long memory in volatility on derivative hedging. This idea is an extension of the work by Fedotov and Tan [Stochastic long memory process in option pricing, Int. J. Theor. Appl. Finance 8 (2005) 381-392] where they incorporate long-memory stochastic volatility in option pricing and derive pricing bands for option values. The starting point is the stochastic Black-Scholes hedging strategy which involves volatility with a long-range dependence. The stochastic hedging strategy is the sum of its deterministic term that is classical Black-Scholes hedging strategy with a constant volatility and a random deviation term which describes the risk arising from the random volatility. Using the fact that stock price and volatility fluctuate on different time scales, we derive an asymptotic equation for this deviation in terms of the Green's function and the fractional Brownian motion. The solution to this equation allows us to find hedging confidence intervals.

Tan, Abby

2006-10-01

387

Scaling properties of foreign exchange volatility  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the scaling properties of foreign exchange volatility. Our methodology is based on a wavelet multi-scaling approach which decomposes the variance of a time series and the covariance between two time series on a scale by scale basis through the application of a discrete wavelet transformation. It is shown that foreign exchange rate volatilities follow different scaling laws at different horizons. Particularly, there is a smaller degree of persistence in intra-day volatility as compared to volatility at one day and higher scales. Therefore, a common practice in the risk management industry to convert risk measures calculated at shorter horizons into longer horizons through a global scaling parameter may not be appropriate. This paper also demonstrates that correlation between the foreign exchange volatilities is the lowest at the intra-day scales but exhibits a gradual increase up to a daily scale. The correlation coefficient stabilizes at scales one day and higher. Therefore, the benefit of currency diversification is the greatest at the intra-day scales and diminishes gradually at higher scales (lower frequencies). The wavelet cross-correlation analysis also indicates that the association between two volatilities is stronger at lower frequencies.

Gençay, Ramazan; Selçuk, Faruk; Whitcher, Brandon

2001-01-01

388

Plant Volatile Compounds: Sensory Cues for Health and Nutritional Value?  

NSDL National Science Digital Library

Plants produce many volatile metabolites. A small subset of these compounds is sensed by animals and humans, and the volatile profiles are defining elements of the distinct flavors of individual foods. Flavor volatiles are derived from an array of nutrients, including amino acids, fatty acids, and carotenoids. In tomato, almost all of the important flavor-related volatiles are derived from essential nutrients. The predominance of volatiles derived from essential nutrients and health-promoting compounds suggests that these volatiles provide important information about the nutritional makeup of foods. Evidence supporting a relation between volatile perception and nutrient or health value will be reviewed.

Stephen A. Goff (Syngenta Biotechnology Inc.;); Harry J. Klee (University of Florida;)

2006-02-10

389

Wall-loss distribution of charge breeding ions in an electron cyclotron resonance ion source  

NASA Astrophysics Data System (ADS)

We investigated the ion-loss distribution on the sidewall of an electron cyclotron resonance (ECR) plasma chamber using the 18-GHz ECR charge breeder at the Tokai Radioactive Ion Accelerator Complex (TRIAC). Similarities and differences between the ion-loss distributions (longitudinal and azimuthal) of different ion species (i.e., radioactive 111In1+ and 140Xe1+ ions that are typical volatile and nonvolatile elements) was qualitatively discussed to understand the element dependence of the charge breeding efficiency. Especially, the similarities represent universal ion loss characteristics in an ECR charge breeder, which are different from the loss patterns of electrons on the ECRIS wall.

Jeong, S. C.; Oyaizu, M.; Imai, N.; Hirayama, Y.; Ishiyama, H.; Miyatake, H.; Niki, K.; Okada, M.; Watanabe, Y. X.; Otokawa, Y.; Osa, A.; Ichikawa, S.

2012-02-01

390

Volatile Emissions from Compressed Tissue  

PubMed Central

Since almost every fifth patient treated in hospital care develops pressure ulcers, early identification of risk is important. A non-invasive method for the elucidation of endogenous biomarkers related to pressure ulcers could be an excellent tool for this purpose. We therefore found it of interest to determine if there is a difference in the emissions of volatiles from compressed and uncompressed tissue. The ultimate goal is to find a non-invasive method to obtain an early warning for the risk of developing pressure ulcers for bed-ridden persons. Chemical analysis of the emissions, collected in compresses, was made with gas-chromatography – mass spectrometry and with a chemical sensor array, the so called electronic nose. It was found that the emissions from healthy and hospitalized persons differed significantly irrespective of the site. Within each group there was a clear difference between the compressed and uncompressed site. Peaks that could be certainly deemed as markers of the compression were, however, not identified. Nonetheless, different compounds connected to the application of local mechanical pressure were found. The results obtained with GC-MS reveal the complexity of VOC composition, thus an array of non-selective chemical sensors seems to be a suitable choice for the analysis of skin emission from compressed tissues; it may represent a practical instrument for bed side diagnostics. Results show that the adopted electronic noses are likely sensitive to the total amount of the emission rather than to its composition. The development of a gas sensor-based device requires then the design of sensor receptors adequate to detect the VOCs bouquet typical of pressure. This preliminary experiment evidences the necessity of studies where each given person is followed for a long time in a ward in order to detect the insurgence of specific VOCs pattern changes signalling the occurrence of ulcers.

Dini, Francesca; Capuano, Rosamaria; Strand, Tillan; Ek, Anna-Christina; Lindgren, Margareta; Paolesse, Roberto; Di Natale, Corrado; Lundstrom, Ingemar

2013-01-01

391

Microparticles containing lemongrass volatile oil: preparation, characterization and thermal stability.  

PubMed

Lemongrass volatile oil (LVO) is an important ingredient in cosmetics, presenting antimicrobial properties, in particular antifungal activity, and it is a promising raw material for the development of pharmaceutical products. However, its volatility and susceptibility to degradation are the major drawbacks for the use of Cymbopogon citratus oil in pharmaceutical compounding. Thus, the aim of this work was to develop and to characterize microparticles containing this oil viewing the stabilization of LVO. Two techniques of preparation were evaluated; spray drying and precipitation, and two encapsulation materials, beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) were tested. The microparticles were characterized in terms of content of water, yield, percentage of inclusion, infrared spectroscopy. Morphology was evaluated by scanning electronic microscopy. Studies of stability were also conducted. The content of citral (neral and geranial), major component of the oil, present in microparticles was assayed by a validated HPLC method. The percentage of inclusion of LVO into the microparticles was 56-60% and 26-29% using beta-CD and HP-beta-CD, respectively. The results showed that the use of the beta-CD as encapsulant material was more efficient. Additionally, an increased inclusion of lemongrass oil was observed with the precipitation technique. PMID:21284257

Weisheimer, V; Miron, D; Silva, C B; Guterres, S S; Schapoval, E E S

2010-12-01

392

Qualitative and Quantitative Prediction of Volatile Compounds from Initial Amino Acid Profiles in Korean Rice Wine (makgeolli) Model.  

PubMed

In Korean rice wine (makgeolli) model, we tried to develop a prediction model capable of eliciting a quantitative relationship between initial amino acids in makgeolli mash and major aromatic compounds, such as fusel alcohols, their acetate esters, and ethyl esters of fatty acids, in makgeolli brewed. Mass-spectrometry-based electronic nose (MS-EN) was used to qualitatively discriminate between makgeollis made from makgeolli mashes with different amino acid compositions. Following this measurement, headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (GC-MS) combined with partial least-squares regression (PLSR) method was employed to quantitatively correlate amino acid composition of makgeolli mash with major aromatic compounds evolved during makgeolli fermentation. In qualitative prediction with MS-EN analysis, the makgeollis were well discriminated according to the volatile compounds derived from amino acids of makgeolli mash. Twenty-seven ion fragments with mass-to-charge ratio (m/z) of 55 to 98 amu were responsible for the discrimination. In GC-MS combined with PLSR method, a quantitative approach between the initial amino acids of makgeolli mash and the fusel compounds of makgeolli demonstrated that coefficient of determination (R(2) ) of most of the fusel compounds ranged from 0.77 to 0.94 in good correlation, except for 2-phenylethanol (R(2) = 0.21), whereas R(2) for ethyl esters of MCFAs including ethyl caproate, ethyl caprylate, and ethyl caprate was 0.17 to 0.40 in poor correlation. PMID:24888253

Kang, Bo-Sik; Lee, Jang-Eun; Park, Hyun-Jin

2014-06-01

393

Analysis of volatile compounds released during the grinding of roasted coffee beans using solid-phase microextraction.  

PubMed

A dynamic solid-phase microextraction (SPME) method to sample fresh headspace volatile compounds released during the grinding of roasted coffee beans was described and the analytical results using gas chromatography/mass spectrometry (GC/MS) and GC/olfactometry (GC/O) were compared to those of the conventional static SPME sampling methods using ground coffee. Volatile compounds released during the grinding of roasted coffee beans (150 g) were obtained by exposing the SPME fiber (poly(dimethylsiloxane)/divinylbenzene, PDMS/ DVB) for 8 min to nitrogen gas (600 mL/min) discharged from a glass vessel in which the electronic coffee grinder was enclosed. Identification and characterization of volatile compounds thus obtained were achieved by GC/MS and GC/O. Peak areas of 47 typical coffee volatile compounds, separated on total ion chromatogram (TIC), obtained by the dynamic SPME method, showed coefficients of variation less than 5% (n = 3) and the gas chromatographic profile of volatile compounds thus obtained was similar to that of the solvent extract of ground coffee, except for highly volatile compounds such as 4-hydroxy-2,5-dimethyl-3(2H)-furanone and 4-ethenyl-2-methoxyphenol. Also, SPME dilution analysis of volatile compounds released during the grinding of roasted coffee beans showed linear plots of peak area versus exposed fiber length (R (2) > 0.89). Compared with those of the headspace volatile compounds of ground coffee using GC/MS and GC/O, the volatile compounds generated during the grinding of roasted coffee beans were rich in nutty- and smoke-roast aromas. PMID:12643659

Akiyama, Masayuki; Murakami, Kazuya; Ohtani, Noboru; Iwatsuki, Keiji; Sotoyama, Kazuyoshi; Wada, Akira; Tokuno, Katsuya; Iwabuchi, Hisakatsu; Tanaka, Kiyofumi

2003-03-26

394

Nanoparticle formation by ozonolysis of inducible plant volatiles  

NASA Astrophysics Data System (ADS)

We present the first laboratory experiments of aerosol formation from oxidation of volatile organic species emitted by living plants, a process which for half a century has been known to take place in the atmosphere. We have treated white cabbage crops with methyl jasmonate in order to induce the production of monoterpenes and certain less-volatile sesqui- and homoterpenes. Ozone was introduced into the growth chamber in which the crops were placed, and the subsequent aerosol formation and growth of aerosols were monitored by measuring the particle size distributions continuously during the experiments. Our observations show similar particle formation rates as in the atmosphere but much higher growth rates. The results indicate that the concentrations of nonvolatile oxidation products of plant released precursors needed to induce the nucleation are roughly an order-of-magnitude higher than their concentrations during atmospheric nucleation events. Our results therefore suggest that atmospheric nucleation events proceed via condensation of oxidized organics on pre-existing molecular clusters rather than via their homogeneous or ion-induced nucleation.

Joutsensaari, J.; Loivamäki, M.; Vuorinen, T.; Miettinen, P.; Nerg, A.-M.; Holopainen, J. K.; Laaksonen, A.

2005-01-01

395

Nanoparticle formation by ozonolysis of inducible plant volatiles  

NASA Astrophysics Data System (ADS)

We present the first laboratory experiments of aerosol formation from oxidation of volatile organic species emitted by living plants, a process which for half a century has been known to take place in the atmosphere. We have treated white cabbage plants with methyl jasmonate in order to induce the production of monoterpenes and certain less-volatile sesqui- and homoterpenes. Ozone was introduced into the growth chamber in which the plants were placed, and the subsequent aerosol formation and growth of aerosols were monitored by measuring the particle size distributions continuously during the experiments. Our observations show similar particle formation rates as in the atmosphere but much higher growth rates. The results indicate that the concentrations of nonvolatile oxidation products of plant released precursors needed to induce the nucleation are roughly an order-of-magnitude higher than their concentrations during atmospheric nucleation events. Our results therefore suggest that if oxidized organics are involved in atmospheric nucleation events, their role is to participate in the growth of pre-existing molecular clusters rather than to form such clusters through homogeneous or ion-induced nucleation.

Joutsensaari, J.; Loivamäki, M.; Vuorinen, T.; Miettinen, P.; Nerg, A.-M.; Holopainen, J. K.; Laaksonen, A.

2005-06-01

396

Housewives’ exposure to volatile organic compounds relative to proximity to roadside service stations  

Microsoft Academic Search

Residents in neighborhoods near a service station and\\/or major roadway would be expected to be exposed to elevated ambient volatile organic compound (VOC) levels compared to those further away from such source(s). We confirmed this and examined whether the anticipated high outdoor levels near a service station and\\/or major roadway outweighed the indoor levels as a factor for the exposure

Wan-Kuen Jo; Kung-Cho Moon

1999-01-01

397

Biosequestration, transformation, and volatilization of mercury by Lysinibacillus fusiformis isolated from industrial effluent.  

PubMed

In the present study, an efficient mercury-tolerant bacterial strain (RS-5) was isolated from heavy-metalcontaminated industrial effluent. Under shake flask conditions, 97% of the supplemented mercuric chloride was sequestered by the biomass of RS-5 grown in a tryptone soy broth. The sequestered mercuric ions were transformed inside the bacterial cells, as an XRD analysis of the biomass confirmed the formation of mercurous chloride, which is only feasible following the reaction of the elemental mercury and the residual mercuric chloride present within the cells. Besides the sequestration and intracellular transformation, a significant fraction of the mercury (63%) was also volatilized. The 16S rRNA gene sequence of RS-5 revealed its phylogenetic relationship with the family Bacillaceae, and a 98% homology with Lysinibacillus fusiformis, a Gram-positive bacterium with swollen sporangia. This is the first observation of the sequestration and volatilization of mercuric ions by Lysinibacillus sp. PMID:22561864

Gupta, Saurabh; Goyal, Richa; Nirwan, Jashan; Cameotra, Swaranjit Singh; Tejoprakash, Nagaraja

2012-05-01

398

Monitoring Trace Contaminants in Air Via Ion Trap Mass Spectrometry  

NASA Technical Reports Server (NTRS)

Recent passage of the Clean Air Act with its stricter regulation of toxic gas emissions, and the ever-growing number of applications which require faster turnaround times between sampling and analysis are two major factors which are helping to drive the development of new instrument technologies for in-situ, on-line, real-time monitoring. The ion trap, with its small size, excellent sensitivity, and tandem mass spectrometry capability is a rapidly evolving technology which is well-suited for these applications. In this paper, we describe the use of a commercial ion trap instrument for monitoring trace levels of chlorofluorocarbons (CFCs) and volatile organic compounds (VOCs) in air. A number of sample introduction devices including a direct transfer line interface, short column GC, and a cryotrapping interface are employed to achieve increasing levels of sensitivity. MS, MS/MS, and MS/MS/MS methods are compared to illustrate trade-offs between sensitivity and selectivity. Filtered Noise Field (FNF) technology is found to be an excellent means for achieving lower detection limits through selective storage of the ion(s) of interest during ionization. Figures of merit including typical sample sizes, detection limits, and response times are provided. The results indicate the potential of these techniques for atmospheric assessments, the High Speed Research Program, and advanced life support monitoring applications for NASA.

Palmer, Peter T.; Karr, Dane; Pearson, Richard; Valero, Gustavo; Wong, Carla

1995-01-01

399

Ion composition and chemistry  

NASA Astrophysics Data System (ADS)

Measurements from the Vega and Giotto probes are used to study the composition and chemistry of Comet Halley. The missing parent molecules of the C+ and S+ ions which are very abundant in the outer coma of Comet Halley at a radial distance of 100,000 km are examined. Consideration is given to the atomic ions, C+, S+, He+, and Na+, the molecular ions, NH4(+), H2CN(+), and HCS(+), formaldehyde polymers and polycylic aromatic hydrogen carbons. It is suggested that the deficiency of N2 and NH3(+) and the abundance of CO and CO2 with a significant amount of H2CO cloud result from the condensation of volatile ices in the solar nebula.

Ip, W.-H.

400

The reduction of iron oxides by volatiles in a rotary hearth furnace process: Part III. The simulation of volatile reduction in a multi-layer rotary hearth furnace process  

SciTech Connect

For reduction of iron oxides by volatiles from coal, the major reductant was found to be H{sub 2, and it can affect the overall reduction of iron oxides. In this study, the reduction by actual volatiles of composite pellets at 1000{sup o}C was studied. The volatile reduction of the hand-packed Fe{sub 2}O{sub 3}/Coal composite pellet as it is devolatilizing out of the pellet was found to be negligible. However, the reduction of iron oxide pellets at the top layer by volatiles from the bottom layers of a three-layer pellet geometry was observed to be about 15 pct. From the morphological observations of partially reduced pellets and the computed rates of bulk mass transfer, volatile reduction appears to be controlled by a mixed-controlled mechanism of bulk gas mass transfer and the limited-mixed control reduction kinetics. Using the reduction rate obtained from the single pellet experiments with pure hydrogen and extrapolating this rate to an H{sub 2 partial pressure corresponding to the H{sub 2 from the volatiles, an empirical relationship was obtained to approximately predict the amount of volatile reduction up to 20 pct.

Sohn, I.; Fruehan, R.J. [Carnegie Mellon University, Pittsburgh, PA (United States)

2006-04-15

401

Proton Transfer Rate Coefficient Measurements of Selected Volatile Organic Molecules  

NASA Astrophysics Data System (ADS)

We have developed an apparatus based on the selected ion flow tube (SIFT)footnote D. Smith and N.G. Adams, Ads. At. Mol. Phys. 24, 1 (1987). that allows the study of proton transfer between various positive ions and volatile organic molecules. Reactions in the flow tube occur at pressures of approximately 300 mTorr, eliminating the requirement of thermal beam production. The proton donor molecule H_3O^+ has been produced using several types of electrical discharges in water vapor, such as a capacitively coupled RF discharge and a DC hollow cathode discharge. Presently we are developing an Asmussen-type microwave cavity discharge using the components of a standard microwave oven that has the advantages of simple design and operation, as well as low cost. We will be presenting the results of the microwave cavity ion source to produce H_3O^+, and compare it to the other studied sources. In addition, we will be presenting a preliminary measurement of the proton transfer rate coefficient in the reaction of H_3O^+ with acetone and methanol.

Brooke, G.; Popovi?, S.; Vuškovi?, L.

2002-05-01

402

Diffusion method for the determination of acid-volatile sulfides (AVS) in sediment  

Microsoft Academic Search

A simplified procedure using diffusion and a sulfide ion selective electrode is described for measuring acid-volatile sulfides (AVS) in sediment. This method yielded at least 10% more AVS than the more common purge-and-trap method. The quantity of AVS (based on dry mass of sediment) was found to be dependent on acid concentration and on mass of wet sediment. The mean

Henry Brouwer; Tom P. Murphy

1994-01-01

403

Adsorption of volatile organic compounds in porous metal–organic frameworks functionalized by polyoxometalates  

Microsoft Academic Search

The functionalization of porous metal–organic frameworks (Cu3(BTC)2) was achieved by incorporating Keggin-type polyoxometalates (POMs), and further optimized via alkali metal ion-exchange. In addition to thermal gravimetric analysis, IR, single-crystal X-ray diffraction, and powder X-ray diffraction, the adsorption properties were characterized by N2 and volatile organic compounds (VOCs) adsorption measurements, including short-chain alcohols (C<4), cyclohexane, benzene, and toluene. The adsorption enthalpies

Feng-Ji Ma; Shu-Xia Liu; Da-Dong Liang; Guo-Jian Ren; Feng Wei; Ya-Guang Chen; Zhong-Min Su

2011-01-01

404

Ponderosa pine forest volatiles: comparison of PTR-MS and PIT-MS instruments  

Microsoft Academic Search

Proton-transfer-reaction mass spectrometry (PTR-MS) has become a standard tool for measurement of volatile organic compounds in ambient air. During a field campaign in a ponderosa pine forest (Blodgett Forest Research Station) in July of 2005, we used a recently-developed ion trap version of this instrument (PIT-MS) for parallel measurements with PTR-MS. Ambient air measurements (16 days) were followed by branch

D. Welsh-Bon; C. Warneke; J. A. de Gouw; R. Holzinger; K. Palitzsch; N. Bouvier-Brown; A. Goldstein; R. Fall

2005-01-01

405

Bacterial volatilization of mercury by immobilized bacteria in fixed and fluidized bed bioreactors  

Microsoft Academic Search

Pseudomonas aeruginosa and Klebsiella pneumoniae, mercury resistant bac- terial strains, which are able to grow at 1200 µM HgCl2 and to reduce mercuric ion to volatile metal mercury, were isolated from hydrocarbons-contaminated river in Morocco. These bacteria were used for removing mercury from synthetic water polluted by mercu- ry using fixed bioreactor and fluidized bed bioreactor. This mercury bio-decontamination system

F. Z. DZAIRI; Y. ZEROUAL; A. MOUTAOUAKKIL; J. TAOUFIK; M. TALBI; M. LOUTFI; K. LEE; M. BLAGHEN