Morphology and composition of condensates on Apollo 17 orange and black glass

NASA Technical Reports Server (NTRS)

Mckay, David S.; Wentworth, Sue J.

1992-01-01

Lunar soil sample 74220 and core samples 74001/2 consist mainly of orange glass droplets, droplet fragments, and their crystallized equivalents. These samples are now generally accepted to be pyroclastic ejecta from early lunar volcanic eruptions. It has been known since early examination of these samples that they contain surface coatings and material rich in volatile condensible phases, including S, Zn, F, Cl, and many volatile metals. The volatiles associated with these orange and black glasses (and the Apollo 15 green glasses) may provide important clues in understanding the differentiation and volcanic history of the Moon. In addition, condensible volatiles can be mobilized and concentrated by volcanic processes. We have reviewed many of our existing photomicrographs and energy dispersive analysis (EDXA) of grain surfaces and have reexamined some of our older SEM mounts using an improved EDXA system capable of light-element detection and analysis (oxygen, nitrogen, and carbon). The results from these investigations are presented.

Photochemical Aging of Organic Aerosols: A Laboratory Study

NASA Astrophysics Data System (ADS)

Papanastasiou, Dimitrios K.; Kostenidou, Evangelia; Gkatzelis, Georgios I.; Psichoudaki, Magdalini; Louvaris, Evangelos; Pandis, Spyros N.

2014-05-01

Organic aerosols (OA) are either emitted directly (primary OA) or formed (secondary OA) in the atmosphere and consist of an extremely complex mixture of thousands of organic compounds. Although the scientific community has put significant effort, in the past few decades, to understand organic aerosol (OA) formation, evolution and fate in the atmosphere, traditional models often fail to reproduce the ambient OA levels. Secondary organic aerosol (SOA) formed, in traditional laboratory chamber experiments, from the gas phase oxidation of known precursors, such as α-pinene, is semi-volatile and with an O:C ratio of around 0.4. In contrast, OA found in the atmosphere is significantly less volatile, while the O:C ratio often ranges from 0.5 to 1. In conclusion, there is a significant gap of knowledge in our understanding of OA formation and photochemical transformation in the atmosphere. There is increased evidence that homogeneous gas phase aging by OH radicals might be able to explain, at least in part, the significantly higher OA mass loadings observed and also the oxidation state and volatility of OA in the atmosphere. In this study, laboratory chamber experiments were performed to study the role of the continued oxidation of first generation volatile and semi-volatile species by OH radicals in the evolution of the SOA characteristics (mass concentration, volatility, and oxidation state). Ambient air mixtures or freshly formed SOA from α-pinene ozonolysis were used as the source of organic aerosols and semi-volatile species. The initial mixture of organic aerosols and gas phase species (volatile and semi-volatile) was then exposed to atmospheric concentrations of OH radicals to study the aging of aerosols. Experiments were performed with various OH radical sources (H2O2 or HONO) and under various NOx conditions. A suite of instruments was employed to characterize both the gas and the aerosol phase. A Scanning Mobility Particle Sizer (SMPS) and a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) were used to measure the organic aerosol mass production and oxidation degree (O:C ratio) following OH aging. A thermodenuder system was used to measure the volatility distribution change as organic aerosol aged upon continuous oxidation. Organic gas phase species were characterized with a Proton Transfer Reaction - Mass Spectrometer (PTR-MS) while NOx and O3 were measured with the use of corresponding analyzers. Results from this study show that organic mass production occurs upon exposure to OH radicals indicating that continuous OH aging of semi-volatile is probably responsible for at least some of the gap between observed and modeled OA levels in the atmosphere. Additionally, this chemical aging process leads to a decrease in volatility and an increase in O:C ratio while the level of change in both properties depends on OH exposure. The atmospheric implications of this study are discussed.

Review article: next generation diagnostic modalities in gastroenterology--gas phase volatile compound biomarker detection.

PubMed

Arasaradnam, R P; Covington, J A; Harmston, C; Nwokolo, C U

2014-04-01

The detection of airborne gas phase biomarkers that emanate from biological samples like urine, breath and faeces may herald a new age of non-invasive diagnostics. These biomarkers may reflect status in health and disease and can be detected by humans and other animals, to some extent, but far more consistently with instruments. The continued advancement in micro and nanotechnology has produced a range of compact and sophisticated gas analysis sensors and sensor systems, focussed primarily towards environmental and security applications. These instruments are now increasingly adapted for use in clinical testing and with the discovery of new gas volatile compound biomarkers, lead naturally to a new era of non-invasive diagnostics. To review current sensor instruments like the electronic nose (e-nose) and ion mobility spectroscopy (IMS), existing technology like gas chromatography-mass spectroscopy (GC-MS) and their application in the detection of gas phase volatile compound biomarkers in medicine - focussing on gastroenterology. A systematic search on Medline and Pubmed databases was performed to identify articles relevant to gas and volatile organic compounds. E-nose and IMS instruments achieve sensitivities and specificities ranging from 75 to 92% in differentiating between inflammatory bowel disease, bile acid diarrhoea and colon cancer from controls. For pulmonary disease, the sensitivities and specificities exceed 90% in differentiating between pulmonary malignancy, pneumonia and obstructive airways disease. These sensitivity levels also hold true for diabetes (92%) and bladder cancer (90%) when GC-MS is combined with an e-nose. The accurate reproducible sensing of volatile organic compounds (VOCs) using portable near-patient devices is a goal within reach for today's clinicians. © 2014 John Wiley & Sons Ltd.

Estimates of the organic aerosol volatility in a boreal forest using two independent methods

NASA Astrophysics Data System (ADS)

Hong, Juan; Äijälä, Mikko; Häme, Silja A. K.; Hao, Liqing; Duplissy, Jonathan; Heikkinen, Liine M.; Nie, Wei; Mikkilä, Jyri; Kulmala, Markku; Prisle, Nønne L.; Virtanen, Annele; Ehn, Mikael; Paasonen, Pauli; Worsnop, Douglas R.; Riipinen, Ilona; Petäjä, Tuukka; Kerminen, Veli-Matti

2017-03-01

The volatility distribution of secondary organic aerosols that formed and had undergone aging - i.e., the particle mass fractions of semi-volatile, low-volatility and extremely low volatility organic compounds in the particle phase - was characterized in a boreal forest environment of Hyytiälä, southern Finland. This was done by interpreting field measurements using a volatility tandem differential mobility analyzer (VTDMA) with a kinetic evaporation model. The field measurements were performed during April and May 2014. On average, 40 % of the organics in particles were semi-volatile, 34 % were low-volatility organics and 26 % were extremely low volatility organics. The model was, however, very sensitive to the vaporization enthalpies assumed for the organics (ΔHVAP). The best agreement between the observed and modeled temperature dependence of the evaporation was obtained when effective vaporization enthalpy values of 80 kJ mol-1 were assumed. There are several potential reasons for the low effective enthalpy value, including molecular decomposition or dissociation that might occur in the particle phase upon heating, mixture effects and compound-dependent uncertainties in the mass accommodation coefficient. In addition to the VTDMA-based analysis, semi-volatile and low-volatility organic mass fractions were independently determined by applying positive matrix factorization (PMF) to high-resolution aerosol mass spectrometer (HR-AMS) data. The factor separation was based on the oxygenation levels of organics, specifically the relative abundance of mass ions at m/z 43 (f43) and m/z 44 (f44). The mass fractions of these two organic groups were compared against the VTDMA-based results. In general, the best agreement between the VTDMA results and the PMF-derived mass fractions of organics was obtained when ΔHVAP = 80 kJ mol-1 was set for all organic groups in the model, with a linear correlation coefficient of around 0.4. However, this still indicates that only about 16 % (R2) of the variation can be explained by the linear regression between the results from these two methods. The prospect of determining of extremely low volatility organic aerosols (ELVOAs) from AMS data using the PMF analysis should be assessed in future studies.

Oxidation/volatilization rates in air for candidate fusion reactor blanket materials, PCA and HT-9

NASA Astrophysics Data System (ADS)

Piet, S. J.; Kraus, H. G.; Neilson, R. M.; Jones, J. L.

1986-11-01

Large uncertainties exist in the quantity of neutron-induced activation products that can be mobilized in potential fusion accidents. The accidental combination of high temperatures and oxidizing conditions might lead to mobilization of a significant amount of activation products from structural materials. Here, the volatilization of constituents of PCA and HT-9 resulting form oxidation in air was investigated. Tests were conducted in flowing air at temperatures from 600 to 1300°C for 1, 5, or 20 h. Elemental volatility was calculated in terms of the weight fraction of the element volatilized from the initial alloy. Molybdenum and manganese were the radiologically significant primary constituents most volatilized, suggesting that molybdenum and manganese should be minimized in fusion steel compositions. Higher chromium content appears beneficial in reducing hazards from mobile activation products. Scanning electron microscopy and energy dispersive spectroscopy were used to study the oxide layer on samples.

Analysis of Listeria using exogenous volatile organic compound metabolites and their detection by static headspace-multi-capillary column-gas chromatography-ion mobility spectrometry (SHS-MCC-GC-IMS).

PubMed

Taylor, Carl; Lough, Fraser; Stanforth, Stephen P; Schwalbe, Edward C; Fowlis, Ian A; Dean, John R

2017-07-01

Listeria monocytogenes is a Gram-positive bacterium and an opportunistic food-borne pathogen which poses significant risk to the immune-compromised and pregnant due to the increased likelihood of acquiring infection and potential transmission of infection to the unborn child. Conventional methods of analysis suffer from either long turn-around times or lack the ability to discriminate between Listeria spp. reliably. This paper investigates an alternative method of detecting Listeria spp. using two novel enzyme substrates that liberate exogenous volatile organic compounds in the presence of α-mannosidase and D-alanyl aminopeptidase. The discriminating capabilities of this approach for identifying L. monocytogenes from other species of Listeria are investigated. The liberated volatile organic compounds (VOCs) are detected using an automated analytical technique based on static headspace-multi-capillary column-gas chromatography-ion mobility spectrometry (SHS-MCC-GC-IMS). The results obtained by SHS-MCC-GC-IMS are compared with those obtained by the more conventional analytical technique of headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results found that it was possible to differentiate between L. monocytogenes and L. ivanovii, based on their VOC response from α-mannosidase activity.

Laser-stimulated desorption of organic molecules from surfaces, as a method of increasing the efficiency of ion mobility spectrometry analysis.

PubMed

Akmalov, Artem E; Chistyakov, Alexander A; Kotkovskii, Gennadii E

2017-08-01

Application of laser-induced desorption was investigated as a method of increasing the efficiency of gas phase analyzers on principles of field asymmetric ion mobility spectrometry. Mass spectrometric data of investigations of laser desorption of pentaerythritoltetranitrate molecules and cyclotetramethylenetetranitramine molecules from quartz substrate under vacuum were obtained. Laser sources a Nd 3+ :YAG with nanosecond pulse duration (λ = 532 nm) and a continuous wave diode laser (λ = 440 nm) were used. It was shown that both laser sources have different desorption abilities. This is expressed in various time of appearance of desorbed products that is caused by different heating mechanisms of surface layer. The desorbed quantity under action of both laser sources exceeds the detection threshold for all modern gas phase analyzers. It should be noted that despite the presence of surface dissociation of explosives under laser radiation, the quantity of nondissociated molecules is large enough for detection by ion mobility and field asymmetric ion mobility spectrometers. The optimal parameters of laser radiation for effective removal (evaporation) molecules of low-volatile compounds from surfaces are defined. The conclusion about preferable use of a Nd 3+ :YAG laser for increasing the detection ability of detectors based on ion mobility spectrometry was made.

Multiphase flow and transport caused by spontaneous gas phase growth in the presence of dense non-aqueous phase liquid

NASA Astrophysics Data System (ADS)

Roy, James W.; Smith, James E.

2007-01-01

Disconnected bubbles or ganglia of trapped gas may occur below the top of the capillary fringe through a number of mechanisms. In the presence of dense non-aqueous phase liquid (DNAPL), the disconnected gas phase experiences mass transfer of dissolved gases, including volatile components from the DNAPL. The properties of the gas phase interface can also change. This work shows for the first time that when seed gas bubbles exist spontaneous gas phase growth can be expected to occur and can significantly affect water-gas-DNAPL distributions, fluid flow, and mass transfer. Source zone behaviour was observed in three different experiments performed in a 2-dimensional flow cell. In each case, a DNAPL pool was created in a zone of larger glass beads over smaller glass beads, which served as a capillary barrier. In one experiment effluent water samples were analyzed to determine the vertical concentration profile of the plume above the pool. The experiments effectively demonstrated a) a cycle of spontaneous gas phase expansion and vertical advective mobilization of gas bubbles and ganglia above the DNAPL source zone, b) DNAPL redistribution caused by gas phase growth and mobilization, and c) that these processes can significantly affect mass transport from a NAPL source zone.

Multiphase flow and transport caused by spontaneous gas phase growth in the presence of dense non-aqueous phase liquid.

PubMed

Roy, James W; Smith, James E

2007-01-30

Disconnected bubbles or ganglia of trapped gas may occur below the top of the capillary fringe through a number of mechanisms. In the presence of dense non-aqueous phase liquid (DNAPL), the disconnected gas phase experiences mass transfer of dissolved gases, including volatile components from the DNAPL. The properties of the gas phase interface can also change. This work shows for the first time that when seed gas bubbles exist spontaneous gas phase growth can be expected to occur and can significantly affect water-gas-DNAPL distributions, fluid flow, and mass transfer. Source zone behaviour was observed in three different experiments performed in a 2-dimensional flow cell. In each case, a DNAPL pool was created in a zone of larger glass beads over smaller glass beads, which served as a capillary barrier. In one experiment effluent water samples were analyzed to determine the vertical concentration profile of the plume above the pool. The experiments effectively demonstrated a) a cycle of spontaneous gas phase expansion and vertical advective mobilization of gas bubbles and ganglia above the DNAPL source zone, b) DNAPL redistribution caused by gas phase growth and mobilization, and c) that these processes can significantly affect mass transport from a NAPL source zone.

Bacterial chemotaxis along vapor-phase gradients of naphthalene.

PubMed

Hanzel, Joanna; Harms, Hauke; Wick, Lukas Y

2010-12-15

The role of bacterial growth and translocation for the bioremediation of organic contaminants in the vadose zone is poorly understood. Whereas air-filled pores restrict the mobility of bacteria, diffusion of volatile organic compounds in air is more efficient than in water. Past research, however, has focused on chemotactic swimming of bacteria along gradients of water-dissolved chemicals. In this study we tested if and to what extent Pseudomonas putida PpG7 (NAH7) chemotactically reacts to vapor-phase gradients forming above their swimming medium by the volatilization from a spot source of solid naphthalene. The development of an aqueous naphthalene gradient by air-water partitioning was largely suppressed by means of activated carbon in the agar. Surprisingly, strain PpG7 was repelled by vapor-phase naphthalene although the steady state gaseous concentrations were 50-100 times lower than the aqueous concentrations that result in positive chemotaxis of the same strain. It is thus assumed that the efficient gas-phase diffusion resulting in a steady, and possibly toxic, naphthalene flux to the cells controlled the chemotactic reaction rather than the concentration to which the cells were exposed. To our knowledge this is the first demonstration of apparent chemotactic behavior of bacteria in response to vapor-phase effector gradients.

Detecting macroeconomic phases in the Dow Jones Industrial Average time series

NASA Astrophysics Data System (ADS)

Wong, Jian Cheng; Lian, Heng; Cheong, Siew Ann

2009-11-01

In this paper, we perform statistical segmentation and clustering analysis of the Dow Jones Industrial Average (DJI) time series between January 1997 and August 2008. Modeling the index movements and log-index movements as stationary Gaussian processes, we find a total of 116 and 119 statistically stationary segments respectively. These can then be grouped into between five and seven clusters, each representing a different macroeconomic phase. The macroeconomic phases are distinguished primarily by their volatilities. We find that the US economy, as measured by the DJI, spends most of its time in a low-volatility phase and a high-volatility phase. The former can be roughly associated with economic expansion, while the latter contains the economic contraction phase in the standard economic cycle. Both phases are interrupted by a moderate-volatility market correction phase, but extremely-high-volatility market crashes are found mostly within the high-volatility phase. From the temporal distribution of various phases, we see a high-volatility phase from mid-1998 to mid-2003, and another starting mid-2007 (the current global financial crisis). Transitions from the low-volatility phase to the high-volatility phase are preceded by a series of precursor shocks, whereas the transition from the high-volatility phase to the low-volatility phase is preceded by a series of inverted shocks. The time scale for both types of transitions is about a year. We also identify the July 1997 Asian Financial Crisis to be the trigger for the mid-1998 transition, and an unnamed May 2006 market event related to corrections in the Chinese markets to be the trigger for the mid-2007 transition.

High Performance Liquid Chromatography

NASA Astrophysics Data System (ADS)

Talcott, Stephen

High performance liquid chromatography (HPLC) has many applications in food chemistry. Food components that have been analyzed with HPLC include organic acids, vitamins, amino acids, sugars, nitrosamines, certain pesticides, metabolites, fatty acids, aflatoxins, pigments, and certain food additives. Unlike gas chromatography, it is not necessary for the compound being analyzed to be volatile. It is necessary, however, for the compounds to have some solubility in the mobile phase. It is important that the solubilized samples for injection be free from all particulate matter, so centrifugation and filtration are common procedures. Also, solid-phase extraction is used commonly in sample preparation to remove interfering compounds from the sample matrix prior to HPLC analysis.

A Physical Model for Three-Phase Compaction in Silicic Magma Reservoirs

NASA Astrophysics Data System (ADS)

Huber, Christian; Parmigiani, Andrea

2018-04-01

We develop a model for phase separation in magma reservoirs containing a mixture of silicate melt, crystals, and fluids (exsolved volatiles). The interplay between the three phases controls the dynamics of phase separation and consequently the chemical and physical evolution of magma reservoirs. The model we propose is based on the two-phase damage theory approach of Bercovici et al. (2001, https://doi.org/10.1029/2000JB900430) and Bercovici and Ricard (2003, https://doi.org/10.1046/j.1365-246X.2003.01854.x) because it offers the leverage of considering interface (in the macroscopic limit) between phases that can deform depending on the mechanical work and phase changes taking place locally in the magma. Damage models also offer the advantage that pressure is defined uniquely to each phase and does not need to be equal among phases, which will enable us to consider, in future studies, the large capillary pressure at which fluids are mobilized in mature, crystal-rich, magma bodies. In this first analysis of three-phase compaction, we solve the three-phase compaction equations numerically for a simple 1-D problem where we focus on the effect of fluids on the efficiency of melt-crystal separation considering the competition between viscous and buoyancy stresses only. We contrast three sets of simulations to explore the behavior of three-phase compaction, a melt-crystal reference compaction scenario (two-phase compaction), a three-phase scenario without phase changes, and finally a three-phase scenario with a parameterized second boiling (crystallization-induced exsolution). The simulations show a dramatic difference between two-phase (melt crystals) and three-phase (melt-crystals-exsolved volatiles) compaction-driven phase separation. We find that the presence of a lighter, significantly less viscous fluid hinders melt-crystal separation.

Different methods for volatile sampling in mammals

PubMed Central

Möller, Manfred; Marcillo, Andrea; Einspanier, Almuth; Weiß, Brigitte M.

2017-01-01

Previous studies showed that olfactory cues are important for mammalian communication. However, many specific compounds that convey information between conspecifics are still unknown. To understand mechanisms and functions of olfactory cues, olfactory signals such as volatile compounds emitted from individuals need to be assessed. Sampling of animals with and without scent glands was typically conducted using cotton swabs rubbed over the skin or fur and analysed by gas chromatography-mass spectrometry (GC-MS). However, this method has various drawbacks, including a high level of contaminations. Thus, we adapted two methods of volatile sampling from other research fields and compared them to sampling with cotton swabs. To do so we assessed the body odor of common marmosets (Callithrix jacchus) using cotton swabs, thermal desorption (TD) tubes and, alternatively, a mobile GC-MS device containing a thermal desorption trap. Overall, TD tubes comprised most compounds (N = 113), with half of those compounds being volatile (N = 52). The mobile GC-MS captured the fewest compounds (N = 35), of which all were volatile. Cotton swabs contained an intermediate number of compounds (N = 55), but very few volatiles (N = 10). Almost all compounds found with the mobile GC-MS were also captured with TD tubes (94%). Hence, we recommend TD tubes for state of the art sampling of body odor of mammals or other vertebrates, particularly for field studies, as they can be easily transported, stored and analysed with high performance instruments in the lab. Nevertheless, cotton swabs capture compounds which still may contribute to the body odor, e.g. after bacterial fermentation, while profiles from mobile GC-MS include only the most abundant volatiles of the body odor. PMID:28841690

Quantitative analysis of volatile organic compounds using ion mobility spectra and cascade correlation neural networks

NASA Technical Reports Server (NTRS)

Harrington, Peter DEB.; Zheng, Peng

1995-01-01

Ion Mobility Spectrometry (IMS) is a powerful technique for trace organic analysis in the gas phase. Quantitative measurements are difficult, because IMS has a limited linear range. Factors that may affect the instrument response are pressure, temperature, and humidity. Nonlinear calibration methods, such as neural networks, may be ideally suited for IMS. Neural networks have the capability of modeling complex systems. Many neural networks suffer from long training times and overfitting. Cascade correlation neural networks train at very fast rates. They also build their own topology, that is a number of layers and number of units in each layer. By controlling the decay parameter in training neural networks, reproducible and general models may be obtained.

Ternary nucleation as a mechanism for the production of diesel nanoparticles: experimental analysis of the volatile and hygroscopic properties of diesel exhaust using the volatilization and humidification tandem differential mobility analyzer.

PubMed

Meyer, N K; Ristovski, Z D

2007-11-01

The volatile and hygroscopic properties of diesel nanoparticles were simultaneously determined under a range of engine loads using the volatilization and humidification tandem differential mobility analyzer (VH-TDMA). Additionally, the VH-TDMA was used to measure changes in the hygroscopic behavior of the heterogeneously nucleated diesel nanoparticles as one or more semivolatile species were removed via thermal evaporation or decomposition. Particles produced at high loads exhibited high, dual-step volatility, while those particles produced at low loads were less volatile and exhibited continuous volatilization curves. The hygroscopic growth factor of the particles was shown to be load dependent with high-load particles exhibiting growth factors similar to that of ammonium sulfate. At 85% relative humidity, particles produced at moderate loads exhibited growth factors of approximately 1.1 while low-load particles were shown to be hydrophobic. Growth factors and volatilization temperatures measured for high-load particles clearly indicate that ternary nucleation is involved in particle formation.

Ammonium Ion Binding to DNA G-Quadruplexes: Do Electrospray Mass Spectra Faithfully Reflect the Solution-Phase Species?

NASA Astrophysics Data System (ADS)

Balthasart, Françoise; Plavec, Janez; Gabelica, Valérie

2013-01-01

G-quadruplex nucleic acids can bind ammonium ions in solution, and these complexes can be detected by electrospray mass spectrometry (ESI-MS). However, because ammonium ions are volatile, the extent to which ESI-MS quantitatively could provide an accurate reflection of such solution-phase equilibria is unclear. Here we studied five G-quadruplexes having known solution-phase structure and ammonium ion binding constants: the bimolecular G-quadruplexes (dG4T4G4)2, (dG4T3G4)2, and (dG3T4G4)2, and the intramolecular G-quadruplexes dG4(T4G4)3 and dG2T2G2TGTG2T2G2 (thrombin binding aptamer). We found that not all mass spectrometers are equally suited to reflect the solution phase species. Ion activation can occur in the electrospray source, or in a high-pressure traveling wave ion mobility cell. When the softest instrumental conditions are used, ammonium ions bound between G-quartets, but also additional ammonium ions bound at specific sites outside the external G-quartets, can be observed. However, even specifically bound ammonium ions are in some instances too labile to be fully retained in the gas phase structures, and although the ammonium ion distribution observed by ESI-MS shows biases at specific stoichiometries, the relative abundances in solution are not always faithfully reflected. Ion mobility spectrometry results show that all inter-quartet ammonium ions are necessary to preserve the G-quadruplex fold in the gas phase. Ion mobility experiments, therefore, help assign the number of inner ammonium ions in the solution phase structure.[Figure not available: see fulltext.

Development and validation of a reversed phase liquid chromatographic method for analysis of oxytetracycline and related impurities.

PubMed

Kahsay, Getu; Shraim, Fairouz; Villatte, Philippe; Rotger, Jacques; Cassus-Coussère, Céline; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

2013-03-05

A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities. Copyright © 2012 Elsevier B.V. All rights reserved.

A Second-Generation Volatile Organic Analyzer for the International Space Station

NASA Technical Reports Server (NTRS)

Limero, Thomas; Reese, Eric; Peters, Randy; James, John T.

1999-01-01

Early in the development of the Crew Health Care System (CHECS) for the International Space Station (ISS), it was recognized that detection of target volatile organic compounds would be a key component of the air monitoring strategy. Experiences during the NASA/Mir program supported the decision to include a real-time volatile organic analyzer (VOA) aboard ISS to help assess the impact of air quality events on crew health and determine the effectiveness of decontamination efforts. Toward this end, a joint development by the Toxicology Laboratory at Johnson Space Center and Graseby Dynamics produced a VOA that has been delivered and is ready for the first 5 years of ISS operation. The first-generation VOA selection criteria included minimizing size, weight, and power consumption while maintaining analytical performance. Measuring available technologies against these criteria, a VOA system based upon gas chromatography/ion mobility spectrometry (GC/IMS) was selected in the mid-90's. However, as NASA looks forward to later-stage ISS operations and to new frontiers such as human exploration of Mars, the ISS VOA (weighing 43 kg and consuming 160 watts) must be replaced by a smaller, less resource-intensive device. This paper will present a possible second-gene ration VOA based upon the same technology as the first-generation unit. Utilizing GC/IMS technology again will permit the instrumental data and experience gained during the initial phase of ISS to be applied to later ISS phases and advanced spacecraft missions. During the past 3 years, efforts to reduce the size of ion mobility spectrometers have been pursued by Graseby Dynamics, the manufacturer of the first-generation VOA. The concept of operation, expected analytical performance, and estimated size of a fully functional second-generation VOA based upon GC/mini-IMS technology will be presented. Furthermore, results of initial laboratory evaluations will be shown.

Measurement of the temperature dependent partitioning of semi-volatile organics onto aerosol near roadways

NASA Astrophysics Data System (ADS)

Wentzell, J. J.; Liggio, J.; Li, S.; Brook, J.; Staebler, R. M.; Evans, G. J.; Jeong, C.; Sheppard, A.; Lu, G.; Gordon, M.; Mihele, C.

2010-12-01

The volatility of the organic aerosol fraction has received a great deal of attention recently in light of new volatility-based modelling approaches and due to the inability of current models to fully account for secondary organic aerosol (SOA). In this regard, evaporation of primary organic aerosol species and their subsequent oxidation may contribute significantly to SOA downwind of sources. This implies that moderate ambient temperature fluctuations can significantly increase or decrease the aerosol bound fraction of semi-volatile and intermediate volatility (SVOC + IVOC) compounds. In order to examine the importance of these more volatile organic components, a temperature controlled inlet was developed with the ability to heat and cool the aerosol in 2 C increments to 15 C above or below ambient temperature. The inlet was coupled to an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and deployed on a mobile platform upwind and downwind of a major Southern Ontario highway as part of the Fast Evolution of Vehicle Emissions near Roadways (FEVER 2010) campaign. Preliminary results suggest that changes in temperature of 5-10 C can alter the partitioning of volatile organic aerosol components by up to 30%. Although the largest affect was observed 10-13 meters downwind of the vehicle emissions, a measurable affect was observed beyond 500 m and in aerosol upwind of the highway. These results suggest that a significant pool of semi-volatile organics exist, which can condense onto particles at slightly lower temperatures or evaporate to the gas phase and be further oxidized. The nature of these organic species at locations upwind and downwind of vehicle emissions will be discussed.

A review of emerging non-volatile memory (NVM) technologies and applications

NASA Astrophysics Data System (ADS)

Chen, An

2016-11-01

This paper will review emerging non-volatile memory (NVM) technologies, with the focus on phase change memory (PCM), spin-transfer-torque random-access-memory (STTRAM), resistive random-access-memory (RRAM), and ferroelectric field-effect-transistor (FeFET) memory. These promising NVM devices are evaluated in terms of their advantages, challenges, and applications. Their performance is compared based on reported parameters of major industrial test chips. Memory selector devices and cell structures are discussed. Changing market trends toward low power (e.g., mobile, IoT) and data-centric applications create opportunities for emerging NVMs. High-performance and low-cost emerging NVMs may simplify memory hierarchy, introduce non-volatility in logic gates and circuits, reduce system power, and enable novel architectures. Storage-class memory (SCM) based on high-density NVMs could fill the performance and density gap between memory and storage. Some unique characteristics of emerging NVMs can be utilized for novel applications beyond the memory space, e.g., neuromorphic computing, hardware security, etc. In the beyond-CMOS era, emerging NVMs have the potential to fulfill more important functions and enable more efficient, intelligent, and secure computing systems.

Visualising the equilibrium distribution and mobility of organic contaminants in soil using the chemical partitioning space.

PubMed

Wong, Fiona; Wania, Frank

2011-06-01

Assessing the behaviour of organic chemicals in soil is a complex task as it is governed by the physical chemical properties of the chemicals, the characteristics of the soil as well as the ambient conditions of the environment. The chemical partitioning space, defined by the air-water partition coefficient (K(AW)) and the soil organic carbon-water partition coefficient (K(OC)), was employed to visualize the equilibrium distribution of organic contaminants between the air-filled pores, the pore water and the solid phases of the bulk soil and the relative importance of the three transport processes removing contaminants from soil (evaporation, leaching and particle erosion). The partitioning properties of twenty neutral organic chemicals (i.e. herbicides, pharmaceuticals, polychlorinated biphenyls and volatile chemicals) were estimated using poly-parameter linear free energy relationships and superimposed onto these maps. This allows instantaneous estimation of the equilibrium phase distribution and mobility of neutral organic chemicals in soil. Although there is a link between the major phase and the dominant transport process, such that chemicals found in air-filled pore space are subject to evaporation, those in water-filled pore space undergo leaching and those in the sorbed phase are associated with particle erosion, the partitioning coefficient thresholds for distribution and mobility can often deviate by many orders of magnitude. In particular, even a small fraction of chemical in pore water or pore air allows for evaporation and leaching to dominate over solid phase transport. Multiple maps that represent soils that differ in the amount and type of soil organic matter, water saturation, temperature, depth of surface soil horizon, and mineral matters were evaluated.

Molecular structure impacts on secondary organic aerosol formation from glycol ethers

NASA Astrophysics Data System (ADS)

Li, Lijie; Cocker, David R.

2018-05-01

Glycol ethers, a class of widely used solvents in consumer products, are often considered exempt as volatile organic compounds based on their vapor pressure or boiling points by regulatory agencies. However, recent studies found that glycol ethers volatilize at ambient conditions nearly as rapidly as the traditional high-volatility solvents indicating the potential of glycol ethers to form secondary organic aerosol (SOA). This is the first work on SOA formation from glycol ethers. The impact of molecular structure, specifically -OH, on SOA formation from glycol ethers and related ethers are investigated in the work. Ethers with and without -OH, with methyl group hindrance on -OH and with -OH at different location are studied in the presence of NOX and under "NOX free" conditions. Photooxidation experiments under different oxidation conditions confirm that the processing of ethers is a combination of carbonyl formation, cyclization and fragmentation. Bulk SOA chemical composition analysis and oxidation products identified in both gas and particle phase suggests that the presence and location of -OH in the carbon bond of ethers determine the occurrence of cyclization mechanism during ether oxidation. The cyclization is proposed as a critical SOA formation mechanism to prevent the formation of volatile compounds from fragmentation during the oxidation of ethers. Glycol ethers with -CH2-O-CH2CH2OH structure is found to readily form cyclization products, especially with the presence of NOx, which is more relevant to urban atmospheric conditions than without NOx. Glycol ethers are evaluated as dominating SOA precursors among all ethers studied. It is estimated that the contribution of glycol ethers to anthropogenic SOA is roughly 1% of the current organic aerosol from mobile sources. The contribution of glycol ethers to anthropogenic SOA is roughly 1% of the current organic aerosol from mobile sources and will play a more important role in future anthropogenic SOA formation.

Ridge Outgassing and Melt Production from 4Ga to Present

NASA Astrophysics Data System (ADS)

Fuentes, J.; Crowley, J.; Dasgupta, R.; Mitrovica, J. X.

2017-12-01

The majority of Earth's volcanism occurs at ocean ridges via decompression melting. This process exerts a strong control on the mantle and surface volatile contents throughout Earth history. In this study, we investigate mantle temperature, ridge melt production, and ridge CO2 outgassing from 4 Ga to present by coupling an analytical mantle convection model (Crowley and O'Connell 2012) with a recent petrologic model of peridotite melting in the presence of CO2 (Dasgupta et al. 2013). By taking advantage of the computational efficiency of the convection model, we simulate time-dependent convection with a large suite of realistic mantle and lithospheric parameters to produce a full range of possible thermal histories. We only accept models which evolve from stagnant-lid convection to mobile-lid convection in order to be consistent with previous geodynamic modeling and geochemical studies (i.e. Condie et al. 2016, Debaille et al. 2013). The presence of volatiles in the mantle leads to deeper, low degree melting. This effect, combined with higher temperatures sustained during the phase of stagnant-lid convection, has a significant effect on the total mass of CO2 outgassed (as well as other volatiles), with major implications for early Earth climate and its continued evolution.

Childhood Income Volatility and Adult Outcomes. University of Kentucky Center for Poverty Research Discussion Paper Series, DP2012-03

ERIC Educational Resources Information Center

Hardy, Bradley

2012-01-01

Using data linked across generations in the Panel Study of Income Dynamics, I estimate the relationship between exposure to volatile income during childhood and a set of socioeconomic outcomes in adulthood. The empirical framework is an augmented intergenerational income mobility model that includes controls for income volatility. I measure income…

Volatile behavior and trace metal transport in the magmatic-geothermal system at Pūtauaki (Mt. Edgecumbe), New Zealand

NASA Astrophysics Data System (ADS)

Norling, B.; Rowe, M. C.; Chambefort, I.; Tepley, F. J.; Morrow, S.

2016-05-01

The present-day hydrothermal system beneath the Kawerau Geothermal Field, in the Taupo Volcanic Zone, New Zealand, is likely heated from the Pūtauaki (Mt. Edgecumbe) magma system. The aim of this work, as an analog for present day processes, is to identify whether or not earlier erupted Pūtauaki magmas show evidence for volatile exsolution. This may have led to the transfer of volatile components from the magmatic to hydrothermal systems. To accomplish this, minerals and melt inclusions from volcanic products were analyzed for abundances of volatile and ore-forming elements (S, Cl, Li, Cu, Sn, Mo, W, Sb, As, and Tl). The variations in abundance of these elements were used to assess magma evolution and volatile exsolution or fluxing in the magma system. Melt inclusions suggest the evolution of Pūtauaki andesite-dacite magmas is predominantly driven by crystallization processes resulting in rhyodacite-rhyolite glass compositions (although textural and geochemical evidence still indicate a role for magma mixing). Measured mineral-melt partition coefficients for trace metals of interest indicates that, with the exception of Tl in biotite, analyzed metals are all incompatible in Pūtauaki crystallization products. Excluding Li and Cu, other volatile and ore metals recorded in melt inclusions behave incompatibly, with concentrations increasing during evolution from rhyodacitic to rhyolitic melt compositions. Li and Cu appear to have increased mobility likely resulting from diffusive exchange post-crystallization, and may be related to late volatile fluxing. Although S and Cl concentrations decrease with melt evolution, no mineralogical evidence exists to indicate the exsolution and mobility of ore-forming metals from the magma at the time of crystallization. This observation cannot rule out the potential for post-crystallization volatile exsolution and ore-forming metal mobilization, which may only be recorded as diffusive re-equilibration of more rapidly diffusing elements (e.g., Li and Cu).

Heavy metal speciation in solid-phase materials from a bacterial sulfate reducing bioreactor using sequential extraction procedure combined with acid volatile sulfide analysis.

PubMed

Jong, Tony; Parry, David L

2004-04-01

Heavy metal mobility, bioavailability and toxicity depends largely on the chemical form of metals and ultimately determines potential for environmental pollution. For this reason, determining the chemical form of heavy metals and metalloids, immobilized in sludges by biological mediated sulfate reduction, is important to evaluate their mobility and bioavailability. A modified Tessier sequential extraction procedure (SEP), complemented with acid volatile sulfide (AVS) and simultaneous extracted metals (SEM) measurements, were applied to determine the partitioning of five heavy metals (defined as Fe, Ni, Zn and Cu, and the metalloid As) in anoxic solid-phase material (ASM) from an anaerobic, sulfate reducing bioreactor into six operationally defined fractions. These fractions were water soluble, exchangeable, bound to carbonates (acid soluble), bound to Fe-Mn oxides (reducible), bound to organic matter and sulfides (oxidizable) and residual. It was found that the distribution of Fe, Ni, Zn, Cu and As in ASM was strongly influenced by its association with the above solid fractions. The fraction corresponding to organic matter and sulfides appeared to be the most important scavenging phases of As, Fe, Ni, Zn and Cu in ASM (59.8-86.7%). This result was supported by AVS and SEM (Sigma Zn, Ni and Cu) measurements, which indicated that the heavy metals existed overwhelmingly as sulfides in the organic matter and sulfide fraction. A substantial amount of Fe and Ni at 16.4 and 20.1%, respectively, were also present in the carbonate fraction, while an appreciable portion of As (18.3%) and Zn (19.4%) was bound to Fe-Mn oxides. A significant amount of heavy metals was also associated with the residual fraction, ranging from 2.1% for Zn to 18.8% for As. Based on the average total extractable heavy metal (TEHM) values, the concentration of heavy metals in the ASM was in the order of Cu > Ni > Zn > Fe > As. If the mobility and bioavailability of heavy metals are assumed to be related to their solubility and chemical forms, and that they decrease with each successive extraction step, then the apparent mobility and bioavailability of these five heavy metals in ASM increase in the order of Cu < As < Ni < Fe < Zn. The SEM/AVS ratio was less than one in eight replicate ASM samples, indicating that the ASM was non-toxic with regards to having a low probability of bioavailable metals in the pore water.

Separation and characterization of allergic polymerized impurities in cephalosporins by 2D-HPSEC×LC-IT-TOF MS.

PubMed

Xu, Yu; Wang, DanDan; Tang, Lan; Wang, Jian

2017-10-25

Eleven unknown allergic impurities in cefodizime, cefmenoxime and cefonicid were separated and characterized by a trap-free two-dimensional high performance size exclusion chromatography (HPSEC) and reversed phase liquid chromatography (RP-HPLC) coupled to high resolution ion trap/time-of-flight mass spectrometry (2D-HPSEC×LC-IT-TOF MS) with positive and negative modes of electrospray ionization method. Separation and characterization the allergic polymerized impurities in β-lactam antibiotics were on the basis of column-switching technique which effectively combined the advantages of HPSEC and the ability of RP-HPLC to identify the special impurities. In the first dimension HPSEC, the column was Xtimate SEC-120 analytical column (7.8mm×30cm, 5μm), and the gradient elution used pH 7.0 buffer-acetonitrile as mobile phase And the second dimension analytical column was ZORBAX SB-C18 (4.6×150mm, 3.5μm) with ammonium formate solution (10mM) and ammonium formate (8mM) in [acetonitrile-water (4:1, v/v)] solution as mobile phase. Structures of eleven unknown impurities were deduced based on the high resolution MS n data with both positive and negative modes, in which nine impurities were polymerized impurities. The forming mechanism of β-lactam antibiotic polymerization in cephalosporins was also studied. The question on incompatibility between non-volatile salt mobile phase and mass spectrometry was solved completely by multidimensional heart-cutting approaches and online demineralization technique, which was worthy of widespread use and application for the advantages of stability and repeatability. Copyright © 2017. Published by Elsevier B.V.

Methods for detecting the mobility of trace elements during medium-temperature pyrolysis

USGS Publications Warehouse

Shiley, R.H.; Konopka, K.L.; Cahill, R.A.; Hinckley, C.C.; Smith, Gerard V.; Twardowska, H.; Saporoschenko, Mykola

1983-01-01

The mobility (volatility) of trace elements in coal during pyrolysis has been studied for distances of up to 40 cm between the coal and the trace element collector, which was graphite or a baffled solvent trap. Nineteen elements not previously recorded as mobile were detected. ?? 1983.

MOBILE EMISSIONS CHARACTERIZATION TEAM (HANDOUT)

EPA Science Inventory

The handout describes the Mobile Emissions Characterization Team of EPA's Office of Research and Development, National Risk Management Research Laboratory, Air Pollution Prevention and Control Division. The team conducts research to characterize and evaluate emissions of volatile...

EVALUATION OF BIOAEROSOL COMPONENTS, GENERATION FACTORS, AND AIRBORNE TRANSPORT ASSOCIATED WITH LIME TREATMENT OF CONTAMINATED SEDIMENT

EPA Science Inventory

Lime treatment has been used in contaminated sediment management activities for many purposes such as dewatering, improvement of physical properties, and reducing contaminant mobility. Exothermic volatilization of volatile organic compounds from lime-treated sediment is well kno...

Acid Volatile Sulfides and Simultaneously Extracted Copper, Lead, and Zinc in Sediments of Sinclair Inlet, Washington

DTIC Science & Technology

1993-09-01

to Doug Vaught, J. Towell, and Eric Schlierman of Puget Sound Naval Shipyard for providing laboratory space, equipment, and logistical support for the...availability and mobility of toxic metal contamination in the sediments of Sinclair Inlet, Puget Sound , Washington, acid volatile sulfide (AVS) and... Puget Sound , Washington ........ 1 2. Apparatus used for measuring acid volatile sulfides ........................... 5 3. Sulfide electrode

Volatility Properties of Internally- and Externally-Mixed Ambient Aerosols at an Anthropogenically-influenced Forest Site in Southeastern USA

NASA Astrophysics Data System (ADS)

Khlystov, A.; Subramanian, R.

2015-12-01

Secondary organic aerosol (SOA) from biogenic sources has a significant contribution to ambient aerosol loadings in Southeastern USA and thus contributes to adverse health effects of air pollution and influences regional and global climate. Volatility properties of biogenic SOA determine its concentration, reactivity, and lifetime, but are still largely unknown. As part of a larger study to assess the effect of biogenic SOA on aerosol optical properties, a set of instruments, including scanning mobility sizers (SMPS), single particle soot photometer (SP2), and a thermodenuder, was deployed during June 2015 at a Duke Forest site near Chapel Hill, NC. The site is characterized by a significant contribution of both biogenic and urban (mostly traffic) sources. Measurements of changes in aerosol volume and optical size upon heating in the thermodenuder at different temperatures are used to derive volatility properties of the ambient aerosol. A limited set of experiments was carried out using the tandem differential mobility analysis (TDMA) approach to investigate whether the ambient aerosol at the Duke Forest site is internally mixed with respect to its volatility properties. In this presentation we will discuss equilibrium and kinetic aspects of aerosol volatility observed during this study and implications of external vs. internal mixing for derivation of bulk volatility properties of ambient aerosol.

Characterization of kerosene-heater emissions inside two mobile homes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burton, R.M.; Seila, R.A.; Wilson, W.E.

1990-03-01

In an effort to determine the impact of kerosene heater emissions on indoor air quality, measurements were made in and around two mobile homes at a rural mobile home park near Apex, NC. The sampling was performed at two single-wide mobile homes equipped with kerosene heaters. The concentrations of acidic aerosols and gases, fine and coarse particulate aerosol mass, carbon monoxide, nitrogen oxides, volatile organic compounds and semivolatiles, were determined for periods of heater operation and for periods in which heaters were not operated. Simultaneous outdoor measurements of acid aerosols and gases, fine and coarse aerosol mass, and volatile organicmore » compounds were conducted to determine the contribution of outdoor pollutants to the indoor concentrations. Comparisons between the concentrations obtained from the analysis of outdoor, heater-on, and heater-off samples allowed the authors to examine the impacts of the kerosene emissions on indoor concentrations. Concentrations of sulfates, aerosol strong acidity, fine and coarse aerosol mass, carbon monoxide, and sulfur dioxide were found to be higher when the heater was operated; however, these heater-on concentrations were comparable to those observed in moderately polluted atmospheres. Indoor concentrations of nitrous acid and nitrogen oxides during heater operation were found to be considerably higher than those observed in polluted atmospheres. Finally, use of kerosene heaters was found to be responsible for increased concentrations of non-methane volatile and semi-volatile organic compounds indoors. Acid aerosol indoor concentrations were quite variable during the study and were found to exist in the presence of excess ammonia.« less

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

DEMONSTRATION BULLETIN: IN-SITU STEAM/HOT AIR SOIL STRIPPING TOXIC TREATMENT (USA) INC.

EPA Science Inventory

This technology uses steam and hot air to strip volatile organics from contaminated soil. The treatment equipment is mobile and treats the soil in-situ without need for soil excavation or transportation. The organic contaminants volatilized from the soil are condensed and col...

Thermal characterization of aminium nitrate nanoparticles.

PubMed

Salo, Kent; Westerlund, Jonathan; Andersson, Patrik U; Nielsen, Claus; D'Anna, Barbara; Hallquist, Mattias

2011-10-27

Amines are widely used and originate from both anthropogenic and natural sources. Recently, there is, in addition, a raised concern about emissions of small amines formed as degradation products of the more complex amines used in CO(2) capture and storage systems. Amines are bases and can readily contribute to aerosol mass and number concentration via acid-base reactions but are also subject to gas phase oxidation forming secondary organic aerosols. To provide more insight into the atmospheric fate of the amines, this paper addresses the volatility properties of aminium nitrates suggested to be produced in the atmosphere from acid-base reactions of amines with nitric acid. The enthalpy of vaporization has been determined for the aminium nitrates of mono-, di-, trimethylamine, ethylamine, and monoethanolamine. The enthalpy of vaporization was determined from volatility measurements of laboratory generated aerosol nanoparticles using a volatility tandem differential mobility analyzer set up. The determined enthalpy of vaporization for aminium nitrates range from 54 up to 74 kJ mol(-1), and the calculated vapor pressures at 298 K are around 10(-4) Pa. These values indicate that aminium nitrates can take part in gas-to-particle partitioning at ambient conditions and have the potential to nucleate under high NO(x) conditions, e.g., in combustion plumes.

Effect of strain on the Curie temperature and band structure of low-dimensional SbSI

NASA Astrophysics Data System (ADS)

Wang, Yiping; Hu, Yang; Chen, Zhizhong; Guo, Yuwei; Wang, Dong; Wertz, Esther A.; Shi, Jian

2018-04-01

Photoferroelectric materials show great promise for developing alternative photovoltaics and photovoltaic-type non-volatile memories. However, the localized nature of the d orbital and large bandgap of most natural photoferroelectric materials lead to low electron/hole mobility and limit the realization of technologically practical devices. Antimony sulpho-iodide (SbSI) is a photoferroelectric material which is expected to have high electron/hole mobility in the ferroelectric state due to its non-local band dispersion and narrow bandgap. However, SbSI exhibits the paraelectric state close to room temperature. In this report, as a proof of concept, we explore the possibility to stabilize the SbSI ferroelectric phase above room temperature via mechanical strain engineering. We synthesized thin low-dimensional crystals of SbSI by chemical vapor deposition, confirmed its crystal structure with electron diffraction, studied its optical properties via photoluminescence spectroscopy and time-resolved photoluminescence spectroscopy, and probed its phase transition using temperature-dependent steady-state photoluminescence spectroscopy. We found that introducing external mechanical strain to these low-dimensional crystals may lead to an increase in their Curie temperature (by ˜60 K), derived by the strain-modified optical phase transition in SbSI and quantified by Kern formulation and Landau theory. The study suggests that strain engineering could be an effective way to stabilize the ferroelectric phase of SbSI at above room temperature, providing a solution enabling its application for technologically useful photoferroelectric devices.

MATRIX-VBS (v1.0): Implementing an Evolving Organic Aerosol Volatility in an Aerosol Microphysics Model

NASA Technical Reports Server (NTRS)

Gao, Chloe Y.; Tsigaridis, Kostas; Bauer, Susanne E.

2017-01-01

The gas-particle partitioning and chemical aging of semi-volatile organic aerosol are presented in a newly developed box model scheme, where its effect on the growth, composition, and mixing state of particles is examined. The volatility-basis set (VBS) framework is implemented into the aerosol microphysical scheme MATRIX (Multiconfiguration Aerosol TRacker of mIXing state), which resolves mass and number aerosol concentrations and in multiple mixing-state classes. The new scheme, MATRIX-VBS, has the potential to significantly advance the representation of organic aerosols in Earth system models by improving upon the conventional representation as non-volatile particulate organic matter, often also with an assumed fixed size distribution. We present results from idealized cases representing Beijing, Mexico City, a Finnish forest, and a southeastern US forest, and investigate the evolution of mass concentrations and volatility distributions for organic species across the gas and particle phases, as well as assessing their mixing state among aerosol populations. Emitted semi-volatile primary organic aerosols evaporate almost completely in the intermediate-volatility range, while they remain in the particle phase in the low-volatility range. Their volatility distribution at any point in time depends on the applied emission factors, oxidation by OH radicals, and temperature. We also compare against parallel simulations with the original scheme, which represented only the particulate and non-volatile component of the organic aerosol, examining how differently the condensed-phase organic matter is distributed across the mixing states in the model. The results demonstrate the importance of representing organic aerosol as a semi-volatile aerosol, and explicitly calculating the partitioning of organic species between the gas and particulate phases.

Chromatographic Techniques for Rare Earth Elements Analysis

NASA Astrophysics Data System (ADS)

Chen, Beibei; He, Man; Zhang, Huashan; Jiang, Zucheng; Hu, Bin

2017-04-01

The present capability of rare earth element (REE) analysis has been achieved by the development of two instrumental techniques. The efficiency of spectroscopic methods was extraordinarily improved for the detection and determination of REE traces in various materials. On the other hand, the determination of REEs very often depends on the preconcentration and separation of REEs, and chromatographic techniques are very powerful tools for the separation of REEs. By coupling with sensitive detectors, many ambitious analytical tasks can be fulfilled. Liquid chromatography is the most widely used technique. Different combinations of stationary phases and mobile phases could be used in ion exchange chromatography, ion chromatography, ion-pair reverse-phase chromatography and some other techniques. The application of gas chromatography is limited because only volatile compounds of REEs can be separated. Thin-layer and paper chromatography are techniques that cannot be directly coupled with suitable detectors, which limit their applications. For special demands, separations can be performed by capillary electrophoresis, which has very high separation efficiency.

Effects of cold temperature and ethanol content on VOC ...

EPA Pesticide Factsheets

Emissions of speciated volatile organic compounds (VOCs), including mobile source air toxics (MSATs), were measured in vehicle exhaust from three light-duty spark ignition vehicles operating on summer and winter grade gasoline (E0) and ethanol blended (E10 and E85) fuels. Vehicle testing was conducted using a three-phase LA92 driving cycle in a temperature-controlled chassis dynamometer at two ambient temperatures (-7 °C and 24 °C). The cold start phase and cold ambient temperature increased VOC and MSAT emissions dramatically by up to several orders of magnitude compared to emissions during other phases and warm ambient temperature testing, respectively. As a result, calculated ozone formation potentials during the cold starts were significantly higher during cold temperature tests by 7 to 21 times the warm temperature values. The use of E85 fuel generally led to substantial reductions in hydrocarbons and increases in oxygenates such as ethanol and acetaldehyde compared to E0 and E10 fuels. However, the VOC emissions from E0 and E10 fuels were not significantly different. Cold temperature effects on cold start MSAT emissions varied by individual MSAT compound, but were consistent over a range of modern spark ignition vehicles. This manuscript communicates APPCD research activities on air toxics VOC emissions from mobile sources from the EPAct dynamometer study. Speciated VOC emissions from light-duty vehicles running on gasoline and ethanol blends at cold tem

Freeze-thaw method improves the detection of volatile compounds in insects using Headspace Solid-Phase Microextraction (HS-SPME)

USDA-ARS?s Scientific Manuscript database

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC-MS) is commonly used in analyzing insect volatiles. In order to improve the detection of volatiles in insects, a freeze-thaw method was applied to insect samples before the HS-SPME-GC-MS analysis. ...

Ion Mobility Spectrometry (IMS) and Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shvartsburg, Alexandre A.

2010-04-20

In a media of finite viscosity, the Coulomb force of external electric field moves ions with some terminal speed. This dynamics is controlled by “mobility” - a property of the interaction potential between ions and media molecules. This fact has been used to separate and characterize gas-phase ions in various modes of ion mobility spectrometry (IMS) developed since 1970. Commercial IMS devices were introduced in 1980-s for field detection of volatile traces such as explosives and chemical warfare agents. Coupling to soft-ionization sources, mass spectrometry (MS), and chromatographic methods in 1990-s had allowed IMS to handle complex samples, enabling newmore » applications in biological and environmental analyses, nanoscience, and other areas. Since 2003, the introduction of commercial systems by major instrument vendors started bringing the IMS/MS capability to broad user community. The other major development of last decade has been the differential IMS or “field asymmetric waveform IMS” (FAIMS) that employs asymmetric time-dependent electric field to sort ions not by mobility itself, but by the difference between its values in strong and weak electric fields. Coupling of FAIMS to conventional IMS and stacking of conventional IMS stages have enabled two-dimensional separations that dramatically expand the power of ion mobility methods.« less

Detection heart failures (HF) biomarkers by proton transfer reaction - mass spectrometry and ion mobility spectrometry

NASA Astrophysics Data System (ADS)

Shaltaeva, Y. R.; Vasilev, V. K.; Yakovlev, D. Y.; Kopylov, F. Iu; Syrkin, A. L.; Chomakhidze, P. Sh; Bykova, A. A.; Malinovskaya, L. K.; Skorokhod, A. I.

2016-10-01

Exhaled breath contains 1% of volatile organic compounds. The concentration of individual biomarkers in hundreds of volatile organic compounds lies within the range ppm- ppb. In compare with control group the concentrations of acetone, acetic acid, ethanol, propylene biomarkers is significantly higher in HF-PEF group.

Method for selective detection of explosives in mass spectrometer or ion mobility spectrometer at parts-per-quadrillion level

DOEpatents

Ewing, Robert G.; Atkinson, David A.; Clowers, Brian H.

2015-09-01

A method for selective detection of volatile and non-volatile explosives in a mass spectrometer or ion mobility spectrometer at a parts-per-quadrillion level without preconcentration is disclosed. The method comprises the steps of ionizing a carrier gas with an ionization source to form reactant ions or reactant adduct ions comprising nitrate ions (NO.sub.3.sup.-); selectively reacting the reactant ions or reactant adduct ions with at least one volatile or non-volatile explosive analyte at a carrier gas pressure of at least about 100 Ton in a reaction region disposed between the ionization source and an ion detector, the reaction region having a length which provides a residence time (tr) for reactant ions therein of at least about 0.10 seconds, wherein the selective reaction yields product ions comprising reactant ions or reactant adduct ions that are selectively bound to the at least one explosive analyte when present therein; and detecting product ions with the ion detector to determine presence or absence of the at least one explosive analyte.

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

NASA Technical Reports Server (NTRS)

Ganguly, Jibamitra; Saxena, Surendra K.

1989-01-01

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.

Detection of colorectal cancer (CRC) by urinary volatile organic compound analysis.

PubMed

Arasaradnam, Ramesh P; McFarlane, Michael J; Ryan-Fisher, Courtenay; Westenbrink, Erik; Hodges, Phoebe; Hodges, Paula; Thomas, Matthew G; Chambers, Samantha; O'Connell, Nicola; Bailey, Catherine; Harmston, Christopher; Nwokolo, Chuka U; Bardhan, Karna D; Covington, James A

2014-01-01

Colorectal cancer (CRC) is a leading cause of cancer related death in Europe and the USA. There is no universally accepted effective non-invasive screening test for CRC. Guaiac based faecal occult blood (gFOB) testing has largely been superseded by Faecal Immunochemical testing (FIT), but sensitivity still remains poor. The uptake of population based FOBt testing in the UK is also low at around 50%. The detection of volatile organic compounds (VOCs) signature(s) for many cancer subtypes is receiving increasing interest using a variety of gas phase analytical instruments. One such example is FAIMS (Field Asymmetric Ion Mobility Spectrometer). FAIMS is able to identify Inflammatory Bowel disease (IBD) patients by analysing shifts in VOCs patterns in both urine and faeces. This study extends this concept to determine whether CRC patients can be identified through non-invasive analysis of urine, using FAIMS. 133 patients were recruited; 83 CRC patients and 50 healthy controls. Urine was collected at the time of CRC diagnosis and headspace analysis undertaken using a FAIMS instrument (Owlstone, Lonestar, UK). Data was processed using Fisher Discriminant Analysis (FDA) after feature extraction from the raw data. FAIMS analyses demonstrated that the VOC profiles of CRC patients were tightly clustered and could be distinguished from healthy controls. Sensitivity and specificity for CRC detection with FAIMS were 88% and 60% respectively. This study suggests that VOC signatures emanating from urine can be detected in patients with CRC using ion mobility spectroscopy technology (FAIMS) with potential as a novel screening tool.

Organic Aerosol Formation Photoenhanced by the Formation of Secondary Photo-sensitizers in ageing Aerosols

NASA Astrophysics Data System (ADS)

Aregahegn, Kifle; Nozière, Barbara; George, Christian

2013-04-01

Humankind is facing a changing environment possibly due to anthropogenic stress on the atmosphere. In this context, aerosols play a key role by affecting the radiative climate forcing, hydrological cycle, and by their adverse effect on health. The role of organic compounds in these processes is however still poorly understood because of their massive chemical complexity and numerous transformations. This is particularly true for Secondary Organic Aerosol (SOA), which are produced in the atmosphere by organic gases. Traditionally, the driving forces for SOA growth is believed to be the partitioning onto aerosol seeds of condensable gases, either emitted primarily or resulting from the gas phase oxidation of organic gases. However, even the most up-to-date models based on such mechanisms can not account for the SOA mass observed in the atmosphere, suggesting the existence of other, yet unknown formation processes. The present study shows experimental evidence that particulate phase chemistry produces photo-sensitizers that lead to photo-induced formation and growth of secondary organic aerosol in the near UV and the presence of volatile organic compounds (VOC) such as terpenes. By means of an aerosol flow tube reactor equipped with Scanning Mobility Particle Sizer (SMPS) having Kr-85 source aerosol neutralizer, Differential Mobility Analyser (DMA) and Condensation Particle Sizer (CPC), we identified that traces of the aerosol phase product of glyoxal chemistry as is explained in Gallway et al., and Yu et al., namely imidazole-2-carboxaldehyde (IC) is a strong photo-sensitizer when irradiated by near-UV in the presence of volatile organic compounds such as terpenes. Furthermore, the influence of pH, type and concentration of VOCs, composition of seed particles, relative humidity and irradiation intensity on particle growth were studied. This novel photo-sensitizer contributed to more than 30% of SOA growth in 19min irradiation time in the presence of terpenes in the system and has linear relationship with the irradiation intensity. These results demonstrate that, upon ageing, organic aerosols can produce photo-sensitizers which auto-photo-catalyses their SOA growth.

40 CFR 53.66 - Test procedure: Volatility test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... mass concentration and the sample filters are conditioned and preweighed. In phase B, the challenge... preweighed filters for a specified time period. In phase C (the blow-off phase), aerosol and aerosol-vapor... on the filters. The candidate sampler passes the volatility test if the acceptance criteria presented...

40 CFR 53.66 - Test procedure: Volatility test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... mass concentration and the sample filters are conditioned and preweighed. In phase B, the challenge... preweighed filters for a specified time period. In phase C (the blow-off phase), aerosol and aerosol-vapor... on the filters. The candidate sampler passes the volatility test if the acceptance criteria presented...

40 CFR 53.66 - Test procedure: Volatility test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... mass concentration and the sample filters are conditioned and preweighed. In phase B, the challenge... preweighed filters for a specified time period. In phase C (the blow-off phase), aerosol and aerosol-vapor... on the filters. The candidate sampler passes the volatility test if the acceptance criteria presented...

40 CFR 53.66 - Test procedure: Volatility test.

Code of Federal Regulations, 2014 CFR

2014-07-01

... mass concentration and the sample filters are conditioned and preweighed. In phase B, the challenge... preweighed filters for a specified time period. In phase C (the blow-off phase), aerosol and aerosol-vapor... on the filters. The candidate sampler passes the volatility test if the acceptance criteria presented...

40 CFR 53.66 - Test procedure: Volatility test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... mass concentration and the sample filters are conditioned and preweighed. In phase B, the challenge... preweighed filters for a specified time period. In phase C (the blow-off phase), aerosol and aerosol-vapor... on the filters. The candidate sampler passes the volatility test if the acceptance criteria presented...

The emission of volatile compounds during the aerobic and the combined anaerobic/aerobic composting of biowaste

NASA Astrophysics Data System (ADS)

Smet, Erik; Van Langenhove, Herman; De Bo, Inge

Two different biowaste composting techniques were compared with regard to their overall emission of volatile compounds during the active composting period. In the aerobic composting process, the biowaste was aerated during a 12-week period, while the combined anaerobic/aerobic composting process consisted of a sequence of a 3-week anaerobic digestion (phase I) and a 2-week aeration period (phase II). While the emission of volatiles during phase I of the combined anaerobic/aerobic composting process was measured in a full-scale composting plant, the aerobic stages of both composting techniques were performed in pilot-scale composting bins. Similar groups of volatile compounds were analysed in the biogas and the aerobic composting waste gases, being alcohols, carbonyl compounds, terpenes, esters, sulphur compounds and ethers. Predominance of alcohols (38% wt/wt of the cumulative emission) was observed in the exhaust air of the aerobic composting process, while predominance of terpenes (87%) and ammonia (93%) was observed in phases I and II of the combined anaerobic/aerobic composting process, respectively. In the aerobic composting process, 2-propanol, ethanol, acetone, limonene and ethyl acetate made up about 82% of the total volatile organic compounds (VOC)-emission. Next to this, the gas analysis during the aerobic composting process revealed a strong difference in emission profile as a function of time between different groups of volatiles. The total emission of VOC, NH 3 and H 2S during the aerobic composting process was 742 g ton -1 biowaste, while the total emission during phases I and II of the combined anaerobic/aerobic composting process was 236 and 44 g ton -1 biowaste, respectively. Taking into consideration the 99% removal efficiency of volatiles upon combustion of the biogas of phase I in the electricity generator, the combined anaerobic/aerobic composting process can be considered as an attractive alternative for aerobic biowaste composting because of its 17 times lower overall emission of the volatiles mentioned.

Zero-static power radio-frequency switches based on MoS2 atomristors.

PubMed

Kim, Myungsoo; Ge, Ruijing; Wu, Xiaohan; Lan, Xing; Tice, Jesse; Lee, Jack C; Akinwande, Deji

2018-06-28

Recently, non-volatile resistance switching or memristor (equivalently, atomristor in atomic layers) effect was discovered in transitional metal dichalcogenides (TMD) vertical devices. Owing to the monolayer-thin transport and high crystalline quality, ON-state resistances below 10 Ω are achievable, making MoS 2 atomristors suitable as energy-efficient radio-frequency (RF) switches. MoS 2 RF switches afford zero-hold voltage, hence, zero-static power dissipation, overcoming the limitation of transistor and mechanical switches. Furthermore, MoS 2 switches are fully electronic and can be integrated on arbitrary substrates unlike phase-change RF switches. High-frequency results reveal that a key figure of merit, the cutoff frequency (f c ), is about 10 THz for sub-μm 2 switches with favorable scaling that can afford f c above 100 THz for nanoscale devices, exceeding the performance of contemporary switches that suffer from an area-invariant scaling. These results indicate a new electronic application of TMDs as non-volatile switches for communication platforms, including mobile systems, low-power internet-of-things, and THz beam steering.

Assessment of Volatile Organic Compound and Hazardous Air Pollutant Emissions from Oil and Natural Gas Well Pads using Mobile Remote and On-site Direct Measurements

EPA Science Inventory

Emissions of volatile organic compounds (VOC) and hazardous air pollutants (HAP) from oil and natural gas production were investigated using direct measurements of component-level emissions on well pads in the Denver-Julesburg (DJ) Basin and remote measurements of production pad-...

Biodiesel and Cold Temperature Effects on Speciated Mobile Source Air Toxics from Modern Diesel Trucks

EPA Science Inventory

Speciated volatile organic compounds (VOCs) with a particular focus on mobile source air toxics (MSATs) were measured in diesel exhaust from three heavy-duty trucks equipped with modern aftertreatment technologies. Emissions testing was conducted on a temperature controlled chass...

Biodiesel and Cold Temperature Effect on Speciated Mobile Source Air Toxics from Modern Diesel Trucks

EPA Science Inventory

Speciated volatile organic compounds (VOCs) with a particular focus on mobile source air toxics (MSATs) were measured in diesel exhaust from three heavy-duty trucks equipped with modern aftertreatment technologies. Emissions testing was conducted on a temperature controlled chass...

[Ion mobility spectrometer (IMS): a novel online monitor of trace volatile organic compounds].

PubMed

Li, Fang; Xie, Zhi-yong; Schmidt, H; Sielemann, S; Baumbach, J I

2002-12-01

The principle, character and developments of the instrument of ion mobility spectrometry are introduced, the applications of IMS to chemical warfare agents, explosives, drugs, environments monitoring and on-site industrial sensing are discussed, and some work on IMS in ISAS is represented.

A Comprehensive Program for Measurement of Military Aircraft Emissions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Mengdawn

2009-11-01

Emissions of gases and particulate matter by military aircraft were characterized inplume by 'extractive' and 'optical remote-sensing (ORS)' technologies. Non-volatile particle size distribution, number and mass concentrations were measured with good precision and reproducibly. Time-integrated particulate filter samples were collected and analyzed for smoke number, elemental composition, carbon contents, and sulfate. Observed at EEP the geometric mean diameter (as measured by the mobility diameter) generally increased as the engine power setting increased, which is consistent with downstream observations. The modal diameters at the downstream locations are larger than that at EEP at the same engine power level. The results indicatemore » that engine particles were processed by condensation, for example, leading to particle growth in-plume. Elemental analysis indicated little metals were present in the exhaust, while most of the exhaust materials in the particulate phase were carbon and sulfate (in the JP-8 fuel). CO, CO{sub 2}, NO, NO{sub 2}, SO{sub 2}, HCHO, ethylene, acetylene, propylene, and alkanes were measured. The last five species were most noticeable under engine idle condition. The levels of hydrocarbons emitted at high engine power level were generally below the detection limits. ORS techniques yielded real-time gaseous measurement, but the same techniques could not be extended directly to ultrafine particles found in all engine exhausts. The results validated sampling methodology and measurement techniques used for non-volatile particulate aircraft emissions, which also highlighted the needs for further research on sampling and measurement for volatile particulate matter and semi-volatile species in the engine exhaust especially at the low engine power setting.« less

The economic mobility in money transfer models

NASA Astrophysics Data System (ADS)

Ding, Ning; Xi, Ning; Wang, Yougui

2006-07-01

In this paper, we investigate the economic mobility in four money transfer models which have been applied into the research on wealth distribution. We demonstrate the mobility by recording the time series of agents’ ranks and observing their volatility. We also compare the mobility quantitatively by employing an index, “the per capita aggregate change in log-income”, proposed by economists. Like the shape of distribution, the character of mobility is also decided by the trading rule in these transfer models. It is worth noting that even though two models have the same type of distribution, their mobility characters may be quite different.

Analysis of flame spread over multicomponent combustibles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohtani, H.; Sato, J.

1985-01-01

A theoretical model of volatile component diffusion in the condensed phase is carried out in order to form a basis for predicting the flame spread rate in thermally thick multicomponent combustibles in a non-fluid condensed phase. The fuels could be, e.g., crude oil, heavy oil, or light oil. Mass transfer occurs only by diffusion so the gas phase volatile concentration at the surface is estimated from the condensed phase volatile concentration and the surface temperature, which increases close to the leading flame edge. The flame spread rate is assumed steady. The velocity of the flame spread is shown to bemore » a function of the initial condensed phase temperature and the temperature at the leading flame edge.« less

Dynamic planar solid phase microextraction-ion mobility spectrometry for rapid field air sampling and analysis of illicit drugs and explosives.

PubMed

Guerra-Diaz, Patricia; Gura, Sigalit; Almirall, José R

2010-04-01

A preconcentration device that targets the volatile chemical signatures associated with illicit drugs and explosives (high and low) has been designed to fit in the inlet of an ion mobility spectrometer (IMS). This is the first reporting of a fast and sensitive method for dynamic sampling of large volumes of air using planar solid phase microextraction (PSPME) incorporating a high surface area for absorption of analytes onto a sol-gel polydimethylsiloxane (PDMS) coating for direct thermal desorption into an IMS. This device affords high extraction efficiencies due to strong retention properties at ambient temperature, resulting in the detection of analyte concentrations in the parts per trillion range when as low as 3.5 L of air are sampled over the course of 10 s (absolute mass detection of less than a nanogram). Dynamic PSPME was used to sample the headspace over the following: 3,4-methylenedioxymethamphetamine (MDMA) tablets resulting in the detection of 12-40 ng of piperonal, high explosives (Pentolite) resulting in the detection of 0.6 ng of 2,4,6-trinitrotoluene (TNT), and low explosives (several smokeless powders) resulting in the detection of 26-35 ng of 2,4-dinitrotoluene (2,4-DNT) and 11-74 ng of diphenylamine (DPA).

Characterization of selenium species in biological extracts by enhanced ion-pair liquid chromatography with inductively coupled plasma-mass spectrometry and by referenced electrospray ionization-mass spectrometry

NASA Astrophysics Data System (ADS)

Kotrebai, Mihály; Bird, Susan M.; Tyson, Julian F.; Block, Eric; Uden, Peter C.

1999-11-01

Selenium is an essential nutrient for humans; selenium compounds catalyze intermediate metabolism reactions and inhibit the toxic effects of heavy metals such as arsenic, cadmium and mercury. Some extracts of selenium-enriched biological materials show cancer preventive effects, tentatively attributable to the biological functions of selenoamino acids. An improved ion pair chromatographic method with methodological enhancements for the separation, qualitative and quantitative determination of non-volatile selenium compounds extracted from different samples has been developed using ICP-MS as an element-selective detector. Separation power early in the chromatogram was increased to baseline separation in the standard mixture as a result of decreasing spray chamber size from 97 to 14 ml, and increasing trifluoracetic acid (TFA) concentration in the mobile phase from 0.1 to 0.6%. The former pH was restored by the addition of ammonia to the mobile phase, which also served to increase the column recovery of inorganic anions. Calibration curves for different selenoamino acids showed statistically different behavior. Biological sample extracts were characterized using HPLC-ICP-MS. Mass spectral behavior of selenoamino acids, using electrospray and ion trap technology with direct infusion and liquid chromatographic sample introduction, is also reported.

Multi-Capillary Column-Ion Mobility Spectrometry of Volatile Metabolites Emitted by Saccharomyces Cerevisiae

PubMed Central

Halbfeld, Christoph; Ebert, Birgitta E.; Blank, Lars M.

2014-01-01

Volatile organic compounds (VOCs) produced during microbial fermentations determine the flavor of fermented food and are of interest for the production of fragrances or food additives. However, the microbial synthesis of these compounds from simple carbon sources has not been well investigated so far. Here, we analyzed the headspace over glucose minimal salt medium cultures of Saccharomyces cerevisiae using multi-capillary column-ion mobility spectrometry (MCC-IMS). The high sensitivity and fast data acquisition of the MCC-IMS enabled online analysis of the fermentation off-gas and 19 specific signals were determined. To four of these volatile compounds, we could assign the metabolites ethanol, 2-pentanone, isobutyric acid, and 2,3-hexanedione by MCC-IMS measurements of pure standards and cross validation with thermal desorption–gas chromatography-mass spectrometry measurements. Despite the huge biochemical knowledge of the biochemistry of the model organism S. cerevisiae, only the biosynthetic pathways for ethanol and isobutyric acid are fully understood, demonstrating the considerable lack of research of volatile metabolites. As monitoring of VOCs produced during microbial fermentations can give valuable insight into the metabolic state of the organism, fast and non-invasive MCC-IMS analyses provide valuable data for process control. PMID:25197771

Organised surfactant assemblies in analytical atomic spectrometry

NASA Astrophysics Data System (ADS)

Sanz-Medel, Alfredo; Fernandez de la Campa, Maria del Rosario; Gonzalez, Elisa Blanco; Fernandez-Sanchez, Maria Luisa

1999-02-01

The use of surfactant-based organised assemblies in analytical atomic spectroscopy is extensively and critically reviewed along three main lines: first, the ability of organised media to enhance detection of atomic spectroscopic methods by favourable manipulation of physical and chemical properties of the sample solution second, the extension of separation mechanisms by resorting to organised media and third a discussion of synergistic combinations of liquid chromatography separations and atomic detectors via the use of vesicular mobile phases. Changes in physical properties of sample solutions aspirated in atomic spectrometry by addition of surfactants can be advantageously used in at least four different ways: (i) to improve nebulisation efficiency; (ii) to enhance wettability of solid surfaces used for atomisation; (iii) to improve compatibility between aqueous and organic phases; and (iv) to achieve good dispersion of small particles in "slurry" techniques. Controversial results and statements published so far are critically discussed. The ability of surfactant-based organised assemblies, such as micelles and vesicles, to organise reactants at the molecular level has also been applied to enhance the characteristics of chemical generation of volalite species of metals and semi-metals (e.g., hydride or ethylide generation of As, Pb, Cd, Se, Sn, and cold vapour Hg generation) used in atomic methods. Enhancements in efficiency/transport of volatile species, increases in the reaction kinetics, stabilisation of some unstable species and changes in the selectivity of the reactions by surfactants are dealt with. Non-chromatographic cloud-point separations to design pre-concentration procedures with subsequent metal determination by atomic methods are addressed along with chromatographic separations of expanded scope by addition of surfactants to the conventional aqueous mobile phases of reversed-phase high-performance liquid chromatography. Finally, the synergistic effect of using vesicles to improve both the separation capabilities of reversed-phase HPLC and the detectability of atomic detectors by on-line vesicular hydride generation is described. In particular, the possible separation mechanisms responsible for micellar and vesicular mobile phases in reversed-phase chromatographies are analysed and compared. The possible effect of modification of stationary phases by monomers of the surfactants should also be taken into account. The application of such on-line couplings to develop new hybrid approaches to tackle modern problems of trace element speciation for As, Hg, Se, and Cd completes this revision of the present interface between analytical atomic spectroscopy and surfactant-based organised assemblies.

Bound Volatile Precursors in Genotypes in the Pedigree of 'Marion' Blackberry (Rubus Sp.)

USDA-ARS?s Scientific Manuscript database

Glycosidically bound volatiles and precursors in genotypes representing the pedigree for 'Marion' blackberry were investigated over two growing seasons. The volatile precursors were isolated using a C18 solid-phase extraction column. After enzymatic hydrolysis, the released volatiles were analyzed u...

COMPACT, CONTINUOUS MONITORING FOR VOLATILE ORGANIC COMPOUNDS - PHASE I

EPA Science Inventory

Improved methods for onsite measurement of multiple volatile organic compounds are needed for process control, monitoring, and remediation. This Phase I SBIR project sets forth an optical measurement method that meets these needs. The proposed approach provides an instantaneous m...

Identification of volatiles in leaves of Alpinia zerumbet 'Variegata' using headspace solid-phase microextraction-gas chromatography-mass spectrometry.

PubMed

Chen, Jian Yan; Ye, Zheng Mei; Huang, Tian Yi; Chen, Xiao Dan; Li, Yong Yu; Wu, Shao Hua

2014-07-01

Alpinia zerumbet 'Variegata' is an aromatic medicinal plant, its foliage producing an intense, unique fragrant odor. This study identified 46 volatile compounds in the leaf tissue of this plant using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The major compounds included 1, 8-cineole (43.5%), p-cymene (14.7%), humulene (5.5%), camphor (5.3%), linalool (4.7%), (E)-methyl cinnamate (3.8%), gamma-cadinene (3.3%), humulene oxide II (2.1%) and a-terpineol (1.5%). The majority of the volatiles were terpenoids of which oxygenated monoterpenes were the most abundant, accounting for 57.2% of the total volatiles. Alcohols made up the largest (52.8%) and aldehydes the smallest (0.2%) portions of the volatiles. Many bioactive compounds were present in the volatiles.

Fate and transport of monoterpenes through soils. Part II: calculation of the effect of soil temperature, water saturation and organic carbon content.

PubMed

van Roon, André; Parsons, John R; Krap, Lenny; Govers, Harrie A J

2005-09-01

This theoretical study was performed to investigate the influence of soil temperature, soil water content and soil organic carbon fraction on the mobility of monoterpenes (C10HnOn') applied as pesticides to a top soil layer. This mobility was expressed as the amount volatilized and leached from the contaminated soil layer after a certain amount of time. For this, (slightly modified) published analytical solutions to a one dimensional, homogeneous medium, diffusion/advection/biodegradation mass balance equation were used. The required input-parameters were determined in a preceding study. Because the monoterpenes studied differ widely in the values for their physico-chemical properties, the relative importance of the various determinants also differed widely. Increasing soil water saturation reduced monoterpene vaporization and leaching losses although a modest increase was usually observed at high soil water contents. Organic matter served as the major retention domain, reducing volatilization and leaching losses. Increasing temperature resulted in higher volatilization and leaching losses. Monoterpene mobility was influenced by vertical water flow. Volatilization losses could be reduced by adding a clean soil layer on top of the contaminated soil. Detailed insight into the specific behaviour of different monoterpenes was obtained by discussing intermediate calculation results; the transport retardation factors and effective soil diffusion coefficients. One insight was that the air-water interface compartment is probably not an important partitioning domain for monoterpenes in most circumstances. The results further indicated that biodegradation is an important process for monoterpenes in soil.

Monitoring of selected skin- and breath-borne volatile organic compounds emitted from the human body using gas chromatography ion mobility spectrometry (GC-IMS).

PubMed

Mochalski, Paweł; Wiesenhofer, Helmut; Allers, Maria; Zimmermann, Stefan; Güntner, Andreas T; Pineau, Nicolay J; Lederer, Wolfgang; Agapiou, Agapios; Mayhew, Christopher A; Ruzsanyi, Veronika

2018-02-15

Human smuggling and associated cross-border crimes have evolved as a major challenge for the European Union in recent years. Of particular concern is the increasing trend of smuggling migrants hidden inside shipping containers or trucks. Therefore, there is a growing demand for portable security devices for the non-intrusive and rapid monitoring of containers to detect people hiding inside. In this context, chemical analysis of volatiles organic compounds (VOCs) emitted from the human body is proposed as a locating tool. In the present study, an in-house made ion mobility spectrometer coupled with gas chromatography (GC-IMS) was used to monitor the volatile moieties released from the human body under conditions that mimic entrapment. A total of 17 omnipresent volatile compounds were identified and quantified from 35 ion mobility peaks corresponding to human presence. These are 7 aldehydes (acrolein, 2-methylpropanal, 3-methylbutanal, 2-ethacrolein, n-hexanal, n-heptanal, benzaldehyde), 3 ketones (acetone, 2-pentanone, 4-methyl-2-pentanone), 5 esters (ethyl formate, ethyl propionate, vinyl butyrate, butyl acetate, ethyl isovalerate), one alcohol (2-methyl-1-propanol) and one organic acid (acetic acid). The limits of detection (0.05-7.2 ppb) and relative standard deviations (0.6-11%) should be sufficient for detecting these markers of human presence in field conditions. This study shows that GC-IMS can be used as a portable field detector of hidden or entrapped people. Copyright © 2018 Elsevier B.V. All rights reserved.

Static headspace analysis using polyurethane phases--application to roasted coffee volatiles characterization.

PubMed

Rodrigues, C; Portugal, F C M; Nogueira, J M F

2012-01-30

Static headspace sorptive extraction using polyurethane foams (HSSE(PU)) followed by gas chromatography coupled to mass spectrometry is proposed for volatile analysis. The application of this novel analytical approach to characterize the volatiles profile from roasted coffee samples, selected as model system, revealed remarkable advantages under convenient experimental conditions. The comparison of HSSE(PU) with other well-established procedures, such as headspace sorptive extraction using polydimethylsiloxane (HSSE(PDMS)) and headspace solid phase microextraction using carboxen/polydimethylsiloxane fibers (HS-SPME(CAR/PDMS)), showed that the former presented much higher capacity, sensitivity and even selectivity, where larger abundance and number of roasted coffee volatile compounds (e.g. furans, pyrazines, ketones, acids and pyrroles) could be achieved, under similar experimental conditions. The data presented herein proved, for the first time, that PU foams present great performance for static headspace sorption-based procedures, showing to be an alternative polymeric phase for volatile analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

Composition and emission dynamics of migratory locust volatiles in response to changes in developmental stages and population density.

PubMed

Wei, Jianing; Shao, Wenbo; Wang, Xianhui; Ge, Jin; Chen, Xiangyong; Yu, Dan; Kang, Le

2017-02-01

Chemical communication plays an important role in density-dependent phase change in locusts. However, the volatile components and emission patterns of the migratory locust, Locusta migratoria, are largely unknown. In this study, we identified the chemical compositions and emission dynamics of locust volatiles from the body and feces and associated them with developmental stages, sexes and phase changes. The migratory locust shares a number of volatile components with the desert locust (Schistocerca gregaria), but the emission dynamics of the two locust species are significantly different. The body odors of the gregarious nymphs in the migratory locust consisted of phenylacetonitrile (PAN), benzaldehyde, guaiacol, phenol, aliphatic acids and 2,3-butanediol, and PAN was the dominant volatile. Volatiles from the fecal pellets of the nymphs primarily consist of guaiacol and phenol. Principal component analysis (PCA) showed significant differences in the volatile profiles between gregarious and solitary locusts. PAN and 4-vinylanisole concentrations were significantly higher in gregarious individuals than in solitary locusts. Gregarious mature males released significantly higher amounts of PAN and 4-vinylanisole during adulthood than mature females and immature adults of both sexes. Furthermore, PAN and 4-vinylanisole were completely lost in gregarious nymphs during the solitarization process, but were obtained by solitary nymphs during gregarization. The amounts of benzaldehyde, guaiacol and phenol only unidirectionally decreased from solitary to crowded treatment. Aliphatic aldehydes (C7 to C10), which were previously reported as locust volatiles, are now identified as environmental contaminants. Therefore, our results illustrate the precise odor profiles of migratory locusts during developmental stages, sexes and phase change. However, the function and role of PAN and other aromatic compounds during phase transition need further investigation. © 2016 Institute of Zoology, Chinese Academy of Sciences.

Modeling solvent evaporation during thin film formation in phase separating polymer mixtures

DOE PAGES

Cummings, John; Lowengrub, John S.; Sumpter, Bobby G.; ...

2018-02-09

Preparation of thin films by dissolving polymers in a common solvent followed by evaporation of the solvent has become a routine processing procedure. However, modeling of thin film formation in an evaporating solvent has been challenging due to a need to simulate processes at multiple length and time scales. In this paper, we present a methodology based on the principles of linear non-equilibrium thermodynamics, which allows systematic study of various effects such as the changes in the solvent properties due to phase transformation from liquid to vapor and polymer thermodynamics resulting from such solvent transformations. The methodology allows for themore » derivation of evaporative flux and boundary conditions near each surface for simulations of systems close to the equilibrium. We apply it to study thin film microstructural evolution in phase segregating polymer blends dissolved in a common volatile solvent and deposited on a planar substrate. Finally, effects of the evaporation rates, interactions of the polymers with the underlying substrate and concentration dependent mobilities on the kinetics of thin film formation are studied.« less

Modeling solvent evaporation during thin film formation in phase separating polymer mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cummings, John; Lowengrub, John S.; Sumpter, Bobby G.

Preparation of thin films by dissolving polymers in a common solvent followed by evaporation of the solvent has become a routine processing procedure. However, modeling of thin film formation in an evaporating solvent has been challenging due to a need to simulate processes at multiple length and time scales. In this paper, we present a methodology based on the principles of linear non-equilibrium thermodynamics, which allows systematic study of various effects such as the changes in the solvent properties due to phase transformation from liquid to vapor and polymer thermodynamics resulting from such solvent transformations. The methodology allows for themore » derivation of evaporative flux and boundary conditions near each surface for simulations of systems close to the equilibrium. We apply it to study thin film microstructural evolution in phase segregating polymer blends dissolved in a common volatile solvent and deposited on a planar substrate. Finally, effects of the evaporation rates, interactions of the polymers with the underlying substrate and concentration dependent mobilities on the kinetics of thin film formation are studied.« less

Secondary organic aerosol formation from isoprene photo-oxidation during cloud condensation-evaporation cycles (CUMULUS project)

NASA Astrophysics Data System (ADS)

Brégonzio-Rozier, Lola; Siekmann, Frank; Giorio, Chiara; Temime-Roussel, Brice; Pangui, Edouard; Morales, Sébastien; Gratien, Aline; Ravier, Sylvain; Monod, Anne; Doussin, Jean-Francois

2014-05-01

It is acknowledged that atmospheric photo-oxidation of Volatile Organic Compounds (VOC) leads to the formation of less volatile oxidized species. These compounds can undergo gas-to-particle conversion, leading to the formation of Secondary Organic Aerosols (SOA) in the atmosphere. Nevertheless, some of these oxidized species are water soluble and could also partition into cloud droplets. Higher molecular weight and less volatile compounds could be produced in the aqueous phase and remain in the particle phase after water evaporation (Ervens et al., 2011). The aim of the present work is to study SOA formation in the presence of cloud droplets during isoprene photo-oxidation. To this end, an original multiphase approach in a simulation chamber was set up in order to investigate the chemistry occurring in the gaseous, particulate and aqueous phases, and the exchange between these phases. Experiments were performed, within the CUMULUS project (CloUd MULtiphase chemistry of organic compoUndS in the troposphere), in the CESAM chamber (Wang et al., 2011). This chamber was designed to investigate multiphase processes under realistic actinic flux, and accurate control of both temperature and relative humidity. A specific protocol was set up to produce cloud events in the simulation chamber exhibiting a significant lifetime in the presence of light (10-12 minutes). By using this protocol, many clouds could be generated in a single experiment. In each experiment, around 800 ppb of isoprene was injected in the chamber together with HONO under dry conditions before irradiation. A Fourier Transform Infrared Spectrometer (FTIR), a Proton Transfer Reaction Mass Spectrometer (PTR-TOF-MS) and NOx and O3 analyzers were used to analyze gas-phase composition. Dried SOA size distributions and total concentrations were measured by a Scanning Mobility Particle Sizer (SMPS). An Aerodyne High Resolution Time-Of-Flight Aerosol Mass Spectrometer (HR-TOF-AMS) was also used to investigate aerosol composition. Cloud droplets size distributions were measured by a white light Optical Particle Counter (OPC). In all experiments, the dissolution of gaseous oxidation products into aqueous phase and SOA production have been observed during isoprene photo-oxidation in the presence of a cloud event. The overall results in additional SOA mass production and the dynamic of gaseous oxidation products and SOA mass concentrations will be presented. Ervens, B. et al. (2011). Atmospheric Chemistry and Physics 11(21): 11069-11102. Wang, J. et al. (2011). Atmospheric Measurement Techniques 4(11): 2465-2494.

Characterization of the volatile profiles of beer using headspace solid-phase microextraction and gas chromatography-mass spectrometry.

PubMed

Rossi, Serena; Sileoni, Valeria; Perretti, Giuseppe; Marconi, Ombretta

2014-03-30

The objective of this study was a multivariate characterization of the volatile profile of beers. Such a characterization is timely considering the increasing worldwide consumption of beer, the continuous growth of microbreweries and the importance of volatile compounds to beer flavour. A method employing solid-phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) was optimized and then applied to a sample set of 36 industrial and craft beers of various styles and fermentation types. The volatile profiles of different beer styles is described, with particular attention paid to the volatile compounds characteristic of a spontaneously fermented lambic raspberry framboise beer. Furthermore, it was also possible to identify which specific volatile compounds are principally responsible for the differences in the volatile profiles of top- and bottom-fermented beers. Moreover, a volatile fingerprint of the craft top-fermented Italian beers was defined, as they show a very similar volatile profile. Finally, the volatile compounds that are characteristic of the bock-style beers are described. The SPME-GC-MS analytical method optimized in this study is suitable for characterizing the volatile fingerprint of different beers, especially on the basis of the kind of fermentation (top, bottom or spontaneous), the method of production and the style of the beer. © 2013 Society of Chemical Industry.

Volatilization Rates from Water to Indoor Air Phase II

EPA Science Inventory

Contaminated water can lead to volatilization of chemicals to residential indoor air. Previous research has focused on only one source (shower stalls) and has been limited to chemicals in which gas-phase resistance to mass transfer is of marginal significance. As a result, attemp...

Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon

PubMed Central

Day, James M. D.; Moynier, Frederic

2014-01-01

The Moon is depleted in volatile elements relative to the Earth and Mars. Low abundances of volatile elements, fractionated stable isotope ratios of S, Cl, K and Zn, high μ (238U/204Pb) and long-term Rb/Sr depletion are distinguishing features of the Moon, relative to the Earth. These geochemical characteristics indicate both inheritance of volatile-depleted materials that formed the Moon and planets and subsequent evaporative loss of volatile elements that occurred during lunar formation and differentiation. Models of volatile loss through localized eruptive degassing are not consistent with the available S, Cl, Zn and K isotopes and abundance data for the Moon. The most probable cause of volatile depletion is global-scale evaporation resulting from a giant impact or a magma ocean phase where inefficient volatile loss during magmatic convection led to the present distribution of volatile elements within mantle and crustal reservoirs. Problems exist for models of planetary volatile depletion following giant impact. Most critically, in this model, the volatile loss requires preferential delivery and retention of late-accreted volatiles to the Earth compared with the Moon. Different proportions of late-accreted mass are computed to explain present-day distributions of volatile and moderately volatile elements (e.g. Pb, Zn; 5 to >10%) relative to highly siderophile elements (approx. 0.5%) for the Earth. Models of early magma ocean phases may be more effective in explaining the volatile loss. Basaltic materials (e.g. eucrites and angrites) from highly differentiated airless asteroids are volatile-depleted, like the Moon, whereas the Earth and Mars have proportionally greater volatile contents. Parent-body size and the existence of early atmospheres are therefore likely to represent fundamental controls on planetary volatile retention or loss. PMID:25114311

MATRIX-VBS Condensing Organic Aerosols in an Aerosol Microphysics Model

NASA Technical Reports Server (NTRS)

Gao, Chloe Y.; Tsigaridis, Konstas; Bauer, Susanne E.

2015-01-01

The condensation of organic aerosols is represented in a newly developed box-model scheme, where its effect on the growth and composition of particles are examined. We implemented the volatility-basis set (VBS) framework into the aerosol mixing state resolving microphysical scheme Multiconfiguration Aerosol TRacker of mIXing state (MATRIX). This new scheme is unique and advances the representation of organic aerosols in models in that, contrary to the traditional treatment of organic aerosols as non-volatile in most climate models and in the original version of MATRIX, this new scheme treats them as semi-volatile. Such treatment is important because low-volatility organics contribute significantly to the growth of particles. The new scheme includes several classes of semi-volatile organic compounds from the VBS framework that can partition among aerosol populations in MATRIX, thus representing the growth of particles via condensation of low volatility organic vapors. Results from test cases representing Mexico City and a Finish forrest condistions show good representation of the time evolutions of concentration for VBS species in the gas phase and in the condensed particulate phase. Emitted semi-volatile primary organic aerosols evaporate almost completely in the high volatile range, and they condense more efficiently in the low volatility range.

Chemical characteristics and origin of H chondrite regolith breccias

NASA Technical Reports Server (NTRS)

Lipschutz, M. E.; Biswas, S.; Mcsween, H. Y., Jr.

1983-01-01

Petrologic data and contents of Ag, Bi, Cd, Co, Cs, Ga, In, Rb, Se, Te, Tl and Zn-trace elements spanning the volatility/mobility range-in light and dark portions of H chondrite regolith breccias and L chondrite fragmental breccias are reported. The chemical/petrologic characteristics of H chondrite regolith breccias differ from those of nonbrecciated chondrites or fragmental breccias. Petrologic characteristics and at least some trace element contents of H chondrite regolith breccias reflect primary processes; contents of the most volatile/mobile elements may reflect either primary or secondary processing, possibly within layered H chondrite parent object(s). Chemical/petrologic differences existed in different regions of the parent(s). Regoligh formation and gardening and meteoroid compaction were not so severe as to alter compositions markedly.

Analysis of Volatile Components of Cape Gooseberry (Physalis peruviana L.) Grown in Turkey by HS-SPME and GC-MS

PubMed Central

2014-01-01

Volatile components in cape gooseberry fruit at ripe stage were collected using headspace-solid phase microextraction, and analyzed by gas chromatography-mass spectrometry. Three solid phase microextraction fiber coatings (DVB/CAR/PDMS, CAR/PDMS, and PDMS/DVB) were tested for evaluation of volatile compounds. DVB/CAR/PDMS fiber showed a strong extraction capacity for volatile compounds and produced the best result in case of total peak areas. A total of 133 volatile compounds were identified in fruit pulp; among them 1-hexanol (6.86%), eucalyptol (6.66%), ethyl butanoate (6.47%), ethyl octanoate (4.01%), ethyl decanoate (3.39%), 4-terpineol (3.27%), and 2-methyl-1-butanol (3.10%) were the major components in the sample extracts. PMID:24741358

Analysis of volatile components of cape gooseberry (Physalis peruviana L.) grown in Turkey by HS-SPME and GC-MS.

PubMed

Yilmaztekin, Murat

2014-01-01

Volatile components in cape gooseberry fruit at ripe stage were collected using headspace-solid phase microextraction, and analyzed by gas chromatography-mass spectrometry. Three solid phase microextraction fiber coatings (DVB/CAR/PDMS, CAR/PDMS, and PDMS/DVB) were tested for evaluation of volatile compounds. DVB/CAR/PDMS fiber showed a strong extraction capacity for volatile compounds and produced the best result in case of total peak areas. A total of 133 volatile compounds were identified in fruit pulp; among them 1-hexanol (6.86%), eucalyptol (6.66%), ethyl butanoate (6.47%), ethyl octanoate (4.01%), ethyl decanoate (3.39%), 4-terpineol (3.27%), and 2-methyl-1-butanol (3.10%) were the major components in the sample extracts.

Analysis of volatile components from Melipona beecheii geopropolis from Southeast Mexico by headspace solid-phase microextraction.

PubMed

Torres-González, Ahira; López-Rivera, Paulina; Duarte-Lisci, Georgina; López-Ramírez, Ángel; Correa-Benítez, Adriana; Rivero-Cruz, J Fausto

2016-01-01

A head space solid-phase microextraction method combined with gas chromatography-mass spectrometry was developed and optimised to extract and analyse volatile compounds of Melipona beecheii geopropolis. Seventy-three constituents were identified using this technique in the sample of geopropolis collected. The main compounds detected include β-fenchene (14.53-15.45%), styrene (8.72-9.98%), benzaldehyde (7.44-7.82%) and the most relevant volatile components presents at high level in the geopropolis were terpenoids (58.17%).

Core-Mantle Partitioning of Volatile Elements and the Origin of Volatile Elements in Earth and Moon

NASA Technical Reports Server (NTRS)

Righter, K.; Pando, K.; Danielson, L.; Nickodem, K.

2014-01-01

Depletions of siderophile elements in mantles have placed constraints on the conditions on core segregation and differentiation in bodies such as Earth, Earth's Moon, Mars, and asteroid 4 Vesta. Among the siderophile elements there are a sub-set that are also volatile (volatile siderophile elements or VSE; Ga, Ge, In, As, Sb, Sn, Bi, Zn, Cu, Cd), and thus can help to constrain the origin of volatile elements in these bodies, and in particular the Earth and Moon. One of the fundamental observations of the geochemistry of the Moon is the overall depletion of volatile elements relative to the Earth, but a satisfactory explanation has remained elusive. Hypotheses for Earth include addition during accretion and core formation and mobilized into the metallic core, multiple stage origin, or addition after the core formed. Any explanation for volatile elements in the Earth's mantle must also be linked to an explanation of these elements in the lunar mantle. New metal-silicate partitioning data will be applied to the origin of volatile elements in both the Earth and Moon, and will evaluate theories for exogenous versus endogenous origin of volatile elements.

Multi-Component Profiling of Trace Volatiles in Blood by Gas Chromatography/Mass Spectrometry with Dynamic Headspace Extraction

PubMed Central

Kakuta, Shoji; Yamashita, Toshiyuki; Nishiumi, Shin; Yoshida, Masaru; Fukusaki, Eiichiro; Bamba, Takeshi

2015-01-01

A dynamic headspace extraction method (DHS) with high-pressure injection is described. This dynamic extraction method has superior sensitivity to solid phase micro extraction, SPME and is capable of extracting the entire gas phase by purging the headspace of a vial. Optimization of the DHS parameters resulted in a highly sensitive volatile profiling system with the ability to detect various volatile components including alcohols at nanogram levels. The average LOD for a standard volatile mixture was 0.50 ng mL−1, and the average LOD for alcohols was 0.66 ng mL−1. This method was used for the analysis of volatile components from biological samples and compared with acute and chronic inflammation models. The method permitted the identification of volatiles with the same profile pattern as in vitro oxidized lipid-derived volatiles. In addition, the concentration of alcohols and aldehydes from the acute inflammation model samples were significantly higher than that for the chronic inflammation model samples. The different profiles between these samples could also be identified by this method. Finally, it was possible to analyze alcohols and low-molecular-weight volatiles that are difficult to analyze by SPME in high sensitivity and to show volatile profiling based on multi-volatile simultaneous analysis. PMID:26819905

Multi-Component Profiling of Trace Volatiles in Blood by Gas Chromatography/Mass Spectrometry with Dynamic Headspace Extraction.

PubMed

Kakuta, Shoji; Yamashita, Toshiyuki; Nishiumi, Shin; Yoshida, Masaru; Fukusaki, Eiichiro; Bamba, Takeshi

2015-01-01

A dynamic headspace extraction method (DHS) with high-pressure injection is described. This dynamic extraction method has superior sensitivity to solid phase micro extraction, SPME and is capable of extracting the entire gas phase by purging the headspace of a vial. Optimization of the DHS parameters resulted in a highly sensitive volatile profiling system with the ability to detect various volatile components including alcohols at nanogram levels. The average LOD for a standard volatile mixture was 0.50 ng mL(-1), and the average LOD for alcohols was 0.66 ng mL(-1). This method was used for the analysis of volatile components from biological samples and compared with acute and chronic inflammation models. The method permitted the identification of volatiles with the same profile pattern as in vitro oxidized lipid-derived volatiles. In addition, the concentration of alcohols and aldehydes from the acute inflammation model samples were significantly higher than that for the chronic inflammation model samples. The different profiles between these samples could also be identified by this method. Finally, it was possible to analyze alcohols and low-molecular-weight volatiles that are difficult to analyze by SPME in high sensitivity and to show volatile profiling based on multi-volatile simultaneous analysis.

Micro Ion Mobility Sensor for In Situ Monitoring of Contaminated Groundwater

DTIC Science & Technology

2012-01-01

volts per ampere V/cm volts per centimeter VC voltage compensation Vd drift velocity VOC volatile organic compounds Technical...experience in field test. 1.3 RESULTS Lab testing showed that a prototype sensor is capable of uniquely identifying 32 volatile organic compounds (VOC...3) water-loop, (4) water-to-vapor chamber, (5) permanent collector , (6) second-stage carrier gas inlet, (7) vapor-to-vapor chamber, (8) permanent

Discovering Volatile Chemicals from Window Weatherstripping through Solid-Phase Microextraction/Gas Chromatography-Mass Spectrometry

ERIC Educational Resources Information Center

Rosu, Cornelia; Cueto, Rafael; Veillion, Lucas; David, Connie; Laine, Roger A.; Russo, Paul S.

2017-01-01

Volatile compounds from polymeric materials such as weatherstripping were identified by solid-phase microextraction (SPME), a solvent-free analytical method, coupled to gas chromatography-mass spectrometry (GC-MS). These compounds, originating from additives and fillers used in weatherstripping processing, were mostly polycyclic aromatic…

MODELING FLUX PATHWAYS TO VEGETATION FOR VOLATILE AND SEMI-VOLATILE ORGANIC COMPOUNDS IN A MULTIMEDIA ENVIRONMENT

EPA Science Inventory

This study evaluates the treatment of gas-phase atmospheric deposition in a screening level model of the multimedia environmental distribution of toxics (MEND-TOX). Recent algorithmic additions to MEND-TOX for the estimation of gas-phase deposition velocity over vegetated surf...

Determination of Plant Volatiles Using Solid Phase Microextraction GC-MS

ERIC Educational Resources Information Center

Van Bramer, Scott; Goodrich, Katherine R.

2015-01-01

This experiment combines analytical techniques of solid phase microextraction and gas chromatography-mass spectrometry with easily relatable and accessible plant volatile chemistry (floral and vegetative scents of local/available plants). The biosynthesis and structure of these chemicals are of interest in the areas of organic chemistry,…

FPGA-based prototype storage system with phase change memory

NASA Astrophysics Data System (ADS)

Li, Gezi; Chen, Xiaogang; Chen, Bomy; Li, Shunfen; Zhou, Mi; Han, Wenbing; Song, Zhitang

2016-10-01

With the ever-increasing amount of data being stored via social media, mobile telephony base stations, and network devices etc. the database systems face severe bandwidth bottlenecks when moving vast amounts of data from storage to the processing nodes. At the same time, Storage Class Memory (SCM) technologies such as Phase Change Memory (PCM) with unique features like fast read access, high density, non-volatility, byte-addressability, positive response to increasing temperature, superior scalability, and zero standby leakage have changed the landscape of modern computing and storage systems. In such a scenario, we present a storage system called FLEET which can off-load partial or whole SQL queries to the storage engine from CPU. FLEET uses an FPGA rather than conventional CPUs to implement the off-load engine due to its highly parallel nature. We have implemented an initial prototype of FLEET with PCM-based storage. The results demonstrate that significant performance and CPU utilization gains can be achieved by pushing selected query processing components inside in PCM-based storage.

SITE TECHNOLOGY CAPSULE: SUBSURFACE VOLATILIZATION AND VENTILATION SYSTEM (SVVS)

EPA Science Inventory

The Subsurface Volatilization and Ventilation System is an integrated technology used for attacking all phases of volatile organic compound (VOC) contamination in soil and groundwater. The SVVS technology promotes insitu remediation of soil and groundwater contaminated with or-ga...

Analysis of volatile organic compounds in pleural effusions by headspace solid-phase microextraction coupled with cryotrap gas chromatography and mass spectrometry.

PubMed

Huang, Zhongping; Zhang, Jie; Zhang, Peipei; Wang, Hong; Pan, Zaifa; Wang, Lili

2016-07-01

Headspace solid-phase microextraction coupled with cryotrap gas chromatography and mass spectrometry was applied to the analysis of volatile organic compounds in pleural effusions. The highly volatile organic compounds were separated successfully with high sensitivity by the employment of a cryotrap device, with the construction of a cold column head by freezing a segment of metal capillary with liquid nitrogen. A total of 76 volatile organic compounds were identified in 50 pleural effusion samples (20 malignant effusions and 30 benign effusions). Among them, 34 more volatile organic compounds were detected with the retention time less than 8 min, by comparing with the normal headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry method. Furthermore, 24 volatile organic compounds with high occurrence frequency in pleural effusion samples, 18 of which with the retention time less than 8 min, were selected for the comparative analysis. The results of average peak area comparison and box-plot analysis showed that except for cyclohexanone, 2-ethyl-1-hexanol, and tetramethylbenzene, which have been reported as potential cancer biomarkers, cyclohexanol, dichloromethane, ethyl acetate, n-heptane, ethylbenzene, and xylene also had differential expression between malignant and benign effusions. Therefore, the proposed approach was valuable for the comprehensive characterization of volatile organic compounds in pleural effusions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aromatherapy: composition of the gaseous phase at equilibrium with liquid bergamot essential oil.

PubMed

Leggio, Antonella; Leotta, Vanessa; Belsito, Emilia Lucia; Di Gioia, Maria Luisa; Romio, Emanuela; Santoro, Ilaria; Taverna, Domenico; Sindona, Giovanni; Liguori, Angelo

2017-11-02

This work compares the composition at different temperatures of gaseous phase of bergamot essential oil at equilibrium with the liquid phase. A new GC-MS methodology to determine quantitatively the volatile aroma compounds was developed. The adopted methodology involved the direct injection of headspace gas into injection port of GC-MS system and of known amounts of the corresponding authentic volatile compounds. The methodology was validated. This study showed that gaseous phase composition is different from that of the liquid phase at equilibrium with it.

A Computer Model for Analyzing Volatile Removal Assembly

NASA Technical Reports Server (NTRS)

Guo, Boyun

2010-01-01

A computer model simulates reactional gas/liquid two-phase flow processes in porous media. A typical process is the oxygen/wastewater flow in the Volatile Removal Assembly (VRA) in the Closed Environment Life Support System (CELSS) installed in the International Space Station (ISS). The volatile organics in the wastewater are combusted by oxygen gas to form clean water and carbon dioxide, which is solved in the water phase. The model predicts the oxygen gas concentration profile in the reactor, which is an indicator of reactor performance. In this innovation, a mathematical model is included in the computer model for calculating the mass transfer from the gas phase to the liquid phase. The amount of mass transfer depends on several factors, including gas-phase concentration, distribution, and reaction rate. For a given reactor dimension, these factors depend on pressure and temperature in the reactor and composition and flow rate of the influent.

A numerical model to simulate foams during devolatilization of polymers

NASA Astrophysics Data System (ADS)

Khan, Irfan; Dixit, Ravindra

2014-11-01

Customers often demand that the polymers sold in the market have low levels of volatile organic compounds (VOC). Some of the processes for making polymers involve the removal of volatiles to the levels of parts per million (devolatilization). During this step the volatiles are phase separated out of the polymer through a combination of heating and applying lower pressure, creating foam with the pure polymer in liquid phase and the volatiles in the gas phase. The efficiency of the devolatilization process depends on predicting the onset of solvent phase change in the polymer and volatiles mixture accurately based on the processing conditions. However due to the complex relationship between the polymer properties and the processing conditions this is not trivial. In this work, a bubble scale model is coupled with a bulk scale transport model to simulate the processing conditions of polymer devolatilization. The bubble scale model simulates the nucleation and bubble growth based on the classical nucleation theory and the popular ``influence volume approach.'' As such it provides the information of bubble size distribution and number density inside the polymer at any given time and position. This information is used to predict the bulk properties of the polymer and its behavior under the applied processing conditions. Initial results of this modeling approach will be presented.

Phase partitioning and volatility of secondary organic aerosol components formed from α-pinene ozonolysis and OH oxidation: the importance of accretion products and other low volatility compounds

DOE PAGES

Lopez-Hilfiker, F. D.; Mohr, C.; Ehn, M.; ...

2015-07-16

We measured a large suite of gas- and particle-phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA) source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer), but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gas andmore » particle phases, the latter being detected by temperature-programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO–HR-ToF-CIMS are highly correlated with, and explain at least 25–50 % of, the organic aerosol mass measured by an Aerodyne aerosol mass spectrometer (AMS). Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from high molecular weight organics and/or oligomers (i.e., multi-phase accretion reaction products). Approximately 50 % of the HR-ToF-CIMS particle-phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption-temperature-based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas-particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing the conversion of lower volatility components into the detected higher volatility compounds.« less

Phase partitioning and volatility of secondary organic aerosol components formed from α-pinene ozonolysis and OH oxidation: the importance of accretion products and other low volatility compounds

DOE PAGES

Lopez-Hilfiker, F. D.; Mohr, C.; Ehn, M.; ...

2015-02-18

We measured a large suite of gas and particle phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA) source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer), but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gasmore » and particle phases, the latter being detected upon temperature programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO HR-ToF-CIMS are highly correlated with, and explain at least 25–50% of, the organic aerosol mass measured by an Aerodyne Aerosol Mass Spectrometer (AMS). Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from large molecular weight organics and/or oligomers (i.e. multi-phase accretion reaction products). Approximately 50% of the HR-ToF-CIMS particle phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption temperature based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas–particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing the conversion of lower volatility components into the detected higher volatility compounds.« less

Toward measurements of volatile behavior at realistic pressure and temperature conditions in planetary deep interiors. (Invited)

NASA Astrophysics Data System (ADS)

McWilliams, R. S.

2013-12-01

Laboratory studies of volatiles at high pressure are constantly challenged to achieve conditions directly relevant to planets. While dynamic compression experiments are confined to adiabatic pathways that frequently exceed relevant temperatures due to the low densities and bulk moduli of volatile samples, static compression experiments are often complicated by sample reactivity and mobility before reaching relevant temperatures. By combining the speed of dynamic compression with the flexibility of experimental path afforded by static compression, optical spectroscopy measurements in volatiles such as H, N, and Ar have been demonstrated at previously-unexplored planetary temperature (up to 11,000 K) and pressure (up to 150 GPa). These optical data characterize the electronic properties of extreme states and have implications for bonding, transport, and mixing behavior in volatiles within planets. This work was conducted in collaboration with D.A. Dalton and A.F. Goncharov (Carnegie Institution of Washington) and M.F. Mahmood (Howard University).

Volatile fingerprints of seeds of four species indicate the involvement of alcoholic fermentation, lipid peroxidation, and Maillard reactions in seed deterioration during ageing and desiccation stress

PubMed Central

Colville, Louise

2012-01-01

The volatile compounds released by orthodox (desiccation-tolerant) seeds during ageing can be analysed using gas chromatography–mass spectrometry (GC-MS). Comparison of three legume species (Pisum sativum, Lathyrus pratensis, and Cytisus scoparius) during artificial ageing at 60% relative humidity and 50 °C revealed variation in the seed volatile fingerprint between species, although in all species the overall volatile concentration increased with storage period, and changes could be detected prior to the onset of viability loss. The volatile compounds are proposed to derive from three main sources: alcoholic fermentation, lipid peroxidation, and Maillard reactions. Lipid peroxidation was confirmed in P. sativum seeds through analysis of malondialdehyde and 4-hydroxynonenal. Volatile production by ageing orthodox seeds was compared with that of recalcitrant (desiccation-sensitive) seeds of Quercus robur during desiccation. Many of the volatiles were common to both ageing orthodox seeds and desiccating recalcitrant seeds, with alcoholic fermentation forming the major source of volatiles. Finally, comparison was made between two methods of analysis; the first used a Tenax adsorbent to trap volatiles, whilst the second used solid phase microextraction to extract volatiles from the headspace of vials containing powdered seeds. Solid phase microextraction was found to be more sensitive, detecting a far greater number of compounds. Seed volatile analysis provides a non-invasive means of characterizing the processes involved in seed deterioration, and potentially identifying volatile marker compounds for the diagnosis of seed viability loss. PMID:23175670

Determination of some volatile compounds in alcoholic beverage by headspace solid-phase microextraction gas chromatography - mass spectrometry

NASA Astrophysics Data System (ADS)

Schmutzer, G.; Avram, V.; Feher, I.; David, L.; Moldovan, Z.

2012-02-01

The volatile composition of alcoholic beverage was studied by headspace solid-phase microextraction (HSSPME) method and gas chromatography - mass spectrometry (GC-MS). Some volatile compounds, such as alcohols, esters, terpenes and other are mainly responsible for the flavor of fortified wines and their amounts specify the quality of the alcoholic beverages. From this perspective it is interesting to develop a rapid, selective and sensitive analytical method suitable for simultaneous quantification of the main molecules being responsible for the organoleptic characteristic of alcoholic beverages. Vermouth fortified drink was analyzed in order to characterize the volatile profile. Using the HS-SPME/GC-MS a number of twenty-six volatile compounds from a commercial market alcoholic beverage were identified. The most abundant compounds were m-thymol, o-thymol and eugenol, alongside of the ethyl ester compounds.

Implications of Low Volatility SOA and Gas-Phase Fragmentation Reactions on SOA Loadings and their Spatial and Temporal Evolution in the Atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrivastava, ManishKumar B.; Zelenyuk, Alla; Imre, Dan

2013-04-27

Recent laboratory and field measurements by a number of groups show that secondary organic aerosol (SOA) evaporates orders of magnitude slower than traditional models assume. In addition, chemical transport models using volatility basis set (VBS) SOA schemes neglect gas-phase fragmentation reactions, which are known to be extremely important. In this work, we present modeling studies to investigate the implications of non-evaporating SOA and gas-phase fragmentation reactions. Using the 3-D chemical transport model, WRF-Chem, we show that previous parameterizations, which neglect fragmentation during multi-generational gas-phase chemistry of semi-volatile/inter-mediate volatility organics ("aging SIVOC"), significantly over-predict SOA as compared to aircraft measurements downwindmore » of Mexico City. In sharp contrast, the revised models, which include gas-phase fragmentation, show much better agreement with measurements downwind of Mexico City. We also demonstrate complex differences in spatial SOA distributions when we transform SOA to non-volatile secondary organic aerosol (NVSOA) to account for experimental observations. Using a simple box model, we show that for same amount of SOA precursors, earlier models that do not employ multi-generation gas-phase chemistry of precursors ("non-aging SIVOC"), produce orders of magnitude lower SOA than "aging SIVOC" parameterizations both with and without fragmentation. In addition, traditional absorptive partitioning models predict almost complete SOA evaporation at farther downwind locations for both "non-aging SIVOC" and "aging SIVOC" with fragmentation. In contrast, in our revised approach, SOA transformed to NVSOA implies significantly higher background concentrations as it remains in particle phase even under highly dilute conditions. This work has significant implications on understanding the role of multi-generational chemistry and NVSOA formation on SOA evolution in the atmosphere.« less

Volatile transport on Venus and implications for surface geochemistry and geology

NASA Technical Reports Server (NTRS)

Brackett, Robert A.; Fegley, Bruce; Arvidson, Raymond E.

1995-01-01

The high vapor pressure of volatile metal halides and chalcogenides (e.g., of Cu, Zn, Sn, Pb, As, Sb, Bi) at typical Venus surface temperatures, coupled with the altitude-dependent temperature gradient of approximately 8.5 K/km, is calculated to transport volatile metal vapors to the highlands of Venus, where condensation and accumulation will occur. The predicted geochemistry of volatile metals on Venus is supported by observations of CuCl in volcanic gases at Kilauea and Nyiragongo, and large enrichments of these and other volatile elements in terrestrial volcanic aerosols. A one-dimensional finite difference vapor transport model shows the diffusive migration of a thickness of 0.01 to greater than 10 microns/yr of moderately to highly volatile phases (e.g., metal halides and chalcogenides) from the hot lowlands (740 K) to the cold highlands (660 K) on Venus. The diffusive transport of volatile phases on Venus may explain the observed low emissivity of the Venusian highlands, hazes at 6-km altitude observed by two Pioneer Venus entry probes, and the Pioneer Venus entry probe anomalies at 12.5 km.

Optimization of biological and instrumental detection of explosives and ignitable liquid residues including canines, SPME/ITMS and GC/MSn

NASA Astrophysics Data System (ADS)

Furton, Kenneth G.; Harper, Ross J.; Perr, Jeannette M.; Almirall, Jose R.

2003-09-01

A comprehensive study and comparison is underway using biological detectors and instrumental methods for the rapid detection of ignitable liquid residues (ILR) and high explosives. Headspace solid phase microextraction (SPME) has been demonstrated to be an effective sampling method helping to identify active odor signature chemicals used by detector dogs to locate forensic specimens as well as a rapid pre-concentration technique prior to instrumental detection. Common ignitable liquids and common military and industrial explosives have been studied including trinitrotoluene, tetryl, RDX, HMX, EGDN, PETN and nitroglycerine. This study focuses on identifying volatile odor signature chemicals present, which can be used to enhance the level and reliability of detection of ILR and explosives by canines and instrumental methods. While most instrumental methods currently in use focus on particles and on parent organic compounds, which are often involatile, characteristic volatile organics are generally also present and can be exploited to enhance detection particularly for well-concealed devices. Specific examples include the volatile odor chemicals 2-ethyl-1-hexanol and cyclohexanone, which are readily available in the headspace of the high explosive composition C-4; whereas, the active chemical cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) is not. The analysis and identification of these headspace 'fingerprint' organics is followed by double-blind dog trials of the individual components using certified teams in an attempt to isolate and understand the target compounds to which dogs are sensitive. Studies to compare commonly used training aids with the actual target explosive have also been undertaken to determine their suitability and effectiveness. The optimization of solid phase microextraction (SPME) combined with ion trap mobility spectrometry (ITMS) and gas chromatography/mass spectrometry/mass spectrometry (GC/MSn) is detailed including interface development and comparisons of limits of detection. These instrumental methods are being optimized in order to detect the same target odor chemicals used by detector dogs to reliably locate explosives and ignitable liquids.

Volatile-bearing phases in carbonaceous chondrites: Compositions, modal abundance, and reaction kinetics

NASA Technical Reports Server (NTRS)

Ganguly, Jibamitra

1990-01-01

The spectral and density characteristics of Phobos and Deimos (the two small natural satellites of Mars) strongly suggest that a significant fraction of the near-earth asteroids are made of carbonaceous chondrites, which are rich in volatile components and, thus, could serve as potential resources for propellants and life supporting systems in future planetary missions. However, in order to develop energy efficient engineering designs for the extraction of volatiles, knowledge of the nature and modal abundance of the minerals in which the volatiles are structurally bound and appropriate kinetic data on the rates of the devolatilization reactions is required. Theoretical calculations to predict the modal abundances and compositions of the major volatile-bearing and other mineral phases that could develop in the bulk compositions of C1 and C2 classes (the most volatile rich classes among the carbonaceous chondrites) were performed as functions of pressure and temperature. The rates of dehydration of talc at 585, 600, 637, and 670 C at P(total) = 1 bar were determine for the reaction: Talc = 3 enstatite + quartz + water. A scanning electron microscopic study was conducted to see if the relative abundance of phases can be determined on the basis of the spectral identification and x ray mapping. The results of this study and the other studies within the project are discussed.

Improvement of a headspace solid phase microextraction-gas chromatography/mass spectrometry method for the analysis of wheat bread volatile compounds.

PubMed

Raffo, Antonio; Carcea, Marina; Castagna, Claudia; Magrì, Andrea

2015-08-07

An improved method based on headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS) was proposed for the semi-quantitative determination of wheat bread volatile compounds isolated from both whole slice and crust samples. A DVB/CAR/PDMS fibre was used to extract volatiles from the headspace of a bread powdered sample dispersed in a sodium chloride (20%) aqueous solution and kept for 60min at 50°C under controlled stirring. Thirty-nine out of all the extracted volatiles were fully identified, whereas for 95 other volatiles a tentative identification was proposed, to give a complete as possible profile of wheat bread volatile compounds. The use of an array of ten structurally and physicochemically similar internal standards allowed to markedly improve method precision with respect to previous HS-SPME/GC-MS methods for bread volatiles. Good linearity of the method was verified for a selection of volatiles from several chemical groups by calibration with matrix-matched extraction solutions. This simple, rapid, precise and sensitive method could represent a valuable tool to obtain semi-quantitative information when investigating the influence of technological factors on volatiles formation in wheat bread and other bakery products. Copyright © 2015 Elsevier B.V. All rights reserved.

Whey acerola-flavoured drink submitted Ohmic Heating: Bioactive compounds, antioxidant capacity, thermal behavior, water mobility, fatty acid profile and volatile compounds.

PubMed

Cappato, Leandro P; Ferreira, Marcus Vinicius S; Moraes, Jeremias; Pires, Roberto P S; Rocha, Ramon S; Silva, Ramon; Neto, Roberto P C; Tavares, Maria Inês B; Freitas, Mônica Q; Rodrigues, Flavio N; Calado, Veronica M A; Raices, Renata S L; Silva, Marcia C; Cruz, Adriano G

2018-10-15

Whey acerola-flavoured drink was subjected to Ohmic Heating (OH) under different operational conditions (45, 60, 80 V at 60 Hz and 10, 100, 1000 Hz with 25 V, 65 °C/30 min) and conventional pasteurization (65 °C/30 min). Bioactive compounds (total phenolics, DPPH, FRAP, ACE levels), fatty acid profile, volatile compounds (CG-MS), thermal behaviors (DSC) and water mobility (TD-NMR) were performed. Reduction of frequency (1000-10 Hz) resulted in a lower bioactive compounds and antioxidant capacity of the samples, except for the DPPH values. Concerning the thermal behaviors, fatty acids profile and volatile compounds, different findings were observed as a function of the parameters used (voltage and frequency). In respect of TD-NMR parameters, OH led to a slightly reduction of the relaxation time when compared to the conventional treatment, suggesting more viscous beverages. Overall, OH may be interesting option to whey acerola-flavoured drink processing. Copyright © 2018 Elsevier Ltd. All rights reserved.

A dynamic two-dimensional system for measuring volatile organic compound volatilization and movement in soils.

PubMed

Allaire, S E; Yates, S R; Ernst, F F; Gan, J

2002-01-01

There is an important need to develop instrumentation that allows better understanding of atmospheric emission of toxic volatile compounds associated with soil management. For this purpose, chemical movement and distribution in the soil profile should be simultaneously monitored with its volatilization. A two-dimensional rectangular soil column was constructed and a dynamic sequential volatilization flux chamber was attached to the top of the column. The flux chamber was connected through a manifold valve to a gas chromatograph (GC) for real-time concentration measurement. Gas distribution in the soil profile was sampled with gas-tight syringes at selected times and analyzed with a GC. A pressure transducer was connected to a scanivalve to automatically measure the pressure distribution in the gas phase of the soil profile. The system application was demonstrated by packing the column with a sandy loam in a symmetrical bed-furrow system. A 5-h furrow irrigation was started 24 h after the injection of a soil fumigant, propargyl bromide (3-bromo-1-propyne; 3BP). The experience showed the importance of measuring lateral volatilization variability, pressure distribution in the gas phase, chemical distribution between the different phases (liquid, gas, and sorbed), and the effect of irrigation on the volatilization. Gas movement, volatilization, water infiltration, and distribution of degradation product (Br-) were symmetric around the bed within 10%. The system saves labor cost and time. This versatile system can be modified and used to compare management practices, estimate concentration-time indexes for pest control, study chemical movement, degradation, and emissions, and test mathematical models.

Hand-portable gas chromatography-ion mobility spectrometer for the determination of the freshness of fish

NASA Technical Reports Server (NTRS)

Snyder, A. Peter; Harden, Charles S.; Davis, Dennis M.; Shoff, Donald B.; Maswadeh, Waleed M.

1995-01-01

A hand-held, portable gas chromatography-ion mobility spectrometer (GC-IMS) device was used to detect the presence of volatile amine compounds in the headspace of decomposing fish. The Food and Drug Administration (FDA) largely relies on olfactory discrimination with respect to fresh and spoiled, frozen and unfrozen fish. The fish are delivered at ship docks on pallets, and each pallet of fish can range from 30-40 thousand dollars in value. Fresh fish were placed in a teflon bag and the direct headspace was interrogated. In the first three days, only low molecular weight volatile amines were detected. On the fourth day, a number of spectral signatures were observed which indicated the presence of 1,5-diaminopentane, cadaverine. Analyses typically took from 0.5-1 minute.

Assessing the influence of NOx concentrations and relative humidity on secondary organic aerosol yields from α-pinene photo-oxidation through smog chamber experiments and modelling calculations

NASA Astrophysics Data System (ADS)

Stirnweis, Lisa; Marcolli, Claudia; Dommen, Josef; Barmet, Peter; Frege, Carla; Platt, Stephen M.; Bruns, Emily A.; Krapf, Manuel; Slowik, Jay G.; Wolf, Robert; Prévôt, Andre S. H.; Baltensperger, Urs; El-Haddad, Imad

2017-04-01

Secondary organic aerosol (SOA) yields from the photo-oxidation of α-pinene were investigated in smog chamber (SC) experiments at low (23-29 %) and high (60-69 %) relative humidity (RH), various NOx / VOC ratios (0.04-3.8) and with different aerosol seed chemical compositions (acidic to neutralized sulfate-containing or hydrophobic organic). A combination of a scanning mobility particle sizer and an Aerodyne high-resolution time-of-flight aerosol mass spectrometer was used to determine SOA mass concentration and chemical composition. We used a Monte Carlo approach to parameterize smog chamber SOA yields as a function of the condensed phase absorptive mass, which includes the sum of OA and the corresponding bound liquid water content. High RH increased SOA yields by up to 6 times (1.5-6.4) compared to low RH. The yields at low NOx / VOC ratios were in general higher compared to yields at high NOx / VOC ratios. This NOx dependence follows the same trend as seen in previous studies for α-pinene SOA. A novel approach of data evaluation using volatility distributions derived from experimental data served as the basis for thermodynamic phase partitioning calculations of model mixtures in this study. These calculations predict liquid-liquid phase separation into organic-rich and electrolyte phases. At low NOx conditions, equilibrium partitioning between the gas and liquid phases can explain most of the increase in SOA yields observed at high RH, when in addition to the α-pinene photo-oxidation products described in the literature, fragmentation products are added to the model mixtures. This increase is driven by both the increase in the absorptive mass and the solution non-ideality described by the compounds' activity coefficients. In contrast, at high NOx, equilibrium partitioning alone could not explain the strong increase in the yields with RH. This suggests that other processes, e.g. reactive uptake of semi-volatile species into the liquid phase, may occur and be enhanced at higher RH, especially for compounds formed under high NOx conditions, e.g. carbonyls.

Compositional heterogeneity of the Sugarloaf melilite nephelinite flow, Honolulu Volcanics, Hawai'i

NASA Astrophysics Data System (ADS)

Clague, David A.; Frey, Frederick A.; Garcia, Michael O.; Huang, Shichun; McWilliams, Michael; Beeson, Melvin H.

2016-07-01

The Sugarloaf flow is a melilite nephelinite erupted from the Tantalus rift during rejuvenated-stage volcanism on O'ahu, the Honolulu Volcanics. The flow ponded in Mānoa Valley forming a ∼15 m thick flow which was cored and sampled in a quarry. Nepheline from a pegmatoid segregation in the flow yielded a 40Ar-39Ar age of 76 ka. This age, combined with others, indicates that the Tantalus rift eruptions are some of the youngest on O'ahu. Honolulu Volcanics erupt on average about every 35-40 ka indicating that future eruptions are possible. We evaluated the compositional variability of 19 samples from the flow, including 14 from the core. Twelve samples are representative of the bulk flow, four are dark- or light-colored variants, one is a heavy rare earth element (REE)-enriched pegmatoid, and two visually resemble the bulk flow, but have chemical characteristics of the dark and light variants. Our objective was to determine intraflow heterogeneity in mineralogy and composition. Variable abundances of Na2O, K2O, Sr, Ba, Rb, Pb and U in the flow were caused by post-eruptive mobility in a vapor phase, most likely during or soon after flow emplacement, and heterogeneous deposition of secondary calcite and zeolites. Relative to fine-grained samples, a pegmatoid vein that crosscuts the flow is enriched in incompatible trace elements except Sr and TiO2. Element mobility after eruption introduced scatter in trace element ratios including light-REE/heavy-REE, and all ratios involving mobile elements K, Rb, Ba, Sr, Pb, and U. Lavas from some of the 37 Honolulu Volcanics vents have crosscutting REE patterns in a primitive mantle-normalized plot. Such patterns have been interpreted to reflect variable amounts of residual garnet during partial melting. Previous studies of lavas from different vents concluded that garnet, phlogopite, amphibole, and Fe-Ti oxides were residual phases of the partial melting processes that created the Honolulu Volcanics (Clague and Frey, 1982; Yang et al., 2003). However post-eruptive processes in the Sugarloaf flow also produced crossing REE patterns. Eruptions on the Tantalus rift, including the Sugarloaf flow, produced volatile- and crystal-rich ash with interstitial glass and melt inclusions in olivine containing 4.2-6.4 wt% MgO compared to the flow average of 11.8 wt%. This flow erupted as a partially crystallized viscous magma at least 100 °C below its liquidus. The slow advance and cooling of the 15-m thick 'a' ā low promoted the segregation of pegmatoids, formation of light and dark bands with differing proportions of melilite and clinopyroxene, and induced volatile-enhanced mobility of incompatible elements.

Two-Step Vapor/Liquid/Solid Purification

NASA Technical Reports Server (NTRS)

Holland, L. R.

1986-01-01

Vertical distillation system combines in single operation advantages of multiple zone refining with those of distillation. Developed specifically to load Bridgman-Stockbarger (vertical-solidification) growth ampoules with ultrapure tellurium and cadmium, system, with suitable modifications, serves as material refiner. In first phase of purification process, ampoule heated to drive off absorbed volatiles. Second phase, evaporator heated to drive off volatiles in charge. Third phase, slowly descending heater causes distillation from evaporator to growing crystal in ampoule.

Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon.

PubMed

Day, James M D; Moynier, Frederic

2014-09-13

The Moon is depleted in volatile elements relative to the Earth and Mars. Low abundances of volatile elements, fractionated stable isotope ratios of S, Cl, K and Zn, high μ ((238)U/(204)Pb) and long-term Rb/Sr depletion are distinguishing features of the Moon, relative to the Earth. These geochemical characteristics indicate both inheritance of volatile-depleted materials that formed the Moon and planets and subsequent evaporative loss of volatile elements that occurred during lunar formation and differentiation. Models of volatile loss through localized eruptive degassing are not consistent with the available S, Cl, Zn and K isotopes and abundance data for the Moon. The most probable cause of volatile depletion is global-scale evaporation resulting from a giant impact or a magma ocean phase where inefficient volatile loss during magmatic convection led to the present distribution of volatile elements within mantle and crustal reservoirs. Problems exist for models of planetary volatile depletion following giant impact. Most critically, in this model, the volatile loss requires preferential delivery and retention of late-accreted volatiles to the Earth compared with the Moon. Different proportions of late-accreted mass are computed to explain present-day distributions of volatile and moderately volatile elements (e.g. Pb, Zn; 5 to >10%) relative to highly siderophile elements (approx. 0.5%) for the Earth. Models of early magma ocean phases may be more effective in explaining the volatile loss. Basaltic materials (e.g. eucrites and angrites) from highly differentiated airless asteroids are volatile-depleted, like the Moon, whereas the Earth and Mars have proportionally greater volatile contents. Parent-body size and the existence of early atmospheres are therefore likely to represent fundamental controls on planetary volatile retention or loss. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Comparison of methods for determining volatile compounds in cheese, milk, and whey powder

USDA-ARS?s Scientific Manuscript database

Solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) are commonly used for qualitative and quantitative analysis of volatile compounds in various dairy products, but selecting the proper procedures presents challenges. Heat is applied to drive volatiles from the samp...

Comparison of the response of four aerosol detectors used with ultra high pressure liquid chromatography.

PubMed

Hutchinson, Joseph P; Li, Jianfeng; Farrell, William; Groeber, Elizabeth; Szucs, Roman; Dicinoski, Greg; Haddad, Paul R

2011-03-25

The responses of four different types of aerosol detectors have been evaluated and compared to establish their potential use as a universal detector in conjunction with ultra high pressure liquid chromatography (UHPLC). Two charged-aerosol detectors, namely Corona CAD and Corona Ultra, and also two different types of light-scattering detectors (an evaporative light scattering detector, and a nano-quantity analyte detector [NQAD]) were evaluated. The responses of these detectors were systematically investigated under changing experimental and instrumental parameters, such as the mobile phase flow-rate, analyte concentration, mobile phase composition, nebulizer temperature, evaporator temperature, evaporator gas flow-rate and instrumental signal filtering after detection. It was found that these parameters exerted non-linear effects on the responses of the aerosol detectors and must therefore be considered when designing analytical separation conditions, particularly when gradient elution is performed. Identical reversed-phase gradient separations were compared on all four aerosol detectors and further compared with UV detection at 200 nm. The aerosol detectors were able to detect all 11 analytes in a test set comprising species having a variety of physicochemical properties, whilst UV detection was applicable only to those analytes containing chromophores. The reproducibility of the detector response for 11 analytes over 10 consecutive separations was found to be approximately 5% for the charged-aerosol detectors and approximately 11% for the light-scattering detectors. The tested analytes included semi-volatile species which exhibited a more variable response on the aerosol detectors. Peak efficiencies were generally better on the aerosol detectors in comparison to UV detection and particularly so for the light-scattering detectors which exhibited efficiencies of around 110,000 plates per metre. Limits of detection were calculated using different mobile phase compositions and the NQAD detector was found to be the most sensitive (LOD of 10 ng/mL), followed by the Corona CAD (76 ng/mL), then UV detection at 200 nm (178 ng/mL) using an injection volume of 25 μL. Copyright © 2011 Elsevier B.V. All rights reserved.

Influence of volatile terpenes on the capacity of leaves to uptake and detoxify ozone. (Invited)

NASA Astrophysics Data System (ADS)

Loreto, F.; Fares, S.

2009-12-01

Tropospheric ozone is considered the most dangerous air pollutant for plant ecosystems, and its concentration is increasing throughout the earth. Oxidative damage takes place when ozone penetrates inside the leaves through the stomata and the cuticles. The latest guidelines suggest considering the dose entering stomata to evaluate ozone risk on vegetation. We have shown that this metric may not consider important detoxification mechanisms activated by the production of volatile antioxidants, especially terpenes. We review here how volatile terpenes may increase ozone uptake by leaves yet reducing the risk of damage to internal leaf structures. We also argue that volatile terpene production by plants phases-in with episodes on high ozone whereas other detoxification mechanisms are phased-out. Our results suggests that volatile isoprenoids play a major role in determining the capacity of ozone removal and detoxification by vegetation.

A comprehensive screen for volatile organic compounds in biological fluids.

PubMed

Sharp, M E

2001-10-01

A headspace gas chromatographic (GC) screen for common volatile organic compounds in biological fluids is reported. Common GC phases, DB-1 and DB-WAX, with split injection provide separation and identification of more than 40 compounds in a single 20-min run. In addition, this method easily accommodates quantitation. The screen detects commonly encountered volatile compounds at levels below 4 mg%. A control mixture, providing qualitative and semiquantitative information, is described. For comparison, elution of the volatiles on a specialty phase, DB-624, is reported. This method is an expansion and modification of a screen that had been used for more than 20 years. During its first year of use, the expanded screen has proven to be advantageous in routine forensic casework.

Analysis of Volatile Fragrance and Flavor Compounds by Headspace Solid Phase Microextraction and GC-MS: An Undergraduate Instrumental Analysis Experiment

NASA Astrophysics Data System (ADS)

Galipo, Randolph C.; Canhoto, Alfredo J.; Walla, Michael D.; Morgan, Stephen L.

1999-02-01

A senior-level undergraduate laboratory experiment that demonstrates the use of solid-phase microextraction (SPME) and capillary gas chromatography-mass spectrometry (GC-MS) was developed for the identification of volatile compounds in consumer products. SPME minimizes sample preparation and concentrates volatile analytes in a solvent-free manner. Volatile flavor and fragrance compounds were extracted by SPME from the headspace of vials containing shampoos, chewing gums, and perfumes and analyzed by GC-MS. Headspace SPME was shown to be more sensitive than conventional headspace analysis of similar samples performed with an airtight syringe. Analysis times were less than 30 min, allowing multiple analyses to be performed in a typical laboratory class period.

High salinity volatile phases in magmatic Ni-Cu-platinum group element deposits

NASA Astrophysics Data System (ADS)

Hanley, J. J.; Mungall, J. E.

2004-12-01

The role of "deuteric" fluids (exsolved magmatic volatile phases) in the development of Ni-Cu-PGE (platinum group element) deposits in mafic-ultramafic igneous systems is poorly understood. Although considerable field evidence demonstrates unambiguously that fluids modified most large primary Ni-Cu-PGE concentrations, models which hypothesize that fluids alone were largely responsible for the economic concentration of the base and precious metals are not widely accepted. Determination of the trace element composition of magmatic volatile phases in such ore-forming systems can offer considerable insight into the origin of potentially mineralizing fluids in such igneous environments. Laser ablation ICP-MS microanalysis allows researchers to confirm the original metal budget of magmatic volatile phases and quantify the behavior of trace ore metals in the fluid phase in the absence of well-constrained theoretical or experimental predictions of ore metal solubility. In this study, we present new evidence from major deposits (Sudbury, Ontario, Canada; Stillwater Complex, Montana, U.S.A.) that compositionally distinct magmatic brines and halide melt phases were exsolved from crystallizing residual silicate melt and trapped within high-T fluid conduits now comprised of evolved rock compositions (albite-quartz graphic granite, orthoclase-quartz granophyre). Petrographic evidence demonstrates that brines and halide melts coexisted with immiscible carbonic phases at the time of entrapment (light aliphatic hydrocarbons, CO2). Brine and halide melt inclusions are rich in Na, Fe, Mn, K, Pb, Zn, Ba, Sr, Al and Cl, and homogenize by either halite dissolution at high T ( ˜450-700° C) or by melting of the salt phase (700-800° C). LA-ICPMS analyses of single inclusions demonstrate that high salinity volatile phases contained abundant base metals (Cu, Fe, Sn, Bi) and precious metals (Pt, Pd, Au, Ag) at the time of entrapment. Notably, precious metal concentrations in the inclusions are comparable to and often exceed the economic concentrations of the metals within the ores themselves. As a consequence of these results, current genetic models must be revised to consider the role played by hydrous saline melts and magmatic brines in deposit development, and the potential for interaction and competition between sulfide liquids (or PGE-bearing sulfide minerals) and hydrosaline volatiles for available PGE and Au in a crystallizing mafic igneous system must be critically evaluated.

CONTROL OF INDUSTRIAL VOC (VOLATILE ORGANIC COMPOUND) EMISSIONS BY CATALYTIC INCINERATION. VOLUME 8. CATALYTIC INCINERATOR PERFORMANCE AT INDUSTRIAL SITE C-6

EPA Science Inventory

The report is part of a two-phase EPA effort to assess the performance, suitability, and costs of various technologies to control emissions of volatile organic compounds (VOCs). In Phase 1, information was assembled from the literature on the use and cost of using catalytic incin...

CONTROL OF INDUSTRIAL VOC (VOLATILE ORGANIC COMPOUND) EMISSIONS BY CATALYTIC INCINERATION. VOLUME 1. ASSESSMENT OF CATALYTIC INCINERATION AND COMPETING CONTROLS

EPA Science Inventory

The report is part of a two-phase EPA effort to assess the performance, suitability, and costs of various technologies to control emissions of volatile organic compounds (VOCs). In Phase 1, information was assembled from the literature on the use and cost of using catalytic incin...

CONTROL OF INDUSTRIAL VOC (VOLATILE ORGANIC COMPOUND) EMISSIONS BY CATALYTIC INCINERATION. VOLUME 7. CATALYTIC INCINERATOR PERFORMANCE AT INDUSTRIAL SITE C-5

EPA Science Inventory

The report is part of a two-phase EPA effort to assess the performance, suitability, and costs of various technologies to control emissions of volatile organic compounds (VOCs). In Phase 1, information was assembled from the literature on the use and cost of using catalytic incin...

CONTROL OF INDUSTRIAL VOC (VOLATILE ORGANIC COMPOUND) EMISSIONS BY CATALYTIC INCINERATION. VOLUME 5. CATALYTIC INCINERATOR PERFORMANCE AT INDUSTRIAL SITE C-3

EPA Science Inventory

The report is part of a two-phase EPA effort to assess the performance, suitability, and costs of various technologies to control emissions of volatile organic compounds (VOCs). In Phase 1, information was assembled from the literature on the use and cost of using catalytic incin...

Neutron Spectrometer Prospecting During the Mojave Volatiles Project Analog Field Test

NASA Technical Reports Server (NTRS)

Elphic, R. C.; Heldmann, J. L.; Colaprete, A.; Hunt, D. R.; Deans, M C.; Lim, D. S.; Foil, G.; Fong, T.

2015-01-01

We know there are volatiles sequestered at the poles of the Moon. While we have evidence of water ice and a number of other compounds based on remote sensing, the detailed distribution, and physical and chemical form are largely unknown. Additional orbital studies of lunar polar volatiles may yield further insights, but the most important next step is to use landed assets to fully characterize the volatile composition and distribution at scales of tens to hundreds of meters. To achieve this range of scales, mobility is needed. Because of the proximity of the Moon, near real-time operation of the surface assets is possible, with an associated reduction in risk and cost. This concept of operations is very different from that of rovers on Mars, and new operational approaches are required to carry out such real-time robotic exploration. The Mojave Volatiles Project (MVP) is a Moon- Mars Analog Mission Activities (MMAMA) program effort aimed at (1) determining effective approaches to operating a real-time but short-duration lunar surface robotic mission, and (2) performing prospecting science in a natural setting, as a test of these approaches. We know there are volatiles sequestered at the poles of the Moon. While we have evidence of water ice and a number of other compounds based on remote sensing, the detailed distribution, and physical and chemical form are largely unknown. Additional orbital studies of lunar polar volatiles may yield further insights, but the most important next step is to use landed assets to fully characterize the volatile composition and distribution at scales of tens to hundreds of meters. To achieve this range of scales, mobility is needed. Because of the proximity of the Moon, near real-time operation of the surface assets is possible, with an associated reduction in risk and cost. This concept of operations is very different from that of rovers on Mars, and new operational approaches are required to carry out such robotic exploration. The Mojave Volatiles Project (MVP) is a Moon- Mars Analog Mission Activities (MMAMA) program effort aimed at (1) determining effective approaches to operating a real-time but short-duration lunar surface robotic mission, and (2) performing prospecting science in a natural setting, as a test of these approaches. Here we describe some results from the first such test, carried out in the Mojave Desert between 16 and 24 October, 2014. The test site was an alluvial fan just E of the Soda Mountains, SW of Baker, California. This site contains desert pavements, ranging from the late Pleistocene to early-Holocene in age. These pavements are undergoing dissection by the ongoing development of washes. A principal objective was to determine the hydration state of different types of desert pavement and bare ground features. The mobility element of the test was provided by the KREX-2 rover, designed and operated by the Intelligent Robotics Group at NASA Ames Research Center.

Fixture For Sampling Volatile Materials In Containers

NASA Technical Reports Server (NTRS)

Melton, Donald; Pratz, Earl Howard

1995-01-01

Fixture based on T-connector enables mass-spectrometric analysis of volatile contents of cylindrical containers without exposing contents to ambient conditions. Used to sample volatile contents of pressurized containers, contents of such enclosed processing systems as gas-phase reactors, gases in automotive emission systems, and gas in hostile environments.

Mobile Measurements of Gas and Particle Emissions from Marcellus Shale Gas Development

NASA Astrophysics Data System (ADS)

DeCarlo, P. F.; Goetz, J. D.; Floerchinger, C. R.; Fortner, E.; Wormhoudt, J.; Knighton, W. B.; Herndon, S.; Kolb, C. E.; Shaw, S. L.; Knipping, E. M.

2013-12-01

Production of natural gas in the Marcellus shale is increasing rapidly due to the vast quantities of natural gas stored in the formation. Transient and long-term activities have associated emissions to the atmosphere of methane, volatile organic compounds, NOx, particulates and other species from gas production and transport infrastructure. In the summer of 2012, a team of researchers from Drexel University and Aerodyne Research deployed the Aerodyne mobile laboratory (AML) and measured in-situ concentrations of gas-phase and aerosol chemical components in the main gas producing regions of Pennsylvania, with the overall goal of understanding the impacts to regional ozone and particulate matter (PM) concentrations. State-of-the-art instruments including quantum cascade laser systems, proton transfer mass spectrometry, tunable diode lasers and a soot particle aerosol mass spectrometer, were used quantify concentrations of pollutants of interest. Chemical species measured include methane, ethane, NO, NO2, CO, CO2, SO2, and many volatile organic compounds, and aerosol size and chemical composition. Tracer-release techniques were employed to link sources with emissions and to quantify emission rates from gas facilities, in order to understand the regional burden of these chemical species from oil and gas development in the Marcellus. Measurements were conducted in two regions of Pennsylvania: the NE region that is predominantly dry gas (95% + methane), and the SW region where wet gas (containing greater than 5% higher hydrocarbons) is found. Regional scale measurements of current levels of air pollutants will be shown and will put into context how further development of the gas resource in one of the largest natural gas fields in the world impacts air quality in a region upwind of the highly urbanized east coast corridor.

VOLATILIZATION RATES FROM WATER TO INDOOR AIR ...

EPA Pesticide Factsheets

Contaminated water can lead to volatilization of chemicals to residential indoor air. Previous research has focused on only one source (shower stalls) and has been limited to chemicals in which gas-phase resistance to mass transfer is of marginal significance. As a result, attempts to extrapolate chemical emissions from high-volatility chemicals to lower volatility chemicals, or to sources other than showers, have been difficult or impossible. This study involved the development of two-phase, dynamic mass balance models for estimating chemical emissions from washing machines, dishwashers, and bathtubs. An existing model was adopted for showers only. Each model required the use of source- and chemical-specific mass transfer coefficients. Air exchange (ventilation) rates were required for dishwashers and washing machines as well. These parameters were estimated based on a series of 113 experiments involving 5 tracer chemicals (acetone, ethyl acetate, toluene, ethylbenzene, and cyclohexane) and 4 sources (showers, bathtubs, washing machines, and dishwashers). Each set of experiments led to the determination of chemical stripping efficiencies and mass transfer coefficients (overall, liquid-phase, gas-phase), and to an assessment of the importance of gas- phase resistance to mass transfer. Stripping efficiencies ranged from 6.3% to 80% for showers, 2.6% to 69% for bathtubs, 18% to 100% for dishwashers, and 3.8% to 100% for washing machines. Acetone and cyclohexane al

Modelling the contribution of biogenic volatile organic compounds to new particle formation in the Jülich plant atmosphere chamber

NASA Astrophysics Data System (ADS)

Roldin, P.; Liao, L.; Mogensen, D.; Dal Maso, M.; Rusanen, A.; Kerminen, V.-M.; Mentel, T. F.; Wildt, J.; Kleist, E.; Kiendler-Scharr, A.; Tillmann, R.; Ehn, M.; Kulmala, M.; Boy, M.

2015-09-01

We used the Aerosol Dynamics gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM) to simulate the contribution of BVOC plant emissions to the observed new particle formation during photooxidation experiments performed in the Jülich Plant-Atmosphere Chamber and to evaluate how well smog chamber experiments can mimic the atmospheric conditions during new particle formation events. ADCHAM couples the detailed gas-phase chemistry from Master Chemical Mechanism with a novel aerosol dynamics and particle phase chemistry module. Our model simulations reveal that the observed particle growth may have either been controlled by the formation rate of semi- and low-volatility organic compounds in the gas phase or by acid catalysed heterogeneous reactions between semi-volatility organic compounds in the particle surface layer (e.g. peroxyhemiacetal dimer formation). The contribution of extremely low-volatility organic gas-phase compounds to the particle formation and growth was suppressed because of their rapid and irreversible wall losses, which decreased their contribution to the nano-CN formation and growth compared to the atmospheric situation. The best agreement between the modelled and measured total particle number concentration (R2 > 0.95) was achieved if the nano-CN was formed by kinetic nucleation involving both sulphuric acid and organic compounds formed from OH oxidation of BVOCs.

Low-cost fabrication of ternary CuInSe{sub 2} nanocrystals by colloidal route using a novel combination of volatile and non-volatile capping agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chawla, Parul; Narain Sharma, Shailesh, E-mail: shailesh@nplindia.org; Singh, Son

2014-11-15

Wet-route synthesis of CuInSe{sub 2} (CISe) nanocrystals has been envisaged with the utilization of the unique combination of coordinating ligand and non coordinating solvent. Our work demonstrates the formation of a single-phase, nearly stoichiometric and monodispersive, stable and well-passivated colloidal ternary CISe nanocrystals (band gap (E{sub g})∼1.16 eV) using a novel combination of ligands; viz. volatile arylamine aniline and non-volatile solvent 1-octadecene. The synthesis and growth conditions have been manoeuvred using the colligative properties of the mixture and thus higher growth temperature (∼250 °C) could be attained that promoted larger grain growth. The beneficial influence of the capping agents (anilinemore » and 1-octadecene) on the properties of chalcopyrite nanocrystals has enabled us to pictorally model the structural, morphological and optoelectronic aspects of CISe nanoparticles. - Graphical abstract: Without resorting to any post-selenization process and using the colligative properties of the mixture comprising of volatile aniline and non-volatile 1-octadecene to manoeuvre the growth conditions to promote Ostwald ripening, a single phase, monodispersive and nearly stoichiometric ternary CISe nanocrystals are formed by wet-synthesis route. - Highlights: • Wet-route synthesis of CISe nanocrystals reported without post-selenization process. • Single-phase, stable and well-passivated colloidal ternary CISe nanocrystals formed. • Novel combination of capping agents: volatile aniline and non-volatile 1-octadecene. • Higher growth temperature attained using the colligative properties of the mixture. • Metallic salts presence explains exp. and theoretical boiling point difference.« less

Characterisation of chamomile volatiles by simultaneous distillation solid-phase extraction in comparison to hydrodistillation and simultaneous distillation extraction.

PubMed

Krüger, Hans

2010-05-01

A new method for complete separation of steam-volatile organic compounds is described using the example of chamomile flowers. This method is based on the direct combination of hydrodistillation and solid-phase extraction in a circulation apparatus. In contrast to hydrodistillation and simultaneous distillation extraction (SDE), an RP-18 solid phase as adsorptive material is used rather than a water-insoluble solvent. Therefore, a prompt and complete fixation of all volatiles takes place, and the circulation of water-soluble bisabololoxides as well as water-soluble and thermolabile en-yne-spiroethers is inhibited. This so-called simultaneous distillation solid-phase extraction (SD-SPE) provides extracts that better characterise the real composition of the vapour phase, as well as the composition of inhalation vapours, than do SDE extracts or essential oils obtained by hydrodistillation. The data indicate that during inhalation therapy with chamomile, the bisabololoxides and spiroethers are more strongly involved in the inhaling activity than so far assumed. Georg Thieme Verlag KG Stuttgart New York.

Rapid determination of the volatile components in tobacco by ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction with gas chromatography-mass spectrometry.

PubMed

Yang, Yanqin; Chu, Guohai; Zhou, Guojun; Jiang, Jian; Yuan, Kailong; Pan, Yuanjiang; Song, Zhiyu; Li, Zuguang; Xia, Qian; Lu, Xinbo; Xiao, Weiqiang

2016-03-01

An ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction was first employed to determine the volatile components in tobacco samples. The method combined the advantages of ultrasound, microwave, and headspace solid-phase microextraction. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, several experimental parameters, such as fiber type, ultrasound power, and irradiation time, were optimized to improve sampling efficiency. Under the optimal conditions, there were 37, 36, 34, and 36 components identified in tobacco from Guizhou, Hunan, Yunnan, and Zimbabwe, respectively, including esters, heterocycles, alkanes, ketones, terpenoids, acids, phenols, and alcohols. The compound types were roughly the same while the contents were varied from different origins due to the disparity of their growing conditions, such as soil, water, and climate. In addition, the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method was compared with the microwave-assisted extraction coupled to headspace solid-phase microextraction and headspace solid-phase microextraction methods. More types of volatile components were obtained by using the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method, moreover, the contents were high. The results indicated that the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction technique was a simple, time-saving and highly efficient approach, which was especially suitable for analysis of the volatile components in tobacco. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pathfinder Innovation Projects: Awardees for 2012

EPA Pesticide Factsheets

PIP2 awardees include ten research projects aimed at high-risk, high-reward projects that include volatile chemical research with flies, water-borne virus testing, medical prescription pollution, and a mobile app for cyanobacteria outbreaks.

Transfer of volatiles and metals from mafic to felsic magmas in composite magma chambers: An experimental study

NASA Astrophysics Data System (ADS)

Guo, Haihao; Audétat, Andreas

2017-02-01

In order to determine the behavior of metals and volatiles during intrusion of mafic magma into the base of silicic, upper crustal magma chambers, fluid-rock partition coefficients (Dfluid/rock) of Li, B, Na, S, Cl, K, Mn, Fe, Rb, Sr, Ba, Ce, Cu, Zn, Ag, Cd, Mo, As, Se, Sb, Te, W, Tl, Pb and Bi were determined experimentally at 2 kbar and 850 °C close to the solidus of mafic magma. In a first step, volatile-bearing mafic glasses were prepared by melting a natural basaltic trachyandesite in the presence of volatile-bearing fluids at 1200 °C/10 kbar in piston cylinder presses. The hydrous glasses were then equilibrated in subsequent experiments at 850 °C/2 kbar in cold-seal pressure vessels, which caused 80-90% of the melt to crystallize. After 0.5-2.0 days of equilibration, the exsolved fluid was trapped by means of in-situ fracturing in the form of synthetic fluid inclusions in quartz. Both the mafic rock residue and the fluid inclusions were subsequently analyzed by laser-ablation ICP-MS for major and trace elements. Reverse experiments were conducted by equilibrating metal-bearing aqueous solutions with rock powder and then trapping the fluid. In two additional experiments, information on relative element mobilities were obtained by reacting fluids that exsolved from crystallizing mafic magma with overlying silicic melts. The combined results suggest that under the studied conditions S, Cl, Cu, Se, Br, Cd and Te are most volatile (Dfluid/rock >10), followed by Li, B, Zn, As, Ag, Sb, Cs, W, Tl, Pb and Bi (Dfluid/rock = 1-10). Less volatile are Na, Mg, K, Ca, Mn, Fe, Rb, Sr, Mo and Rb (Dfluid/rock 0.1-1), and the least fluid-mobile elements are Al, Si, Ti, Zr, Ba and Ce (Dfluid/rock <0.1). This trend is broadly consistent with relative element volatilities determined on natural high-temperature fumarole gases, although some differences exist. Based on the volatility data and measured mineral-melt and sulfide-melt partition coefficients, volatile fluxing in felsic natural samples may be identified by Cu, Se, Te and Cd-enrichment in magmatic sulfides, and by As, Se, Cd and Bi-enrichment in magmatic apatite.

The leaf volatile constituents of Isatis tinctoria by Solid-Phase Microextraction and Gas chromatography/Mass Spectrometry.

PubMed

Condurso, Cettina; Verzera, Antonella; Romeo, Vincenza; Ziino, Marisa; Trozzi, Alessandra; Ragusa, Salvatore

2006-08-01

The leaf volatile constituents of Isatis tinctoria L. (Brassicaceae) have been studied by Solid-Phase Microextraction and Gas chromatography/Mass Spectrometry (SPME/GC-MS). Seventy components were fully characterized by mass spectra, linear retention indices, and injection of standards; the average composition (ppm) as single components and classes of substances is reported. Aliphatic hydrocarbons, acids, alcohols, aldehydes and esters, aromatic aldehydes, esters and ethers, furans, isothiocyanates and thiocyanates, sulfurated compounds, nitriles, terpenes and sesquiterpenes were identified. Leaf volatiles in Isatis tinctoria L. were characterized by a high amount of isothiocyanates which accounted for about 40 % of the total volatile fraction. Isothiocyanates are important and characteristic flavour compounds in Brassica vegetables and the cancer chemo-protective attributes are recently responsible for their growing interest.

Characterisation of volatile profiles in 50 native Peruvian chili pepper using solid phase microextraction-gas chromatography mass spectrometry (SPME-GCMS).

PubMed

Patel, Kirti; Ruiz, Candy; Calderon, Rosa; Marcelo, Mavel; Rojas, Rosario

2016-11-01

The volatiles were characterised by headspace solid phase micro extraction (HS-SPME), gas chromatography mass spectrometry (GC-FID/MS). A total of 127 compounds were identified with terpenes (including mono terpenes and sesquiterpenes - a total of 45 compounds), esters (31 compounds) and hydrocarbons (20 compounds) were the predominant volatile compounds. Principal component analysis (PCA) of the volatile compounds yielded 2 significant PC's, which together accounted for 90.3% of the total variance in the data set and the scatter plot generated between PC1 and PC2 successfully segregated the 50 chili pepper samples into 7 groups. Clusters of hydrocarbons, esters, terpenes, aldehyde and ketones formed the major determinants of the difference. Copyright © 2016 Elsevier Ltd. All rights reserved.

An Organic Geochemical Assessment of CO2-Coal Interactions During Sequestration

USGS Publications Warehouse

Kolak, Jonathan J.; Burruss, Robert A.

2003-01-01

Three well-characterized coal samples of varying rank were extracted with supercritical CO2 to determine the amount of polycyclic aromatic hydrocarbons (PAHs) that could be mobilized during simulated CO2 injection/sequestration in deep coal beds. The supercritical CO2 extractions were conducted at 40?C and 100 bars, roughly corresponding to a depth of 1 km. The greatest amount of PAHs was extracted from the high-volatile C bituminous coal sample. Extracts from the subbituminous C and anthracite coal samples contained lower concentrations of these compounds. The effectiveness of supercritical CO2 in liberating PAHs from the coal sample was evaluated in a comparison with a parallel series of Soxhlet extractions using 100% dichloromethane. More PAHs were extracted from the lower rank coal samples with dichloromethane than with supercritical CO2. The results from this investigation indicate that, regardless of coal rank, CO2 injection into deep coal beds may mobilize PAHs from the coal matrix. However, more PAHs could be mobilized during CO2 sequestration in a high-volatile C bituminous coal bed than in either of the other two coal ranks studied.

Mobility and fluxes of major, minor and trace metals during basalt weathering and groundwater transport at Mt. Etna volcano (Sicily)

NASA Astrophysics Data System (ADS)

Aiuppa, Alessandro; Allard, Patrick; D'Alessandro, Walter; Michel, Agnes; Parello, Francesco; Treuil, Michel; Valenza, Mariano

2000-06-01

The concentrations and fluxes of major, minor and trace metals were determined in 53 samples of groundwaters from around Mt Etna, in order to evaluate the conditions and extent of alkali basalt weathering by waters enriched in magma-derived CO 2 and the contribution of aqueous transport to the overall metal discharge of the volcano. We show that gaseous input of magmatic volatile metals into the Etnean aquifer is small or negligible, being limited by cooling of the rising fluids. Basalt leaching by weakly acidic, CO 2-charged water is the overwhelming source of metals and appears to be more extensive in two sectors of the S-SW (Paternò) and E (Zafferana) volcano flanks, where out flowing groundwaters are the richest in metals and bicarbonate of magmatic origin. Thermodynamic modeling of the results allows to evaluate the relative mobility and chemical speciation of various elements during their partitioning between solid and liquid phases through the weathering process. The facts that rock-forming minerals and groundmass dissolve at different rates and secondary minerals are formed are taken into account. At Mt. Etna, poorly mobile elements (Al, Th, Fe) are preferentially retained in the solid residue of weathering, while alkalis, alkaline earth and oxo-anion-forming elements (As, Se, Sb, Mo) are more mobile and released to the aqueous system. Transition metals display an intermediate behavior and are strongly dependent on either the redox conditions (Mn, Cr, V) or solid surface-related processes (V, Zn, Cu). The fluxes of metals discharged by the volcanic aquifer of Etna range from 7.0 × 10 -3 t/a (Th) to 7.3 × 10 4 t/a (Na). They are comparable in magnitude to the summit crater plume emissions for a series of elements (Na, K, Ca, Mg, U, V, Li) with lithophile affinity, but are minor for volatile elements. Basalt weathering at Mt Etna also consumes about 2.1 × 10 5 t/a of magma-derived carbon dioxide, equivalent to ca. 7% of contemporaneous crater plume emissions. The considerable transport of some metals in Etna's aquifer reflects a particularly high chemical erosion rate, evaluated at 2.3∗10 5 t/a, enhanced by the initial acidity of magmatic CO 2-rich groundwater.

Fungal succession in relation to volatile organic compounds emissions from Scots pine and Norway spruce leaf litter-decomposing fungi

NASA Astrophysics Data System (ADS)

Isidorov, Valery; Tyszkiewicz, Zofia; Pirożnikow, Ewa

2016-04-01

Leaf litter fungi are partly responsible for decomposition of dead material, nutrient mobilization and gas fluxes in forest ecosystems. It can be assumed that microbial destruction of dead plant materials is an important source of volatile organic compounds (VOCs) emitted into the atmosphere from terrestrial ecosystems. However, little information is available on both the composition of fungal VOCs and their producers whose community can be changed at different stages of litter decomposition. The fungal community succession was investigated in a litter bag experiment with Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) needle litter. The succession process can be divided into a several stages controlled mostly by changes in litter quality. At the very first stages of decomposition the needle litter was colonized by ascomycetes which can use readily available carbohydrates. At the later stages, the predominance of Trichoderma sp., the known producers of cellulolytic enzymes, was documented. To investigate the fungi-derived VOCs, eight fungi species were isolated. As a result of gas chromatographic analyses, as many as 75C2sbnd C15 fungal volatile compounds were identified. Most components detected in emissions were very reactive substances: the principal groups of VOCs were formed by monoterpenes, carbonyl compounds and aliphatic alcohols. It was found that production of VOCs by fungi is species specific: only 10 metabolites were emitted into the gas phase by all eight species. The reported data confirm that the leave litter decomposition is important source of reactive organic compounds under the forest canopy.

Volatilization of low vapor pressure--volatile organic compounds (LVP-VOCs) during three cleaning products-associated activities: Potential contributions to ozone formation.

PubMed

Shin, Hyeong-Moo; McKone, Thomas E; Bennett, Deborah H

2016-06-01

There have been many studies to reduce ozone formation mostly from volatile organic compound (VOC) sources. However, the role of low vapor pressure (LVP)-VOCs from consumer products remains mostly unexplored and unaddressed. This study explores the impact of high production volume LVP-VOCs on ozone formation from three cleaning products-associated activities (dishwashing, clothes washing, and surface cleaning). We develop a model framework to account for the portion available for ozone formation during the use phase and from the down-the-drain disposal. We apply experimental studies that measured emission rates or models that were developed for estimating emission rates of organic compounds during the use phase. Then, the fraction volatilized (fvolatilized) and the fraction disposed down the drain (fdown-the-drain) are multiplied by the portion available for ozone formation for releases to the outdoor air (fO3|volatilized) and down-the-drain (fO3|down-the-drain), respectively. Overall, for chemicals used in three specific cleaning-product uses, fvolatilized is less than 0.6% for all studied LVP-VOCs. Because greater than 99.4% of compounds are disposed of down the drain during the use phase, when combined with fO3|volatilized and fO3|down-the-drain, the portion available for ozone formation from the direct releases to outdoor air and the down-the-drain disposal is less than 0.4% and 0.2%, respectively. The results from this study indicate that the impact of the studied LVP-VOCs on ozone formation is very sensitive to what occurs during the use phase and suggest the need for future research on experimental work at the point of use. Copyright © 2016 Elsevier Ltd. All rights reserved.

40 CFR 63.6675 - What definitions apply to this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., in a two-step reaction, promotes the conversion of excess oxygen, NOX, CO, and volatile organic... reciprocating motion to convert heat energy into mechanical work and which is not mobile. Stationary RICE differ...

Solid-phase microextraction for the determination of volatile compounds in the spoilage of raw ground beef.

PubMed

Pérez, Rosa Ana; Rojo, Maria Dolores; González, Gema; De Lorenzo, Cristina

2008-01-01

A method using solid-phase microextraction (SPME) and gas chromatography/mass spectrometry was developed and applied to the determination of volatile compounds generated in meat, at different times, from ground beef stored under refrigeration. Selection of the extractive fiber, extraction time, and headspace (HS) or direct extraction was optimized for the determination of volatile compounds from ground meat. Various fibers were investigated, and carboxen/polydimethylsiloxane was selected for these analyses. The HS analysis of the solid sample by HS-SPME produced a higher volatile signal than did direct-SPME. The meat samples were stored under refrigeration and analyzed after 0, 3, and 6 days of storage. These analyses at different times showed important changes in the volatile profile of the evaluated samples. The ketones 3-hydroxy-2-butanone and 2,3-butanedione, and the alcohol 3-methyl-1-butanol were the most representative compounds generated during the meat storage. In general, compounds associated with a butter off-flavor were detected during the storage of raw ground beef.

Breath Analysis as a Potential and Non-Invasive Frontier in Disease Diagnosis: An Overview

PubMed Central

Pereira, Jorge; Porto-Figueira, Priscilla; Cavaco, Carina; Taunk, Khushman; Rapole, Srikanth; Dhakne, Rahul; Nagarajaram, Hampapathalu; Câmara, José S.

2015-01-01

Currently, a small number of diseases, particularly cardiovascular (CVDs), oncologic (ODs), neurodegenerative (NDDs), chronic respiratory diseases, as well as diabetes, form a severe burden to most of the countries worldwide. Hence, there is an urgent need for development of efficient diagnostic tools, particularly those enabling reliable detection of diseases, at their early stages, preferably using non-invasive approaches. Breath analysis is a non-invasive approach relying only on the characterisation of volatile composition of the exhaled breath (EB) that in turn reflects the volatile composition of the bloodstream and airways and therefore the status and condition of the whole organism metabolism. Advanced sampling procedures (solid-phase and needle traps microextraction) coupled with modern analytical technologies (proton transfer reaction mass spectrometry, selected ion flow tube mass spectrometry, ion mobility spectrometry, e-noses, etc.) allow the characterisation of EB composition to an unprecedented level. However, a key challenge in EB analysis is the proper statistical analysis and interpretation of the large and heterogeneous datasets obtained from EB research. There is no standard statistical framework/protocol yet available in literature that can be used for EB data analysis towards discovery of biomarkers for use in a typical clinical setup. Nevertheless, EB analysis has immense potential towards development of biomarkers for the early disease diagnosis of diseases. PMID:25584743

Breath analysis as a potential and non-invasive frontier in disease diagnosis: an overview.

PubMed

Pereira, Jorge; Porto-Figueira, Priscilla; Cavaco, Carina; Taunk, Khushman; Rapole, Srikanth; Dhakne, Rahul; Nagarajaram, Hampapathalu; Câmara, José S

2015-01-09

Currently, a small number of diseases, particularly cardiovascular (CVDs), oncologic (ODs), neurodegenerative (NDDs), chronic respiratory diseases, as well as diabetes, form a severe burden to most of the countries worldwide. Hence, there is an urgent need for development of efficient diagnostic tools, particularly those enabling reliable detection of diseases, at their early stages, preferably using non-invasive approaches. Breath analysis is a non-invasive approach relying only on the characterisation of volatile composition of the exhaled breath (EB) that in turn reflects the volatile composition of the bloodstream and airways and therefore the status and condition of the whole organism metabolism. Advanced sampling procedures (solid-phase and needle traps microextraction) coupled with modern analytical technologies (proton transfer reaction mass spectrometry, selected ion flow tube mass spectrometry, ion mobility spectrometry, e-noses, etc.) allow the characterisation of EB composition to an unprecedented level. However, a key challenge in EB analysis is the proper statistical analysis and interpretation of the large and heterogeneous datasets obtained from EB research. There is no standard statistical framework/protocol yet available in literature that can be used for EB data analysis towards discovery of biomarkers for use in a typical clinical setup. Nevertheless, EB analysis has immense potential towards development of biomarkers for the early disease diagnosis of diseases.

Detection of volatile spoilage metabolites in fermented cucumbers using nontargeted, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS)

USDA-ARS?s Scientific Manuscript database

A nontargeted, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS) method was developed for the analysis of fermented cucumber volatiles before and after anaerobic spoilage. Volatiles extracted by solid-phase microextraction were separated on a polyethyle...

Aerosol volatility in a boreal forest environment

NASA Astrophysics Data System (ADS)

Häkkinen, S. A. K.; ńijälä, M.; Lehtipalo, K.; Junninen, H.; Virkkula, A.; Worsnop, D. R.; Kulmala, M.; Petäjä, T.; Riipinen, I.

2012-04-01

Climate and health effects of atmospheric aerosols are determined by their properties such as their chemical composition. Aerosol chemical composition can be studied indirectly by measuring volatility of aerosol particles. The volatility of submicron aerosol particles (20-500 nm) was studied in a boreal forest site at SMEAR II (Station for Measuring Ecosystem-Atmosphere Relations II) station (Vesala et al., 1998) in Hyytiälä, Finland, during 01/2008-05/2010. The instrument used for the measurements was VDMPS (Volatility Differential Mobility Particle Sizer), which consists of two separate instruments: DMPS (Differential Mobility Particle Sizer, Aalto et al., 2001) and TD (Thermodenuder, Wehner et al., 2002). Aerosol evaporation was examined by heating the aerosol and comparing the total aerosol mass before and after heating. In the VDMPS system ambient aerosol sample was heated up to temperatures ranging from 80 °C to 280 °C. The higher the heating temperature was the more aerosol material was evaporated. There was a non-volatile residual present in aerosol particles when heated up to 280 °C. This residual explained (20±8)% of the total aerosol mass. Aerosol non-volatile mass fraction was highest during winter and smallest during summer months. The role of black carbon in the observed non-volatile residual was determined. Black carbon explained 40 to 90% of the non-volatile mass. Especially during colder seasons noticeable amount of non-volatile material, something else than black carbon, was observed. According to Kalberer et al. (2004) some atmospheric organic species can form polymers that have high evaporation temperatures. Also low-volatile organic salts may contribute to the non-volatile aerosol (Smith et al., 2010). Aerosol mass composition measured directly with AMS (Aerosol Mass Spectrometer, Jayne et al., 2000) was analyzed in order to examine the properties of the non-volatile material (other than black carbon). The AMS measurements were performed during spring and autumn 2008. Results from the aerosol mass spectrometry indicate that the non-volatile residual consists of nitrate and organic compounds, especially during autumn. These compounds may be low-volatile organic nitrates or salts. During winter and spring the non-volatile core (black carbon removed) correlated markedly with carbon monoxide, which is a tracer of anthropogenic emissions. Due to this, the non-volatile residual may also contain other pollutants in addition to black carbon. Thus, it seems that the amount of different compounds in submicron aerosol particles varies with season and as a result the chemical composition of the non-volatile residual changes within a year. This work was supported by University of Helsinki three-year research grant No 490082 and Maj and Tor Nessling Foundation grant No 2010143. Aalto et al., (2001). Physical characterization of aerosol particles during nucleation events. Tellus B, 53, 344-358. Jayne, et al., (2000). Development of an aerosol mass spectrometer for size and composition analysis of submicron particles. Aerosol Sci. Technol., 33(1-2), 49-70. Kalberer et al., (2004). Identification of Polymers as Major Components of Atmospheric Organic Aerosols. Science, 303, 1659-1662. Smith et al., (2010). Observations of aminium salts in atmospheric nanoparticles and possible climatic implications. P. Natl. Acad. Sci., 107(15). Vesala et al., (1998). Long-term field measurements of atmosphere-surface interactions in boreal forest combining forest ecology, micrometeorology, aerosol physics and atmospheric chemistry. Trends Heat, Mass Mom. Trans., 4, 17-35. Wehner et al., (2002). Design and calibration of a thermodenuder with an improved heating unit to measure the size-dependent volatile fraction of aerosol particles. J. Aerosol Sci., 33, 1087-1093.

Heating-Induced Evaporation of Nine Different Secondary Organic Aerosol Types

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolesar, Katheryn R.; Li, Ziyue; Wilson, Kevin R.

The volatility of the compounds comprising organic aerosol (OA) determines their distribution between the gas and particle phases. However, there is a disconnect between volatility distributions as typically derived from secondary OA (SOA) growth experiments and the effective particle volatility as probed in evaporation experiments. Specifically, the evaporation experiments indicate an overall much less volatile SOA. This raises questions regarding the use of traditional volatility distributions in the simulation and prediction of atmospheric SOA concentrations. Here, we present results from measurements of thermally induced evaporation of SOA for nine different SOA types (i.e., distinct volatile organic compound and oxidant pairs)more » encompassing both anthropogenic and biogenic compounds and O 3 and OH to examine the extent to which the low effective volatility of SOA is a general phenomenon or specific to a subset of SOA types. The observed extents of evaporation with temperature were similar for all the SOA types and indicative of a low effective volatility. Furthermore, minimal variations in the composition of all the SOA types upon heating-induced evaporation were observed. These results suggest that oligomer decomposition likely plays a major role in controlling SOA evaporation, and since the SOA formation time scale in these measurements was less than a minute, the oligomer-forming reactions must be similarly rapid. Overall, these results emphasize the importance of accounting for the role of condensed phase reactions in altering the composition of SOA when assessing particle volatility.« less

Heating-Induced Evaporation of Nine Different Secondary Organic Aerosol Types

DOE PAGES

Kolesar, Katheryn R.; Li, Ziyue; Wilson, Kevin R.; ...

2015-09-22

The volatility of the compounds comprising organic aerosol (OA) determines their distribution between the gas and particle phases. However, there is a disconnect between volatility distributions as typically derived from secondary OA (SOA) growth experiments and the effective particle volatility as probed in evaporation experiments. Specifically, the evaporation experiments indicate an overall much less volatile SOA. This raises questions regarding the use of traditional volatility distributions in the simulation and prediction of atmospheric SOA concentrations. Here, we present results from measurements of thermally induced evaporation of SOA for nine different SOA types (i.e., distinct volatile organic compound and oxidant pairs)more » encompassing both anthropogenic and biogenic compounds and O 3 and OH to examine the extent to which the low effective volatility of SOA is a general phenomenon or specific to a subset of SOA types. The observed extents of evaporation with temperature were similar for all the SOA types and indicative of a low effective volatility. Furthermore, minimal variations in the composition of all the SOA types upon heating-induced evaporation were observed. These results suggest that oligomer decomposition likely plays a major role in controlling SOA evaporation, and since the SOA formation time scale in these measurements was less than a minute, the oligomer-forming reactions must be similarly rapid. Overall, these results emphasize the importance of accounting for the role of condensed phase reactions in altering the composition of SOA when assessing particle volatility.« less

Characterization of the Key Aroma Compounds in Proso Millet Wine Using Headspace Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry.

PubMed

Liu, Jingke; Zhao, Wei; Li, Shaohui; Zhang, Aixia; Zhang, Yuzong; Liu, Songyan

2018-02-20

The volatile compounds in proso millet wine were extracted by headspace solid-phase microextraction (85 μm polyacrylate (PA), 100 μm polydimethylsiloxane (PDMS), 75 μm Carboxen (CAR)/PDMS, and 50/30 μm divinylbenzene (DVB)/CAR/PDMS fibers), and analyzed using gas chromatography-mass spectrometry; the odor characteristics and intensities were analyzed by the odor activity value (OAV). Different sample preparation factors were used to optimize this method: sample amount, extraction time, extraction temperature, and content of NaCl. A total of 64 volatile compounds were identified from the wine sample, including 14 esters, seven alcohols, five aldehydes, five ketones, 12 benzene derivatives, 12 hydrocarbons, two terpenes, three phenols, two acids, and two heterocycles. Ethyl benzeneacetate, phenylethyl alcohol, and benzaldehyde were the main volatile compounds found in the samples. According to their OAVs, 14 volatile compounds were determined to be odor-active compounds (OAV > 1), and benzaldehyde, benzeneacetaldehyde, 1-methyl-naphthalene, 2-methyl-naphthalene, and biphenyl were the prominent odor-active compounds (OAV > 50), having a high OAV. Principal component analysis (PCA) showed the difference of distribution of the 64 volatile compounds and 14 odor-active compounds with four solid-phase microextraction (SPME) fibers.

Quantitative variation and biosynthesis of hindgut volatiles associated with the red turpentine beetle, Dendroctonus valens LeConte, at different attack phases.

PubMed

Shi, Z-H; Sun, J-H

2010-06-01

The red turpentine beetle (RTB), Dendroctonus valens LeConte, is a destructive invasive forest pest in China. For such tree-killing species, how to initiate a volatile-mediated mass attack is of great importance during the course of establishment. To understand the hindgut volatile production mechanism underlying mass attack initiated by RTB, coupled gas chromatography-mass spectrometry and 13C-labelled precursors were applied to explore the quantitative variation and biosynthesis of volatiles associated with RTB at different attack phases. Five previously described volatiles, trans-verbenol, myrtenol, cis-verbenol, myrtenal and verbenone, were identified and quantified from extracts of female and male hindguts, with the first two compounds as the major components and the latter three as minor constituents. In newly emerged females and males, only minute amounts of these compounds were detected. The quantity of volatiles from female adults significantly increased after they fed on bolts. Male adults also yielded larger quantities of volatiles after they joined females in galleries, which suggested that RTB males could accelerate the mass colonization on host trees. We also confirmed that RTB produced the five volatiles through oxidizing the major host monoterpene, alpha-pinene, but not synthesized de novo since products were labeled without 13C. The implication of this study in understanding the successful invasion of RTB is discussed.

Procedure for chromatography involving sample solvent with higher elution strength than the mobile phase.

PubMed

Patil, Nitin S; Mendhe, Rakesh B; Sankar, Ajeet A; Iyer, Harish

2008-01-11

In preparative chromatography, often the solubility of the sample in the mobile phase is limited, making the mobile phase unsuitable as a solvent for preparation of load. Generally, solvents that have high solubility for the sample also have higher elution strengths than the mobile phase. Additionally, at high loading volumes, these strong sample solvents are known to adversely affect the band profiles leading to poor chromatographic performance. Here, we show that controlling the mobile phase strength during loading and post-load elution resulted in improved band profiles when the sample solvent was stronger than the mobile phase. Such an approach improves performance in preparative chromatography by allowing either higher sample loading or higher organic content in mobile phase (without loss of yield). Alternately, the approach can be used for improvement in performance by increase in yield or product purity.

30 CFR 77.900 - Low- and medium-voltage circuits serving portable or mobile three-phase alternating current...

Code of Federal Regulations, 2011 CFR

2011-07-01

... portable or mobile three-phase alternating current equipment; circuit breakers. 77.900 Section 77.900... mobile three-phase alternating current equipment; circuit breakers. Low- and medium-voltage circuits supplying power to portable or mobile three-phase alternating current equipment shall be protected by...

Biochar provides a safe and value-added solution for hyperaccumulating plant disposal: A case study of Phytolacca acinosa Roxb. (Phytolaccaceae).

PubMed

Wang, Shengsen; Gao, Bin; Li, Yuncong; Ok, Yong Sik; Shen, Chaofeng; Xue, Shengguo

2017-07-01

In this work, an innovative approach using biochar technology for hyperaccumulator disposal was developed and evaluated. The heavy metal enriched P. acinosa biomass (PBM) was pyrolyzed to produce biochar (PBC). Both PBM and PBC were characterized with X-ray diffraction (XRD) for crystal phases, scanning electron microscopy (SEM) for surface topography, and analyzed for elemental composition and mobility. The results revealed that whewellite, a dominant crystal form in biomass, was decomposed to calcite after pyrolysis. Elemental analysis indicated that 91-99% total non-volatile elements in the biomass were retained in the biochar. The toxicity characteristic leaching procedure (TCLP) results revealed that 94.6% and 0.15% of total Mn was extracted for biomass and biochar, respectively. This suggests that mobility and bioavailability of Mn in biochar was much lower relative to pristine biomass. Batch sorption experiment showed that excellent removal of aqueous silver, lead, cadmium, and copper ions can be achieved with PBC. Findings from this work indicated that biochar technology can provide a value-added solution for hyperaccumulator disposal. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sensitivity analysis of simulated SOA loadings using a variance-based statistical approach: SENSITIVITY ANALYSIS OF SOA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrivastava, Manish; Zhao, Chun; Easter, Richard C.

We investigate the sensitivity of secondary organic aerosol (SOA) loadings simulated by a regional chemical transport model to 7 selected tunable model parameters: 4 involving emissions of anthropogenic and biogenic volatile organic compounds, anthropogenic semi-volatile and intermediate volatility organics (SIVOCs), and NOx, 2 involving dry deposition of SOA precursor gases, and one involving particle-phase transformation of SOA to low volatility. We adopt a quasi-Monte Carlo sampling approach to effectively sample the high-dimensional parameter space, and perform a 250 member ensemble of simulations using a regional model, accounting for some of the latest advances in SOA treatments based on our recentmore » work. We then conduct a variance-based sensitivity analysis using the generalized linear model method to study the responses of simulated SOA loadings to the tunable parameters. Analysis of SOA variance from all 250 simulations shows that the volatility transformation parameter, which controls whether particle-phase transformation of SOA from semi-volatile SOA to non-volatile is on or off, is the dominant contributor to variance of simulated surface-level daytime SOA (65% domain average contribution). We also split the simulations into 2 subsets of 125 each, depending on whether the volatility transformation is turned on/off. For each subset, the SOA variances are dominated by the parameters involving biogenic VOC and anthropogenic SIVOC emissions. Furthermore, biogenic VOC emissions have a larger contribution to SOA variance when the SOA transformation to non-volatile is on, while anthropogenic SIVOC emissions have a larger contribution when the transformation is off. NOx contributes less than 4.3% to SOA variance, and this low contribution is mainly attributed to dominance of intermediate to high NOx conditions throughout the simulated domain. The two parameters related to dry deposition of SOA precursor gases also have very low contributions to SOA variance. This study highlights the large sensitivity of SOA loadings to the particle-phase transformation of SOA volatility, which is neglected in most previous models.« less

Determination of the solubility of inorganic salts by headspace gas chromatography.

PubMed

Chai, X S; Zhu, J Y

2003-05-09

This work reports a novel method for determination of salt solubility using headspace gas chromatography. A very small amount of volatile compound (such as methanol) is added in the studied solution. Due to the molecular interaction in the solution, the vapor-liquid equilibrium (VLE) partitioning coefficient of the volatile species will change with different salt contents in the solution. Therefore, the concentration of volatile species in the vapor phase is proportional to the salt concentration in the liquid phase, which can be easily determined by headspace gas chromatography. Until the salt concentration in the solution is saturated, the concentration of volatile compound in the vapor phase will continue to increase further and a breakpoint will appear on the VLE curve. The solubility of the salts can be determined by the identification of the breakpoint. It was found that the measured solubility of sodium carbonate and sodium sulfate in aqueous solutions is slightly higher (about 6-7%) than those reported in the literature method. The present method can be easily applied to industrial solution systems.

Analytical methodologies for broad metabolite coverage of exhaled breath condensate.

PubMed

Aksenov, Alexander A; Zamuruyev, Konstantin O; Pasamontes, Alberto; Brown, Joshua F; Schivo, Michael; Foutouhi, Soraya; Weimer, Bart C; Kenyon, Nicholas J; Davis, Cristina E

2017-09-01

Breath analysis has been gaining popularity as a non-invasive technique that is amenable to a broad range of medical uses. One of the persistent problems hampering the wide application of the breath analysis method is measurement variability of metabolite abundances stemming from differences in both sampling and analysis methodologies used in various studies. Mass spectrometry has been a method of choice for comprehensive metabolomic analysis. For the first time in the present study, we juxtapose the most commonly employed mass spectrometry-based analysis methodologies and directly compare the resultant coverages of detected compounds in exhaled breath condensate in order to guide methodology choices for exhaled breath condensate analysis studies. Four methods were explored to broaden the range of measured compounds across both the volatile and non-volatile domain. Liquid phase sampling with polyacrylate Solid-Phase MicroExtraction fiber, liquid phase extraction with a polydimethylsiloxane patch, and headspace sampling using Carboxen/Polydimethylsiloxane Solid-Phase MicroExtraction (SPME) followed by gas chromatography mass spectrometry were tested for the analysis of volatile fraction. Hydrophilic interaction liquid chromatography and reversed-phase chromatography high performance liquid chromatography mass spectrometry were used for analysis of non-volatile fraction. We found that liquid phase breath condensate extraction was notably superior compared to headspace extraction and differences in employed sorbents manifested altered metabolite coverages. The most pronounced effect was substantially enhanced metabolite capture for larger, higher-boiling compounds using polyacrylate SPME liquid phase sampling. The analysis of the non-volatile fraction of breath condensate by hydrophilic and reverse phase high performance liquid chromatography mass spectrometry indicated orthogonal metabolite coverage by these chromatography modes. We found that the metabolite coverage could be enhanced significantly with the use of organic solvent as a device rinse after breath sampling to collect the non-aqueous fraction as opposed to neat breath condensate sample. Here, we show the detected ranges of compounds in each case and provide a practical guide for methodology selection for optimal detection of specific compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

A Water Recovery System Evolved for Exploration

NASA Technical Reports Server (NTRS)

ORourke, Mary Jane E.; Perry, Jay L.; Carter, Donald L.

2006-01-01

A new water recovery system designed towards fulfillment of NASA's Vision for Space Exploration is presented. This water recovery system is an evolution of the current state-of-the-art system. Through novel integration of proven technologies for air and water purification, this system promises to elevate existing technology to higher levels of optimization. The novel aspect of the system is twofold: Volatile organic contaminants will be removed from the cabin air via catalytic oxidation in the vapor phase, prior to their absorption into the aqueous phase, and vapor compression distillation technology will be used to process the condensate and hygiene waste streams in addition to the urine waste stream. Oxidation kinetics dictate that removal of volatile organic contaminants from the vapor phase is more efficient. Treatment of the various waste streams by VCD will reduce the load on the expendable ion exchange and adsorption media which follow, and on the aqueous-phase volatile removal assembly further downstream. Incorporating these advantages will reduce the weight, volume, and power requirements of the system, as well as resupply.

Electrode structure and methods of making same

DOEpatents

Ruud, James Anthony; Browall, Kenneth Walter; Rehg, Timothy Joseph; Renou, Stephane; Striker, Todd-Michael

2010-04-06

A method of making an electrode structure is provided. The method includes disposing an electrocatalytic material on an electrode, applying heat to the electrocatalytic material to form a volatile oxide of the electrocatalytic material, and applying a voltage to the electrode to reduce the volatile oxide to provide a number of nano-sized electrocatalytic particles on or proximate to a triple phase boundary, where the number of nano-sized electrocatalytic particles is greater on or proximate to the triple phase boundary than in an area that is not on or proximate to the triple phase boundary, and where the triple phase boundary is disposed on the electrode.

Mobile Payload Element (MPE): Concept study for a sample fetching rover for the ESA Lunar Lander Mission

NASA Astrophysics Data System (ADS)

Haarmann, R.; Jaumann, R.; Claasen, F.; Apfelbeck, M.; Klinkner, S.; Richter, L.; Schwendner, J.; Wolf, M.; Hofmann, P.

2012-12-01

In late 2010, the DLR Space Administration invited the German industry to submit a proposal for a study about a Mobile Payload Element (MPE), which could be a German national contribution to the ESA Lunar Lander Mission. Several spots in the south polar region of the moon come into consideration as landing site for this mission. All possible spots provide sustained periods of solar illumination, interrupted by darkness periods of several 10 h. The MPE is outlined to be a small, autonomous, innovative vehicle in the 10 kg class for scouting and sampling the environment in the vicinity of the lunar landing site. The novel capabilities of the MPE will be to acquire samples of lunar regolith from surface, subsurface as well as shadowed locations, define their geological context and bring them back to the lander. This will enable access to samples that are not contaminated by the lander descent propulsion system plumes to increase the chances of detecting any indigenous lunar volatiles contained within the samples. Kayser-Threde, as prime industrial contractor for Phase 0/A, has assembled for this study a team of German partners with relevant industrial and institutional competence in space robotics and lunar science. The primary scientific objective of the MPE is to acquire clearly documented samples and to bring them to the lander for analysis with the onboard Lunar Dust Analysis Package (L-DAP) and Lunar Volatile Resources Analysis Package (L-VRAP). Due to the unstable nature of volatiles, which are of particular scientific interest, the MPE design needs to provide a safe storage and transportation of the samples to the lander. The proposed MPE rover concept has a four-wheeled chassis configuration with active suspension, being a compromise between innovation and mass efficiency. The suspension chosen allows a compact stowage of the MPE on the lander as well as precise alignment of the solar generators and instruments. Since therefore no further complex mechanics are necessary, the active suspension significantly contributes to the lightweight MPE design. The thermal control system enables the MPE to operate in shaded areas for about 2 h and hibernate darkness periods of about 14 h. Increasing the hibernation capability requires additional battery capacity and thus increases the MPE mass. As operational modes teleoperations from earth and autonomous navigation are foreseen. The MPE payload includes navigation cameras, a close-up imager and a mole as sampling device. The MPE phase 0/A study finished in early 2012. This article describes the resulting MPE rover concept with focus on its scientific benefit for the Lunar Lander Mission.

Observing BVOC Emissions, Oxidation, Deposition, and Interactions with Anthropogenic Pollutants to Form SOA in the Southeast United States

NASA Astrophysics Data System (ADS)

Goldstein, A. H.; Isaacman, G. A.; Misztal, P. K.; Yee, L.; Olson, K. F.; Moss, J.; Kreisberg, N. M.; Hering, S. V.; Park, J. H.; Kaser, L.; Seco, R.; Guenther, A. B.; Su, L.; Mak, J. E.; Holzinger, R.; Hu, W.; Campuzano Jost, P.; Palm, B. B.; Day, D. A.; Jimenez, J. L.; Koss, A.; De Gouw, J. A.

2014-12-01

Our overarching goals in the SOAS 2013 campaign were to 1) quantify biogenic VOC emission and VOC deposition to understand the processes controlling these bi-directional exchanges, 2) observe a broad suite of primary VOC and their oxidation products in the field and in controlled laboratory experiments, and 3) investigate their fate to understand how anthropogenic pollution alters oxidation pathways and secondary organic aerosol (SOA) formation. We pursued these goals through measurement of atmospheric organics ranging from very volatile (using in-situ GC-MS and proton transfer reaction time-of-flight MS, PTR-ToF-MS) to semi-volatile gas and particle phase compounds (using the Semi-Volatile Thermal desorption Aerosol Gas chromatograph, SV-TAG). Measured concentrations and fluxes of VOCs at the top of the SEARCH tower were coordinated with concentration gradients and fluxes at the AABC flux tower site, and vertical profiles using the Long-EZ aircraft to provide equivalent observations across sites. These results are informed through measurements using the same instrument during the FIXIT controlled laboratory oxidation study at CalTech that investigated oxidation pathways of BVOC with varying levels of anthropogenic pollutants. Measurements by SV-TAG of particle-phase and total gas-plus-particle-phase compounds at the SEARCH tower provide hourly quantification of semi-volatile compounds, including the oxidation products of measured VOCs. Derivatization of hydroxyl groups prior to GC analysis allows analysis of highly oxidized chemicals, including most known tracers. Methyl tetrols, an oxidation product of isoprene, had a significant day-time gas-phase component, and their abundance was strongly correlated with particle-phase sulfate, indicative of anthropogenic influence on the formation or partitioning processes. Similar observations of pinic acid (monterpene oxidation product) and many other BVOC oxidation products were made in both the gas and particle phases. Through measurements of specific chemical tracers across a wide range of volatilities, we explore the chemical lifecycle of BVOCs to understand anthropogenic-biogenic interactions in aerosol formation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lucachick, Glenn; Curran, Scott; Storey, John Morse

Our work explores the volatility of particles produced from two diesel low temperature combustion (LTC) modes proposed for high-efficiency compression ignition engines. It also explores mechanisms of particulate formation and growth upon dilution in the near-tailpipe environment. Moreover, the number distribution of exhaust particles from low- and mid-load dual-fuel reactivity controlled compression ignition (RCCI) and single-fuel premixed charge compression ignition (PPCI) modes were experimentally studied over a gradient of dilution temperature. Particle volatility of select particle diameters was investigated using volatility tandem differential mobility analysis (V-TDMA). Evaporation rates for exhaust particles were compared with V-TDMA results for candidate pure n-alkanesmore » to identify species with similar volatility characteristics. The results show that LTC particles are mostly comprised of material with volatility similar to engine oil alkanes. V-TDMA results were used as inputs to an aerosol condensation and evaporation model to support the finding that smaller particles in the distribution are comprised of lower volatility material than large particles under primary dilution conditions. Although the results show that saturation levels are high enough to drive condensation of alkanes onto existing particles under the dilution conditions investigated, they are not high We conclude that observed particles from LTC operation must grow from low concentrations of highly non-volatile compounds present in the exhaust.« less

Melt focusing and geochemical evolution at mid-ocean ridges: simulations of reactive two-phase flow

NASA Astrophysics Data System (ADS)

Keller, T.; Katz, R. F.; Hirschmann, M. M.

2017-12-01

The geochemical character of MORB and related off-axis volcanic products reflects the signature of chemical reservoirs in the mantle, the processes of melt transport from source to surface, or both. Focusing of partial melt to the ridge axis controls the proportion of deep, volatile- and incompatible-rich melts that contribute to MORB formation. However, the effect of volatiles, including CO2 and H2O, on melt segregation and focusing remains poorly understood. We investigate this transport using 2-D numerical simulations of reactive two-phase flow. The phases are solid mantle and liquid magma. Major elements and volatiles are represented by a system with 4 or 6 pseudo-components. This captures accepted features of mantle melting with volatiles. The fluid-dynamical model is McKenzie's formulation [1], while melting and reactive transport use the R_DMC method [2,3]. Trace element transport is computed for 5 idealized elements between highly incompatible and compatible behavior. Our results indicate that volatiles cause channelized melt transport, which leads to fluctuations in volume and composition of melt focused to the axis. The volatile-induced expansion of the melting regime at depth, however, has no influence on melt focusing. Up to 50% of deep, volatile-rich melts are not focused to the axis, but are emplaced along the oceanic LAB. There, crystallization of accumulated melt leads to enrichment of volatiles and incompatibles in the deep lithosphere. This has implications for volatile recycling by subduction, seismic properties of the oceanic LAB, and potential sources for seamount volcanism. Results from a suite of simulations, constrained by catalogued observational data [4,5,6], enable prediction of global MORB and volatile output and systematic variations of major, volatile and trace element concentrations as a function of mantle conditions and dynamic properties. REFERENCES[1] McKenzie (1984), doi:10.1093/petrology/25.3.713.[2] Rudge, Bercovici & Spiegelman (2011), doi:10.1111/j.1365-246X.2010.04870.x.[3] Keller & Katz (2016), doi:10.1093/petrology/egw030.[4] Dalton, Langmuir & Gale (2014), doi:10.1126/science.1249466.[5] Gale, Langmuir & Dalton (2014), doi:10.1093/petrology/egu017.[6] White et al. (2001), doi:10.1093/petrology/42.6.1171.

Volatility characterization of nanoparticles from single and dual-fuel low temperature combustion in compression ignition engines

DOE PAGES

Lucachick, Glenn; Curran, Scott; Storey, John Morse; ...

2016-03-10

Our work explores the volatility of particles produced from two diesel low temperature combustion (LTC) modes proposed for high-efficiency compression ignition engines. It also explores mechanisms of particulate formation and growth upon dilution in the near-tailpipe environment. Moreover, the number distribution of exhaust particles from low- and mid-load dual-fuel reactivity controlled compression ignition (RCCI) and single-fuel premixed charge compression ignition (PPCI) modes were experimentally studied over a gradient of dilution temperature. Particle volatility of select particle diameters was investigated using volatility tandem differential mobility analysis (V-TDMA). Evaporation rates for exhaust particles were compared with V-TDMA results for candidate pure n-alkanesmore » to identify species with similar volatility characteristics. The results show that LTC particles are mostly comprised of material with volatility similar to engine oil alkanes. V-TDMA results were used as inputs to an aerosol condensation and evaporation model to support the finding that smaller particles in the distribution are comprised of lower volatility material than large particles under primary dilution conditions. Although the results show that saturation levels are high enough to drive condensation of alkanes onto existing particles under the dilution conditions investigated, they are not high We conclude that observed particles from LTC operation must grow from low concentrations of highly non-volatile compounds present in the exhaust.« less

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

NASA Technical Reports Server (NTRS)

Limero, Thomas F.; James, John T.

1994-01-01

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.

The Fe-C-O-H-N system at 6.3-7.8 GPa and 1200-1400 °C: implications for deep carbon and nitrogen cycles

NASA Astrophysics Data System (ADS)

Sokol, Alexander G.; Tomilenko, Anatoly A.; Bul'bak, Taras A.; Kruk, Alexey N.; Zaikin, Pavel A.; Sokol, Ivan A.; Seryotkin, Yurii V.; Palyanov, Yury N.

2018-06-01

Interactions in a Fe-C-O-H-N system that controls the mobility of siderophile nitrogen and carbon in the Fe0-saturated upper mantle are investigated in experiments at 6.3-7.8 GPa and 1200-1400 °C. The results show that the γ-Fe and metal melt phases equilibrated with the fluid in a system unsaturated with carbon and nitrogen are stable at 1300 °C. The interactions of Fe3C with an N-rich fluid in a graphite-saturated system produce the ɛ-Fe3N phase (space group P63/ mmc or P6322) at subsolidus conditions of 1200-1300 °C, while N-rich melts form at 1400 °C. At IW- and MMO-buffered hydrogen fugacity ( fH2), fluids vary from NH3- to H2O-rich compositions (NH3/N2 > 1 in all cases) with relatively high contents of alkanes. The fluid derived from N-poor samples contains less H2O and more carbon which mainly reside in oxygenated hydrocarbons, i.e., alcohols and esters at MMO-buffered fH2 and carboxylic acids at unbuffered fH2 conditions. In unbuffered conditions, N2 is the principal nitrogen host (NH3/N2 ≤ 0.1) in the fluid equilibrated with the metal phase. Relatively C- and N-rich fluids in equilibrium with the metal phase (γ-Fe, melt, or Fe3N) are stable at the upper mantle pressures and temperatures. According to our estimates, the metal/fluid partition coefficient of nitrogen is higher than that of carbon. Thus, nitrogen has a greater affinity for iron than carbon. The general inference is that reduced fluids can successfully transport volatiles from the metal-saturated mantle to metal-free shallow mantle domains. However, nitrogen has a higher affinity for iron and selectively accumulates in the metal phase, while highly mobile carbon resides in the fluid phase. This may be a controlling mechanism of the deep carbon and nitrogen cycles.

Changes in volatile compound composition of Antrodia camphorata during solid state fermentation.

PubMed

Xia, Yongjun; Zhang, Baorong; Li, Weijiang; Xu, Ganrong

2011-10-01

Although the volatiles present in mushrooms and fungi have been investigated by many researchers, including Antrodia camphorata in submerged fermentation, there are few data available regarding changes in volatile compounds during fermentation. Our research has revealed that solid state fermentation of A. camphorata is highly odiferous compared with submerged cultures and the odor changed with increasing culture time. Therefore the aim of this study was to investigate the changes in volatile compound composition of A. camphorata during solid state fermentation. Altogether, 124 major volatile compounds were identified. The volatile compounds produced by A. camphorata during growth in solid state fermentation were quite different. Oct-1-en-3-ol, octan-3-one and methyl 2-phenylacetate were predominant in exponential growth phase production, while the dominant volatiles produced in stationary phase were octan-3-one and methyl 2-phenylacetate. In stationary phase, lactone compounds in A. camphorata, such as 5-butyloxolan-2-one, 5-heptyloxolan-2-one, 6-heptyloxan-2-one, contributed greatly to peach and fruit-like flavor. Terpene and terpene alcohol compounds, such as 1-terpineol, L-linalool, T-cadinol, (E, E)-farnesol, β-elemene, cis-α-bisabolene and α-muurolene, made different contributions to herbal fresh aroma in A. camphorata. Nineteen volatile sesquiterpenes were detected from solid state fermentation of A. camphorata. The compounds 5-n-butyl-5H-furan-2-one, β-ionone, (-)-caryophyllene oxide, aromadendrene oxide, diepi-α-cedrene epoxide, β-elemene, α-selinene, α-muurolene, azulene, germacrene D, γ-cadinene and 2-methylpyrazine have not hitherto been reported in A. camphorata. The preliminary results suggest that the aroma-active compounds produced by A camphorata in solid state fermentation might serve as an important source of natural aroma compounds for the food and cosmetic industries or antibiotic activity compounds. The sesquiterpenes could be identified as possible taxonomic markers for A. camphorata. Copyright © 2011 Society of Chemical Industry.

SPECIATED VOC EMISSIONS FROM MODERN GDI LIGHT DUTY VEHICLES

EPA Science Inventory

Chassis dynamometer emissions testing was conducted to characterize speciated volatile organic compounds (VOCs), including mobile source air toxics (MSATs) and ozone precursors, in exhaust emissions from three modern gasoline direct injection (GDI) light-duty vehicles. Each GDI v...

A review of the contrasting behavior of two magmatic volatiles: Chlorine and carbon dioxide

USGS Publications Warehouse

Lowenstern, J. B.

2000-01-01

Chlorine (Cl) and carbon dioxide (CO2) are common magmatic volatiles with contrasting behaviors. CO2 solubility increases with pressure whereas Cl solubility shows relatively little pressure or temperature effect. CO2 speciation changes with silicate melt composition, dissolving as carbonate in basaltic magmas and molecular CO2 in more silicic compositions. In H2O-bearing systems, the strongly non-ideal behavior of alkali chlorides causes unmixing of the volatile phase to form a H2O-rich vapor and a hydrosaline phase with important implications for the maximum concentration of Cl in magmas. Addition of CO2 to magma hastens immiscibility at crustal pressures (<500 MPa), inducing the formation of CO2-rich vapors and Cl-rich hydrosaline melts. (C) 2000 Elsevier Science B.V. All rights reserved.Chlorine (Cl) and carbon dioxide (CO2) are common magmatic volatiles with contrasting behaviors. CO2 solubility increases with pressure whereas Cl solubility shows relatively little pressure or temperature effect. CO2 speciation changes with silicate melt composition, dissolving as carbonate in basaltic magmas and molecular CO2 in more silicic compositions. In H2O-bearing systems, the strongly non-ideal behavior of alkali chlorides causes unmixing of the volatile phase to form a H2O-rich vapor and a hydrosaline phase with important implications for the maximum concentration of Cl in magmas. Addition of CO2 to magma hastens immiscibility at crustal pressures (<500 MPa), inducing the formation of CO2-rich vapors and Cl-rich hydrosaline melts.

Volatile element loss during planetary magma ocean phases

NASA Astrophysics Data System (ADS)

Dhaliwal, Jasmeet K.; Day, James M. D.; Moynier, Frédéric

2018-01-01

Moderately volatile elements (MVE) are key tracers of volatile depletion in planetary bodies. Zinc is an especially useful MVE because of its generally elevated abundances in planetary basalts, relative to other MVE, and limited evidence for mass-dependent isotopic fractionation under high-temperature igneous processes. Compared with terrestrial basalts, which have δ66Zn values (per mille deviation of the 66Zn/64Zn ratio from the JMC-Lyon standard) similar to some chondrite meteorites (∼+0.3‰), lunar mare basalts yield a mean δ66Zn value of +1.4 ± 0.5‰ (2 st. dev.). Furthermore, mare basalts have average Zn concentrations ∼50 times lower than in typical terrestrial basaltic rocks. Late-stage lunar magmatic products, including ferroan anorthosite, Mg- and Alkali-suite rocks have even higher δ66Zn values (+3 to +6‰). Differences in Zn abundance and isotopic compositions between lunar and terrestrial rocks have previously been interpreted to reflect evaporative loss of Zn, either during the Earth-Moon forming Giant Impact, or in a lunar magma ocean (LMO) phase. To explore the mechanisms and processes under which volatile element loss may have occurred during a LMO phase, we developed models of Zn isotopic fractionation that are generally applicable to planetary magma oceans. Our objective was to identify conditions that would yield a δ66Zn signature of ∼+1.4‰ within the lunar mantle. For the sake of simplicity, we neglect possible Zn isotopic fractionation during the Giant Impact, and assumed a starting composition equal to the composition of the present-day terrestrial mantle, assuming both the Earth and Moon had zinc 'consanguinity' following their formation. We developed two models: the first simulates evaporative fractionation of Zn only prior to LMO mixing and crystallization; the second simulates continued evaporative fractionation of Zn that persists until ∼75% LMO crystallization. The first model yields a relatively homogenous bulk solid LMO δ66Zn value, while the second results in a stratification of δ66Zn values within the LMO sequence. Loss and/or isolation mechanisms for volatiles are critical to these models; hydrodynamic escape was not a dominant process, but loss of a nascent lunar atmosphere or separation of condensates into a proto-lunar crust are possible mechanisms by which volatiles could be separated from the lunar interior. The results do not preclude models that suggest a lunar volatile depletion episode related to the Giant Impact. Conversely, LMO models for volatile loss do not require loss of volatiles prior to lunar formation. Outgassing during planetary magma ocean phases likely played a profound role in setting the volatile inventories of planets, particularly for low mass bodies that experienced the greatest volatile loss. In turn, our results suggest that the initial compositions of planets that accreted from smaller, highly differentiated planetesimals were likely to be severely volatile depleted.

Optimization of headspace solid phase micro-extraction of volatile compounds from papaya fruit assisted by GC-olfactometry.

PubMed

da Rocha, Renier Felinto Julião; da Silva Araújo, Ídila Maria; de Freitas, Sílvia Maria; Dos Santos Garruti, Deborah

2017-11-01

Optimization of the extraction conditions to investigate the volatile composition of papaya fruit involving headspace solid phase micro-extraction was carried out using multivariate strategies such as factorial design and response surface methodology. The performance of different combinations of time for reaching the equilibrium in the headspace and time for maximum extraction of volatiles was evaluated by GC-olfactometry of the extract (intensity of papaya characteristic aroma), number of peaks and total area in the chromatogram. Thirty-two compounds were identified by GC-MS under the optimized extraction conditions, the majority of which were aldehydes, both in number of compounds and area. Major compounds were δ-octalactone, β-citral, benzaldehyde, heptanal, benzyl isothiocyanate, isoamyl acetate, γ-octalactone, (E)-linalool oxide and benzyl alcohol. Seven aldehydes and two other compounds are reported for the first time in papaya's volatile profile.

Characterization of Aronia melanocarpa volatiles by headspace-solid-phase microextraction (HS-SPME), simultaneous distillation/extraction (SDE), and gas chromatography-olfactometry (GC-O) methods.

PubMed

Kraujalytė, Vilma; Leitner, Erich; Venskutonis, Petras Rimantas

2013-05-22

The profiles of volatile constituents of berry fruit of two Aronia melanocarpa genotypes were evaluated by headspace-solid-phase microextraction (HS-SPME), simultaneous distillation and extraction (SDE), and gas chromatography-olfactometry (GC-O). In total, 74 volatile compounds were identified in chokeberry juice, 3-penten-2-one, 3,9-epoxy-p-menth-1-ene, and benzaldehyde being the most abundant constituents; however, their percentage concentrations were remarkably different in the HS-SPME and SDE profiles. Twenty two aroma-active compounds were detected and characterized by the trained panelists in HS-SPME using GC-O detection frequency analysis. Olfactometry revealed that ethyl-2-methyl butanoate, ethyl-3-methyl butanoate, ethyl decanoate ("fruity" aroma notes), nonanal ("green" notes), unidentified compound possessing "moldy" odor, and some other volatiles may be very important constituents in formation of chokeberry aroma of both analyzed plant cultivars.

Evaluation of volatilization as a natural attenuation pathway for MTBE

USGS Publications Warehouse

Lahvis, Matthew A.; Baehr, Arthur L.; Baker, Ronald J.

2004-01-01

Volatilization and diffusion through the unsaturated zone can be an important pathway for natural attenuation remediation of methyl tert-butyl ether (MTBE) at gasoline spill sites. The significance of this pathway depends primarily on the distribution of immiscible product within the unsaturated zone and the relative magnitude of aqueous-phase advection (ground water recharge) to gaseous-phase diffusion. At a gasoline spill site in Laurel Bay, South Carolina, rates of MTBE volatilization from ground water downgradient from the source are estimated by analyzing the distribution of MTBE in the unsaturated zone above a solute plume. Volatilization rates of MTBE from ground water determined by transport modeling ranged from 0.0020 to 0.0042 g m-2/year, depending on the assumed rate of ground water recharge. Although diffusive conditions at the Laurel Bay site are favorable for volatilization, mass loss of MTBE is insignificant over the length (230 m) of the solute plume. Based on this analysis, significant volatilization of MTBE from ground water downgradient from source areas at other sites is not likely. In contrast, model results indicate that volatilization coupled with diffusion to the atmosphere could be a significant mass loss pathway for MTBE in source areas where residual product resides above the capillary zone. Although not documented, mass loss of MTBE at the Laurel Bay site due to volatilization and diffusion to the atmosphere are predicted to be two to three times greater than mass loading of MTBE to ground water due to dissolution and recharge. This result would imply that volatilization in the source zone may be the critical natural attenuation pathway for MTBE at gasoline spill sites, especially when considering capillary zone limitations on volatilization of MTBE from ground water and the relative recalcitrance of MTBE to biodegradation.

Degradation and Volatilization of Chlorofluorocarbons in Contaminated Groundwater Explored by Stable Carbon Isotope Analysis

NASA Astrophysics Data System (ADS)

Horst, A.; Lacrampe-Couloume, G.; Sherwood Lollar, B.

2015-12-01

Chlorofluorocarbons (CFCs) are ozone depleting compounds whose production was phased out by the regulations of the Montreal Protocol (1987). Accidental release and disposal also led to contamination of groundwater at many locations, however, and this legacy persists. Although very stable, CFCs may degrade via abiotic and biotic pathways. Quantification of the degree of transformation of CFCs has been challenging due to other processes such as dilution, sorption and volatilization. Compound specific stable carbon isotope analysis (CSIA) has been successfully applied for a variety of priority pollutants to distinguish degradation from other processes and to quantify transformation rates. A Purge & Trap - CSIA method developed in our lab was applied to determine the stable carbon isotopic signature of CFCs and HCFCs (hydrochlorofluorocarbons) in groundwater samples from a contaminated site. Preliminary results suggest that degradation of CFCs and HCFCs may result in enriched δ13C values, consistent with fractionation during bond breakage as has been reported for many other hydrocarbon pollutants. The effect of volatile loss during sampling on the isotopic signatures of CFCs was examined in laboratory experiments. Volatilization from pure phase CFCs showed a small inverse isotope effect during open system volatilization, opposite to the normal isotope effect generally observed during biodegradation. For volatilization of CFCs dissolved in water a much smaller isotope effect was observed. An important result from this work is that any volatile loss may introduce only a small change in CFC isotopic signatures in groundwater, and importantly, due to the opposite direction of isotope effects associated with volatilization versus degradation, any effects of volatile loss on the isotopic signatures cannot be confused with transformation of CFCs. At most, volatilization might contribute to a conservative estimate of the extent of degradation.

Evidence of a Pre-eruptive Fluid Phase for the Millennium Eruption, Paektu Volcano, North Korea

NASA Astrophysics Data System (ADS)

Iacovino, K.; Sisson, T. W.; Lowenstern, J. B.

2014-12-01

We present initial results of a study of comenditic to trachytic melt inclusions from the Millennium Eruption (ME) of Paektu volcano (AD 946; VEI≥7; 25 km3 DRE). Paektu volcano (aka Changbaishan) is a remote and poorly studied intraplate stratovolcano whose 37 km2 caldera is bisected by the political border between North Korea and China, limiting studies of its proximal deposits. ME magmas are predominantly phenocryst-poor (≤3 vol%) comendites plus a volumetrically minor late-stage, more phenocryst-rich (10-20 vol%) trachyte. Sizeable (100-500 µm diameter) glassy but bubble-bearing melt inclusions are widespread in anorthoclase and hedenbergite phenocrysts, as well as in rarer quartz and fayalite phenocrysts. Comparing the relative enrichments of incompatible volatile and non-volatile elements in melt inclusions along a liquid line of descent shows decreasing volatile/Zr ratios suggesting the partitioning of volatiles into a fluid phase. This suggests that current gas-yield estimates (Horn & Schminke, 2000) for the ME, based on the petrologic method (difference in volatiles between melt inclusions and matrix glass), could be severe underestimates. Establishing the composition and quantity of a pre-eruptive fluid phase is the primary goal of this study and has implications for eruption triggering and for modeling the climatic effects of one of the largest eruptions in the last 10,000 years. Including results from Horne and Schminke (2000), melt inclusions from within a single pumice fall unit show a wide range in dissolved volatile contents and magma chemistries. Concentrations of H2O are moderate (2-3.5 wt% via FTIR), with Cl and F ranging from 500-4600 ppm and 1100-4700 ppm (via EPMA). CO2 is below the detection limit of 2 ppm (FTIR with N2 purge) in bubble-bearing melt inclusions, but is detectable (≤56 ppm) in melt inclusions homogenized at 100 MPa and 850-900 °C for ~30 min (conditions also leading to reduction of dissolved H2O to 0.6-2 wt%). Characterization of a co-existing fluid phase in ME magmas is being investigated with further melt inclusion analyses, mineral-melt-fluid equilibrium calculations, and phase equilibrium experiments on fluid-saturated liquid lines of descent and on volatile solubilities of the ME trachyite-comendite suite.

Materials for Tc Capture to Increase Tc Retention in Glass Waste Form

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luksic, Steven A.; Hrma, Pavel R.; Kruger, Albert A.

99Technetium is a long-lived fission product found in the tank waste at the Hanford site in Washington State. In its heptavalent species, it is volatile at the temperatures used in Hanford Tank Waste Treatment and Immobilization Plant vitrification melters, and thus is challenging to incorporate into waste glass. In order to decrease volatility and thereby increase retention, technetium can be converted into more thermally stable species. Several mineral phases, such as spinel, are able to incorporate tetravalent technetium in a chemically durable and thermally stable lattice, and these hosts may promote the decreased volatility that is desired. In order tomore » be usefully implemented, there must be a synthetic rout to these phases that is compatible with both technetium chemistry and current Hanford Tank Waste Treatment and Immobilization Plant design. Synthetic routes for spinel and other potential host phases are examined.« less

Stochastic volatility of the futures prices of emission allowances: A Bayesian approach

NASA Astrophysics Data System (ADS)

Kim, Jungmu; Park, Yuen Jung; Ryu, Doojin

2017-01-01

Understanding the stochastic nature of the spot volatility of emission allowances is crucial for risk management in emissions markets. In this study, by adopting a stochastic volatility model with or without jumps to represent the dynamics of European Union Allowances (EUA) futures prices, we estimate the daily volatilities and model parameters by using the Markov Chain Monte Carlo method for stochastic volatility (SV), stochastic volatility with return jumps (SVJ) and stochastic volatility with correlated jumps (SVCJ) models. Our empirical results reveal three important features of emissions markets. First, the data presented herein suggest that EUA futures prices exhibit significant stochastic volatility. Second, the leverage effect is noticeable regardless of whether or not jumps are included. Third, the inclusion of jumps has a significant impact on the estimation of the volatility dynamics. Finally, the market becomes very volatile and large jumps occur at the beginning of a new phase. These findings are important for policy makers and regulators.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vanheusden, K.; Warren, W.L.; Devine, R.A.B.

It is shown how mobile H{sup +} ions can be generated thermally inside the oxide layer of Si/SiO{sub 2}/Si structures. The technique involves only standard silicon processing steps: the nonvolatile field effect transistor (NVFET) is based on a standard MOSFET with thermally grown SiO{sub 2} capped with a poly-silicon layer. The capped thermal oxide receives an anneal at {approximately}1100 C that enables the incorporation of the mobile protons into the gate oxide. The introduction of the protons is achieved by a subsequent 500-800 C anneal in a hydrogen-containing ambient, such as forming gas (N{sub 2}:H{sub 2} 95:5). The mobile protonsmore » are stable and entrapped inside the oxide layer, and unlike alkali ions, their space-charge distribution can be controlled and rapidly rearranged at room temperature by an applied electric field. Using this principle, a standard MOS transistor can be converted into a nonvolatile memory transistor that can be switched between normally on and normally off. Switching speed, retention, endurance, and radiation tolerance data are presented showing that this non-volatile memory technology can be competitive with existing Si-based non-volatile memory technologies such as the floating gate technologies (e.g. Flash memory).« less

A flowing atmospheric pressure afterglow as an ion source coupled to a differential mobility analyzer for volatile organic compound detection.

PubMed

Bouza, Marcos; Orejas, Jaime; López-Vidal, Silvia; Pisonero, Jorge; Bordel, Nerea; Pereiro, Rosario; Sanz-Medel, Alfredo

2016-05-23

Atmospheric pressure glow discharges have been widely used in the last decade as ion sources in ambient mass spectrometry analyses. Here, an in-house flowing atmospheric pressure afterglow (FAPA) has been developed as an alternative ion source for differential mobility analysis (DMA). The discharge source parameters (inter-electrode distance, current and helium flow rate) determining the atmospheric plasma characteristics have been optimized in terms of DMA spectral simplicity with the highest achievable sensitivity while keeping an adequate plasma stability and so the FAPA working conditions finally selected were: 35 mA, 1 L min(-1) of He and an inter-electrode distance of 8 mm. Room temperature in the DMA proved to be adequate for the coupling and chemical analysis with the FAPA source. Positive and negative ions for different volatile organic compounds were tested and analysed by FAPA-DMA using a Faraday cup as a detector and proper operation in both modes was possible (without changes in FAPA operational parameters). The FAPA ionization source showed simpler ion mobility spectra with narrower peaks and a better, or similar, sensitivity than conventional UV-photoionization for DMA analysis in positive mode. Particularly, the negative mode proved to be a promising field of further research for the FAPA ion source coupled to ion mobility, clearly competitive with other more conventional plasmas such as corona discharge.

Application of solid-phase microextraction with gas chromatography and mass spectrometry for the early detection of active moulds on historical woollen objects.

PubMed

Sawoszczuk, Tomasz; Syguła-Cholewińska, Justyna; Del Hoyo-Meléndez, Julio M

2017-02-01

The goal of this work was to determine the microbial volatile organic compounds emitted by moulds growing on wool in search of particular volatiles mentioned in the literature as indicators of active mould growth. The keratinolytically active fungi were inoculated on two types of media: (1) samples of wool placed on broths, and (2) on broths containing amino acids that are elements of the structure of keratin. All samples were prepared inside 20 mL vials (closed system). In the first case (1) the broths did not contain any sources of organic carbon, nitrogen, or sulfur, i.e. wool was the only nutrient for the moulds. A third type of sample was historical wool prepared in a Petri dish without a broth and inoculated with a keratinolytically active mould (open system). The microbial volatiles emitted by moulds were sampled with the headspace solid-phase microextraction method. Volatiles extracted on solid-phase microextraction fibers were analyzed in a gas chromatography with mass spectrometry system. Qualitative and quantitative analyses of chromatograms were carried out in search of indicators of metabolic activity. The results showed that there are three groups of volatiles that can be used for the detection of active forms of moulds on woollen objects. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bubble-facilitated VOC transport: Laboratory experiments and numerical modelling

NASA Astrophysics Data System (ADS)

Mumford, K. G.; Soucy, N. C.

2017-12-01

Most conceptual and numerical models of vapor intrusion assume that the transport of volatile organic compounds (VOCs) from the source to near the building foundation is a diffusion-limited processes. However, the transport of VOCs by mobilized gas bubbles through the saturated zone could lead to increased rates of transport and advection through the unsaturated zone, thereby increasing mass flux and risks associated with vapor intrusion. This mobilized gas could be biogenic (methanogenic) but could also result from the partitioning of VOC to trapped atmospheric gases in light non-aqueous phase liquid (LNAPL) smear zones. The potential for bubble-facilitated VOC transport to increase mass flux was investigated in a series of 1D and 2D laboratory experiments. Pentane source zones were emplaced in sand using sequential drainage and imbibition steps to mimic a water table fluctuation and trap air alongside LNAPL residual. This source was placed below an uncontaminated, water saturated sand (occlusion zone) and a gravel-sized (glass beads) unsaturated zone. Water was pumped laterally through the source zone and occlusion zone to deliver the dissolved gases (air) that are required for the expansion of trapped gas bubbles. Images from 2D flow cell experiments were used to demonstrate fluid rearrangement in the source zone and gas expansion to the occlusion zone, and 1D column experiments were used to measure gas-phase pentane mass flux. This flux was found to be 1-2 orders of magnitude greater than that measured in diffusion-dominated control columns, and showed intermittent behavior consistent with bubble transport by repeated expansion, mobilization, coalescence and trapping. Numerical simulation results under a variety of conditions using an approach that couples macroscopic invasion percolation with mass transfer (MIP-MT) between the aqueous and gas phases will also be presented. The results of this study demonstrate the potential for bubble-facilitated transport to increase transport rates linked to vapor intrusion, and will serve as a basis for further development of conceptual and numerical models to investigate the conditions under which this mechanism may play an important role.

Targeting Human Serum Fucome by an Integrated Liquid-phase Multi Column Platform Operating in “Cascade” to Facilitate Comparative Mass Spectrometric Analysis of Disease-Free and Breast Cancer Sera

PubMed Central

Selvaraju, Subhashini; Rassi, Ziad El

2013-01-01

A fully integrated platform was developed for capturing/fractionating human fucome from disease-free and breast cancer sera. It comprised multicolumn operated by HPLC pumps and switching valves for the simultaneous depletion of high abundance proteins via affinity-based subtraction and the capturing of fucosylated glycoproteins via lectin affinity chromatography followed by the fractionation of the captured glycoproteins by reversed phase chromatography (RPC). Two lectin columns specific to fucose, namely Aleuria aurantia lectin (AAL) and Lotus tetragonolobus agglutinin (LTA) were utilized. The platform allowed the “cascading” of the serum sample from column-to-column in the liquid phase with no sample manipulation between the various steps. This guaranteed no sample loss and no propagation of experimental biases between the various columns. Finally, the fucome was fractionated by RPC yielding desalted fractions in volatile acetonitrile-rich mobile phase, which after vacuum evaporation were subjected to trypsinolysis for LC-MS/MS analysis. This permitted the identification of the differentially expressed proteins (DEP) in breast cancer serum yielding a broad panel of 35 DEP from the combined LTA and AAL captured proteins and a narrower panel of 8 DEP that were commonly differentially expressed in both LTA and AAL fractions, which are considered as more representative of cancer altered fucome. PMID:23533108

Effect of inorganic salts on the volatility of organic acids.

PubMed

Häkkinen, Silja A K; McNeill, V Faye; Riipinen, Ilona

2014-12-02

Particulate phase reactions between organic and inorganic compounds may significantly alter aerosol chemical properties, for example, by suppressing particle volatility. Here, chemical processing upon drying of aerosols comprised of organic (acetic, oxalic, succinic, or citric) acid/monovalent inorganic salt mixtures was assessed by measuring the evaporation of the organic acid molecules from the mixture using a novel approach combining a chemical ionization mass spectrometer coupled with a heated flow tube inlet (TPD-CIMS) with kinetic model calculations. For reference, the volatility, i.e. saturation vapor pressure and vaporization enthalpy, of the pure succinic and oxalic acids was also determined and found to be in agreement with previous literature. Comparison between the kinetic model and experimental data suggests significant particle phase processing forming low-volatility material such as organic salts. The results were similar for both ammonium sulfate and sodium chloride mixtures, and relatively more processing was observed with low initial aerosol organic molar fractions. The magnitude of low-volatility organic material formation at an atmospherically relevant pH range indicates that the observed phenomenon is not only significant in laboratory conditions but is also of direct atmospheric relevance.

Volcanic Structures Within Niger and Dao Valles, Mars, and Implications for Outflow Channel Evolution and Hellas Basin Rim Development

NASA Astrophysics Data System (ADS)

Korteniemi, J.; Kukkonen, S.

2018-04-01

Outflow channel formation on the eastern Hellas rim region is traditionally thought to have been triggered by activity phases of the nearby volcanoes Hadriacus and Tyrrhenus Montes: As a result of volcanic heating subsurface volatiles were mobilized. It is, however, under debate, whether eastern Hellas volcanism was in fact more extensive, and if there were volcanic centers separate from the identified central volcanoes. This work describes previously unrecognized structures in the Niger-Dao Valles outflow channel complex. We interpret them as volcanic edifices: cones, a shield, and a caldera. The structures provide evidence of an additional volcanic center within the valles and indicate volcanic activity both prior to and following the formation of the outflow events. They expand the extent, type, and duration of volcanic activity in the Circum-Hellas Volcanic Province and provide new information on interaction between volcanism and fluvial activity.

[Study on transformation mechanism of SOA from biogenic VOC under UV-B condition].

PubMed

Li, Ying-Ying; Li, Xiang; Chen, Jian-Min

2011-12-01

A laboratory study was carried out to investigate the biogenic volatile organic compounds (BVOC) in a lab-made glass chamber. The secondary organic aerosol (SOA) products can be detected under the UV photooxidation of BVOC. Pelargonium x Citrenella was chosen as the target plant in this research because it can release a large amount of BVOCs. The predominant 7 alkene and ketol compounds were detected by using solid phase microextraction (SPME) sampling and gas chromatography/mass spectrometry (GC/MS) analysis. The photochemical experiment indicated that these BVOC can be rapidly oxidized into SOA under UV-B irradiation. A tandem differential mobility analyzer (TDMA) was used to measure the size distribution and the hygroscopicity of the SOA. The particle diameter was in the range of 50 nm to 320 nm. The high hygroscopicity of SOA was also obtained and the size increased from 1.05 to 1.11 during the wet experiment.

State of research: environmental pathways and food chain transfer.

PubMed Central

Vaughan, B E

1984-01-01

Data on the chemistry of biologically active components of petroleum, synthetic fuel oils, certain metal elements and pesticides provide valuable generic information needed for predicting the long-term fate of buried waste constituents and their likelihood of entering food chains. Components of such complex mixtures partition between solid and solution phases, influencing their mobility, volatility and susceptibility to microbial transformation. Estimating health hazards from indirect exposures to organic chemicals involves an ecosystem's approach to understanding the unique behavior of complex mixtures. Metabolism by microbial organisms fundamentally alters these complex mixtures as they move through food chains. Pathway modeling of organic chemicals must consider the nature and magnitude of food chain transfers to predict biological risk where metabolites may become more toxic than the parent compound. To obtain predictions, major areas are identified where data acquisition is essential to extend our radiological modeling experience to the field of organic chemical contamination. PMID:6428875

Bacterial Volatile Discovery using Solid Phase Microextraction and Comprehensive Two-Dimensional Gas Chromatography–Time-of-Flight Mass Spectrometry

PubMed Central

Bean, Heather D.; Dimandja, Jean-Marie D.; Hill, Jane E.

2014-01-01

Bacteria produce unique volatile mixtures that could be used to identify infectious agents to the species, and possibly the strain level. However, due to the immense variety of human pathogens, and the close relatedness of some of these bacteria, the robust identification of the bacterium based on its volatile metabolome is likely to require a large number of volatile compounds for each species. We applied comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC×GC-TOFMS) to the identification of the headspace volatiles of P. aeruginosa PA14 grown for 24 h in lysogeny broth. This is the first reported use of GC×GC-TOFMS for the characterization of bacterial headspace volatiles. The analytical purity that is afforded by this chromatographic method facilitated the identification of 28 new P. aeruginosa-derived volatiles, nearly doubling the list of volatiles for this species. PMID:22727751

Space exploration and the history of solar-system volatiles

NASA Technical Reports Server (NTRS)

Fanale, F. P.

1976-01-01

The thermochemical history of volatile substances in all solar-system planets, satellites, and planetoids is discussed extensively. The volatiles are viewed as an interface between the abiotic and biotic worlds and as a key to the history of bodies of the solar system. A flowsheet of processes and states is exhibited. Differences in bulk volatiles distribution between the planetary bodies and between the interior, surface, and atmosphere of each body are considered, as well as sinks for volatiles in degassing. The volatiles-rich Jovian and Saturnian satellites, the effect of large-planet magnetosphere sweeps on nearby satellites, volatiles of asteroids and comets, and the crucial importance of seismic, gravity, and libration data are treated. A research program encompassing analysis of the elemental and isotopic composition of rare gas in atmospheres, assay of volatiles-containing phases in regoliths, and examination of present or past atmospheric escape/accretion processes is recommended.

[Analyze on volatile compounds of Antrodia camphorata using HS-SPME-GC-MS].

PubMed

He, Zhe; Lu, Zhen-Ming; Xu, Hong-Yu; Shi, Jing-Song; Xu, Zheng-Hong

2011-11-01

To analyze the volatile compounds of Antrodia camphorata in solid-state and submerged cultures. A headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry(GC-MS) were used to evaluate the profile of the volatile compounds. 49 volatile compounds were identified in A. camphorata mycelia in submerged culture, while 43 volatile compounds were identified in mycelia in solid-state culture. 1-octen-3-ol, 3-octanone, 1-octen-3-ylacetate, acetic acid octyl ester and ethanol were the main volatile compounds in A. camphorata mycelia in submerged culture, while 1-octen-3-ol, 3-octanone, 3-methyl-butyraldenhyde, gamma-podecalactone and methyl 2-furozte were the most potent key volatile compounds in mycelia in solid-state culture. The volatile compounds in the mycelia of A. camphorata in solid-state and submerged cultures are similar but their relative contents are different.

Negative-ion atmospheric pressure ionisation of semi-volatile fluorinated compounds for ultra-high-performance liquid chromatography tandem mass spectrometry analysis.

PubMed

Ayala-Cabrera, Juan F; Javier Santos, F; Moyano, Encarnación

2018-05-24

In this work, the feasibility of negative-ion atmospheric pressure chemical ionisation (APCI) and atmospheric pressure photoionisation (APPI) for ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) determination of fluorotelomer alcohols (FTOHs), fluorinated octanesulfonamides (FOSAs) and fluorinated octanesulfonamido-ethanols (FOSEs) was evaluated. The study of the effect of mobile phase composition on the atmospheric pressure ionisation of these compounds indicated that methanol/water mixtures provided the best responses in APCI, while acetonitrile/water with a post-column addition of toluene as dopant was the most appropriated mixture in APPI. Under the optimal working conditions, most of the target compounds produced the ion [M-H] - as base peak, although in-source collision-induced dissociation fragment ions in APCI and APPI and superoxide adduct ions [M+O 2 ] -• in APPI were also present. These ions proved to be more useful as precursor ions for MS/MS determination than the adduct ions generated in electrospray. Although the UHPLC-APCI-MS/MS method allowed the determination of these semi-volatile compounds at low concentration levels, the analysis by UHPLC-APPI-MS/MS provided the lowest limits of detection and it was applied to the analysis of water samples in combination with solid-phase extraction. Quality parameters demonstrated the good performance of the proposed method, providing low method limits of detection (0.3-6 ng L -1 ), good precision (RSD % < 5%) and an accurate quantification (relative error % < 14%). Among the river water samples analysed by the developed method, 4:2 FTOH and N-EtFOSA were determined at 30 and 780 ng L -1 , respectively.

Gradient enhanced-fluidity liquid hydrophilic interaction chromatography of ribonucleic acid nucleosides and nucleotides: A "green" technique.

PubMed

Beilke, Michael C; Beres, Martin J; Olesik, Susan V

2016-03-04

A "green" hydrophilic interaction liquid chromatography (HILIC) technique for separating the components of mixtures with a broad range of polarities is illustrated using enhanced-fluidity liquid mobile phases. Enhanced-fluidity liquid chromatography (EFLC) involves the addition of liquid CO2 to conventional liquid mobile phases. Decreased mobile phase viscosity and increased analyte diffusivity results when a liquefied gas is dissolved in common liquid mobile phases. The impact of CO2 addition to a methanol:water (MeOH:H2O) mobile phase was studied to optimize HILIC gradient conditions. For the first time a fast separation of 16 ribonucleic acid (RNA) nucleosides/nucleotides was achieved (16min) with greater than 1.3 resolution for all analyte pairs. By using a gradient, the analysis time was reduced by over 100% compared to similar separations conducted under isocratic conditions. The optimal separation using MeOH:H2O:CO2 mobile phases was compared to MeOH:H2O and acetonitrile:water (ACN:H2O) mobile phases. Based on chromatographic performance parameters (efficiency, resolution and speed of analysis) and an assessment of the environmental impact of the mobile phase mixtures, MeOH:H2O:CO2 mixtures are preferred over ACN:H2O or MeOH:H2O mobile phases for the separation of mixtures of RNA nucleosides and nucleotides. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of Cold Temperature and Ethanol Content on VOC Emissions from Light-Duty Gasoline Vehicles.

PubMed

George, Ingrid J; Hays, Michael D; Herrington, Jason S; Preston, William; Snow, Richard; Faircloth, James; George, Barbara Jane; Long, Thomas; Baldauf, Richard W

2015-11-03

Emissions of speciated volatile organic compounds (VOCs), including mobile source air toxics (MSATs), were measured in vehicle exhaust from three light-duty spark ignition vehicles operating on summer and winter grade gasoline (E0) and ethanol blended (E10 and E85) fuels. Vehicle testing was conducted using a three-phase LA92 driving cycle in a temperature-controlled chassis dynamometer at two ambient temperatures (-7 and 24 °C). The cold start driving phase and cold ambient temperature increased VOC and MSAT emissions up to several orders of magnitude compared to emissions during other vehicle operation phases and warm ambient temperature testing, respectively. As a result, calculated ozone formation potentials (OFPs) were 7 to 21 times greater for the cold starts during cold temperature tests than comparable warm temperature tests. The use of E85 fuel generally led to substantial reductions in hydrocarbons and increases in oxygenates such as ethanol and acetaldehyde compared to E0 and E10 fuels. However, at the same ambient temperature, the VOC emissions from the E0 and E10 fuels and OFPs from all fuels were not significantly different. Cold temperature effects on cold start MSAT emissions varied by individual MSAT compound, but were consistent over a range of modern spark ignition vehicles.

Hot air injection for removal of dense, non-aqueous-phase liquid contaminants from low-permeability soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Payne, F.C.

1996-08-01

The performance of soil vapor extraction systems for the recovery of volatile and semi-volatile organic compounds is potentially enhanced by the injection of heated air to increase soil temperatures. The soil temperature increase is expected to improve soil vapor extraction (SVE) performance by increasing target compound vapor pressures and by increasing soil permeability through drying. The vapor pressure increase due to temperature rise relieves the vapor pressure limit on the feasibility of soil vapor extraction. However, the system still requires an air flow through the soil system to deliver heat and to recover mobilized contaminants. Although the soil permeability canmore » be increased through drying, very low permeability soils and low permeability soils adjacent to high permeability air flow pathways will be treated slowly, if at all. AR thermal enhancement methods face this limitation. Heated air injection offers advantages relative to other thermal techniques, including low capital and operation costs. Heated air injection is at a disadvantage relative to other thermal techniques due to the low heat capacity of air. To be effective, heated air injection requires that higher air flows be established than for steam injection or radio frequency heating. Heated air injection is not economically feasible for the stratified soil system developed as a standard test for this document. This is due to the inability to restrict heated air flow to the clay stratum when a low-resistance air flow pathway is available in the adjoining sand. However, the technology should be especially attractive, both technically and economically, for low-volatile contaminant recovery from relatively homogeneous soil formations. 16 refs., 2 tabs.« less

Partitioning Behavior of Organic Contaminants in Carbon Storage Environments: A Critical Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burant, Aniela; Lowry, Gregory V; Karamalidis, Athanasios K

2012-12-04

Carbon capture and storage is a promising strategy for mitigating the CO{sub 2} contribution to global climate change. The large scale implementation of the technology mandates better understanding of the risks associated with CO{sub 2} injection into geologic formations and the subsequent interactions with groundwater resources. The injected supercritical CO{sub 2} (sc-CO{sub 2}) is a nonpolar solvent that can potentially mobilize organic compounds that exist at residual saturation in the formation. Here, we review the partitioning behavior of selected organic compounds typically found in depleted oil reservoirs in the residual oil–brine–sc-CO{sub 2} system under carbon storage conditions. The solubility ofmore » pure phase organic compounds in sc-CO{sub 2} and partitioning of organic compounds between water and sc-CO{sub 2} follow trends predicted based on thermodynamics. Compounds with high volatility and low aqueous solubility have the highest potential to partition to sc-CO{sub 2}. The partitioning of low volatility compounds to sc-CO{sub 2} can be enhanced by co-solvency due to the presence of higher volatility compounds in the sc-CO{sub 2}. The effect of temperature, pressure, salinity, pH, and dissolution of water molecules into sc-CO{sub 2} on the partitioning behavior of organic compounds in the residual oil-brine-sc-CO{sub 2} system is discussed. Data gaps and research needs for models to predict the partitioning of organic compounds in brines and from complex mixtures of oils are presented. Models need to be able to better incorporate the effect of salinity and co-solvency, which will require more experimental data from key classes of organic compounds.« less

Receptor model comparisons and wind direction analyses of volatile organic compounds and submicrometer particles in an arid, binational, urban air shed.

PubMed

Mukerjee, Shaibal; Norris, Gary A; Smith, Luther A; Noble, Christopher A; Neas, Lucas M; Ozkaynak, A Halûk; Gonzales, Melissa

2004-04-15

The relationship between continuous measurements of volatile organic compounds sources and particle number was evaluated at a Photochemical Assessment Monitoring Station Network (PAMS) site located near the U.S.-Mexico Border in central El Paso, TX. Sources of volatile organic compounds (VOCs) were investigated using the multivariate receptor model UNMIX and the effective variance least squares receptor model known as Chemical Mass Balance (CMB, Version 8.0). As expected from PAMS measurements, overall findings from data screening as well as both receptor models confirmed that mobile sources were the major source of VOCs. Comparison of hourly source contribution estimates (SCEs) from the two receptor models revealed significant differences in motor vehicle exhaust and evaporative gasoline contributions. However, the motor vehicle exhaust contributions were highly correlated with each other. Motor vehicle exhaust was also correlated with the ultrafine and accumulation mode particle count, which suggests that motor vehicle exhaust is a source of these particles at the measurement site. Wind sector analyses were performed using the SCE and pollutant data to assess source location of VOCs, particle count, and criteria pollutants. Results from this study have application to source apportionment studies and mobile source emission control strategies that are ongoing in this air shed.

Diel variation in fig volatiles across syconium development: making sense of scents.

PubMed

Borges, Renee M; Bessière, Jean-Marie; Ranganathan, Yuvaraj

2013-05-01

Plants produce volatile organic compounds (VOCs) in a variety of contexts that include response to abiotic and biotic stresses, attraction of pollinators and parasitoids, and repulsion of herbivores. Some of these VOCs may also exhibit diel variation in emission. In Ficus racemosa, we examined variation in VOCs released by fig syconia throughout syconium development and between day and night. Syconia are globular enclosed inflorescences that serve as developing nurseries for pollinating and parasitic fig wasps. Syconia are attacked by gallers early in their development, serviced by pollinators in mid phase, and are attractive to parasitoids in response to the development of gallers at later stages. VOC bouquets of the different development phases of the syconium were distinctive, as were their day and night VOC profiles. VOCs such as α-muurolene were characteristic of the pollen-receptive diurnal phase, and may serve to attract the diurnally-active pollinating wasps. Diel patterns of release of volatiles could not be correlated with their predicted volatility as determined by Henry's law constants at ambient temperatures. Therefore, factors other than Henry's law constant such as stomatal conductance or VOC synthesis must explain diel variation in VOC emission. A novel use of weighted gene co-expression network analysis (WGCNA) on the volatilome resulted in seven distinct modules of co-emitted VOCs that could be interpreted on the basis of syconium ecology. Some modules were characterized by the response of fig syconia to early galling by parasitic wasps and consisted largely of green leaf volatiles (GLVs). Other modules, that could be characterized by a combination of syconia response to oviposition and tissue feeding by larvae of herbivorous galler pollinators as well as of parasitized wasps, consisted largely of putative herbivore-induced plant volatiles (HIPVs). We demonstrated the usefulness of WGCNA analysis of the volatilome in making sense of the scents produced by the syconia at different stages and diel phases of their development.

Thermal decomposition in thermal desorption instruments: importance of thermogram measurements for analysis of secondary organic aerosol

NASA Astrophysics Data System (ADS)

Stark, H.; Yatavelli, R. L. N.; Thompson, S.; Kang, H.; Krechmer, J. E.; Kimmel, J.; Palm, B. B.; Hu, W.; Hayes, P.; Day, D. A.; Campuzano Jost, P.; Ye, P.; Canagaratna, M. R.; Jayne, J. T.; Worsnop, D. R.; Jimenez, J. L.

2017-12-01

Understanding the chemical composition of secondary organic aerosol (SOA) is crucial for explaining sources and fate of this important aerosol class in tropospheric chemistry. Further, determining SOA volatility is key in predicting its atmospheric lifetime and fate, due to partitioning from and to the gas phase. We present three analysis approaches to determine SOA volatility distributions from two field campaigns in areas with strong biogenic emissions, a Ponderosa pine forest in Colorado, USA, from the BEACHON-RoMBAS campaign, and a mixed forest in Alabama, USA, from the SOAS campaign. We used a high-resolution-time-of-flight chemical ionization mass spectrometer (CIMS) for both campaigns, equipped with a micro-orifice volatilization impactor (MOVI) inlet for BEACHON and a filter inlet for gases and aerosols (FIGAERO) for SOAS. These inlets allow near simultaneous analysis of particle and gas-phase species by the CIMS. While gas-phase species are directly measured without heating, particles undergo thermal desorption prior to analysis. Volatility distributions can be estimated in three ways: (1) analysis of the thermograms (signal vs. temperature); (2) via partitioning theory using the gas- and particle-phase measurements; (3) from measured chemical formulas via a group contribution model. Comparison of the SOA volatility distributions from the three methods shows large discrepancies for both campaigns. Results from the thermogram method are the most consistent of the methods when compared with independent AMS-thermal denuder measurements. The volatility distributions estimated from partitioning measurements are very narrow, likely due to signal-to-noise limits in the measurements. The discrepancy between the formula and the thermogram methods indicates large-scale thermal decomposition of the SOA species. We will also show results of citric acid thermal decomposition, where, in addition to the mass spectra, measurements of CO, CO2 and H2O were made, showing thermal decomposition of up to 65% of the citric acid molecules.

Effectiveness of Liquid-Liquid Extraction, Solid Phase Extraction, and Headspace Technique for Determination of Some Volatile Water-Soluble Compounds of Rose Aromatic Water

PubMed Central

2017-01-01

Steam distillation is used to isolate scent of rose flowers. Rose aromatic water is commonly used in European cuisine and aromatherapy besides its use in cosmetic industry for its lovely scent. In this study, three different sampling techniques, liquid-liquid extraction (LLE), headspace technique (HS), and solid phase extraction (SPE), were compared for the analysis of volatile water-soluble compounds in commercial rose aromatic water. Some volatile water-soluble compounds of rose aromatic water were also analyzed by gas chromatography mass spectrometry (GCMS). In any case, it was concluded that one of the solid phase extraction methods led to higher recoveries for 2-phenylethyl alcohol (PEA) in the rose aromatic water than the liquid-liquid extraction and headspace technique. Liquid-liquid extraction method provided higher recovery ratios for citronellol, nerol, and geraniol than others. Ideal linear correlation coefficient values were observed by GCMS for quantitative analysis of volatile compounds (r2 ≥ 0.999). Optimized methods showed acceptable repeatability (RSDs < 5%) and excellent recovery (>95%). For compounds such as α-pinene, linalool, β-caryophyllene, α-humulene, methyl eugenol, and eugenol, the best recovery values were obtained with LLE and SPE. PMID:28791049

The troika of business cycle, efficiency and volatility. An East Asian perspective

NASA Astrophysics Data System (ADS)

Arshad, Shaista; Rizvi, Syed Aun R.

2015-02-01

The EMH has been the subject of much debate over the past few decades, with a recent surge in interest in Asian markets. Asian markets which traditionally comprise of many emerging markets are more volatile and speculative in nature. The heart of our study focuses on the East Asian economies, which have experienced massive capital inflows. This begs the question of whether or not the stock markets are efficient enough for further investment and development. Our paper differs from existing literature as it focuses on deriving weak form efficiency rankings during different business cycle phases. We endeavour further to assess the volatility and business cycle phases. Taking Malaysia, Indonesia, Singapore and South Korea owing to their economic and financial development, we use MF-DFA to derive efficiency rankings and find firstly, the overall efficiency has improved over the past two decades and secondly, markets are more efficient in growth phases in comparison to its preceding decline. Similarly, employing wavelet decomposition in conjunction with EGARCH, we obtain volatility of stock markets in two distinct time horizons, i.e. short term and long term. We find the markets to be more stable during economic boom than its preceding bust. Our results confer with mainstream literature.

Separation of metallic residues from the dissolution of a high-burnup BWR fuel using nitrogen trifluoride

DOE Office of Scientific and Technical Information (OSTI.GOV)

McNamara, Bruce K.; Buck, Edgar C.; Soderquist, Chuck Z.

2014-03-23

Nitrogen trifluoride (NF 3) was used to fluorinate the metallic residue from the dissolution of a high burnup, boiling water reactor fuel (~70 MWd/kgU). The metallic residue included the noble metal phase (containing ruthenium, rhodium, palladium, technetium, and molybdenum), and smaller amounts of zirconium, selenium, tellurium, and silver. Exposing the noble metal phase to 10% NF 3 in argon between 400 and 550°C, removed molybdenum and technetium near 400°C as their volatile fluorides, and ruthenium near 500C as its volatile fluoride. The events were thermally and temporally distinct and the conditions specified are a recipe to separate these transition metalsmore » from each other and from the noble metal phase nonvolatile residue. Depletion of the volatile fluorides resulted in substantial exothermicity. Thermal excursion behavior was recorded under non-adiabatic, isothermal conditions that typically minimize heat release. Physical characterization of the metallic noble phase and its thermal behavior are consistent with high kinetic velocity reactions encouraged by the nanoparticulate phase or perhaps catalytic influences of the mixed platinum metals with nearly pure phase structure. Post-fluorination, only two phases were present in the residual nonvolatile fraction. These were identified as a nano-crystalline, metallic palladium cubic phase and a hexagonal rhodium trifluoride (RhF 3) phase. The two phases were distinct as the sub-µm crystallites of metallic palladium were in contrast to the RhF 3 phase, which grew from the parent nano-crystalline noble-metal phase during fluorination, to acicular crystals exceeding 20-µm in length.« less

Contributions of wood smoke and vehicle emissions to ambient concentrations of volatile organic compounds and particulate matter during the Yakima wintertime nitrate study

NASA Astrophysics Data System (ADS)

VanderSchelden, Graham; de Foy, Benjamin; Herring, Courtney; Kaspari, Susan; VanReken, Tim; Jobson, Bertram

2017-02-01

A multiple linear regression (MLR) chemical mass balance model was applied to data collected during an air quality field experiment in Yakima, WA, during January 2013 to determine the relative contribution of residential wood combustion (RWC) and vehicle emissions to ambient pollutant levels. Acetonitrile was used as a chemical tracer for wood burning and nitrogen oxides (NOx) as a chemical tracer for mobile sources. RWC was found to be a substantial source of gas phase air toxics in wintertime. The MLR model found RWC primarily responsible for emissions of formaldehyde (73%), acetaldehyde (69%), and black carbon (55%) and mobile sources primarily responsible for emissions of carbon monoxide (CO; 83%), toluene (81%), C2-alkylbenzenes (81%), and benzene (64%). When compared with the Environmental Protection Agency's 2011 winter emission inventory, the MLR results suggest that the contribution of RWC to CO emissions was underestimated in the inventory by a factor of 2. Emission ratios to NOx from the MLR model agreed to within 25% with wintertime emission ratios predicted from the Motor Vehicle Emissions Simulator (MOVES) 2010b emission model for Yakima County for all pollutants modeled except for CO, C2-alkylbenzenes, and black carbon. The MLR model results suggest that MOVES was overpredicting mobile source emissions of CO relative to NOx by a factor of 1.33 and black carbon relative to NOx by about a factor of 3.

Subduction and volatile recycling in Earth's mantle

NASA Technical Reports Server (NTRS)

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

1994-01-01

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.

Portable Medical Diagnosis Instrument

NASA Technical Reports Server (NTRS)

Coleman, Matthew A. (Inventor); Straume, Tore (Inventor); Loftus, David J. (Inventor); Li, Jing (Inventor); Singh, Anup K. (Inventor); Davis, Cristina E. (Inventor)

2017-01-01

A system that integrates several technologies into a single, portable medical diagnostic apparatus for analyzing a sample body fluid (liquid and/or gas): (1) a mechanism to capture airborne microdroplets and to separate the body fluid into a first fluid component (primarily gas) and a second fluid component (primarily liquid); (2) a volatilizer to convert a portion of the second fluid component into a third fluid component that is primarily a gas; (3) a functionalized nanostructure (NS) array configured to receive, identify, and estimate concentration of at least one constituent in the first and/or third fluid components; (4) a miniaturized differential mobility spectrometer (DMS) module; and (5) a biomarker sensor, to detect volatile and non-volatile molecules in a sample fluid, which may contain one or more components of blood, breath, perspiration, saliva, and urine.

Experimental formation of Pb, Sn, Ge and Sb sulfides, selenides and chlorides in the presence of sal ammoniac: A contribution to the understanding of the mineral formation processes in coal wastes self-burning

NASA Astrophysics Data System (ADS)

Laufek, František; Veselovsky, František; Drábek, Milan; Kříbek, Bohdan; Klementová, Mariana

2017-04-01

The formation of sulfides, selenides and chlorides was experimentally studied at 800 or 900°C in the presence of sal ammoniac in a sealed silica glass tube. Synthetic PbS, PbSe, SnS, GeS, SnGeS2, PbSnS3, SnS and Sb2S3 or natural uraninite were used as a starting charge. Depending on the chemical composition of the sulfide/selenide charge, galena, unnamed SnGeS3 phase, herzenbergite, berndite, ottenmannite, stibnite and unnamed SnSb2S4 and Sn2Sb3S6 phases were identified in sublimates, together with cotunnite and an unnamed (NH4)2SnCl6 phase. When natural uraninite in a mixture with sal ammoniac was used as a charge, the reaction product comprised abundant cotunnite and minor challacolloite due to volatilization of radiogenic lead. When sulfur was introduced to the charge with uraninite and sal ammoniac, galena was found in reaction products. The results of our experiments revealed that if sulfide or selenide phases and NH4Cl are placed in a thermal gradient, it is possible to accelerate their mobility through a process of hydrogen chloride vapor transport. Within the transport process, new solid products are either isochemical or non-isochemical. The isochemical composition of resulting phases with charge probably represents simple sublimation of the original solid phase in form of self-vapor. The non-isochemical phases are probably formed due to combination of sublimation and condensation of various gas components including gaseous HCl. The valency change of metals (e.g. Sn2+ to Sn3+) in several reaction products indicates redox reactions in the gas mixture or during the solidification of resulting products. The role of ammoniac is not clear; however, formation of unnamed (NH4)2SnCl6 compound identified in one of our experiment, indicate possible formation of ammonium complexes. In contrast to experiments where sulfides or selenides were used as a part of charge, mobility of uraninite was not proved under experimental conditions employed. It is consistent with an absence of uranium minerals in products of self-burning. The product of uraninite thermal decomposition was predominantly lead chloride (cotunnite) resulting from the release of radiogenic lead from uraninite structure. However, when sulfur was added to the charge, skeletal crystals of galena were found in the reaction products. Acknowledgments: This study was carried out within the Czech Science Foundation grant project "A model of mobilization and geochemical cycles of potentially hazardous elements and organic compounds in burnt coal heaps" (GACR 15-11674S panel P210).

Determination of volatile organic acids in oriental tobacco by needle-based derivatization headspace liquid-phase microextraction coupled to gas chromatography/mass spectrometry.

PubMed

Sun, Shi-Hao; Xie, Jian-Ping; Xie, Fu-Wei; Zong, Yong-Li

2008-02-01

A method coupling needle-based derivatization headspace liquid-phase microextraction with gas chromatography-mass spectrometry (HS-LPME/GC-MS) was developed to determine volatile organic acids in tobacco. The mixture of N,O-bis(trimethylsilyl)trifluoroacetamide and decane was utilized as the solvent for HS-LPME, resulting that extraction and derivatization were simultaneously completed in one step. The solvent served two purposes. First, it pre-concentrated volatile organic acids in the headspace of tobacco sample. Second, the volatile organic acids extracted were derivatized to form silyl derivatives in the drop. The main parameters affecting needle-based derivatization HS-LPME procedure such as extraction and derivatization reagent, microdrop volume, extraction and derivatization time, and preheating temperature and preheating time were optimized. The standard addition approach was essential to obtain accurate measurements by minimizing matrix effects. Good linearity (R(2)> or =0.9804) and good repeatability (RSDs< or =15.3%, n=5) for 16 analytes in spiked standard analytes sample were achieved. The method has the additional advantages that at the same time it is simple, fast, effective, sensitive, selective, and provides an overall profile of volatile organic acids in the oriental tobacco. This paper does offer an alternative approach to determine volatile organic acids in tobacco.

High-mobility BaSnO 3 grown by oxide molecular beam epitaxy

DOE PAGES

Raghavan, Santosh; Schumann, Timo; Kim, Honggyu; ...

2016-01-28

High-mobility perovskite BaSnO 3 films are of significant interest as newwide bandgap semiconductors for power electronics, transparent conductors, and as high mobility channels for epitaxial integration with functional perovskites. Despite promising results for single crystals, high-mobility BaSnO 3 films have been challenging to grow. Here, we demonstrate a modified oxide molecular beam epitaxy (MBE) approach, which supplies pre-oxidized SnO x. This technique addresses issues in the MBE of ternary stannates related to volatile SnO formation and enables growth of epitaxial, stoichiometric BaSnO 3. We demonstrate room temperature electron mobilities of 150 cm 2 V -1 s -1 in films grownmore » on PrScO 3. Lastly, the results open up a wide range of opportunities for future electronic devices.« less

Evaluation of volatile metabolites as markers in Lycopersicon esculentum L. cultivars discrimination by multivariate analysis of headspace solid phase microextraction and mass spectrometry data.

PubMed

Figueira, José; Câmara, Hugo; Pereira, Jorge; Câmara, José S

2014-02-15

To gain insights on the effects of cultivar on the volatile metabolomic expression of different tomato (Lycopersicon esculentum L.) cultivars--Plum, Campari, Grape, Cherry and Regional, cultivated under similar edafoclimatic conditions, and to identify the most discriminate volatile marker metabolites related to the cultivar, the chromatographic profiles resulting from headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-qMS) analysis, combined with multivariate analysis were investigated. The data set composed by the 77 volatile metabolites identified in the target tomato cultivars, 5 of which (2,2,6-trimethylcyclohexanone, 2-methyl-6-methyleneoctan-2-ol, 4-octadecyl-morpholine, (Z)-methyl-3-hexenoate and 3-octanone) are reported for the first time in tomato volatile metabolomic composition, was evaluated by chemometrics. Firstly, principal component analysis was carried out in order to visualise data trends and clusters, and then, linear discriminant analysis in order to detect the set of volatile metabolites able to differentiate groups according to tomato cultivars. The results obtained revealed a perfect discrimination between the different Lycopersicon esculentum L. cultivars considered. The assignment success rate was 100% in classification and 80% in prediction ability by using "leave-one-out" cross-validation procedure. The volatile profile was able to differentiate all five cultivars and revealed complex interactions between them including the participation in the same biosynthetic pathway. The volatile metabolomic platform for tomato samples obtained by HS-SPME/GC-qMS here described, and the interrelationship detected among the volatile metabolites can be used as a roadmap for biotechnological applications, namely to improve tomato aroma and their acceptance in the final consumer, and for traceability studies. Copyright © 2013 Elsevier Ltd. All rights reserved.

Vaporization or Chemical Reaction: Which controls the fate of contaminants treated by in situ thermal remediation?

EPA Science Inventory

Thermal remediation technologies, which includes steam enhanced extraction, electrical resistance heating, and thermal conductive heating, have been developed based on technologies employed by the enhanced oil recovery industry. Although mobilization and/or volatilization of con...

Multicriteria adaptation principle on example of groups of mobile robots

NASA Astrophysics Data System (ADS)

Nelyubin, A. P.; Misyurin, S. Yu

2017-12-01

The article presents a multicriteria approach to the adaptation of groups of search, explore or research robots to unknown and volatile environment conditions. The basis of this approach is the application of multicriteria analysis both at the design stage of a group of mobile robots and at the stage of its adaptation in real-time conditions. It is proposed to maintain a variety of robots by properties and by optimality criteria in order to take into account the preferred mode of operation.

The Exploration Water Recovery System

NASA Technical Reports Server (NTRS)

ORourke, Mary Jane E.; Carter, Layne; Holder, Donald W.; Tomes, Kristin M.

2006-01-01

The Exploration Water Recovery System is designed towards fulfillment of NASA s Vision for Space Exploration, which will require elevation of existing technologies to higher levels of optimization. This new system, designed for application to the Exploration infrastructure, presents a novel combination of proven air and water purification technologies. The integration of unit operations is modified from that of the current state-of-the-art water recovery system so as to optimize treatment of the various waste water streams, contaminant loads, and flow rates. Optimization is achieved primarily through the removal of volatile organic contaminants from the vapor phase prior to their absorption into the liquid phase. In the current state-of-the-art system, the water vapor in the cabin atmosphere is condensed, and the volatile organic contaminants present in that atmosphere are absorbed into the aqueous phase. Removal of contaminants the5 occurs via catalytic oxidation in the liquid phase. Oxidation kinetics, however, dictate that removal of volatile organic contaminants from the vapor phase can inherently be more efficient than their removal from the aqueous phase. Taking advantage of this efficiency reduces the complexity of the water recovery system. This reduction in system complexity is accompanied by reductions in the weight, volume, power, and resupply requirements of the system. Vapor compression distillation technology is used to treat the urine, condensate, and hygiene waste streams. This contributes to the reduction in resupply, as incorporation of vapor compression distillation technology at this point in the process reduces reliance on the expendable ion exchange and adsorption media used in the current state-of-the-art water recovery system. Other proven technologies that are incorporated into the Exploration Water Recovery System include the Trace Contaminant Control System and the Volatile Removal Assembly.

Phased Arrays of Ground and Airborne Mobile Terminals for Satellite Communications

NASA Technical Reports Server (NTRS)

Huang, John

1996-01-01

Phased array antenna is beginning to play an important in the arena of mobile/satellite communications. Two examples of mobile terminal phased arrays will be shown. Their technical background, challenges, and cost drivers will be discussed. A possible solution to combat some of the deficiencies of the conventional phased array by exploiting the phased reflectarray technology will be briefly presented.

Effects of sulfur on lead partitioning during sludge incineration based on experiments and thermodynamic calculations.

PubMed

Liu, Jing-yong; Huang, Shu-jie; Sun, Shui-yu; Ning, Xun-an; He, Rui-zhe; Li, Xiao-ming; Chen, Tao; Luo, Guang-qian; Xie, Wu-ming; Wang, Yu-Jie; Zhuo, Zhong-xu; Fu, Jie-wen

2015-04-01

Experiments in a tubular furnace reactor and thermodynamic equilibrium calculations were conducted to investigate the impact of sulfur compounds on the migration of lead (Pb) during sludge incineration. Representative samples of typical sludge with and without the addition of sulfur compounds were combusted at 850 °C, and the partitioning of Pb in the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that three types of sulfur compounds (S, Na2S and Na2SO4) added to the sludge could facilitate the volatilization of Pb in the gas phase (fly ash and flue gas) into metal sulfates displacing its sulfides and some of its oxides. The effect of promoting Pb volatilization by adding Na2SO4 and Na2S was superior to that of the addition of S. In bottom ash, different metallic sulfides were found in the forms of lead sulfide, aluminosilicate minerals, and polymetallic-sulfides, which were minimally volatilized. The chemical equilibrium calculations indicated that sulfur stabilizes Pb in the form of PbSO4(s) at low temperatures (<1000 K). The equilibrium calculation prediction also suggested that SiO2, CaO, TiO2, and Al2O3 containing materials function as condensed phase solids in the temperature range of 800-1100 K as sorbents to stabilize Pb. However, in the presence of sulfur or chlorine or the co-existence of sulfur and chlorine, these sorbents were inactive. The effect of sulfur on Pb partitioning in the sludge incineration process mainly depended on the gas phase reaction, the surface reaction, the volatilization of products, and the concentration of Si, Ca and Al-containing compounds in the sludge. These findings provide useful information for understanding the partitioning behavior of Pb, facilitating the development of strategies to control the volatilization of Pb during sludge incineration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Emission of intermediate, semi and low volatile organic compounds from traffic and their impact on secondary organic aerosol concentrations over Greater Paris

NASA Astrophysics Data System (ADS)

Sartelet, K.; Zhu, S.; Moukhtar, S.; André, M.; André, J. M.; Gros, V.; Favez, O.; Brasseur, A.; Redaelli, M.

2018-05-01

Exhaust particle emissions are mostly made of black carbon and/or organic compounds, with some of these organic compounds existing in both the gas and particle phases. Although emissions of volatile organic compounds (VOC) are usually measured at the exhaust, emissions in the gas phase of lower volatility compounds (POAvapor) are not. However, these gas-phase emissions may be oxidised after emission and enhance the formation of secondary organic aerosols (SOA). They are shown here to contribute to most of the SOA formation in Central Paris. POAvapor emissions are usually estimated from primary organic aerosol emissions in the particle phase (POA). However, they could also be estimated from VOC emissions for both gasoline and diesel vehicles using previously published measurements from chamber measurements. Estimating POAvapor from VOC emissions and ageing exhaust emissions with a simple model included in the Polyphemus air-quality platform compare well to measurements of SOA formation performed in chamber experiments. Over Greater Paris, POAvapor emissions estimated using POA and VOC emissions are compared using the HEAVEN bottom-up traffic emissions model. The impact on the simulated atmospheric concentrations is then assessed using the Polyphemus/Polair3D chemistry-transport model. Estimating POAvapor emissions from VOC emissions rather than POA emissions lead to lower emissions along motorway axes (between -50% and -70%) and larger emissions in urban areas (up to between +120% and +140% in Central Paris). The impact on total organic aerosol concentrations (gas plus particle) is lower than the impact on emissions: between -8% and 25% along motorway axes and in urban areas respectively. Particle-phase organic concentrations are lower when POAvapor emissions are estimated from VOC than POA emissions, even in Central Paris where the total organic aerosol concentration is higher, because of different assumptions on the emission volatility distribution, stressing the importance of characterizing not only the emission strength, but also the emission volatility distribution.

Simulated molecular-scale interaction of supercritical fluid mobile and stationary phases.

PubMed

Siders, Paul D

2017-12-08

In supercritical fluid chromatography, molecules from the mobile phase adsorb on the stationary phase. Stationary-phase alkylsilane-terminated silica surfaces might adsorb molecules at the silica, among the silanes, on a silane layer, or in pore space between surfaces. Mobile phases of carbon dioxide, pure and modified with methanol, and stationary phases were simulated at the molecular scale. Classical atomistic force fields were used in Gibbs-ensemble hybrid Monte Carlo calculations. Excess adsorption of pure carbon dioxide mobile phase peaked at fluid densities of 0.002-0.003Å -3 . Mobile phase adsorption from 7% methanol in carbon dioxide peaked at lower fluid density. Methanol was preferentially adsorbed from the mixed fluid. Surface silanes prevented direct interaction of fluid-phase molecules with silica. Some adsorbed molecules mixed with tails of bonded silanes; some formed layers above the silanes. Much adsorption occurred by filling the space between surfaces in the stationary-phase model. The distribution in the stationary phase of methanol molecules from a modified fluid phase varied with pressure. Copyright © 2017 Elsevier B.V. All rights reserved.

Core-Mantle Partitioning of Volatile Siderophile Elements and the Origin of Volatile Elements in the Earth

NASA Technical Reports Server (NTRS)

Nickodem, K.; Righter, K.; Danielson, L.; Pando, K.; Lee, C.

2012-01-01

There are currently several hypotheses on the origin of volatile siderophile elements in the Earth. One hypothesis is that they were added during Earth s accretion and core formation and mobilized into the metallic core [1], others claim multiple stage origin [2], while some hypothesize that volatiles were added after the core already formed [3]. Several volatile siderophile elements are depleted in Earth s mantle relative to the chondrites, something which continues to puzzle many scientists. This depletion is likely due to a combination of volatility and core formation. The Earth s core is composed of Fe and some lighter constituents, although the abundances of these lighter elements are unknown [4]. Si is one of these potential light elements [5] although few studies have analyzed the effect of Si on metal-silicate partitioning, in particular the volatile elements. As, In, Ge, and Sb are trace volatile siderophile elements which are depleted in the mantle but have yet to be extensively studied. The metal-silicate partition coefficients of these elements will be measured to determine the effect of Si. Partition coefficients depend on temperature, pressure, oxygen fugacity, and metal and silicate composition and can constrain the concentrations of volatile, siderophile elements found in the mantle. Reported here are the results from 13 experiments examining the partitioning of As, In, Ge, and Sb between metallic and silicate liquid. These experiments will examine the effect of temperature, and metal-composition (i.e., Si content) on these elements in or-der to gain a greater understanding of the core-mantle separation which occurred during the Earth s early stages. The data can then be applied to the origin of volatile elements in the Earth.

Evaluation of the separation characteristics of application-specific (volatile organic compounds) open-tubular columns for gas chromatography.

PubMed

Poole, Colin F; Qian, Jing; Kiridena, Waruna; Dekay, Colleen; Koziol, Wladyslaw W

2006-11-17

The solvation parameter model is used to characterize the separation characteristics of two application-specific open-tubular columns (Rtx-Volatiles and Rtx-VGC) and a general purpose column for the separation of volatile organic compounds (DB-WAXetr) at five equally spaced temperatures over the range 60-140 degrees C. System constant differences and retention factor correlation plots are then used to determine selectivity differences between the above columns and their closest neighbors in a large database of system constants and retention factors for forty-four open-tubular columns. The Rtx-Volatiles column is shown to have separation characteristics predicted for a poly(dimethyldiphenylsiloxane) stationary phase containing about 16% diphenylsiloxane monomer. The Rtx-VGC column has separation properties similar to the poly(cyanopropylphenyldimethylsiloxane) stationary phase containing 14% cyanopropylphenylsiloxane monomer DB-1701 for non-polar and dipolar/polarizable compounds but significantly different characteristics for the separation of hydrogen-bond acids. For all practical purposes the DB-WAXetr column is shown to be selectivity equivalent to poly(ethylene glycol) columns prepared using different chemistries for bonding and immobilizing the stationary phase. Principal component analysis and cluster analysis are then used to classify the system constants for the above columns and a sub-database of eleven open-tubular columns (DB-1, HP-5, DB-VRX, Rtx-20, DB-35, Rtx-50, Rtx-65, DB-1301, DB-1701, DB-200, and DB-624) commonly used for the separation of volatile organic compounds. A rationale basis for column selection based on differences in intermolecular interactions is presented as an aid to method development for the separation of volatile organic compounds.

Heterogeneously entrapped, vapor-rich melt inclusions record pre-eruptive magmatic volatile contents

NASA Astrophysics Data System (ADS)

Steele-MacInnis, Matthew; Esposito, Rosario; Moore, Lowell R.; Hartley, Margaret E.

2017-04-01

Silicate melt inclusions (MI) commonly provide the best record of pre-eruptive H2O and CO2 contents of subvolcanic melts, but the concentrations of CO2 and H2O in the melt (glass) phase within MI can be modified by partitioning into a vapor bubble after trapping. Melt inclusions may also enclose vapor bubbles together with the melt (i.e., heterogeneous entrapment), affecting the bulk volatile composition of the MI, and its post-entrapment evolution. In this study, we use numerical modeling to examine the systematics of post-entrapment volatile evolution within MI containing various proportions of trapped vapor from zero to 95 volume percent. Modeling indicates that inclusions that trap only a vapor-saturated melt exhibit significant decrease in CO2 and moderate increase in H2O concentrations in the melt upon nucleation and growth of a vapor bubble. In contrast, inclusions that trap melt plus vapor exhibit subdued CO2 depletion at equivalent conditions. In the extreme case of inclusions that trap mostly the vapor phase (i.e., CO2-H2O fluid inclusions containing trapped melt), degassing of CO2 from the melt is negligible. In the latter scenario, the large fraction of vapor enclosed in the MI during trapping essentially serves as a buffer, preventing post-entrapment modification of volatile concentrations in the melt. Hence, the glass phase within such heterogeneously entrapped, vapor-rich MI records the volatile concentrations of the melt at the time of trapping. These numerical modeling results suggest that heterogeneously entrapped MI containing large vapor bubbles represent amenable samples for constraining pre-eruptive volatile concentrations of subvolcanic melts.

A new acetonitrile-free mobile phase method for LC-ELSD quantification of fructooligosaccharides in onion (Allium cepa L.).

PubMed

Downes, Katherine; Terry, Leon A

2010-06-30

Onion soluble non-structural carbohydrates consist of fructose, glucose and sucrose plus fructooligosaccharides (FOS) with degrees of polymerisation (DP) in the range of 3-19. In onion, sugars and FOS are typically separated using liquid chromatography (LC) with acetonitrile (ACN) as a mobile phase. In recent times, however, the production of ACN has diminished due, in part, to the current worldwide economic recession. A study was therefore undertaken, to find an alternative LC method to quantify sugars and FOS from onion without the need for ACN. Two mobile phases were compared; the first taken from a paper by Vågen and Slimestad (2008) using ACN mobile phase, the second, a newly reported method using ethanol (EtOH). The EtOH mobile phase eluted similar concentrations of all FOS compared to the ACN mobile phase. In addition, limit of detection, limit of quantification and relative standard deviation values were sufficiently and consistently lower for all FOS using the EtOH mobile phase. The drawback of the EtOH mobile phase was mainly the inability to separate all individual sugar peaks, yet FOS could be successfully separated. However, using the same onion extract, a previously established LC method based on an isocratic water mobile phase could be used in a second run to separate sugars. Although the ACN mobile phase method is more convenient, in the current economic climate a method based on inexpensive and plentiful ethanol is a valid alternative and could potentially be applied to other fresh produce types. In addition to the mobile phase solvent, the effect of extraction solvents on sugar and FOS concentration was also investigated. EtOH is still widely used to extract sugars from onion although previous literature has concluded that MeOH is a superior solvent. For this reason, an EtOH-based extraction method was compared with a MeOH-based method to extract both sugars and FOS. The MeOH-based extraction method was more efficacious at extracting sugars and FOS from onion flesh, eluting significantly higher concentrations of glucose, kestose, nystose and DP5-DP8. Copyright 2010 Elsevier B.V. All rights reserved.

Traders' behavioral coupling and market phase transition

NASA Astrophysics Data System (ADS)

Ma, Rong; Zhang, Yin; Li, Honggang

2017-11-01

Traditional economic theory is based on the assumption that traders are completely independent and rational; however, trading behavior in the real market is often coupled by various factors. This paper discusses behavioral coupling based on the stock index in the stock market, focusing on the convergence of traders' behavior, its effect on the correlation of stock returns and market volatility. We find that the behavioral consensus in the stock market, the correlation degree of stock returns, and the market volatility all exhibit significant phase transitions with stronger coupling.

Untargeted metabolomic analysis using liquid chromatography quadrupole time-of-flight mass spectrometry for non-volatile profiling of wines.

PubMed

Arbulu, M; Sampedro, M C; Gómez-Caballero, A; Goicolea, M A; Barrio, R J

2015-02-09

The current study presents a method for comprehensive untargeted metabolomic fingerprinting of the non-volatile profile of the Graciano Vitis vinifera wine variety, using liquid chromatography/electrospray ionization time of flight mass spectrometry (LC-ESI-QTOF). Pre-treatment of samples, chromatographic columns, mobile phases, elution gradients and ionization sources, were evaluated for the extraction of the maximum number of metabolites in red wine. Putative compounds were extracted from the raw data using the extraction algorithm, molecular feature extractor (MFE). For the metabolite identification the WinMet database was designed based on electronic databases and literature research and includes only the putative metabolites reported to be present in oenological matrices. The results from WinMet were compared with those in the METLIN database to evaluate how much the databases overlap for performing identifications. The reproducibility of the analysis was assessed using manual processing following replicate injections of Vitis vinifera cv. Graciano wine spiked with external standards. In the present work, 411 different metabolites in Graciano Vitis vinifera red wine were identified, including primary wine metabolites such as sugars (4%), amino acids (23%), biogenic amines (4%), fatty acids (2%), and organic acids (32%) and secondary metabolites such as phenols (27%) and esters (8%). Significant differences between varieties Tempranillo and Graciano were related to the presence of fifteen specific compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

Polycyclic Aromatic Hydrocarbon Sources and Trapping within Secondary Organic Aerosol

NASA Astrophysics Data System (ADS)

Wallace, H. W., IV; Sanchez, N. P.; Flynn, J. H., III; Lefer, B. L.; Bottenus, C. L. H.; VanReken, T. M.; Griffin, R. J.

2017-12-01

As part of the BEETEX field study, which occurred from Feburary 7 to 27, 2015, a mobile air quality laboratory was stationed near a major refinery proximate to the Houston Ship Channel to characterize the chemical nature and sources of atmospheric particulate matter (PM) using a high-resolution time-of-flight mass spectrometer. Positive matrix factorization (PMF) was performed on the organic signal of the aerosol mass spectra, resulting in five factors totaling an average of 4.1 μg/m3 of organic aerosol: hydrocarbon-like (0.67 μg/m3), cooking (0.35 μg/m3), biomass burning (1.14 μg/m3), low-volatility oxidized (1.15 μg/m3), and semi-volatile oxidized (0.78 μg/m3). As part of this study, two techniques to quantify particulate polycyclic aromatic hydrocarbons (PAHs) were compared: one capable of quantifying non-refractory molecular ion PAHs and the other sensitive only to surface bound PAHs. Together with PMF model results on the non-refractory organic PM data, we show that particulate PAHs likely are trapped inside secondary organic aerosol (SOA) as it deposits onto particles and that the two major sources of PAHs in the area are from biomass burning and use of internal combustion engines. Because this SOA may prevent particle-phase consumption of the PAH material, these results have important implications for long-range transport of particulate PAHs.

Development of Electrospun Nanomaterials and their Applications in Separation Science

NASA Astrophysics Data System (ADS)

Newsome, Toni Elwell

In separations, efficiency is inversely related to the diameter of the sorbent particles of the stationary phase. Thus, materials research in separation science has primarily been directed towards reducing the diameter of the sorbent particle used in the stationary phase. In this dissertation, innovative methods designed for the fabrication and application of electrospun sorbent nanomaterials for separation science are described. Electrospinning is a facile, cost-effective technique that relies on repulsive electrostatic forces to produce nanofibers from a viscoelastic solution. Here, electrospinning is used to generate polymer, carbon, and silica-based nanofibers which are employed as sorbent nanomaterials in extractions and separations. Electrospun carbon nanofibers have proven to be ideal extractive phases for solid-phase microextraction (SPME) when coupled to gas chromatography (GC) for headspace sampling of volatile analytes. Herein, these carbon nanofibers were employed in the direct extraction of nonvolatile analytes and coupled to liquid chromatography (LC) for the first time. The high surface area of the coatings led to enhanced extraction efficiencies; they offered a 3-33 fold increase in efficiency relative to a commercial SPME phase. Carbon nanofibers proved to be stable when immersed in liquids common to LC demonstrating the enhanced stability of these coatings in SPME coupled to LC relative to conventional SPME fibers. The enhanced chemical and mechanical stability of the carbon SPME coatings considerably expanded the range of compounds applicable to SPME and extended the lifetimes of the fibers. Electrospun nanofibers have also proven to be ideal stationary phases in ultra-thin layer chromatography (UTLC). Nanofibers provide faster separations and enhanced separation efficiencies compared to commercial particle-based stationary phases in a relatively short distance. Here, the electrospun-UTLC technology was extended for the first time to nanofibers composed of silica, the most commonly used surface for TLC. An electrospinning method was optimized to produce silica-based nanofibers with the smallest diameter possible (300-380 nm) while maintaining homogenous nanofiber morphology. Highly efficient separations were performed in 15 mm with observed plate heights as low as 8.6 mum. Silica-based nanofibers proved to be chemically stable with a wide variety of TLC reagents demonstrating the enhanced compatibility of these phases with common TLC methods relative to polymer and carbon nanofiber UTLC plates. The extension of electrospun UTLC to silica-based nanofibers vastly expanded the range of analytes and TLC methods which can be used with this technology. The main disadvantage of conventional TLC development methods is that the mobile phase velocity decreases with increasing separation distance. Here, the chromatographic performance of electrospun polymer stationary phases was further improved by using a forced-flow mobile phase in planar electrochromatography (PEC) in which mobile phase velocity does not diminish with increasing distance. Separations were performed on polymer nanofiber UTLC plates in 1-2 min. Compared to UTLC, PEC offered unique selectivity, decreased analysis times (> 4 times faster), and enhanced efficiency (2-3 times lower plate height). In addition, two-dimensional (2D) separations of a complex analyte mixture using UTLC followed by PEC required only 11 min and exhibited a significant increase in separation number (70-77).

Preparation of novel alumina nanowire solid-phase microextraction fiber coating for ultra-selective determination of volatile esters and alcohols from complicated food samples.

PubMed

Zhang, Zhuomin; Ma, Yunjian; Wang, Qingtang; Chen, An; Pan, Zhuoyan; Li, Gongke

2013-05-17

A novel alumina nanowire (ANW) solid-phase microextraction (SPME) fiber coating was prepared by a simple and rapid anodization-chemical etching method for ultra-selective determination of volatile esters and alcohols from complicated food samples. Preparation conditions for ANW SPME fiber coating including corrosion solution concentration and corrosion time were optimized in detail for better surface morphology and higher surface area based on scanning electron microscope (SEM). Under the optimum conditions, homogeneous alumina nanowire structure of ANW SPME fiber coating was achieved with the average thickness of 20 μm around. Compared with most of commercial SPME fiber coatings, ANW SPME fiber coatings achieved the higher extraction capacity and special selectivity for volatile esters and alcohols. Finally, an efficient gas sampling technique based on ANW SPME fiber coating as the core was established and successfully applied for the ultra-selective determination of trace volatile esters and alcohols from complicated banana and fermented glutinous rice samples coupled with gas chromatography/mass spectrometry (GC/MS) detection. It was interesting that 25 esters and 2 alcohols among 30 banana volatile organic compounds (VOCs) identified and 4 esters and 7 alcohols among 13 identified VOCs of fermented glutinous rice were selectively sampled by ANW SPME fiber coatings. Furthermore, new analytical methods for the determination of some typical volatile esters and alcohols from banana and fermented glutinous rice samples at specific storage or brewing phases were developed and validated. Good recoveries for banana and fermented glutinous rice samples were achieved in range of 108-115% with relative standard deviations (RSDs) of 2.6-6.7% and 80.0-91.8% with RSDs of 0.3-1.3% (n=3), respectively. This work proposed a novel and efficient gas sampling technique of ANW SPME which was quite suitable for ultra-selectively sampling trace volatile esters and alcohols from complicated food samples. Copyright © 2013 Elsevier B.V. All rights reserved.

77 FR 32092 - Mobility Fund Phase I Auction Scheduled for September 27, 2012; Notice and Filing Requirements...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-31

... Mobility Fund Phase I support they seek, including any agreements relating to post-auction market structure... FEDERAL COMMUNICATIONS COMMISSION [AU Docket No. 12-25; DA 12-641 and DA 12-721] Mobility Fund... million in one-time Mobility Fund Phase I support scheduled to commence on September 27, 2012. The Bureaus...

Comparative Demonstration of Active and Semi-Passive In Situ Bioremediation Approaches for Perchlorate-Impacted Groundwater at Longhorn Army Ammunitions Plant

DTIC Science & Technology

2009-01-01

lactate, citric acid , or ethanol have been used in field applications. Biomass grows rapidly during the active phase when high concentrations of...6.7.4 Results of Oxidation Reduction Potential (ORP) Monitoring.............39 6.7.5 Results of Volatile Fatty Acids (VFA) Analysis...trinitrotoluene USEPA U.S. Environmental Protection Agency VC vinyl chloride VFA volatile fatty acid VOC volatile organic compounds Technical

Profiles of Volatile Compounds in Black Currant (Ribes nigrum) Cultivars with Special Focus on Influence of Growth Latitude and Weather Conditions.

PubMed

Marsol-Vall, Alexis; Kortesniemi, Maaria Katariina; Karhu, Saila; Kallio, Heikki; Yang, Baoru

2018-06-25

The volatile profile of three blackcurrant (Ribes nigrum L.) cultivars grown in Finland and their response to growth latitude and weather conditions were studied over an eight-year period by headspace solid-phase microextraction (HS-SPME) followed by gas chromatographic-mass spectrometric (GC-MS) analysis. Monoterpene hydrocarbons and oxygenated monoterpenes were the major classes of volatiles. The cultivar 'Melalahti' presented lower content of volatiles compared with 'Ola' and 'Mortti', the two latter showing a very similar composition. Higher contents of volatiles were found in berries cultivated at higher latitude (66° 34' N) than in those from the southern location (60° 23' N). Among the meteorological variables, radiation and temperature during the last month before harvest were negatively linked with the volatile content. Storage time had a negative impact on the amount of blackcurrant volatiles.

Pluto and Charon Seen with the New Horizons Spacecraft

NASA Technical Reports Server (NTRS)

Cruikshank, D. P.; Stern, S. A.; Weaver, H. A.; Young, L. A.; Ennico, K.; Olkin, C. B.

2016-01-01

After nearly a decade en route, New Horizons flew through the Pluto system in July 2015. The encounter hemisphere of Pluto shows ongoing surface geological activity centered on a vast basin (Sputnik Planum [SP]*) containing a thick layer of volatile ices with a crater retention age no greater than approximately 10 Ma. Surrounding terrains show active glacial flow, apparent transport and rotation of large buoyant water-ice crustal blocks, and pitting, likely by sublimation erosion and/or collapse. Also seen are constructional mounds with central depressions, and ridges with complex bladed textures. Pluto has ancient cratered terrains up to approximately 4 Ga old that are fractured and mantled, and perhaps eroded by glacial processes. Charon does not appear to be currently active, but experienced major tectonism and resurfacing nearly 4 Ga ago. Imaging spectrometer observations of Pluto reveal the encounter hemisphere to be dominated by volatile ices of N2, CO, and CH4, along with non-volatile components that include H2O and tholins. The most volatile of Pluto's ices (N2 and CO) are especially prevalent in the western half of Tombaugh Regio (TR), and the strikingly flat Sputnik Planum basin, which lies a few km below surrounding elevations. The high mobility of N2 and CO ices enables SP's surface to refresh itself sufficiently rapidly that no impact craters are seen there. This likely occurs through a combination of solid state convective overturning and sublimation/ condensation that produces regular patterns of pits and ridges on scales of 102 to 103 m. In many areas, CH4 appears to favor topographically high regions. Its propensity to condense on ridges could play a role in forming the bladed terrain seen in Tartarus Dorsa. H2O can be discerned across much of Cthulhu Regio, and also in a few isolated spots. In many regions, H2O ice is associated with reddish tholin coloration. Pluto's atmosphere was probed with the radio science experiment (REX) and the Alice UV spectrometer, as well as imaging at high phase angles. The surface pressure, due mostly to N2, is approximately 11 microbars. Extensive multiple haze layers are seen in the images. Alice has detected hydrocarbons in addition to CH4 in the atmosphere. Since both are inert, H2O ice and tholin could have similar geological behaviors on Pluto, possibly including aeolian transport or mobilization by volatile ice glaciation. While Pluto's H2O ice is sculpted and at least partially veiled by more volatile ices, Charon's heavily cratered H2O ice is exposed globally. H2O ice spectral bands characteristic of crystalline ice are seen everywhere on the encounter hemisphere. Charon's north polar region is strikingly red, possibly the result of the unique thermal environment of Charon's poles, which become exceptionally cold during the long, dark winters. Extremely cold regions on Charon' could cold trap gases expanding outward from Pluto as ices, and thereby subject them to rapid radiolytic processing. Charon also exhibits a weak NH3 absorption band over most or all of its surface, with small local concentrations. Detailed results of the radio science, small satellite, particles and plasma, and atmosphere investigations are in press.

LOW-VOC COATINGS FOR AUTOMOBILE REFINISHING USING NOVEL POLYMER RESINS

EPA Science Inventory

Coating operations release a significant portion of the non-mobile source, volatile organic compounds (VOCs) into the air. The U.S. EPA's Emissions Characterization and Prevention Branch has formulated novel low-VOC coatings for the automotive refinishing sector that reduce VOC l...

Combined effects of mobile phase composition and temperature on the retention of phenolic antioxidants on an octylsilica polydentate column.

PubMed

Jandera, Pavel; Vyňuchalová, Kateřina; Nečilová, Kateřina

2013-11-22

Combined effects of temperature and mobile-phase composition on retention and separation selectivity of phenolic acids and flavonoid compounds were studied in liquid chromatography on a polydentate Blaze C8 silica based column. The temperature effects on the retention can be described by van't Hoff equation. Good linearity of lnk versus 1/T graphs indicates that the retention is controlled by a single mechanism in the mobile phase and temperature range studied. Enthalpic and entropic contributions to the retention were calculated from the regression lines. Generally, enthalpic contributions control the retention at lower temperatures and in mobile phases with lower concentrations of methanol in water. Semi-empirical retention models describe the simultaneous effects of temperature and the volume fraction of the organic solvent in the mobile phase. Using the linear free energy-retention model, selective dipolarity/polarizability, hydrogen-bond donor, hydrogen-bond acceptor and molecular size contributions to retention were estimated at various mobile phase compositions and temperatures. In addition to mobile phase gradients, temperature programming can be used to reduce separation times. Copyright © 2013 Elsevier B.V. All rights reserved.

Coexistence of non-volatile bi-polar resistive switching and tunneling magnetoresistance in spatially confined La0.3Pr0.4Ca0.3MnO3 films

NASA Astrophysics Data System (ADS)

Jeon, J.; Jung, J.; Chow, K. H.

2017-12-01

We report the coexistence of non-volatile bi-polar resistive switching (RS) and tunneling magnetoresistance (TMR) in spatially confined La0.3Pr0.4Ca0.3MnO3 films grown on LaAlO3 substrates. At certain temperatures, the arrangement of electronic phase domains in these narrow systems mimics those found in heterostructured metal-insulator-metal devices. The relative spin orientations between adjacent ferromagnetic metallic phase domains enable the TMR effect, while the creation/annihilation of conduction filaments between the metallic phase domains produces the RS effect.

Corona discharge ion mobility spectrometry with orthogonal acceleration time of flight mass spectrometry for monitoring of volatile organic compounds.

PubMed

Sabo, Martin; Matejčík, Štefan

2012-06-19

We demonstrate the application of corona discharge ion mobility spectrometry with orthogonal acceleration time of flight mass spectrometry (CD IMS-oaTOF) for volatile organic compounds (VOCs) monitoring. Two-dimensional (2D) IMS-oaTOF spectra of VOCs were recorded in nearly real time. The corona discharge atmospheric pressure chemical ionization (APCI) source was operated in positive mode in nitrogen and air. The CD ion source generates in air H(3)O(+)(H(2)O)(n) and NO(+). The NO(+) offers additional possibility for selective ionization and for an increase of the sensitivity of monoaromatic compounds. In addition to H(3)O(+)(H(2)O)(n) and NO(+), we have carried out ionization of VOCs using acetone as dopant gas ((CH(3))(2)COH(+)). Sixteen model VOCs (tetrahydrofuran, butanol, n-propanol, iso-propano, acetone, methanol, ethanol, toluene, benzene, amomnia, dioxan, triethylamine, acetonitrile, formaldehyde, m-xylene, 2,2,2-trifluoroethylamine) were tested using these ionization techniques.

Influence of enzymatic extrusion liquefaction pretreatment for Chinese rice wine on the volatiles generated from extruded rice.

PubMed

Xu, Enbo; Li, Hongyan; Wu, Zhengzong; Wang, Fang; Xu, Xueming; Jin, Zhengyu; Jiao, Aiquan

2015-01-01

Volatile compounds in enzymatic extruded rice, produced under different conditions of varying barrel temperature (BT), α-amylase concentration (AC) and moisture content (MC), were extracted and identified by headspace solid phase microextraction (HS-SPME) and gas chromatography-linked mass spectrometry (GC-MS). Statistical analyses reflected that the Maillard reaction could be inhibited both by the mild extrusion conditions and the enhanced hydrolysis caused by thermostable α-amylase. Relative amounts of total volatiles in enzymatic extruded rice were far less than those in severe processed extruded rice. Reverse-phase high-performance liquid chromatography (RP-HPLC) showed that the amino acids (AAs) involved in Maillrad reaction were utmostly preserved in extruded rice with highest amylase concentration by comparison of total AA content of different extrudates. These results suggest that enzymatic extrusion liquefaction is an effective way to control the generation of volatiles from extruded rice for Chinese rice wine production. © 2014 Institute of Food Technologists®

The influence of emulsion structure on the Maillard reaction of ghee.

PubMed

Newton, Angela E; Fairbanks, Antony J; Golding, Matt; Andrewes, Paul; Gerrard, Juliet A

2015-04-15

Food systems, such as cream and butter, have an emulsion or emulsion-like structure. When these food emulsions are heated to high temperatures to make products such as ghee, the Maillard reaction forms a range of volatile flavour compounds. The objective of this paper was to unravel the specific influence of emulsion structure on the Maillard reaction pathways that occur during the cooking of ghee using model systems. Switching the dispersed phase from oil to water provided a means of altering the ratios of volatile compounds produced in the cooked samples. The oil-in-water emulsion generated a volatile compound profile similar to that of the fat containing two phase model matrix, whereas the water-in-oil emulsion produced a different ratio of these compounds. The ability to generate different volatile compound profiles through the use of inverted emulsion structures could point to a new avenue for control of the Maillard reaction in high temperature food systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

Review of the fate and transformation of per- and polyfluoroalkyl substances (PFASs) in landfills.

PubMed

Hamid, Hanna; Li, Loretta Y; Grace, John R

2018-04-01

A critical review of existing publications is presented i) to summarize the occurrence of various classes of per- and polyfluoroalkyl substances (PFASs) and their sources in landfills, ii) to identify temporal and geographical trends of PFASs in landfills; iii) to delineate the factors affecting PFASs in landfills; and iv) to identify research gaps and future research directions. Studies have shown that perfluoroalkyl acids (PFAAs) are routinely detected in landfill leachate, with short chain (C4-C7) PFAAs being most abundant, possibly indicating their greater mobility, and reflecting the industrial shift towards shorter-chain compounds. Despite its restricted use, perfluorooctanoic acid (PFOA) remains one of the most abundant PFAAs in landfill leachates. Recent studies have also documented the presence of PFAA-precursors (e.g., saturated and unsaturated fluorotelomer carboxylic acids) in landfill leachates at concentrations comparable to, or higher than, the most frequently detected PFAAs. Landfill ambient air also contains elevated concentrations of PFASs, primarily semi-volatile precursors (e.g., fluorotelomer alcohols) compared to upwind control sites, suggesting that landfills are potential sources of atmospheric PFASs. The fate of PFASs inside landfills is controlled by a combination of biological and abiotic processes, with biodegradation releasing most of the PFASs from landfilled waste to leachate. Biodegradation in simulated anaerobic reactors has been found to be closely related to the methanogenic phase. The methane-yielding stage also results in higher pH (>7) of leachates, correlated with higher mobility of PFAAs. Little information exists regarding PFAA-precursors in landfills. To avoid significant underestimation of the total PFAS released from landfills, PFAA-precursors and their degradation products should be determined in future studies. Owing to the semi-volatile nature of some precursor compounds and their degradation products, future studies also need to include landfill gas to clarify degradation pathways and the overall fate of PFASs. Copyright © 2017 Elsevier Ltd. All rights reserved.

It's the little things that matter most: The role of volatiles in volcanoes and their magmatic roots

NASA Astrophysics Data System (ADS)

Keller, T.; Suckale, J.

2017-12-01

Many volcanic eruptions are driven by volatiles - mostly H2O and CO2 - that degas from magmas rising up beneath the volcano. Gas expands during ascent, thus frequently creating lavas with upward of 50% vesicularity. That is a particularly compelling observation considering that volatiles are only present at concentrations of order 100 ppm in the mantle source. Yet, even at these small concentrations, volatiles significantly lower the peridotite solidus. That leads to the production of reactive volatile-rich melts at depth, which has important consequences for melt transport in the asthenosphere. Thus, volatiles have a pivotal role both at the beginning and the end of the magmatic storyline. A growing amount of observational evidence provides various perspectives on these systems. Volcanic products are characterised increasingly well by geochemical and petrological data. And, volcano monitoring now often provides continuous records of degassing flux and composition. What is missing to better interpret these data are coupled fluid mechanic and thermodynamic models that link melt production and reactive transport in the mantle and crust with degassing-driven volcanic activity at the surface. Such models need to describe the deformation and segregation of multiple material phases (liquids, solids, gases) and track the reactive transport of diverse chemical components (major elements, trace elements, volatiles). I will present progress towards a generalization of existing two-phase model for melt transport in the mantle, extending them to three-phase flows appropriate for magma circulation and degassing in volcanoes. What sets the two environments apart is the presence of a compressible vapor in volcanoes. Also, volcanic degassing may occur by convecting suspensions as well as porous segregation. The model framework we are developing for these processes is based on mixture theory. Uncovering the underlying physics that connects these diverse expressions of magma transport will provide an opportunity to gain deeper insights into magmatic and volcanic phenomena as related rather than separate processes. In time we may thus come to more fully understand how it is that the little things that are mantle volatiles do matter most in volcanoes and their magmatic roots.

Measurement of spatial and temporal variation in volatile hazardous air pollutants in Tacoma, Washington, using a mobile membrane introduction mass spectrometry (MIMS) system.

PubMed

Davey, Nicholas G; Fitzpatrick, Cole T E; Etzkorn, Jacob M; Martinsen, Morten; Crampton, Robert S; Onstad, Gretchen D; Larson, Timothy V; Yost, Michael G; Krogh, Erik T; Gilroy, Michael; Himes, Kathy H; Saganić, Erik T; Simpson, Christopher D; Gill, Christopher G

2014-09-19

The objective of this study was to use membrane introduction mass spectrometry (MIMS), implemented on a mobile platform, in order to provide real-time, fine-scale, temporally and spatially resolved measurements of several hazardous air pollutants. This work is important because there is now substantial evidence that fine-scale spatial and temporal variations of air pollutant concentrations are important determinants of exposure to air pollution and adverse health outcomes. The study took place in Tacoma, WA during periods of impaired air quality in the winter and summer of 2008 and 2009. Levels of fine particles were higher in winter compared to summer, and were spatially uniform across the study area. Concentrations of vapor phase pollutants measured by membrane introduction mass spectrometry (MIMS), notably benzene and toluene, had relatively uniform spatial distributions at night, but exhibited substantial spatial variation during the day-daytime levels were up to 3-fold higher at traffic-impacted locations compared to a reference site. Although no direct side-by-side comparison was made between the MIMS system and traditional fixed site monitors, the MIMS system typically reported higher concentrations of specific VOCs, particularly benzene, ethylbenzene and naphthalene, compared to annual average concentrations obtained from SUMA canisters and gas chromatographic analysis at the fixed sites.

Influence of harvest maturity and fruit logistics on pineapple (Ananas comosus [L.] Merr.) volatiles assessed by headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC/MS).

PubMed

Steingass, Christof B; Grauwet, Tara; Carle, Reinhold

2014-05-01

Profiling of volatiles from pineapple fruits was performed at four ripening stages using headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC/MS). In total, 142 volatiles were detected, of which 132 were identified. Multivariate data analysis was carried out to assess the effect of post-harvest storage on volatiles composition of green-ripe sea-freighted pineapple in comparison to air-freighted fruits harvested at full maturity. The latter fruits were characterised by volatiles described as potent odorants in pineapples, such as δ-octalactone, γ-lactones, 1-(E,Z)-3,5-undecatriene and 1,3,5,8-undecatetraene, as well as various methyl esters. In contrast, post-harvest storage of green-ripe sea-freighted fruits resulted in an increased formation of ethyl esters, acetates, acetoxy esters and alcohols, thus allowing the authentication of sea- and air-freighted pineapples, respectively. Particularly, compounds presumably derived from methyl-branched amino acid catabolism were identified in the fruits at later post-harvest stages. In addition, physicochemical traits were determined to characterise the fruit maturity stages. Copyright © 2013 Elsevier Ltd. All rights reserved.

Headspace-Solid-Phase Microextraction-Gas Chromatography as Analytical Methodology for the Determination of Volatiles in Wild Mushrooms and Evaluation of Modifications Occurring during Storage

PubMed Central

Costa, Rosaria; De Grazia, Selenia; Grasso, Elisa; Trozzi, Alessandra

2015-01-01

Mushrooms are sources of food, medicines, and agricultural means. Not much is reported in the literature about wild species of the Mediterranean flora, although many of them are traditionally collected for human consumption. The knowledge of their chemical constituents could represent a valid tool for both taxonomic and physiological characterizations. In this work, a headspace-solid-phase microextraction (HS-SPME) method coupled with GC-MS and GC-FID was developed to evaluate the volatile profiles of ten wild mushroom species collected in South Italy. In addition, in order to evaluate the potential of this analytical methodology for true quantitation of volatiles, samples of the cultivated species Agaricus bisporus were analyzed. The choice of this mushroom was dictated by its ease of availability in the food market, due to the consistent amounts required for SPME method development. For calibration of the main volatile compounds, the standard addition method was chosen. Finally, the assessed volatile composition of A. bisporus was monitored in order to evaluate compositional changes occurring during storage, which represents a relevant issue for such a wide consumption edible product. PMID:25945282

Effect of Inorganic Salts on the Volatility of Organic Acids

PubMed Central

2014-01-01

Particulate phase reactions between organic and inorganic compounds may significantly alter aerosol chemical properties, for example, by suppressing particle volatility. Here, chemical processing upon drying of aerosols comprised of organic (acetic, oxalic, succinic, or citric) acid/monovalent inorganic salt mixtures was assessed by measuring the evaporation of the organic acid molecules from the mixture using a novel approach combining a chemical ionization mass spectrometer coupled with a heated flow tube inlet (TPD-CIMS) with kinetic model calculations. For reference, the volatility, i.e. saturation vapor pressure and vaporization enthalpy, of the pure succinic and oxalic acids was also determined and found to be in agreement with previous literature. Comparison between the kinetic model and experimental data suggests significant particle phase processing forming low-volatility material such as organic salts. The results were similar for both ammonium sulfate and sodium chloride mixtures, and relatively more processing was observed with low initial aerosol organic molar fractions. The magnitude of low-volatility organic material formation at an atmospherically relevant pH range indicates that the observed phenomenon is not only significant in laboratory conditions but is also of direct atmospheric relevance. PMID:25369247

Volatile components of vine leaves from two Portuguese grape varieties (Vitis vinifera L.), Touriga Nacional and Tinta Roriz, analysed by solid-phase microextraction.

PubMed

Fernandes, Bruno; Correia, Ana C; Cosme, Fernanda; Nunes, Fernando M; Jordão, António M

2015-01-01

The purpose of this work was to study the volatile composition of vine leaves and vine leaf infusion prepared from vine leaves collected at 30 and 60 days after grape harvest of two Vitis vinifera L. species. Eighteen volatile compounds were identified by gas chromatography-mass spectrometry in vine leaves and in vine leaf infusions. It was observed that the volatile compounds present in vine leaves are dependent on the time of harvest, with benzaldehyde being the major volatile present in vine leaves collected at 30 days after harvesting. There are significant differences in the volatile composition of the leaves from the two grape cultivars, especially in the sample collected at 60 days after grape harvest. This is not reflected in the volatile composition of the vine leaf infusion made from this two cultivars, the more important being the harvesting date for the volatile profile of vine leaf infusion than the vine leaves grape cultivar.

GCMS investigation of volatile compounds in green coffee affected by potato taste defect and the Antestia bug.

PubMed

Jackels, Susan C; Marshall, Eric E; Omaiye, Angelica G; Gianan, Robert L; Lee, Fabrice T; Jackels, Charles F

2014-10-22

Potato taste defect (PTD) is a flavor defect in East African coffee associated with Antestiopsis orbitalis feeding and 3-isopropyl-2-methoxypyrazine (IPMP) in the coffee. To elucidate the manifestation of PTD, surface and interior volatile compounds of PTD and non-PTD green coffees were sampled by headspace solid phase microextraction and analyzed by gas chromatography mass spectrometry. Principal component analysis of the chromatographic data revealed a profile of surface volatiles distinguishing PTD from non-PTD coffees dominated by tridecane, dodecane, and tetradecane. While not detected in surface volatiles, IPMP was found in interior volatiles of PTD coffee. Desiccated antestia bugs were analyzed by GCMS, revealing that the three most prevalent volatiles were tridecane, dodecane, and tetradecane, as was found in the surface profile PTD coffee. Coffee having visible insect damage exhibited both a PTD surface volatile profile and IPMP in interior volatiles, supporting the hypothesis linking antestia bug feeding activity with PTD profile compounds on the surface and IPMP in the interior of the beans.

Molecular Diffusion of Volatiles in Lunar Regolith during the Resource Prospector Mission Sample Acquisition

NASA Astrophysics Data System (ADS)

Teodoro, L. A.; Colaprete, A.; Roush, T. L.; Elphic, R. C.; Cook, A.; Kleinhenz, J.; Fritzler, E.; Smith, J. T.; Zacny, K.

2016-12-01

In the context of NASA's Resource Prospector (RP) mission to the high latitudes and permanently shadowed regions of the Moon, we study 3D models of volatile transport in the lunar regolith. This mission's goal is to extract and identify volatile species in the top meter of the lunar regolith layer. Roughly, RP consists of 5 elements: i) the Neutron Spectrometer System will search for high hydrogen concentrations and in turn select optimum drilling locations; ii) The Near Infrared Volatile Spectrometer System (NIRVSS) will characterize the nature of the surficial water ice; iii) The Drill Sub-system will extract samples from the top meter of the lunar surface and deliver them to the Oxygen and Volatile Extraction Node (OVEN); iv) OVEN will heat up the sample and extract the volatiles therein, that will be v) transferred to the Lunar Advanced Volatiles Analysis system for chemical composition analysis. A series of vacuum cryogenic experiments have been carried out at Glenn Research Center with the aim of quantifying the volatile losses during the drilling/sample acquisition phase and sample delivery to crucibles steps. These experiments' outputs include: i) Pressure measurements of several chemical species (e.g. H2O, Ar); ii) Temperature measurements within and at the surface of the lunar simulant using thermocouples; and iii) Surficial temperature NIRVSS measurements. Here, we report on the numerical modeling we are carrying out to understand the physics underpinning these experiments. The models include 2 main parts: i) reliable computation of temperature variation throughout the lunar soil container during the experiment as constrained by temperature measurements; and ii) molecular diffusion of volatiles. The latter includes both Fick's (flight of the molecules in the porous) and Knudsen's (sublimation of volatile molecules at the grain surface) laws. We also mimic the soil porosity by randomly allocating 75 microns particles in the simulation volume. Our preliminary results show both diffusion laws play a major role during the drilling phase.

Adherence of volatile propofol to various types of plastic tubing.

PubMed

Maurer, F; Lorenz, D J; Pielsticker, G; Volk, T; Sessler, D I; Baumbach, J I; Kreuer, S

2017-01-23

Propofol is an intravenous anesthetic. Currently, it is not possible to routinely measure blood concentration of the drug in real time. However, multi-capillary column ion-mobility spectrometry of exhaled gas can estimate blood propofol concentration. Unfortunately, adhesion of volatile propofol on plastic materials complicates measurements. Therefore, it is necessary to consider the extent to which volatile propofol adheres to various plastics used in sampling tubing. Perfluoralkoxy (PFA), polytetrafluorethylene (PTFE), polyurethane (PUR), silicone, and Tygon tubing were investigated in an experimental setting using a calibration gas generator (HovaCAL). Propofol gas was measured for one hour at 26 °C, 50 °C, and 90 °C tubing temperature. Test tubing segments were then flushed with N 2 to quantify desorption. PUR and Tygon sample tubing absorbed all volatile propofol. The silicone tubing reached the maximum propofol concentration after 119 min which was 29 min after propofol gas exposure stopped. The use of PFA or PTFE tubing produced comparable and reasonably accurate propofol measurements. The desaturation time for the PFA was 10 min shorter at 26 °C than for PTFE. PFA tubing thus seems most suitable for measurement of volatile propofol, with PTFE as an alternative.

Influence of maturity and ripening on aroma volatiles and flavor in avocado

USDA-ARS?s Scientific Manuscript database

Changes in aroma volatiles were determined using solid phase microextraction (SPME) and gas chromatography in ripe avocados (Persea americana Mill.) throughout an eight-month maturation period and related to the sensory properties of the fruit. As maturation progressed sensory panelists found the li...

Headspace Volatiles of Scutellaria Baicalensis Georgi Flowers

USDA-ARS?s Scientific Manuscript database

Volatile constituents of Baikal skullcap (Scutellaria baicalensis Georgi) flowers were isolated by solid-phase microextraction (SPME) and analyzed by GC and GC/MS. A total of 64 constituents was identified (constituting 57.1 – 89.9% of the total area), 13 of which were tentatively identified. beta...

MODIFICATION OF METAL PARTITIONING BY SUPPLEMENTING ACID VOLATILE SULFIDE IN FRESHWATER SEDIMENTS

EPA Science Inventory

Acid volatile sulfide is a component of sediments which complexes some cationic metals and thereby influences the toxicity of these metals to benthic organisms. EPA has proposed AVS as a key normalization phase for the development of sediment quality criteria for metals. Experime...

Volatile out gassing characteristics of highly filled ethylene vinyl acetate binder materials: Gas phase infra-red spectroscopy

DOE PAGES

Patel, Mogon; Bowditch, Martin; Jones, Ben; ...

2012-12-08

Gas phase Infra-red (IR) spectroscopy has been used to investigate volatile out gassing properties of highly filled poly (ethylene-co-vinyl acetate) materials. In these studies, a Scout-EN TM heated gas cell was interfaced to a vacuum FTIR spectrometer, and the quantification of evolved species was achieved through calibration of the gas cell with certified gas standards. The volatile out gassing properties were monitored as a function of time during storage at 75°C under vacuum conditions (< 1mbar). Acetic acid, carbon dioxide and water were identified as the major out gassing products through IR absorption peaks at 1797, 2354 and 3853 cmmore » -1, respectively. We present a comparison of three highly filled poly (ethyleneco- vinyl acetate) resins.« less

Sensitivity of Aerosol Mass and Microphysics to Treatments of Condensational Growth of Secondary Organic Compounds in a Regional Model

NASA Astrophysics Data System (ADS)

Topping, D. O.; Lowe, D.; McFiggans, G.; Zaveri, R. A.

2016-12-01

Gas to particle partitioning of atmospheric compounds occurs through disequilibrium mass transfer rather than through instantaneous equilibrium. However, it is common to treat only the inorganic compounds as partitioning dynamically whilst organic compounds, represented by the Volatility Basis Set (VBS), are partitioned instantaneously. In this study we implement a more realistic dynamic partitioning of organic compounds in a regional framework and assess impact on aerosol mass and microphysics. It is also common to assume condensed phase water is only associated with inorganic components. We thus also assess sensitivity to assuming all organics are hygroscopic according to their prescribed molecular weight.For this study we use WRF-Chem v3.4.1, focusing on anthropogenic dominated North-Western Europe. Gas-phase chemistry is represented using CBM-Z whilst aerosol dynamics are simulated using the 8-section MOSAIC scheme, including a 9-bin volatility basis set (VBS) treatment of organic aerosol. Results indicate that predicted mass loadings can vary significantly. Without gas phase ageing of higher volatility compounds, dynamic partitioning always results in lower mass loadings downwind of emission sources. The inclusion of condensed phase water in both partitioning models increases the predicted PM mass, resulting from a larger contribution from higher volatility organics, if present. If gas phase ageing of VBS compounds is allowed to occur in a dynamic model, this can often lead to higher predicted mass loadings, contrary to expected behaviour from a simple non-reactive gas phase box model. As descriptions of aerosol phase processes improve within regional models, the baseline descriptions of partitioning should retain the ability to treat dynamic partitioning of organic compounds. Using our simulations, we discuss whether derived sensitivities to aerosol processes in existing models may be inherently biased.This work was supported by the Nature Environment Research Council within the RONOCO (NE/F004656/1) and CCN-Vol (NE/L007827/1) projects.

Charge carrier mobility in a two-phase disordered organic system in the low-carrier concentration regime

NASA Astrophysics Data System (ADS)

Woellner, Cristiano F.; Li, Zi; Freire, José A.; Lu, Gang; Nguyen, Thuc-Quyen

2013-09-01

In this paper we use a three-dimensional Pauli master equation to investigate the charge carrier mobility of a two-phase system which can mimic donor-acceptor and amorphous-crystalline bulk heterojunctions. By taking the energetic disorder of each phase, their energy offset, and domain morphology into consideration, we show that the carrier mobility can have a completely different behavior when compared to a one-phase system. When the energy offset is equal to zero, the mobility is controlled by the more disordered phase. When the energy offset is nonzero, we show that the mobility electric field dependence switches from negative to positive at a threshold field proportional to the energy offset. Additionally, the influence of morphology, through the domain size and volume ratio parameters, on the transport is investigated and an approximate analytical expression for the zero field mobility is provided.

Mobility of icy sand packs, with application to Martian permafrost

USGS Publications Warehouse

Durham, W.B.; Pathare, A.V.; Stern, L.A.; Lenferink, H.J.

2009-01-01

[1] The physical state of water on Mars has fundamental ramifications for both climatology and astrobiology. The widespread presence of "softened" Martian landforms (such as impact craters) can be attributed to viscous creep of subsurface ground ice. We present laboratory experiments designed to determine the minimum amount of ice necessary to mobilize topography within Martian permafrost. Our results show that the jammed-to-mobile transition of icy sand packs neither occurs at fixed ice content nor is dependent on temperature or stress, but instead correlates strongly with the maximum dry packing density of the sand component. Viscosity also changes rapidly near the mobility transition. The results suggest a potentially lower minimum volatile inventory for the impact-pulverized megaregolith of Mars. Furthermore, the long-term preservation of partially relaxed craters implies that the ice content of Martian permafrost has remained close to that at the mobility transition throughout Martian history. Copyright 2009 by the American Geophysical Union.

On-site Rapid Detection of Trace Non-volatile Inorganic Explosives by Stand-alone Ion Mobility Spectrometry via Acid-enhanced Evaporization

PubMed Central

Peng, Liying; Hua, Lei; Wang, Weiguo; Zhou, Qinghua; Li, Haiyang

2014-01-01

New techniques for the field detection of inorganic improvised explosive devices (IEDs) are urgently developed. Although ion mobility spectrometry (IMS) has been proved to be the most effective method for screening organic explosives, it still faces a major challenge to detect inorganic explosives owing to their low volatilities. Herein, we proposed a strategy for detecting trace inorganic explosives by thermal desorption ion mobility spectrometry (TD-IMS) with sample-to-sample analysis time less than 5 s based on in-situ acidification on the sampling swabs. The responses for typical oxidizers in inorganic explosives, such as KNO3, KClO3 and KClO4 were at least enhanced by a factor of 3000 and their limits of detection were found to be subnanogram. The common organic explosives and their mixtures with inorganic oxidizers were detected, indicating that the acidification process did not affect the detection of organic explosives. Moreover, the typical inorganic explosives such as black powders, firecrackers and match head could be sensitively detected as well. These results demonstrated that this method could be easily employed in the current deployed IMS for on-site sensitive detection of either inorganic explosives or organic ones. PMID:25318960

Differential Profiling of Volatile Organic Compound Biomarker Signatures Utilizing a Logical Statistical Filter-Set and Novel Hybrid Evolutionary Classifiers

DTIC Science & Technology

2012-04-01

for automated SPME headspace sampling and in-line with a Thermo DSQII single quadrupole mass spectrometer. Collection of organic volatiles from the...urine was accomplished using a 2cm CAR/DVB/PDMS solid phase micro extraction fiber ( SPME ), Supelco supplier, inserted by the Triplus autosampler into...automated direct injection. Volatiles gathered by the SPME fiber were analyzed through desorption of the fiber by heating to elevated temperature and

VOLATILIZATION OF ALKYLBENZENES FROM WATER.

USGS Publications Warehouse

Rathbun, R.E.; Tai, D.Y.

1985-01-01

Volatilization is a physical process of importance in determining the fate of many organic compounds in streams and rivers. This process is frequently described by the conceptual-two-film model. The model assumes uniformly mixed water and air phases separated by thin films of water and air in which mass transfer is by molecular diffusion. Mass-transfer coefficients for the water and air films are related to an overall mass-transfer coefficient for volatilization through the Henry's law constant.

Volatile Concentrations and H-Isotope Composition of Unequilibrated Eucrites

NASA Technical Reports Server (NTRS)

Sarafian, Adam R.; Nielsen, Sune G.; Marschall, Horst R.; Gaetani, Glenn A.; Hauri, Erik H.; Righter, Kevin; Berger, Eve L.

2017-01-01

Eucrites are among the oldest and best studied asteroidal basalts (1). They represent magmatism that occurred on their parent asteroid, likely 4-Vesta, starting at 4563 Ma and continuing for approx. 30 Myr. Two hypotheses are debated for the genesis of eucrites, a magma ocean model (2), and a mantle partial melting model. In general, volatiles (H, C, F, Cl) have been ignored for eucrites and 4-Vesta, but solubility of wt% levels of H2O are possible at Vestan interior PT conditions. Targeted measurements on samples could aid our understanding considerably. Recent studies have found evidence of volatile elements in eucrites, but quantifying the abundance of volatiles remains problematic (6). Volatile elements have a disproportionately large effect on melt properties and phase stability, relative to their low abundance. The source of volatile elements can be elucidated by examining the hydrogen isotope ratio (D/H), as different H reservoirs have drastically different H isotope compositions. Recent studies of apatite in eucrites have shown that the D/H of 4-Vesta matches that of Earth and carbonaceous chondrites, however, the D/H of apatites may not represent the D/H of a primitive 4-Vesta melt due to the possibility of degassing prior to the crystallization of apatite. Therefore, the D/H of early crystallizing phases must be measured to determine if the D/H of 4-Vesta is equal to that of the Earth and carbonaceous chondrites.

Analysis of volatile compounds produced by 2 strains of Lactococcus lactis isolated from leben (Tunisian fermented milk) using solid-phase microextraction-gas chromatography.

PubMed

Ziadi, M; Wathelet, J P; Marlier, M; Hamdi, M; Thonart, P

2008-08-01

The volatile compounds that characterize Leben during fermentation with 2 Lactococcus lactis strains (SLT6 and SLT10) in flasks, in a 100-L fermentor, and during storage at 4 degrees C, were investigated and compared to those from commercial Leben. Volatile compounds from Leben were concentrated by a Carboxen-PDMS fiber and analyzed by GC-MS. These compounds include acids, alcohols, aldehydes, ketones, sulfur compounds, and hydrocarbons. Commercial Leben presented a poor volatile profile compared to the laboratory-made Leben. The mixed culture of 2 Lactococcus lactis strains resulted in higher volatile compound formation than the single strain culture. The GC volatile profiles of Leben produced in flask and in the 100-L fermentor were similar. Changes in volatile compounds were observed during storage at 4 degrees C. The effect of culture conditions on production of volatiles by SLT6 strain was studied. Aeration (0.1 mL/min) and agitation enhanced the production of diacetyl, acetoin, 3-methylbutanal, and 3-methylbutanol. Fermentation at pH 5 had no effect on volatile production.

Gas Phase Chromatography of some Group 4, 5, and 6 Halides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sylwester, Eric Robert

1998-10-01

Gas phase chromatography using The Heavy Element Volatility Instrument (HEVI) and the On Line Gas Apparatus (OLGA III) was used to determine volatilities of ZrBr 4, HfBr 4, RfBr 4, NbBr 5, TaOBr 3, HaCl 5, WBr 6, FrBr, and BiBr 3. Short-lived isotopes of Zr, Hf, Rf, Nb, Ta, Ha, W, and Bi were produced via compound nucleus reactions at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory and transported to the experimental apparatus using a He gas transport system. The isotopes were halogenated, separated from the other reaction products, and their volatilities determined by isothermal gas phase chromatography.more » Adsorption Enthalpy (ΔH a) values for these compounds were calculated using a Monte Carlo simulation program modeling the gas phase chromatography column. All bromides showed lower volatility than molecules of similar molecular structures formed as chlorides, but followed similar trends by central element. Tantalum was observed to form the oxybromide, analogous to the formation of the oxychloride under the same conditions. For the group 4 elements, the following order in volatility and ΔH a was observed: RfBr 4 > ZrBr 4 > HfBr 4. The ΔH a values determined for the group 4, 5, and 6 halides are in general agreement with other experimental data and theoretical predictions. Preliminary experiments were performed on Me-bromides. A new measurement of the half-life of 261Rf was performed. 261Rf was produced via the 248Cm( 18O, 5n) reaction and observed with a half-life of 74 -6 +7 seconds, in excellent agreement with the previous measurement of 78 -6 +11 seconds. We recommend a new half-life of 75±7 seconds for 261Rf based on these two measurements. Preliminary studies in transforming HEVI from an isothermal (constant temperature) gas phase chromatography instrument to a thermochromatographic (variable temperature) instrument have been completed. Thermochromatography is a technique that can be used to study the volatility and ΔH a of longer-lived isotopes off-line, Future work will include a comparison between the two techniques and the use of thermochromatography to study isotopes in a wider range of half-lives and molecular structures.« less

Micro versus macro solid phase extraction for monitoring water contaminants: a preliminary study using trihalomethanes.

PubMed

Alexandrou, Lydon D; Spencer, Michelle J S; Morrison, Paul D; Meehan, Barry J; Jones, Oliver A H

2015-04-15

Solid phase extraction is one of the most commonly used pre-concentration and cleanup steps in environmental science. However, traditional methods need electrically powered pumps, can use large volumes of solvent (if multiple samples are run), and require several hours to filter a sample. Additionally, if the cartridge is open to the air volatile compounds may be lost and sample integrity compromised. In contrast, micro cartridge based solid phase extraction can be completed in less than 2 min by hand, uses only microlitres of solvent and provides comparable concentration factors to established methods. It is also an enclosed system so volatile components are not lost. The sample can also be eluted directly into a detector (e.g. a mass spectrometer) if required. However, the technology is new and has not been much used for environmental analysis. In this study we compare traditional (macro) and the new micro solid phase extraction for the analysis of four common volatile trihalomethanes (trichloromethane, bromodichloromethane, dibromochloromethane and tribromomethane). The results demonstrate that micro solid phase extraction is faster and cheaper than traditional methods with similar recovery rates for the target compounds. This method shows potential for further development in a range of applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Computation of Phase Equilibria, State Diagrams and Gas/Particle Partitioning of Mixed Organic-Inorganic Aerosols

NASA Astrophysics Data System (ADS)

Zuend, A.; Marcolli, C.; Peter, T.

2009-04-01

The chemical composition of organic-inorganic aerosols is linked to several processes and specific topics in the field of atmospheric aerosol science. Photochemical oxidation of organics in the gas phase lowers the volatility of semi-volatile compounds and contributes to the particulate matter by gas/particle partitioning. Heterogeneous chemistry and changes in the ambient relative humidity influence the aerosol composition as well. Molecular interactions between condensed phase species show typically non-ideal thermodynamic behavior. Liquid-liquid phase separations into a mainly polar, aqueous and a less polar, organic phase may considerably influence the gas/particle partitioning of semi-volatile organics and inorganics (Erdakos and Pankow, 2004; Chang and Pankow, 2006). Moreover, the phases present in the aerosol particles feed back on the heterogeneous, multi-phase chemistry, influence the scattering and absorption of radiation and affect the CCN ability of the particles. Non-ideal thermodynamic behavior in mixtures is usually described by an expression for the excess Gibbs energy, enabling the calculation of activity coefficients. We use the group-contribution model AIOMFAC (Zuend et al., 2008) to calculate activity coefficients, chemical potentials and the total Gibbs energy of mixed organic-inorganic systems. This thermodynamic model was combined with a robust global optimization module to compute potential liquid-liquid (LLE) and vapor-liquid-liquid equilibria (VLLE) as a function of particle composition at room temperature. And related to that, the gas/particle partitioning of semi-volatile components. Furthermore, we compute the thermodynamic stability (spinodal limits) of single-phase solutions, which provides information on the process type and kinetics of a phase separation. References Chang, E. I. and Pankow, J. F.: Prediction of activity coefficients in liquid aerosol particles containing organic compounds, dissolved inorganic salts, and water - Part 2: Consideration of phase separation effects by an XUNIFAC model, Atmos. Environ., 40, 6422-6436, 2006. Erdakos, G. B. and Pankow, J. F.: Gas/particle partitioning of neutral and ionizing compounds to single- and multi-phase aerosol particles. 2. Phase separation in liquid particulate matter containing both polar and low-polarity organic compounds, Atmos. Environ., 38, 1005-1013, 2004. Zuend, A., Marcolli, C., Luo, B. P., and Peter, T.: A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients, Atmos. Chem. Phys., 8, 4559-4593, 2008.

Heating of solid earthen material, measuring moisture and resistivity

DOEpatents

Heath, W.O.; Richardson, R.L.; Goheen, S.C.

1994-07-19

The present invention includes a method of treating solid earthen material having volatile, semi-volatile, and non-volatile contaminants. Six electrodes are inserted into a region of earthen material to be treated in a substantially equilateral hexagonal arrangement. Six phases of voltages are applied to corresponding electrodes. The voltages are adjusted within a first range of voltages to create multiple current paths between pairs of the electrodes. The current paths are evenly distributed throughout the region defined by the electrodes and therefore uniformly heat the region. The region of earthen material is heated to a temperature sufficient to substantially remove volatile and semi-volatile contaminants by promoting microbial action. This temperature is less than a melting temperature of the earthen material. 13 figs.

Heating of solid earthen material, measuring moisture and resistivity

DOEpatents

Heath, William O.; Richardson, Richard L.; Goheen, Steven C.

1994-01-01

The present invention includes a method of treating solid earthen material having volatile, semi-volatile, and non-volatile contaminants. Six electrodes are inserted into a region of earthen material to be treated in a substantially equilateral hexagonal arrangement. Six phases of voltages are applied to corresponding electrodes. The voltages are adjusted within a first range of voltages to create multiple current paths between pairs of the electrodes. The current paths are evenly distributed throughout the region defined by the electrodes and therefore uniformly heat the region. The region of earthen material is heated to a temperature sufficient to substantially remove volatile and semi-volatile contaminants by promoting microbial action. This temperature is less than a melting temperature of the earthen material.

Translational diffusion coefficients of volatile compounds in various aqueous solutions at low and subzero temperatures.

PubMed

Covarrubias-Cervantes, Marco; Champion, Dominique; Debeaufort, Frédéric; Voilley, Andrée

2005-08-24

Translational diffusion coefficients (D(12)) of volatile compounds were measured in model media with the profile concentration method. The influence of sample temperature (from 25 to -10 degrees C) was studied on translational diffusion in sucrose or maltodextrin solutions at various concentrations. Results show that diffusivity of volatile compounds in sucrose solutions is controlled by temperature, molecule size, and the viscosity of the liquid phase as expected with the Stokes-Einstein equation; moreover, physicochemical interactions between volatile compounds and the medium are determinant for diffusion estimation. At negative temperature, the winding path induced by an ice crystal content of >70% lowered volatile compound diffusion. On the contrary, no influence on translational diffusion coefficients was observed for lower ice content.

Volatile compounds of dry beans (Phaseolus vulgaris L.).

PubMed

Oomah, B Dave; Liang, Lisa S Y; Balasubramanian, Parthiba

2007-12-01

Volatile compounds of uncooked dry bean (Phaseolus vulgaris L.) cultivars representing three market classes (black, dark red kidney and pinto) grown in 2005 were isolated with headspace solid phase microextraction (HS-SPME), and analyzed with gas chromatography mass spectrometry (GC-MS). A total of 62 volatiles consisting of aromatic hydrocarbons, aldehydes, alkanes, alcohols and ketones represented on average 62, 38, 21, 12, and 9 x 10(6) total area counts, respectively. Bean cultivars differed in abundance and profile of volatiles. The combination of 18 compounds comprising a common profile explained 79% of the variance among cultivars based on principal component analysis (PCA). The SPME technique proved to be a rapid and effective method for routine evaluation of dry bean volatile profile.

Characterization of diesel particles: effects of fuel reformulation, exhaust aftertreatment, and engine operation on particle carbon composition and volatility.

PubMed

Alander, Timo J A; Leskinen, Ari P; Raunemaa, Taisto M; Rantanen, Leena

2004-05-01

Diesel exhaust particles are the major constituent of urban carbonaceous aerosol being linked to a large range of adverse environmental and health effects. In this work, the effects of fuel reformulation, oxidation catalyst, engine type, and engine operation parameters on diesel particle emission characteristics were investigated. Particle emissions from an indirect injection (IDI) and a direct injection (DI) engine car operating under steady-state conditions with a reformulated low-sulfur, low-aromatic fuel and a standard-grade fuel were analyzed. Organic (OC) and elemental (EC) carbon fractions of the particles were quantified by a thermal-optical transmission analysis method and particle size distributions measured with a scanning mobility particle sizer (SMPS). The particle volatility characteristics were studied with a configuration that consisted of a thermal desorption unit and an SMPS. In addition, the volatility of size-selected particles was determined with a tandem differential mobility analyzer technique. The reformulated fuel was found to produce 10-40% less particulate carbon mass compared to the standard fuel. On the basis of the carbon analysis, the organic carbon contributed 27-61% to the carbon mass of the IDI engine particle emissions, depending on the fuel and engine operation parameters. The fuel reformulation reduced the particulate organic carbon emissions by 10-55%. In the particles of the DI engine, the organic carbon contributed 14-26% to the total carbon emissions, the advanced engine technology, and the oxidation catalyst, thus reducing the OC/EC ratio of particles considerably. A relatively good consistency between the particulate organic fraction quantified with the thermal optical method and the volatile fraction measured with the thermal desorption unit and SMPS was found.

Comparison of methods for determining volatile compounds in milk, cheese, and whey powder

USDA-ARS?s Scientific Manuscript database

Solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) are commonly used for qualitative and quantitative analysis of volatile compounds in various dairy products, but conditions have to be adjusted for optimal SPME release while not generating new compounds that are abs...

Identification of volatiles from waste larval rearing media that attract gravid screwworm flies to oviposit

USDA-ARS?s Scientific Manuscript database

The waste product of the artificial larval rearing media of the primary screwworm, Cochliomyia hominivorax, attracts gravid female screwworm flies to oviposit. The volatile component of this waste product was collected using solid phase microextraction techniques and subjected to gas chromatography-...

Characterization of volatile and polar compounds of Jiaogulan Tea [Gynostemma pentaphyllum (Thunb.) Makino] by hyphenated analytical techniques

USDA-ARS?s Scientific Manuscript database

Jiaogulan [Gynostemma pentaphyllum (Thunb.) Makino] is a Chinese medical plant from southern Asia that has rapidly gained popularity and interest for its health-promotive and therapeutic properties. The volatile composition of jiaogulan tea was analyzed by using headspace-solid phase microextraction...

78 FR 45071 - Annual Report for Mobility Fund Phase I Support and Record Retention

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-26

... for Mobility Fund Phase I Support and Record Retention AGENCY: Federal Communications Commission... information collection associated with the Commission's Annual Report for Mobility Fund Phase I Support and... or sponsor a collection of information unless it displays a current, valid OMB Control Number. No...

47 CFR 54.1005 - Application process.

Code of Federal Regulations, 2012 CFR

2012-10-01

... for Mobility Fund Phase I Support. In addition to providing information specified in § 1.21001(b) of... competitive bidding for Mobility Fund Phase I support also shall: (1) Provide ownership information as set... Mobility Fund Phase I Support—(1) Deadline. Unless otherwise provided by public notice, winning bidders for...

47 CFR 54.1005 - Application process.

Code of Federal Regulations, 2013 CFR

2013-10-01

... for Mobility Fund Phase I support. In addition to providing information specified in § 1.21001(b) of... competitive bidding for Mobility Fund Phase I support also shall: (1) Provide ownership information as set... Mobility Fund Phase I support.—(1) Deadline. Unless otherwise provided by public notice, winning bidders...

47 CFR 54.1005 - Application process.

Code of Federal Regulations, 2014 CFR

2014-10-01

... for Mobility Fund Phase I support. In addition to providing information specified in § 1.21001(b) of... competitive bidding for Mobility Fund Phase I support also shall: (1) Provide ownership information as set... Mobility Fund Phase I support.—(1) Deadline. Unless otherwise provided by public notice, winning bidders...

Removing volatile contaminants from the unsaturated zone by inducing advective air-phase transport

USGS Publications Warehouse

Baehr, A.L.; Hoag, G.E.; Marley, M.C.

1989-01-01

Organic liquids inadvertently spilled and then distributed in the unsaturated zone can pose a long-term threat to ground water. Many of these substances have significant volatility, and thereby establish a premise for contaminant removal from the unsaturated zone by inducing advective air-phase transport with wells screened in the unsaturated zone. In order to focus attention on the rates of mass transfer from liquid to vapour phases, sand columns were partially saturated with gasoline and vented under steady air-flow conditions. The ability of an equilibrium-based transport model to predict the hydrocarbon vapor flux from the columns implies an efficient rate of local phase transfer for reasonably high air-phase velocities. Thus the success of venting remediations will depend primarily on the ability to induce an air-flow field in a heterogeneous unsaturated zone that will intersect the distributed contaminant. To analyze this aspect of the technique, a mathematical model was developed to predict radially symmetric air flow induced by venting from a single well. This model allows for in-situ determinations of air-phase permeability, which is the fundamental design parameter, and for the analysis of the limitations of a single well design. A successful application of the technique at a site once contaminated by gasoline supports the optimism derived from the experimental and modeliing phases of this study, and illustrates the well construction and field methods used to document the volatile contaminant recovery. ?? 1989.

Evolution of the protolunar disk: Dynamics, cooling timescale and implantation of volatiles onto the Earth

NASA Astrophysics Data System (ADS)

Charnoz, Sébastien; Michaut, Chloé

2015-11-01

It is thought that the Moon accreted from the protolunar disk that was assembled after the last giant impact on Earth. Due to its high temperature, the protolunar disk may act as a thermochemical reactor in which the material is processed before being incorporated into the Moon. Outstanding issues like devolatilisation and istotopic evolution are tied to the disk evolution, however its lifetime, dynamics and thermodynamics are unknown. Here, we numerically explore the long term viscous evolution of the protolunar disk using a one dimensional model where the different phases (vapor and condensed) are vertically stratified. Viscous heating, radiative cooling, phase transitions and gravitational instability are accounted for whereas Moon's accretion is not considered for the moment. The viscosity of the gas, liquid and solid phases dictates the disk evolution. We find that (1) the vapor condenses into liquid in ∼10 years, (2) a large fraction of the disk mass flows inward forming a hot and compact liquid disk between 1 and 1.7 Earth's radii, a region where the liquid is gravitationally stable and can accumulate, (3) the disk finally solidifies in 103 to 105 years. Viscous heating is never balanced by radiative cooling. If the vapor phase is abnormally viscous, due to magneto-rotational instability for instance, most of the disk volatile components are transported to Earth leaving a disk enriched in refractory elements. This opens a way to form a volatile-depleted Moon and would suggest that the missing Moon's volatiles are buried today into the Earth. The disk cooling timescale may be long enough to allow for planet/disk isotopic equilibration. However large uncertainties on the disk physics remain because of the complexity of its multi-phased structure.

Headspace solid-phase microextraction coupled to comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry for the analysis of aerosol from tobacco heating product.

PubMed

Savareear, Benjamin; Lizak, Radoslaw; Brokl, Michał; Wright, Chris; Liu, Chuan; Focant, Jean-Francois

2017-10-20

A method involving headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS) was developed and optimised to elucidate the volatile composition of the particulate phase fraction of aerosol produced by tobacco heating products (THPs). Three SPME fiber types were studied in terms of extraction capacity and precision measurements. Divinylbenzene polydimethylsiloxane appeared as the most efficient coating for these measurements. A central composite design of experiment was utilised for the optimization of the extraction conditions. Qualitative and semi-quantitative analysis of the headspace above THP aerosol condensate was carried out using optimised extraction conditions. Semi-quantitative analyses of detected constituents were performed by assuming that their relative response factors to the closest internal standard ( i t R ) were equal to 1. Using deconvoluted mass spectral data (library similarity and reverse match >750) and linear retention indices (match window of ±15 index units), 205 peaks were assigned to individual compounds, 82 of which (including 43 substances previously reported to be present in tobacco) have not been reported previously in tobacco aerosol. The major volatile fraction of the headspace contained ketones, alcohols, aldehydes, alicyclic hydrocarbons alkenes, and alkanes. The method was further applied to compare the volatiles from the particulate phase of aerosol composition of THP with that of reference cigarette smoke and showed that the THP produced a less complex chemical mixture. This new method showed good efficiency and precision for the peak areas and peak numbers from the volatile fraction of aerosol particulate phase for both THP and reference cigarettes. Copyright © 2017 Elsevier B.V. All rights reserved.

A Laterally-Mobile Mixed Polymer/Polyelectrolyte Brush Undergoes a Macroscopic Phase Separation

NASA Astrophysics Data System (ADS)

Lee, Hoyoung; Park, Hae-Woong; Tsouris, Vasilios; Choi, Je; Mustafa, Rafid; Lim, Yunho; Meron, Mati; Lin, Binhua; Won, You-Yeon

2013-03-01

We studied mixed PEO and PDMAEMA brushes. The question we attempted to answer was: When the chain grafting points are laterally mobile, how will this lateral mobility influence the structure and phase behavior of the mixed brush? Two different model mixed PEO/PDMAEMA brush systems were prepared: a mobile mixed brush by spreading a mixture of two diblock copolymers, PEO-PnBA and PDMAEMA-PnBA, onto the air-water interface, and an inseparable mixed brush using a PEO-PnBA-PDMAEMA triblock copolymer having respective brush molecular weights matched to those of the diblock copolymers. These two systems were investigated by surface pressure-area isotherm, X-ray reflectivity and AFM imaging measurements. The results suggest that the mobile mixed brush undergoes a lateral macroscopic phase separation at high chain grafting densities, whereas the inseparable system is only microscopically phase separated under comparable brush density conditions. We also conducted an SCF analysis of the phase behavior of the mixed brush system. This analysis further supported the experimental findings. The macroscopic phase separation observed in the mobile system is in contrast to the microphase separation behavior commonly observed in two-dimensional laterally-mobile small molecule mixtures.

Variation of total aroma and polyphenol content of dark chocolate during three phase of conching.

PubMed

Albak, F; Tekin, A R

2016-01-01

Variation in the volatiles, total polyphenol, theobromine and caffein was investigated both qualitatively and quantitatively for all phases of conching with GC/MS/SPME, HPLC, GC/O, and UV-visible spectrophotometry. The volatile compounds being identified during the three phases consisted of aldehydes, ketones, pyrazines, acids, alcohols and esters. The number and concentration of these compounds were observed to be 31-25,681 ppb, 44-34,838 ppb and 44-29,809 ppb in the dry, pasty, and liquid phases respectively. The odor of dark chocolate was described as nutty, sweet, caramel, green and chocolate using olfactometry. The percent decrease in the concentration of total polyphenol, caffein and theobromine was observed to be only 3.0, 11.0, and 32.0 respectively.

Global transformation and fate of SOA: Implications of Low Volatility SOA and Gas-Phase Fragmentation Reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrivastava, ManishKumar B.; Easter, Richard C.; Liu, Xiaohong

2015-05-16

Secondary organic aerosols (SOA) are large contributors to fine particle loadings and radiative forcing, but are often represented crudely in global models. We have implemented three new detailed SOA treatments within the Community Atmosphere Model version 5 (CAM5) that allow us to compare the semi-volatile versus non-volatile SOA treatments (based on some of the latest experimental findings) and also investigate the effects of gas-phase fragmentation reactions. For semi-volatile SOA treatments, fragmentation reactions decrease simulated SOA burden from 7.5 Tg to 1.8 Tg. For the non-volatile SOA treatment with fragmentation, the burden is 3.1 Tg. Larger differences between non-volatile and semi-volatilemore » SOA (upto a factor of 5) correspond to continental outflow over the oceans. Compared to a global dataset of surface Aerosol Mass Spectrometer measurements and the US IMPROVE network measurements, the non-volatile SOA with fragmentation treatment (FragNVSOA) agrees best at rural locations. Urban SOA is under-predicted but this may be due to the coarse model resolution. All our three revised treatments show much better agreement with aircraft measurements of organic aerosols (OA) over the N. American Arctic and sub-Arctic in spring and summer, compared to the standard CAM5 formulation. This is due to treating SOA precursor gases from biomass burning, and long-range transport of biomass burning OA at elevated levels. The revised model configuration that include fragmentation (both semi-volatile and non-volatile SOA) show much better agreement with MODIS AOD data over regions dominated by biomass burning during the summer, and predict biomass burning as the largest global source of OA followed by biogenic and anthropogenic sources. The non-volatile and semi-volatile configuration predict the direct radiative forcing of SOA as -0.5 W m-2 and -0.26 W m-2 respectively, at top of the atmosphere, which are higher than previously estimated by most models, but in reasonable agreement with a recent constrained modeling study. This study highlights the importance of improving process-level representation of SOA in global models.« less

New technique for heterogeneous vapor-phase synthesis of nanostructured metal layers from low-dimensional volatile metal complexes

NASA Astrophysics Data System (ADS)

Badalyan, A. M.; Bakhturova, L. F.; Kaichev, V. V.; Polyakov, O. V.; Pchelyakov, O. P.; Smirnov, G. I.

2011-09-01

A new technique for depositing thin nanostructured layers on semiconductor and insulating substrates that is based on heterogeneous gas-phase synthesis from low-dimensional volatile metal complexes is suggested and tried out. Thin nanostructured copper layers are deposited on silicon and quartz substrates from low-dimensional formate complexes using a combined synthesis-mass transport process. It is found that copper in layers thus deposited is largely in a metal state (Cu0) and has the form of closely packed nanograins with a characteristic structure.

From quantum mechanics to finance: Microfoundations for jumps, spikes and high volatility phases in diffusion price processes

NASA Astrophysics Data System (ADS)

Henkel, Christof

2017-03-01

We present an agent behavior based microscopic model that induces jumps, spikes and high volatility phases in the price process of a traded asset. We transfer dynamics of thermally activated jumps of an unexcited/excited two state system discussed in the context of quantum mechanics to agent socio-economic behavior and provide microfoundations. After we link the endogenous agent behavior to price dynamics we establish the circumstances under which the dynamics converge to an Itô-diffusion price processes in the large market limit.

Phase transition thermodynamics of bisphenols.

PubMed

Costa, José C S; Dávalos, Juan Z; Santos, Luís M N B F

2014-10-16

Herein we have studied, presented, and analyzed the phase equilibria thermodynamics of a bisphenols (BP-A, BP-E, BP-F, BP-AP, and BP-S) series. In particular, the heat capacities, melting temperatures, and vapor pressures at different temperatures as well as the standard enthalpies, entropies, and Gibbs energies of phase transition (fusion and sublimation) were experimentally determined. Also, we have presented the phase diagrams of each bisphenol derivative and investigated the key parameters related to the thermodynamic stability of the condensed phases. When all the bisphenol derivatives are compared at the same conditions, solids BP-AP and BP-S present lower volatilities (higher Gibbs energy of sublimation) and high melting temperatures due to the higher stability of their solid phases. Solids BP-A and BP-F present similar stabilities, whereas BP-E is more volatile. The introduction of -CH3 groups in BP-F (giving BP-E and BP-A) leads an entropic differentiation in the solid phase, whereas in the isotropic liquids the enthalpic and entropic differentiations are negligible.

Major and Trace Element Variations in Impact Crater Clay from Chicxulub, Lonar, and Mistastin, Implications for the Martian Soil

NASA Technical Reports Server (NTRS)

Newsom, H. E.; Nelson, M. J.; Shearer, C. K.; Rietmeijer, F. J. M.; Gakin, R.; Lee, K.

2004-01-01

The catastrophic Chicxulub event should have generated a large hydrothermal system with volatile element mobilization, producing interesting alteration materials and clays. The Yaxcopoil-1 (YAX) drill hole is located in the annular trough, about 70 km southwest of the crater center, in an area where the impactite layers are relatively thin (approx. 100 m thick). We have analyzed samples from the YAX drill core and from other impact craters including Mistastin and Lonar to determine the nature of alteration and trace element mobilization.

Speciation, Characterization, And Mobility Of As, Se and Hg In Flue Gas Desulphurization Residues

EPA Science Inventory

Flue gas from coal combustion contains significant amounts of volatile toxic trace elements such as arsenic (As), selenium (Se) and mercury (Hg). The capture of these elements in the flue gas desulphurization (FGD) scrubber unit has resulted in generation of a metal-laden residue...

Speciation, Characterization, And Mobility Of As, Se, and Hg In Flue Gas Desulphurization Residues

EPA Science Inventory

Flue gas from coal combustion contains significant amounts of volatile elements, such as arsenic (As), selenium (Se) and mercury (Hg), which could lead to serious environmental health risks. The capture of these toxic elements in the scrubber with a flue gas desulphurization (FGD...

40 CFR 270.17 - Specific part B information requirements for surface impoundments.

Code of Federal Regulations, 2011 CFR

2011-07-01

... volume, physical, and chemical characteristics of the wastes, including their potential to migrate through soil or to volatilize or escape into the atmosphere; (2) The attenuative properties of underlying and surrounding soils or other materials; (3) The mobilizing properties of other materials co-disposed...

Effects of cold temperature and ethanol content on VOC emissions from light-duty gasoline vehicles

EPA Science Inventory

Emissions of speciated volatile organic compounds (VOCs), including mobile source air toxics (MSATs), were measured in vehicle exhaust from three light-duty spark ignition vehicles operating on summer and winter grade gasoline (E0) and ethanol blended (E10 and E85) fuels. Vehicle...

EXPOSURE TO PARTICULATE MATTER, VOLATILE ORGANIC COMPOUNDS, AND OTHER AIR POLLUTANTS INSIDE PATROL CARS

EPA Science Inventory

People driving in a vehicle might receive an enhanced dose of mobile source pollutants that are considered a potential risk for cardiovascular diseases. The exposure to components of air pollution in highway patrol vehicles, at an ambient, and a roadside location was determined d...

Characteristics of volatile organic compounds produced from five pathogenic bacteria by headspace-solid phase micro-extraction/gas chromatography-mass spectrometry.

PubMed

Chen, Juan; Tang, Junni; Shi, Hui; Tang, Cheng; Zhang, Rong

2017-03-01

The characteristics of volatile compounds from five different bacterial species, Escherichia coli O157:H7, Salmonella Enteritidis, Shigella flexneri, Staphylococcus aureus, and Listeria monocytogenes, growing, respectively, in trypticase soy broth were monitored by headspace solid-phase micro-extraction/gas chromatography-mass spectrometry. The results showed that most volatile organic compounds (VOCs) of five pathogens started to increase after the sixth to tenth hour. Methyl ketones and long chain alcohols were representative volatiles for three Gram-negative bacteria. The especially high production of indole was characterized to E. coli O157:H7. The production of 3-hydroxy-2-butanone was indicative of the presence of two Gram-positive bacteria. Both 3-methyl-butanoic acid and 3-methyl-butanal were unique biomarkers for S. aureus. The population dynamics of individual pathogen could be monitored using the accumulation of VOCs correlated with its growth. And these five pathogens could be distinguishable though principle component analysis of 18 volatile metabolites. Moreover, the mixed culture of S. aureus and E. coli O157:H7 was also investigated. The levels of 3-methyl-butanal and 3-methyl-butanoic acid were largely reduced; while the level of indole almost unchanged and correlated with E. coli O157:H7 growth very well. The characteristics of volatiles from the five foodborne pathogens could lay a fundamental basis for further research into pathogen contamination control by detecting volatile signatures of pathogens. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of black pepper volatiles by solid phase microextraction-gas chromatography: A comparison of terpenes profiles with hydrodistillation.

PubMed

Jeleń, Henryk H; Gracka, Anna

2015-10-30

Solid phase microextraction (SPME) is widely used in food flavor compounds analysis in majority for profiling volatile compounds. Based on such profiles conclusions are often drawn concerning the percentage composition of volatile compounds in particular food, spices or raw materials. This paper focuses on the usefulness of SPME for the profiling of volatile compounds from spices using black pepper as an example. SPME profiles obtained in different analytical conditions were compared to the profile of pepper volatiles obtained using hydrodistillation in Clevenger apparatus. The profiles of both monoterpenes and sesquiterpenes of black pepper were highly dependent on sample weight (0.1 and 1g samples were tested), and extraction time (durations from 2 to 120min were tested), regardless of the SPME fiber used (PDMS and CAR/PDMS coatings were used). The characteristic phenomenon for extraction from dry ground pepper was the decrease of monoterpenes % share in volatiles with increasing extraction times, whereas at the same time the % contents of sesquiterpenes increased. Addition of water to ground pepper substantially changed extraction kinetics and mutual proportions of mono to sesquiterpenes compared to dry samples by minimizing changes in mono- to sesquiterpenes ratio in different extraction times. Obtained results indicate that SPME can be a fast extraction method for volatiles of black pepper. Short extraction times (2-10min) in conjunction with the fast GC analysis (2.1min) proposed here may offer fast alternative to hydrodistillation allowing black pepper terpenes characterization. Copyright © 2015 Elsevier B.V. All rights reserved.

Constraining the Volatility Distributions and Possible Diffusion Limitations of Secondary Organic Aerosols Using Laboratory Dilution Experiments

NASA Astrophysics Data System (ADS)

Ye, Q.; Robinson, E. S.; Mahfouz, N.; Sullivan, R. C.; Donahue, N. M.

2016-12-01

Secondary organic aerosols (SOA) dominate the mass of fine particles in the atmosphere. Their formation involves both oxidation of volatile organics from various sources that produce products with uncertain volatilities, and diffusion of these products into the condensed phase. Therefore, constraining volatility distribution and diffusion timescales of the constituents in SOA are important in predicting size, concentration and composition of SOA, as well as how these properties of SOA evolve in the atmosphere. In this work, we demonstrate how carefully designed laboratory isothermal dilution experiments in smog chambers can shed light into the volatility distribution and any diffusion barriers of common types of SOA over time scales relevant to atmospheric transport and diurnal cycling. We choose SOA made from mono-terpenes (alpha-pinene and limonene) and toluene to represent biogenic and anthropogenic SOA. We look into how moisture content can alter any evaporation behaviors of SOA by varying relative humidity during SOA generation and during dilution process. This provides insight into whether diffusion in the condensed phase is rate limiting in reaching gas/particle equilibrium of semi-volatile organic compounds. Our preliminary results show that SOA from alpha-pinene evaporates continuously over several hours of experiments, and there is no substantial discernible differences over wide ranges of the chamber humidity. SOA from toluene oxidation shows slower evaporation. We fit these experimental data using absorptive partitioning theory and a particle dynamic model to obtain volatility distributions and to predict particle size evolution. This in the end will help us to improve representation of SOA in large scale chemical transport models.

Study of the aroma formation and transformation during the manufacturing process of oolong tea by solid-phase micro-extraction and gas chromatography-mass spectrometry combined with chemometrics.

PubMed

Ma, Chengying; Li, Junxing; Chen, Wei; Wang, Wenwen; Qi, Dandan; Pang, Shi; Miao, Aiqing

2018-06-01

Oolong tea is a typical semi-fermented tea and is famous for its unique aroma. The aim of this study was to compare the volatile compounds during manufacturing process to reveal the formation of aroma. In this paper, a method was developed based on head-space solid phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS) combined with chemometrics to assess volatile profiles during manufacturing process (fresh leaves, sun-withered leaves, rocked leaves and leaves after de-enzyming). A total of 24 aroma compounds showing significant differences during manufacturing process were identified. Subsequently, according to these aroma compounds, principal component analysis and hierarchical cluster analysis showed that the four samples were clearly distinguished from each other, which suggested that the 24 identified volatile compounds can represent the changes of volatile compounds during the four steps. Additionally, sun-withering, rocking and de-enzyming can influence the variations of volatile compounds in different degree, and we found the changes of volatile compounds in withering step were less than other two manufacturing process, indicating that the characteristic volatile compounds of oolong tea might be mainly formed in rocking stage by biological reactions and de-enzyming stage through thermal chemical transformations rather than withering stage. This study suggested that HS-SPME/GC-MS combined with chemometrics methods is accurate, sensitive, fast and ideal for rapid routine analysis of the aroma compounds changes in oolong teas during manufacturing processing. Copyright © 2018 Elsevier Ltd. All rights reserved.

Partitioning of U, Th and K Between Metal, Sulfide and Silicate, Insights into the Volatile-Content of Mercury

NASA Technical Reports Server (NTRS)

Habermann, M.; Boujibar, A.; Righter, K.; Danielson, L.; Rapp, J.; Righter, M.; Pando, K.; Ross, D. K.; Andreasen, R.; Chidester, B.

2016-01-01

During the early stages of the Solar System formation, especially during the T-Tauri phase, the Sun emitted strong solar winds, which are thought to have expelled a portion of the volatile elements from the inner solar system. It is therefore usually believed that the volatile depletion of a planet is correlated with its proximity to the Sun. This trend was supported by the K/Th and K/U ratios of Venus, the Earth, and Mars. Prior to the MESSENGER mission, it was expected that Mercury is the most volatile-depleted planet. However, the Gamma Ray Spectrometer of MESSENGER spacecraft revealed elevated K/U and K/Th ratios for the surface of Mercury, much higher than previous expectations. It is possible that the K/Th and K/U ratios on the surface are not a reliable gauge of the bulk volatile content of Mercury. Mercury is enriched in sulfur and is the most reduced of the terrestrial planets, with oxygen fugacity (fO2) between IW-6.3 and IW-2.6 log units. At these particular compositions, U, Th and K behave differently and can become more siderophile or chalcophile. If significant amounts of U and Th are sequestered in the core, the apparent K/U and K/Th ratios measured on the surface may not represent the volatile budget of the whole planet. An accurate determination of the partitioning of these elements between silicate, metal, and sulfide phases under Mercurian conditions is therefore essential to better constrain Mercury's volatile content and assess planetary formation models.

Degassing vs. eruptive styles at Mt. Etna volcano (Sicily, Italy): Volatile stocking, gas fluxing, and the shift from low-energy to highly-explosive basaltic eruptions

NASA Astrophysics Data System (ADS)

Moretti, Roberto; Métrich, Nicole; Di Renzo, Valeria; Aiuppa, Alessandro; Allard, Patrick; Arienzo, Ilenia

2017-04-01

Basaltic magmas can transport and release large amounts of volatiles into the atmosphere, especially in subduction zones, where slab-derived fluids enrich the mantle wedge. Depending on magma volatile content, basaltic volcanoes thus display a wide spectrum of eruptive styles, from common Strombolian-type activity to Plinian events. Mt. Etna in Sicily, is a typical basaltic volcano where the volatile control on such a variable activity can be investigated. Based on a melt inclusion study in products from Strombolian or lava-fountain activity to Plinian eruptions, here we show that for the same initial volatile content, different eruptive styles reflect variable degassing paths throughout the composite Etnean plumbing system. The combined influence of i) crystallization, ii) deep degassing and iii) CO2 gas fluxing can explain the evolution of H2O, CO2, S and Cl in products from such a spectrum of activity. Deep crystallization produces the CO2-rich gas fluxing the upward magma portions, which will become buoyant and easily mobilized in small gas-rich batches stored within the plumbing system. When reaching gas dominated conditions (i.e., a gas/melt mass ratio of 0.3 and CO2,gas/H2Ogas molar ratio 5 ), these will erupt effusively or mildly explosively, whilst in case of the 122 BC Plinian eruption, open-system degassing conditions took place within the plumbing system, such that continuous CO2-fluxing determined gas accumulation on top of the magmatic system. The emission of such a cap in the early eruptive phase triggered the arrival of deep H2O-rich whose fast decompression and bubble nucleation lead to the highly explosive character, enhanced by abundant microlite crystallization and consequent increase of magma effective viscosity. This could explain why open system basaltic systems like Etna may experience highly explosive or even Plinian episodes during eruptions that start with effusive to mildly explosive phases. The proposed mechanism also determines a depression of chlorine contents in CO2-fluxed (and less explosive) magmas with respect to those feeding Plinian events like 122 BC one. The opposite is seen for sulfur: low to mild-explosive fluxed magmas are S-enriched, whereas the 122 BC Plinian products are relatively S-poor, likely because of early sulfide separation accompanying magma crystallization. The proposed mechanism involving CO2 separation and fluxing may suggest a subordinate role for variable mixing of different sources having different degrees of K-enrichment. However, such a mechanism requires further experimental studies about the effects on S and Cl dissolution and does not exclude self-mixing between degassed and undegassed batches within the Etna plumbing system. Finally, our findings may represent a new interpretative tool for the geochemical and petrological monitoring of plume gas discharges and melt inclusions, and allow tracking the switch from mild-explosive to highly explosive or even Plinian events at Etna.

SPECIATED VOC EMISSIONS FROM MODERN GDI LIGHT ...

EPA Pesticide Factsheets

Chassis dynamometer emissions testing was conducted to characterize speciated volatile organic compounds (VOCs), including mobile source air toxics (MSATs) and ozone precursors, in exhaust emissions from three modern gasoline direct injection (GDI) light-duty vehicles. Each GDI vehicle tested in this study utilized slightly different fuel injection technology: Vehicle 1 used a 2.4 liter, naturally aspirated, wall-guided GDI; Vehicle 2 used a 1.8 liter, turbocharged GDI engine; Vehicle 3 used a 1.5 liter, turbocharged, spray-guided GDI engine. Vehicle testing was conducted in a temperature controlled chassis dynamometer test cell at 22 °C over the EPA Federal Test Procedure (FTP) and a portion of the Supplemental FTP (SFTP). The FTP was conducted as a three phase cycle with a cold start, hot transient, and warm start phase (also known as the FTP-75 driving cycle). The SFTP consisted of the US06 driving cycle (conducted without the vehicle’s air conditioning on), which provides a more aggressive driving pattern than the FTP. The vehicles operated on 10 percent ethanol blended gasoline (E10). VOC emissions from diluted vehicle exhaust were sampled over each FTP phase and over the Supplemental FTP with SUMMA canisters for EPA Method TO-15 analysis and with DNPH cartridges for carbonyl analysis by EPA Method TO-11A. This presentation will report the impact of driving cycle and GDI technology on speciated MSAT emissions. MSAT emission rates will be compared

Micellar electrokinetic chromatography with acid labile surfactant.

PubMed

Stanley, Bob; Lucy, Charles A

2012-02-24

We present a study of a degradable surfactant, sodium 4-[(2-methyl-2-undecyl-1,3-dioxolan-4-yl)methoxy]-1-propane sulfonate that is also known as an acid-labile surfactant (ALS). The performance of ALS as a pseudostationary phase is assessed and compared with established pseudostationary phases such as sodium dodecyl sulphate (SDS), volatile surfactants and polymeric micelles. ALS achieves separation efficiency of 100,000-145,000 theoretical plates and relative standard deviation (RSD) of electrophoretic mobility (n=5) of less than 3%. Retention factors with ALS are strongly correlated with those with SDS. This is shown by the R2=0.79 for all eleven analytes and an R2=0.992 for specifically the non-hydrogen bonding (NHB) analytes. However, ALS displays different selectivity than SDS for hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) solutes (R2 of 0.74 and 0.88, respectively). ALS is degraded to less surface active compounds in acidic solution. These less surface-active compounds are more compatible with the electrospray ionization mass spectrometry (ESI-MS). ALS has a half-life of 48 min at pH 4. ALS has the potential to couple micellar electrokinetic chromatography (MEKC) with the ESI-MS. ALS can be used as a pseudostationary phase for a high efficiency separation and later acid hydrolyzed to enable an ESI-MS analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

Analytical and semipreparative chiral separation of cis-itraconazole on cellulose stationary phases by high-performance liquid chromatography.

PubMed

Kurka, Ondřej; Kučera, Lukáš; Bednář, Petr

2016-07-01

cis-Itraconazole is a chiral antifungal drug administered as a racemate. The knowledge of properties of individual cis-itraconazole stereoisomers is vital information for medicine and biosciences as different stereoisomers of cis-itraconazole may possess different affinity to certain biological pathways in the human body. For this purpose, either chiral synthesis of enantiomers or chiral separation of racemate can be used. This paper presents a two-step high-performance liquid chromatography approach for the semipreparative isolation of four stereoisomers (two enantiomeric pairs) of itraconazole using polysaccharide stationary phases and volatile organic mobile phases without additives in isocratic mode. The approach used involves the separation of the racemate into three fractions (i.e. two pure stereoisomers and one mixed fraction containing the remaining two stereoisomers) in the first run and consequent separation of the collected mixed fraction in the second one. For this purpose, combination of cellulose tris-(4-methylbenzoate) and cellulose tris-(3,5-dimehylphenylcarbamate) columns with complementary selectivity for cis-itraconazole provided full separation of all four stereoisomers (with purity of each isomer > 97%). The stereoisomers were collected, their optical rotation determined and their identity confirmed based on the results of a previously published study. Pure separated stereoisomers are subjected to further biological studies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New approach on volatile contents determination in silicate melt inclusions: A coupling X-ray microtomography and geochemical approach in Los Humeros caldera complex (Eastern Mexican Volcanic Belt)

NASA Astrophysics Data System (ADS)

Creon, L.; Levresse, G.; Carrasco Nuñez, G.

2016-12-01

Volatile contents and magma degassing behavior are known to affect the style, frequency, and intensity of near-surface magmatic processes. For this reason, much effort have been devoted to characterize the volatile evolution of shallow magmatic systems to better constrain volcanic history. Silicate melt inclusions (SMI) represent samples of melt that were isolated from the bulk magma at depth, thus preserving the PTX conditions of the pre-eruptive material. SMI are often affected by the formation of a bubble after trapping; this is a natural consequence of the PVTX properties of crystal-melt-volatile systems. Previous workers have recognized that bubble formation is an obstacle, which affects the interpretation of SMI trapping conditions based only on analysis of the glass phase. Indeed, they explained that bubbles can contain a significant percentage of the volatiles, particularly for those with low solubility in the melt (e.g. CO2). In this study, we propose to define the pre-eruptive PTX conditions of Los Humeros magma chamber using SMI from the various eruption events within 460 and 30 Ka. An innovative analytical coupling has been used in order to determine: (1) the volume of the SMI glass and bubble, using high resolution 3D X-ray microtomography; (2) the density and composition of the bubbles, using Raman spectroscopy; (3) the volatile element contents in glass, using NanoSIMS; and, (4) the major elements composition of the glass, using EPMA. The recalculated volatile concentrations of the total SMI (glass + bubble), illustrate clearly that the volatile content determinations using only the glass phase, underestimate drastically the total volatile content and therefore induce significant error on the determination of the pre-eruptive volcanic budget and on the constrain on the volcanic and thermal history. This study had moreover highlighted the complex evolution of Los Humeros composite magma chamber and, gave constrains for geothermal exploration purpose.

Characterization by volatile compounds of microbial deep spoilage in Iberian dry-cured ham.

PubMed

Martín, Alberto; Benito, María J; Aranda, Emilio; Ruiz-Moyano, Santiago; Córdoba, Juan J; Córdoba, María G

2010-08-01

In the present study, volatile compounds of spoiled dry-cured Iberian ham with deep spoilage or "bone taint" were analyzed and correlated with level of spoilage and the microorganisms detected. Volatile compounds extracted by a solid phase micro-extraction technique were assayed by gas chromatography/mass spectrometry. The spoiled hams were evaluated sensorially, and the correlations among volatile compounds, spoilage level, and microbial counts were studied. The spoiled hams had higher concentrations of hydrocarbons, alcohols, acids, esters, pyrazines, sulfur compounds, and other minor volatile compounds than unspoiled hams. The sensorial analysis showed that the spoilage level of hams correlated with several volatile compounds, most of them associated with Gram-positive catalase positive cocci and Enterobacteriaceae counts. Cyclic compounds such as cyclohexanone, some ethers, and pyrazines should be considered as indicators to monitor incipient microbial deep spoilage in the elaboration of this meat product.

Characterization of traditional Istrian dry-cured ham by means of physical and chemical analyses and volatile compounds.

PubMed

Marušić, Nives; Petrović, Marinko; Vidaček, Sanja; Petrak, Tomislav; Medić, Helga

2011-08-01

The aroma-active compounds of Istrian dry-cured ham were investigated by using headspace-solid phase microextraction and gas chromatography-mass spectrometry (GC-MS). Samples of biceps femoris were also evaluated by measuring physical and chemical characteristics: moisture, protein, fat, ash and NaCl content, a(w) value; colour: L*, a*, b* and oxidation of fat: TBARS test. About 50 volatile compounds were identified and quantified which belonged to several classes of chemical: 5 alcohols, 8 aldehydes, 7 alkanes, 1 ketone, 2 esters, 9 monoterpenes and 15 sesquiterpenes. Except volatile compounds derived from lipolysis and proteolysis the most abundant constituents were terpenes (62.97; 41.43%) that originate from spices added in the salting phase of the production process. Copyright © 2011 Elsevier Ltd. All rights reserved.

Controlled Growth of Rubrene Nanowires by Eutectic Melt Crystallization

NASA Astrophysics Data System (ADS)

Chung, Jeyon; Hyon, Jinho; Park, Kyung-Sun; Cho, Boram; Baek, Jangmi; Kim, Jueun; Lee, Sang Uck; Sung, Myung Mo; Kang, Youngjong

2016-03-01

Organic semiconductors including rubrene, Alq3, copper phthalocyanine and pentacene are crystallized by the eutectic melt crystallization. Those organic semiconductors form good eutectic systems with the various volatile crystallizable additives such as benzoic acid, salicylic acid, naphthalene and 1,3,5-trichlorobenzene. Due to the formation of the eutectic system, organic semiconductors having originally high melting point (Tm > 300 °C) are melted and crystallized at low temperature (Te = 40.8-133 °C). The volatile crystallizable additives are easily removed by sublimation. For a model system using rubrene, single crystalline rubrene nanowires are prepared by the eutectic melt crystallization and the eutectic-melt-assisted nanoimpinting (EMAN) technique. It is demonstrated that crystal structure and the growth direction of rubrene can be controlled by using different volatile crystallizable additives. The field effect mobility of rubrene nanowires prepared using several different crystallizable additives are measured and compared.

Water Vapor Effects on Silica-Forming Ceramics

NASA Technical Reports Server (NTRS)

Opila, E. J.; Greenbauer-Seng, L. (Technical Monitor)

2000-01-01

Silica-forming ceramics such as SiC and Si3N4 are proposed for applications in combustion environments. These environments contain water vapor as a product of combustion. Oxidation of silica-formers is more rapid in water vapor than in oxygen. Parabolic oxidation rates increase with the water vapor partial pressure with a power law exponent value close to one. Molecular water vapor is therefore the mobile species in silica. Rapid oxidation rates and large amounts of gases generated during the oxidation reaction in high water vapor pressures may result in bubble formation in the silica and nonprotective scale formation. It is also shown that silica reacts with water vapor to form Si(OH)4(g). Silica volatility has been modeled using a laminar flow boundary layer controlled reaction equation. Silica volatility depends on the partial pressure of water vapor, the total pressure, and the gas velocity. Simultaneous oxidation and volatilization reactions have been modeled with paralinear kinetics.

Solid phase microextraction-comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry for the analysis of honey volatiles.

PubMed

Cajka, Tomás; Hajslová, Jana; Cochran, Jack; Holadová, Katerina; Klimánková, Eva

2007-03-01

Head-space solid phase microextration (SPME), followed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS), has been implemented for the analysis of honey volatiles, with emphasis on the optimal selection of SPME fibre and the first- and second-dimension GC capillaries. From seven SPME fibres investigated, a divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) 50/30 microm fibre provided the best sorption capacity and the broadest range of volatiles extracted from the headspace of a mixed honey sample. A combination of DB-5ms x SUPELCOWAX 10 columns enabled the best resolution of sample components compared to the other two tested column configurations. Employing this powerful analytical strategy led to the identification of 164 volatile compounds present in a honey mixture during a 19-min GC run. Combination of this simple and inexpensive SPME-based sampling/concentration technique with the advanced separation/identification approach represented by GCxGC-TOFMS allows a rapid and comprehensive examination of the honey volatiles profile. In this way, the laboratory sample throughput can be increased significantly and, at the same time, the risk of erroneous identification, which cannot be avoided in one-dimensional GC separation, is minimised.

Comprehensive Study of Volatile Compounds in Two Australian Rosé Wines: Aroma Extract Dilution Analysis (AEDA) of Extracts Prepared Using Solvent-Assisted Flavor Evaporation (SAFE) or Headspace Solid-Phase Extraction (HS-SPE).

PubMed

Wang, Jiaming; Gambetta, Joanna M; Jeffery, David W

2016-05-18

Two rosé wines, representing a tropical and a fruity/floral style, were chosen from a previous study for further exploration by aroma extract dilution analysis (AEDA) and quantitative analysis. Volatiles were extracted using either liquid-liquid extraction (LLE) followed by solvent-assisted flavor evaporation (SAFE) or a recently developed dynamic headspace (HS) sampling method utilizing solid-phase extraction (SPE) cartridges. AEDA was conducted using gas chromatography-mass spectrometry/olfactometry (GC-MS/O) and a total of 51 aroma compounds with a flavor dilution (FD) factor ≥3 were detected. Quantitative analysis of 92 volatiles was undertaken in both wines for calculation of odor activity values. The fruity and floral wine style was mostly driven by 2-phenylethanol, β-damascenone, and a range of esters, whereas 3-SHA and several volatile acids were seen as essential for the tropical style. When extraction methods were compared, HS-SPE was as efficient as SAFE for extracting most esters and higher alcohols, which were associated with fruity and floral characters, but it was difficult to capture volatiles with greater polarity or higher boiling point that may still be important to perceived wine aroma.

Comparison of two extraction techniques, solid-phase microextraction versus continuous liquid-liquid extraction/solvent-assisted flavor evaporation, for the analysis of flavor compounds in gueuze lambic beer.

PubMed

Thompson-Witrick, Katherine A; Rouseff, Russell L; Cadawallader, Keith R; Duncan, Susan E; Eigel, William N; Tanko, James M; O'Keefe, Sean F

2015-03-01

Lambic is a beer style that undergoes spontaneous fermentation and is traditionally produced in the Payottenland region of Belgium, a valley on the Senne River west of Brussels. This region appears to have the perfect combination of airborne microorganisms required for lambic's spontaneous fermentation. Gueuze lambic is a substyle of lambic that is made by mixing young (approximately 1 year) and old (approximately 2 to 3 years) lambics with subsequent bottle conditioning. We compared 2 extraction techniques, solid-phase microextraction (SPME) and continuous liquid-liquid extraction/solvent-assisted flavor evaporation (CCLE/SAFE), for the isolation of volatile compounds in commercially produced gueuze lambic beer. Fifty-four volatile compounds were identified and could be divided into acids (14), alcohols (12), aldehydes (3), esters (20), phenols (3), and miscellaneous (2). SPME extracted a total of 40 volatile compounds, whereas CLLE/SAFE extracted 36 volatile compounds. CLLE/SAFE extracted a greater number of acids than SPME, whereas SPME was able to isolate a greater number of esters. Neither extraction technique proved to be clearly superior and both extraction methods can be utilized for the isolation of volatile compounds found in gueuze lambic beer. © 2015 Institute of Food Technologists®

Trace-Level Volatile Quantitation by Direct Analysis in Real Time Mass Spectrometry following Headspace Extraction: Optimization and Validation in Grapes.

PubMed

Jastrzembski, Jillian A; Bee, Madeleine Y; Sacks, Gavin L

2017-10-25

Ambient ionization mass spectrometric (AI-MS) techniques like direct analysis in real time (DART) offer the potential for rapid quantitative analyses of trace volatiles in food matrices, but performance is generally limited by the lack of preconcentration and extraction steps. The sensitivity and selectivity of AI-MS approaches can be improved through solid-phase microextraction (SPME) with appropriate thin-film geometries, for example, solid-phase mesh-enhanced sorption from headspace (SPMESH). This work improves the SPMESH-DART-MS approach for use in food analyses and validates the approach for trace volatile analysis for two compounds in real samples (grape macerates). SPMESH units prepared with different sorbent coatings were evaluated for their ability to extract a range of odor-active volatiles, with poly(dimethylsiloxane)/divinylbenzene giving the most satisfactory results. In combination with high-resolution mass spectrometry (HRMS), detection limits for SPMESH-DART-MS under 4 ng/L in less than 30 s acquisition times could be achieved for some volatiles [3-isobutyl-2-methoxypyrazine (IBMP) and β-damascenone]. A comparison of SPMESH-DART-MS and SPME-GC-MS quantitation of linalool and IBMP demonstrates excellent agreement between the two methods for real grape samples (r 2 ≥ 0.90), although linalool measurements appeared to also include isobaric interference.

Thermodynamic Parameterization of Subduction-Zone Devolatilization and Application to Quantify Carbon Fluxes from Slab

NASA Astrophysics Data System (ADS)

Tian, M.; Katz, R. F.; Rees Jones, D. W.; May, D.

2017-12-01

Compared with other plate-tectonic boundaries, subduction zones (SZ) host the most drastic mechanical, thermal, and chemical changes. The transport of carbon through this complex environment is crucial to mantle carbon budget but remains the subject of active debate. Synthesis of field studies suggests that carbon subducted with the incoming slab is almost completely returned to the surface environment [Kelemen and Manning, 2015], whereas thermodynamic modelling indicates that a significant portion of carbon is retained in the slab and descends into the deep mantle [Gorman et al., 2006]. To address this controversy and quantify the carbon fluxes within SZs, it is necessary to treat the chemistry of fluid/volatile-rock interaction and the mechanics of porous fluid/volatile migration in a consistent modelling framework. This requirement is met by coupling a thermodynamic parameterization of de/re-volatilization with a two-phase flow model of subduction zones. The two-phase system is assumed to comprise three chemical components: rock containing only non-volatile oxides, H2O and CO2; the fluid phase includes only the latter two. Perple_X is used to map out the binary subsystems rock+H2O and rock+CO2; the results are parameterised in terms of volatile partition coefficients as a function of pressure and temperature. In synthesising the binary subsystems to describe phase equilibria that incorporate all three components, a Margules coefficient is introduced to account for non-ideal mixing of CO2/H2O in the fluid, such that the partition coefficients depend further on bulk composition. This procedure is applied to representative compositions of sediment, MORB, and gabbro for the slab, and peridotite for the mantle. The derived parameterization of each rock type serves as a lightweight thermodynamic module interfaceable with two-phase flow models of SZs. We demonstrate the application of this thermodynamic module through a simple model of carbon flux with a prescribed flow direction through (and out of) the slab. This model allows us to evaluate the effects of flow path and lithology on carbon storage within the slab.

Identification of Campylobacter infection in chickens from volatile faecal emissions.

PubMed

Garner, Catherine E; Smith, Stephen; Elviss, Nicola C; Humphrey, Tom J; White, Paul; Ratcliffe, Norman M; Probert, Christopher S

2008-06-01

Volatile organic compounds from chicken faeces were investigated as biomarkers for Campylobacter infection. Campylobacter are major poultry-borne zoonotic pathogens, colonizing the avian intestinal tract. Chicken faeces are the principal source of contamination of carcasses. Fresh faeces were collected on farm sites, and Campylobacter status established microbiologically. Volatile organic compounds were pre-concentrated from the headspace above 71 separate faecal samples using solid-phase microextraction and separated and identified by gas chromatography/mass spectrometry. A Campylobacter-specific profile was identified using six of the extracted volatile organic compounds. The model developed reliably identified the presence or absence of Campylobacter in >95% of chickens. The volatile biomarker identification approach for assessing avian infection is a novel approach to enhancing biosecurity in the poultry industry and should reduce the risk of disease transmission to humans.

Volatile profiles of toxigenic and non-toxigenic Aspergillus flavus using SPME for solid phase extraction

USDA-ARS?s Scientific Manuscript database

Toxigenic and atoxigenic strains of Aspergillus flavus were grown on potato dextrose agar (PDA) and wetted sterile, cracked corn for 21 and 14 days, respectively. Volatile compounds produced by A. flavus, as well as those present in the PDA controls and sterile cracked corn, were collected using sol...

COMPARISON OF PRESSURIZED LIQUID EXTRACTION AND MATRIX SOLID PHASE DISPERSION FOR THE MEASUREMENT OF SEMI-VOLATILE ORGANIC COMPOUND ACCUMULATION IN TADPOLES

EPA Science Inventory

Analytical methods capable of trace measurement of semi-volatile organic compounds (SOCs) are necessary to assess the exposure of tadpoles to contaminants as a result of long-range and regional atmospheric transport and deposition. The following study compares the results of two ...

Additive Effects on Si3n4 Oxidation/Volatilization in Water Vapor

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Robinson, R. Craig; Fox, Dennis S.; Wenglarz, Richard A.; Ferber, Mattison K.

2002-01-01

Two commercially available additive-containing silicon nitride materials were exposed in four environments which range in severity from dry oxygen at 1 atm pressure, and low gas velocity to an actual turbine engine. Oxidation and volatilization kinetics were monitored at temperatures ranging from 1066 to 1400 C. The main purpose of this paper is to examine the surface oxide morphology resulting from the exposures. It was found that the material surface was enriched in rare earth silicate phases in combustion environments when compared to the oxides formed on materials exposed in dry oxygen. However, the in situ formation of rare earth disilicate phases offered little additional protection from the volatilization of silica observed in combustion environments. It was concluded that externally applied environmental barrier coatings are needed to protect additive-containing silicon nitride materials from volatilization reactions in combustion environments. Introduction Si3N4 is proposed for use as components, such as vanes, in turbine applications. Tens of thousands of hours of life are needed for both land-based turbines and aeropropulsion applications. Additive-containing SisN4 materials are

An Effective Method to Detect Volatile Intermediates Generated in the Bioconversion of Coal to Methane by Gas Chromatography-Mass Spectrometry after In-Situ Extraction Using Headspace Solid-Phase Micro-Extraction under Strict Anaerobic Conditions.

PubMed

Liu, Jianmin; Wang, Baoyu; Tai, Chao; Wu, Li; Zhao, Han; Guan, Jiadong; Chen, Linyong

2016-01-01

Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2-C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2-C7) generated in the bioconversion process were 0.01-1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane.

An Effective Method to Detect Volatile Intermediates Generated in the Bioconversion of Coal to Methane by Gas Chromatography-Mass Spectrometry after In-Situ Extraction Using Headspace Solid-Phase Micro-Extraction under Strict Anaerobic Conditions

PubMed Central

Liu, Jianmin; Wang, Baoyu; Tai, Chao; Wu, Li; Zhao, Han; Guan, Jiadong; Chen, Linyong

2016-01-01

Bioconversion of coal to methane has gained increased attention in recent decades because of its economic and environmental advantages. However, the mechanism of this process is difficult to study in depth, partly because of difficulties associated with the analysis of intermediates generated in coal bioconversion. In this investigation, we report on an effective method to analyze volatile intermediates generated in the bioconversion of coal under strict anaerobic conditions. We conduct in-situ extraction of intermediates using headspace solid-phase micro-extraction followed by detection by gas chromatography-mass spectrometry. Bioconversion simulation equipment was modified and combined with a solid-phase micro-extraction device. In-situ extraction could be achieved by using the combined units, to avoid a breakdown in anaerobic conditions and to maintain the experiment continuity. More than 30 intermediates were identified qualitatively in the conversion process, and the variation in trends of some typical intermediates has been discussed. Volatile organic acids (C2–C7) were chosen for a quantitative study of the intermediates because of their importance during coal bioconversion to methane. Fiber coating, extraction time, and solution acidity were optimized in the solid-phase micro-extraction procedure. The pressure was enhanced during the bioconversion process to investigate the influence of headspace pressure on analyte extraction. The detection limits of the method ranged from 0.0006 to 0.02 mmol/L for the volatile organic acids and the relative standard deviations were between 4.6% and 11.5%. The volatile organic acids (C2–C7) generated in the bioconversion process were 0.01–1.15 mmol/L with a recovery range from 80% to 105%. The developed method is useful for further in-depth research on the bioconversion of coal to methane. PMID:27695055

Biogeochemical transformations of mercury in solid waste landfills and pathways for release.

PubMed

Lee, Sung-Woo; Lowry, Gregory V; Hsu-Kim, Heileen

2016-02-01

Mercury (Hg) is present in a variety of solid wastes including industrial wastes, household products, consumer electronics, and medical wastes, some of which can be disposed in conventional landfills. The presence of this neurotoxic metal in landfills is a concern due to the potential for it to leach or volatilize from the landfill and impact local ecosystems. The objective of this review is to describe general practices for the disposal of mercury-bearing solid wastes, summarize previous studies on the release of mercury from landfills, and delineate the expected transformations of Hg within landfill environments that would influence transport of Hg via landfill gas and leachate. A few studies have documented the emissions of Hg as landfill gas, primarily as gaseous elemental Hg(0) and smaller amounts as methylated Hg species. Much less is known regarding the release of Hg in leachate. Landfill conditions are unique from other subsurface environments in that they can contain water with very high conductivity and organic carbon concentration. Landfills also experience large changes in redox potential (and the associated microbial community) that greatly influence Hg speciation, transformations, and mobilization potential. Generally, Hg is not likely to persist in large quantities as dissolved species, since Hg(0) tends to evolve in the gas phase and divalent Hg(ii) sorbs strongly to particulate phases including organic carbon and sulfides. However, Hg(ii) has the potential to associate with or form colloidal particles that can be mobilized in porous media under high organic carbon conditions. Moreover, the anaerobic conditions within landfills can foster the growth of microorganisms that produced monomethyl- and dimethyl-Hg species, the forms of mercury with high potential for bioaccumulation. Much advancement has recently been made in the mercury biogeochemistry research field, and this study seeks to incorporate these findings for landfill settings.

Zinc and volatile element loss during planetary magma ocean phases

NASA Astrophysics Data System (ADS)

Dhaliwal, Jasmeet K.; Day, James M. D.; Moynier, Frédéric

2016-10-01

Zinc is a moderately volatile element and a key tracer of volatile depletion on planetary bodies due to lack of significant isotopic fractionation under high-temperature processes. Terrestrial basalts have δ66Zn values similar to some chondrites (+ 0.15 to 0.3‰ where [{66Zn/64Znsample/66Zn/64ZnJMC-Lyon-1} × 1000]) and elevated Zn concentrations (100 ppm). Lunar mare basalts yield a mean δ66Zn value of +1.4 ± 0.5‰ and have low Zn concentrations (~2 ppm). Late-stage lunar magmatic products, such as ferroan anorthosite, Mg-suite and Alkali suite rocks exhibit heavier δ66Zn values (+3 to +6‰). The heavy δ66Zn lunar signature is thought to reflect evaporative loss and fractionation of zinc, either during a giant impact or in a magma ocean phase.We explore conditions of volatile element loss within a lunar magma ocean (LMO) using models of Zn isotopic fractionation that are widely applicable to planetary magma oceans. For the Moon, our objective was to identify conditions that would yield a δ66Zn signature of ~ +1.4‰ within the mantle, assuming a terrestrial mantle zinc starting composition.We examine two cases of zinc evaporative fractionation: (1) lunar surface zinc fractionation that was completed prior to LMO crystallization and (2) lunar surface zinc fractionation that was concurrent with LMO crystallization. The first case resulted in a homogeneous lunar mantle and the second case yielded a stratified lunar mantle, with the greatest zinc isotopic enrichment in late-stage crystallization products. This latter case reproduces the distribution of zinc isotope compositions in lunar materials quite well.We find that hydrodynamic escape was not a dominant process in losing Zn, but that erosion of a nascent lunar atmosphere, or separation of condensates into a proto-lunar crust are possible. While lunar volatile depletion is still possible as a consequence of the giant impact, this process cannot reproduce the variable δ66Zn found in the Moon. Outgassing during magma ocean phases would have led to volatile-depleted planetesimal feed-stocks that would have profoundly affected the ultimate volatile inventories of larger planetary bodies.

The influence of addition of ion-pairing acid and organic modifier of the mobile phase on retention and migration of peptides in pressurized planar electrochromatography system with octadecyl silica-based adsorbent.

PubMed

Gwarda, Radosław Ł; Dzido, Tadeusz H

2018-07-13

In our previous papers we have investigated the influence of the mobile phase composition on mechanism of retention, selectivity and efficiency of peptide separation in various high-performance thin-layer chromatography (HPTLC) systems with commercially available silica-based adsorbents. We have also investigated the influence of pH of the mobile phase buffer on migration and separation of peptides in pressurized planar electrochromatography (PPEC). Here we investigate the influence of concentration of ion-pairing additive, and concentration and type of organic modifier of the mobile phase on migration of peptides in PPEC system with octadecyl silica-based adsorbent, and with the same set of the solutes as before. We compare our current results with the results obtained before for similar HPTLC and PPEC systems, and discuss the influence of particular variables on retention, electrophoretic mobility of solutes and electroosmotic flow of the mobile phase. We show, that the final selectivity of peptide separation results from co-influence of all the three factors mentioned. Concentration of organic modifier of the mobile phase, as well as concentration of ion-pairing additive, affect the retention, the electrophoretic mobility, and the electroosmotic flow simultaneously. This makes independent optimization of these factors rather difficult. Anyway PPEC offers much faster separation of peptides with quite different selectivity, in comparison to HPTLC, with similar adsorbents and similar mobile phase composition. However, we also present and discuss the issue of extensive tailing of peptide zones in the PPEC in comparison to similar HPTLC systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Pattern recognition and genetic algorithms for discrimination of orange juices and reduction of significant components from headspace solid-phase microextraction.

PubMed

Rinaldi, Maurizio; Gindro, Roberto; Barbeni, Massimo; Allegrone, Gianna

2009-01-01

Orange (Citrus sinensis L.) juice comprises a complex mixture of volatile components that are difficult to identify and quantify. Classification and discrimination of the varieties on the basis of the volatile composition could help to guarantee the quality of a juice and to detect possible adulteration of the product. To provide information on the amounts of volatile constituents in fresh-squeezed juices from four orange cultivars and to establish suitable discrimination rules to differentiate orange juices using new chemometric approaches. Fresh juices of four orange cultivars were analysed by headspace solid-phase microextraction (HS-SPME) coupled with GC-MS. Principal component analysis, linear discriminant analysis and heuristic methods, such as neural networks, allowed clustering of the data from HS-SPME analysis while genetic algorithms addressed the problem of data reduction. To check the quality of the results the chemometric techniques were also evaluated on a sample. Thirty volatile compounds were identified by HS-SPME and GC-MS analyses and their relative amounts calculated. Differences in composition of orange juice volatile components were observed. The chosen orange cultivars could be discriminated using neural networks, genetic relocation algorithms and linear discriminant analysis. Genetic algorithms applied to the data were also able to detect the most significant compounds. SPME is a useful technique to investigate orange juice volatile composition and a flexible chemometric approach is able to correctly separate the juices.

Development of a headspace-solid phase micro extraction method to monitor changes in volatile profile of rose (Rosa hybrida, cv David Austin) petals during processing.

PubMed

Bianchi, Giulia; Nuzzi, Monica; Avitabile Leva, Alexa; Rizzolo, Anna

2007-05-25

In the present study, headspace solid phase microextraction combined to capillary gas chromatography (HS-SPME-GC) has been applied for the determination of changes in the volatile profile of rose petals (Rosa hybrida, cvs David Austin) following processing (heat treatment and addition as an ingredient to a food product--for example yoghurt). Four SPME fibres at two sampling temperatures (40 and 60 degrees C) with a sampling time of 30 min were examined. Volatile profiles were detected either by FID or/and by olfactometry (ODP-II, Gerstel). Fibre testing was performed using raw rose petals for sampling temperature selection and an 18 characteristic rose volatile standard mixture in water was used to compare fibre performances at the sampling temperature of 60 degrees C. Polydimethylsiloxane-divinylbenzene (PDMS-DVB) fibre at the sampling temperature of 60 degrees C was the most suitable to sample the rose alcohols phenyl ethanol, citronellol, nerol, geraniol and eugenol, as assessed by GC-olfactometry, not only from raw petals, but also from processed rose petals and the food product. PDMS-DVB fibre also showed a desired low affinity to volatiles from yoghurt, which reduces the influence of food matrix on the volatile profile. The method was linear over two orders of magnitude and had satisfactory repeatability, with limits of detection for the rose alcohols ranging from <1 to 10 ng/ml concentration levels.

Reactivity and mobility of new and old mercury deposition in a boreal forest ecosystem during the first year of the METAALICUS study

USGS Publications Warehouse

Hintelmann, H.; Harris, R.; Heyes, A.; Hurley, J.P.; Kelly, C.A.; Krabbenhoft, D.P.; Lindberg, S.; Rudd, J.W.M.; Scott, K.J.; St. Louis, V.L.

2002-01-01

The METAALICUS (Mercury Experiment To Assess Atmospheric Loading In Canada and the US) project is a whole ecosystem experiment designed to study the activity, mobility, and availability of atmospherically deposited mercury. To investigate the dynamics of mercury newly deposited onto a terrestrial ecosystem, an enriched stable isotope of mercury (202Hg) was sprayed onto a Boreal forest subcatchment in an experiment that allowed us, for the first time, to monitor the fate of "new" mercury in deposition and to distinguish it from native mercury historically stored in the ecosystem. Newly deposited mercury was more reactive than the native mercury with respect to volatilization and methylation pathways. Mobility through runoff was very low and strongly decreased with time because of a rapid equilibration with the large native pool of "bound" mercury. Over one season, only ???8% of the added 202Hg volatilized to the atmosphere and less than 1% appeared in runoff. Within a few months, approximately 66% of the applied 202Hg remained associated with above ground vegetation, with the rest being incorporated into soils. The fraction of 202Hg bound to vegetation was much higher than seen for native Hg (<5% vegetation), suggesting that atmospherically derived mercury enters the soil pool with a time delay, after plants senesce and decompose. The initial mobility of mercury received through small rain events or dry deposition decreased markedly in a relatively short time period, suggesting that mercury levels in terrestrial runoff may respond slowly to changes in mercury deposition rates.

Mobile Gas and Particulate Emission Studies of the New York City Transit Bus Fleet

NASA Astrophysics Data System (ADS)

Jayne, J. T.; Canagaratna, M.; Herndon, S.; Shorter, J.; Zahniser, M.; Shi, Q.; Kolb, C.; Worsnop, D.; Jimenez, J.; Drewnick, F.; Demerjian, K.; Lanni, T.

2001-12-01

Emissions from both diesel and gasoline powered motor vehicles are a significant source of particulate (PM2.5) and trace gas pollution, especially in urban environments. Emission characterizations of motor vehicles can be performed using a dynamometer but these studies make fleet characterization impractical. Few studies have been performed which characterize emissions from in-use vehicles using a mobile sampling platform. This work describes application of new technology instrumentation for rapid (1-5 second) and real-time characterization of both gas and particulate emissions from in-use vehicles and is part of the PM2.5 Technology Assessment and Characterization Study in New York (PMTACS-NY). An aerosol mass spectrometer (AMS) and a tunable infrared laser differential absorption spectrometer (TILDAS) system were deployed on the Aerodyne Research mobile laboratory designed to "chase" target vehicles in and around the New York City area and measure their emissions under actual driving conditions. The AMS provides particle size and composition information for volatile and semi-volatile matter while the TILDAS system was configured to measure NO, NO2, CO, CH4, SO2 and formaldehyde. In addition to a GPS, an ELPI and a condensation particle counter, the mobile laboratory was also equipped with a CO2 monitor to allow emission ratios to be computed for the targeted vehicles. Emission ratios for both particulate and trace gases are reported for a representative fraction of the NYC Metropolitan Transit Authority (MTA) bus fleet in an effort to characterize new emission control technologies currently implemented by the NYC MTA.

Volatility and change in chronic pain severity predict outcomes of treatment for prescription opioid addiction.

PubMed

Worley, Matthew J; Heinzerling, Keith G; Shoptaw, Steven; Ling, Walter

2017-07-01

Buprenorphine-naloxone (BUP-NLX) can be used to manage prescription opioid addiction among persons with chronic pain, but post-treatment relapse is common and difficult to predict. This study estimated whether changes in pain over time and pain volatility during BUP-NLX maintenance would predict opioid use during the taper BUP-NLX taper. Secondary analysis of a multi-site clinical trial for prescription opioid addiction, using data obtained during a 12-week BUP-NLX stabilization and 4-week BUP-NLX taper. Community clinics affiliated with a national clinical trials network in 10 US cities. Subjects with chronic pain who entered the BUP-NLX taper phase (n = 125) with enrollment occurring from June 2006 to July 2009 (52% male, 88% Caucasian, 31% married). Outcomes were weekly biologically verified and self-reported opioid use from the 4-week taper phase. Predictors were estimates of baseline severity, rate of change and volatility in pain from weekly self-reports during the 12-week maintenance phase. Controlling for baseline pain and treatment condition, increased pain [odds ratio (OR) = 2.38, P = 0.02] and greater pain volatility (OR = 2.43, P = 0.04) predicted greater odds of positive opioid urine screen during BUP-NLX taper. Increased pain (IRR = 1.40, P = 0.04) and greater pain volatility [incidence-rate ratio (IRR) = 1.66, P = 0.009] also predicted greater frequency of self-reported opioid use. Adults with chronic pain receiving out-patient treatment with buprenorphine-naloxone (BUP-NLX) for prescription opioid addiction have an elevated risk for opioid use when tapering off maintenance treatment. Those with relative persistence in pain over time and greater volatility in pain during treatment are less likely to sustain abstinence during BUP-NLX taper. © 2017 Society for the Study of Addiction.

Geographic Mobility of Postsecondary Occupational Education Graduates. Phase II.

ERIC Educational Resources Information Center

Winter, Gene M.; Fadale, LaVerna M.

This report of the second phase of a study of the geographic mobility patterns of postsecondary occupational education graduates in New York State provides a further examination of reasons for the mobility of program completers, verifies the general magnitude of the identified mobility trends, and examines the occupational status of program…

High-performance liquid chromatographic separations of stereoisomers of chiral basic agrochemicals with polysaccharide-based chiral columns and polar organic mobile phases.

PubMed

Matarashvili, Iza; Shvangiradze, Iamze; Chankvetadze, Lali; Sidamonidze, Shota; Takaishvili, Nino; Farkas, Tivadar; Chankvetadze, Bezhan

2015-12-01

The separation of the stereoisomers of 23 chiral basic agrochemicals was studied on six different polysaccharide-based chiral columns in high-performance liquid chromatography with various polar organic mobile phases. Along with the successful separation of analyte stereoisomers, emphasis was placed on the effect of the chiral selector and mobile phase composition on the elution order of stereoisomers. The interesting phenomenon of reversal of enantiomer/stereoisomer elution order function of the polysaccharide backbone (cellulose or amylose), type of derivative (carbamate or benzoate), nature, and position of the substituent(s) in the phenylcarbamate moiety (methyl or chloro) and the nature of the mobile phase was observed. For several of the analytes containing two chiral centers all four stereoisomers were resolved with at least one chiral selector/mobile phase combination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Volatile properties of particles emitted by compressed natural gas and diesel buses during steady-state and transient driving modes.

PubMed

Jayaratne, E R; Meyer, N K; Ristovski, Z D; Morawska, L

2012-01-03

Volatile properties of particle emissions from four compressed natural gas (CNG) and four diesel buses were investigated under steady-state and transient driving modes on a chassis dynamometer. The exhaust was diluted utilizing a full-flow continuous volume sampling system and passed through a thermodenuder at controlled temperature. Particle number concentration and size distribution were measured with a condensation particle counter and a scanning mobility particle sizer, respectively. We show that while almost all the particles emitted by the CNG buses were in the nanoparticle size range, at least 85% and 98% were removed at 100 and 250 °C, respectively. Closer analysis of the volatility of particles emitted during transient cycles showed that volatilization began at around 40 °C, with the majority occurring by 80 °C. Particles produced during hard acceleration from rest exhibited lower volatility than those produced during other times of the cycle. On the basis of our results and the observation of ash deposits on the walls of the tailpipes, we suggest that these nonvolatile particles were composed mostly of ash from lubricating oil. Heating the diesel bus emissions to 100 °C removed ultrafine particle numbers by 69-82% when a nucleation mode was present and just 18% when it was not.

Prediction of peak shape in hydro-organic and micellar-organic liquid chromatography as a function of mobile phase composition.

PubMed

Baeza-Baeza, J J; Ruiz-Angel, M J; García-Alvarez-Coque, M C

2007-09-07

A simple model is proposed that relates the parameters describing the peak width with the retention time, which can be easily predicted as a function of mobile phase composition. This allows the further prediction of peak shape with global errors below 5%, using a modified Gaussian model with a parabolic variance. The model is useful in the optimisation of chromatographic resolution to assess an eventual overlapping of close peaks. The dependence of peak shape with mobile phase composition was studied for mobile phases containing acetonitrile in the presence and absence of micellised surfactant (micellar-organic and hydro-organic reversed-phase liquid chromatography, RPLC). In micellar RPLC, both modifiers (surfactant and acetonitrile) were observed to decrease or improve the efficiencies in the same percentage, at least in the studied concentration ranges. The study also revealed that the problem of achieving smaller efficiencies in this chromatographic mode, compared to hydro-organic RPLC, is not only related to the presence of surfactant covering the stationary phase, but also to the smaller concentration of organic solvent in the mobile phase.

The effects of interplanetary dust impacts on the accumulation of volatiles in the lunar permanently shadowed regions

NASA Astrophysics Data System (ADS)

Horanyi, Mihaly; Szalay, Jamey

2017-10-01

The lunar regolith has been formed, and remains continually reworked, by the intermitten impacts of comets, asteroids, meteoroids, and the continual bombardment by interplanetary dust particles (IDP). Thick atmospheres protect Venus, Earth, and Mars, ablating the incoming IDPs into “shooting stars” that rarely reach the surface. However, the surfaces of airless bodies near 1 AU are directly exposed to the high-speed (>> 1 km/s) IDP impacts. The Moon is expected to be bombarded by 5x103 kg/day of IDPs arriving with a characteristic speed of ~ 20 km/s. The IDP sources impacting the Moon at high latitudes remain largely uncharacterized due to the lack of optical and radar observations in the polar regions on Earth. These high latitude sources have very large impact speeds in the range of 30 < v < 50 km/ hence they are expected to have a significant effect on the lunar surface, including the removal and burial of volatile deposits in the lunar polar regions.Water is thought to be continually delivered to the Moon through geological timescales by water-bearing comets and asteroids, and produced continuously in situ by the impacts of solar wind protons of oxygen rich minerals exposed on the surface. IDPs are an unlikely source of water due to their long UV exposure in the inner solar system, but their high-speed impacts can mobilize secondary ejecta dust particles, atoms and molecules, some with high-enough speed to escape the Moon. Other surface processes that can lead to mobilization, transport and loss of water molecules and other volatiles include solar heating, photochemical processes, and solar wind sputtering. Since none of these are at work in permanently shadowed regions (PSR), dust impacts remain the dominant process to dictate the evolution of volatiles in PSRs. The competing effects of dust impacts are: a) ejecta production leading to loss out of a PSR; b) gardening and overturning the regolith; and c) the possible accumulation of impact ejecta, leading to the burial of the volatiles. This talk will summarize the expected effects of dust impacts on volatile accumulation in the lunar PSRs based on theoretical models, recent laboratory results, and observations by the LADEE spacecraft.

Comparison of the peak resolution and the stationary phase retention between the satellite and the planetary motions using the coil satellite centrifuge with counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives.

PubMed

Shinomiya, Kazufusa; Zaima, Kazumasa; Harada, Yukina; Yasue, Miho; Harikai, Naoki; Tokura, Koji; Ito, Yoichiro

2017-01-20

Coil satellite centrifuge (CSC) produces the complex satellite motion consisting of the triplicate rotation of the coiled column around three axes including the sun axis (the angular velocity, ω 1 ), the planet axis (ω 2 ) and the satellite axis (the central axis of the column) (ω 3 ) according to the following formula: ω 1 =ω 2 +ω 3 . Improved peak resolution in the separation of 4-methylumbelliferyl sugar derivatives was achieved using the conventional multilayer coiled columns with ethyl acetate/1-butanol/water (3: 2: 5, v/v) for the lower mobile phase at the combination of the rotation speeds (ω 1 , ω 2 , ω 3 )=(300, 150, 150rpm), and (1:4:5, v/v) for the upper mobile phase at (300:100:200rpm). The effect of the satellite motion on the peak resolution and the stationary phase retention was evaluated by each CSC separation with the different rotation speeds of ω 2 and ω 3 under the constant revolution speed at ω 1 =300rpm. With the lower mobile phase, almost constant peak resolution and stationary phase retention were yielded regardless of the change of ω 2 and ω 3 , while with the upper mobile phase these two values were sensitively varied according to the different combination of ω 2 and ω 3 . For example, when ω 2 =147 or 200rpm is used, no stationary phase was retained in the coiled column while ω 2 =150rpm could retain enough volume of stationary phase for separation. On the other hand, the combined rotation speeds at (ω 1 , ω 2 , ω 3 )=(300, 300, 0rpm) or (300, 0, 300rpm) produced insufficient peak resolution regardless of the choice of the mobile phase apparently due to the lack of rotation speed except at (300, 0, 300rpm) with the upper mobile phase. At lower rotation speed of ω 1 =300rpm, better peak resolution and stationary phase retention were obtained by the satellite motion (ω 3 ) than by the planetary motion (ω 2 ), or ω 3 >ω 2 . The effect of the hydrophobicity of the two-phase solvent systems on the stationary phase retention was further examined using the n-hexane/ethyl acetate/1-butanol/methanol/water system at different volume ratios. In the satellite motion at (ω 1 , ω 2 , ω 3 )=(300, 150, 150rpm), almost constant stationary phase retention was obtained with the lower mobile phase regardless of the hydrophobicity of the solvent system whereas the stationary phase retention varied according to the volume ratio of the two-phase solvent system for the upper mobile phase. However, stable stationary phase retention was observed with either phase used as the mobile phase. In order to analyze the acceleration acting on the coiled column, an acceleration sensor was set on the column holder by displacing the multilayer column. The combination of the rotation speeds at (300, 100, 200rpm) showed double loops in the acceleration track, whereas (300, 150, 150rpm) showed a single loop, and all other combinations showed, complex tracks. The overall results indicate that the satellite motion is seriously affected by the combination of rotation speeds and the hydrophobicity of the two-phase solvent system when the upper phase was used as the mobile phase for separation. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of the peak resolution and the stationary phase retention between the satellite and the planetary motions using the coil satellite centrifuge with counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives

PubMed Central

Shinomiya, Kazufusa; Zaima, Kazumasa; Harada, Yukina; Yasue, Miho; Harikai, Naoki; Tokura, Koji; Ito, Yoichiro

2016-01-01

Coil satellite centrifuge (CSC) produces the complex satellite motion consisting of the triplicate rotation of the coiled column around three axes including the sun axis (the angular velocity, ω1), the planet axis (ω2) and the satellite axis (the central axis of the column) (ω3) according to the following formula: ω1 = ω2 + ω3. Improved peak resolution in the separation of 4-methylumbelliferyl sugar derivatives was achieved using the conventional multilayer coiled columns with ethyl acetate/1-butanol/water (3 : 2 : 5, v/v) for the lower mobile phase at the combination of the rotation speeds (ω1, ω2, ω3) = (300, 150, 150 rpm), and (1 : 4 : 5, v/v) for the upper mobile phase at (300 : 100 : 200 rpm). The effect of the satellite motion on the peak resolution and the stationary phase retention was evaluated by each CSC separation with the different rotation speeds of ω2 and ω3 under the constant revolution speed at ω1 = 300 rpm. With the lower mobile phase, almost constant peak resolution and stationary phase retention were yielded regardless of the change of ω2 and ω3, while with the upper mobile phase these two values were sensitively varied according to the different combination of ω2 and ω3. For example, when ω2 = 147 or 200 rpm is used, no stationary phase was retained in the coiled column while ω2 = 150 rpm could retain enough volume of stationary phase for separation. On the other hand, the combined rotation speeds at (ω1, ω2, ω3) = (300, 300, 0 rpm) or (300, 0, 300 rpm) produced insufficient peak resolution regardless of the choice of the mobile phase apparently due to the lack of rotation speed except at (300, 0, 300 rpm) with the upper mobile phase. At lower rotation speed of ω1 = 300 rpm, better peak resolution and stationary phase retention were obtained by the satellite motion (ω3) than by the planetary motion (ω2), or ω3 > ω2. The effect of the hydrophobicity of the two-phase solvent systems on the stationary phase retention was further examined using the n-hexane/ethyl acetate/1-butanol/methanol/water system at different volume ratios. In the satellite motion at (ω1, ω2, ω3) = (300, 150, 150 rpm), almost constant stationary phase retention was obtained with the lower mobile phase regardless of the hydrophobicity of the solvent system whereas the stationary phase retention varied according to the volume ratio of the two-phase solvent system for the upper mobile phase. However, stable stationary phase retention was observed with either phase used as the mobile phase. In order to analyze the acceleration acting on the coiled column, an acceleration sensor was set on the column holder by displacing the multilayer column. The combination of the rotation speeds at (300, 100, 200 rpm) showed double loops in the acceleration track, whereas (300, 150, 150 rpm) showed a single loop, and all other combinations showed, complex tracks. The overall results indicate that the satellite motion is seriously affected by the combination of rotation speeds and the hydrophobicity of the two-phase solvent system when the upper phase was used as the mobile phase for separation. PMID:28040269

78 FR 46947 - Adequacy Status of the Houston-Galveston-Brazoria, Texas Reasonable Further Progress and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-02

...) State Implementation Plan (SIP) revisions, submitted on May 6, 2013 by the Texas Commission on... effective August 19, 2013. FOR FURTHER INFORMATION CONTACT: The essential information in this notice will be... to EPA. The word ``budget(s)'' refers to the mobile source emissions budget for volatile organic...

Near-Road Mulltipollutant Profiles: Association between Volatile Organic Compounds and a Tracer Gas Surrogate Near a Busy Highway

EPA Science Inventory

This research characterizes associations between multiple pollutants in the near-road environment attributed to a roadway line source. It also examines the use of a tracer gas as a surrogate of mobile source pollutants. Air samples were collected in summa canisters along a 300 m ...

CO-OCCURRENCE OF METHYL- TERT-BUTYL ETHER (MTBE) AND BTEX COMPOUNDS AT MARINAS IN A LARGE RESEVOIR

EPA Science Inventory

Methyl tert-butyl ether (MTBE) is released into the environment as one of some gasoline components, not as a pure compound. BTEX compounds (benzene, tolune, ethylbenzene, and xylenes) are major volatile constituents found in gasoline and are water soluble and mobile. This study...

Effects of elevated temperature and mobile phase composition on a novel C18 silica column.

PubMed

Lippert, J Andreas; Johnson, Todd M; Lloyd, Jarem B; Smith, Jared P; Johnson, Bryce T; Furlow, Jason; Proctor, Angela; Marin, Stephanie J

2007-05-01

A novel polydentate C18 silica column was evaluated at an elevated temperature under acidic, basic, and neutral mobile phase conditions using ACN and methanol as the mobile phase organic modifier. The temperature range was 40-200 degrees C. The mobile phase compositions were from 0 to 80% organic-aqueous v/v and the mobile phase pH levels were between 2 and 12. The maximum operating temperature of the column was affected by the amount and type of organic modifier used in the mobile phase. Under neutral conditions, the column showed good column thermal stability at temperatures ranging between 120 and 200 degrees C in methanol-water and ACN-water solvent systems. At pH 2 and 3, the column performed well up to about 160 degrees C at two fixed ACN-buffer compositions. Under basic conditions at elevated temperatures, the column material deteriorated more quickly, but still remained stable up to 100 degrees C at pH 9 and 60 degrees C at pH 10. The results of this study indicate that this novel C18 silica-based column represents a significant advancement in RPLC column technology with enhanced thermal and pH stability when compared to traditional bonded phase silica columns.

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

NASA Astrophysics Data System (ADS)

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

2011-11-01

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.

A field-deployable GC-EI-HRTOF-MS for in situ characterization of volatile organic compounds

NASA Astrophysics Data System (ADS)

Lerner, B. M.; Herndon, S. C.; Yacovitch, T. I.; Roscioli, J. R.; Fortner, E.; Knighton, W. B.; Sueper, D.; Isaacman-VanWertz, G. A.; Jayne, J. T.; Worsnop, D. R.

2017-12-01

Previous authors have demonstrated the value of coupling conventional gas chromatograph (GC) separation techniques with the new generation of electron-impact high-resolution time-of-flight mass spectrometry (EI-HR-ToF-MS) detectors for the measurement of halocarbons and semi-volatile organic species. Here, we present new instrumentation, analytical techniques and field data from the deployment of a GC-EI-HR-ToF-MS system in the mini Aerodyne mobile laboratory to sites upwind and downwind of San Antonio, Texas in May 2017. The instrument employed a multi-component adsorbent trap pre-concertation system followed by single-column separation. We will show results from the field work, including inter-comparison with other VOC measurements and characterization of C5-C10 hydrocarbon mixing ratios to distinguish urban and oil/gas emission sources in characterized air. We will discuss practical aspects of deployment of the GC-EI-HRTOF-MS in a mobile laboratory and system performance in the field. Will we also present further development of Aerodyne's TERN software package for chromatographic data analysis to processing of HRTOF-MS datasets.

[Influence of mobile phase composition on chiral separation of organic selenium racemates].

PubMed

Han, Xiao-qian; Qi, Bang-feng; Dun, Hui-juan; Zhu, Xin-yi; Na, Peng-jun; Jiang, Sheng-xiang; Chen, Li-ren

2002-05-01

The chiral separation of some chiral compounds with similar structure on the cellulose tris (3,5-dimethylphenylcarbamate) chiral stationary phase prepared by us was obtained. Ternary mobile phases influencing chiral recognition were investigated. A mode of interaction between the structural character of samples and chiral stationary phase is discussed. The results indicated that the retention and chiral separation of the analytes had a bigger change with minute addition of alcohols or acetonitrile as modifier in n-hexane/2-propanol (80/20, volume ratio) binary mobile phase.

Endogenous Lunar Volatiles

NASA Technical Reports Server (NTRS)

McCubbin, F. M.; Liu, Y.; Barnes, J. J.; Boyce, J. W.; Day, J. M. D.; Elardo, S. M.; Hui, H.; Magna, T.; Ni, P.; Tartese, R.;

Project inspection using mobile technology - phase II : assessing the impacts of mobile technology on project inspection.

DOT National Transportation Integrated Search

2015-01-01

As mobile technology becomes widely available and affordable, transportation agencies can use this : technology to streamline operations involved within project inspection. This research, conducted in two : phases, identified opportunities for proces...

MobileSat (R): A characteristically Australian MSS

NASA Technical Reports Server (NTRS)

Wagg, Michael; Jansen, Michael

1995-01-01

Optus launched its mobile satellite telephone service MobileSat in August 1994. This provided Australia and its neighboring waters with nation-wide mobile telephone coverage and still is the world's only domestic mobile satellite telephone system. This paper provides details of Optus' experience in developing and launching the MobileSat service, including (1) a retrospective of the issues that have waxed and waned in importance during the development and implementation phases, and (2) the strategy for future activities based on the experience gained in the development phase.

Multi-Phase Extraction: State-of-the-Practice

EPA Pesticide Factsheets

This report describes the state-of-the-practice for multi-phase extraction (MPE) of contaminated soil and groundwater, focusing primarily on the application and use of MPE at sites with halogenated volatile organic compounds (VOCs).

VLEACH

EPA Science Inventory

VLEACH is a one-dimensional, finite difference model for making preliminary assessments of the effects on ground water from the leaching of volatile, sorbed contaminants through the vadose zone. The program models four main processes: liquid-phase advection, solid-phase sorption,...

Volatile and non-volatile/semi-volatile compounds and in vitro bioactive properties of Chilean Ulmo (Eucryphia cordifolia Cav.) honey.

PubMed

Acevedo, Francisca; Torres, Paulina; Oomah, B Dave; de Alencar, Severino Matias; Massarioli, Adna Prado; Martín-Venegas, Raquel; Albarral-Ávila, Vicenta; Burgos-Díaz, César; Ferrer, Ruth; Rubilar, Mónica

2017-04-01

Ulmo honey originating from Eucryphia cordifolia tree, known locally in the Araucania region as the Ulmo tree is a natural product with valuable nutritional and medicinal qualities. It has been used in the Mapuche culture to treat infections. This study aimed to identify the volatile and non-volatile/semi-volatile compounds of Ulmo honey and elucidate its in vitro biological properties by evaluating its antioxidant, antibacterial, antiproliferative and hemolytic properties and cytotoxicity in Caco-2 cells. Headspace volatiles of Ulmo honey were isolated by solid-phase microextraction (SPME); non-volatiles/semi-volatiles were obtained by removing all saccharides with acidified water and the compounds were identified by GC/MS analysis. Ulmo honey volatiles consisted of 50 compounds predominated by 20 flavor components. Two of the volatile compounds, lyrame and anethol have never been reported before as honey compounds. The non-volatile/semi-volatile components of Ulmo honey comprised 27 compounds including 13 benzene derivatives accounting 75% of the total peak area. Ulmo honey exhibited weak antioxidant activity but strong antibacterial activity particularly against gram-negative bacteria and methicillin-resistant Staphylococcus aureus (MRSA), the main strain involved in wounds and skin infections. At concentrations >0.5%, Ulmo honey reduced Caco-2 cell viability, released lactate dehydrogenase (LDH) and increased reactive oxygen species (ROS) production in a dose dependent manner in the presence of foetal bovine serum (FBS). The wide array of volatile and non-volatile/semi-volatile constituents of Ulmo honey rich in benzene derivatives may partly account for its strong antibacterial and antiproliferative properties important for its therapeutic use. Our results indicate that Ulmo honey can potentially inhibit cancer growth at least partly by modulating oxidative stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

ANALYSIS OF 1,4-DIOXANE AND OTHER WATER SOLUBLE VOLATILE ORGANIC COMPOUNDS BY SOLID PHASE EXTRACTION AND GC/MS

EPA Science Inventory

1,4-Dioxane is emerging as a drinking water contaminant of concern. Because of its volatility and water solubility, 1,4-dioxane is difficult to extract and and concentrate from aqueous matrices. Because 1,4-dioxane is under consideration for the next drinking water Contaminant ...

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR ANALYSIS OF VOLATILE ORGANIC COMPOUNDS COLLECTED WITH A PASSIVE SAMPLER (BCO-L-17.1)

EPA Science Inventory

The purpose of this SOP is to describe the methodology used for the analysis of the 3M OVM 3500 Organic Vapor Monitors for volatile organic compounds (VOCs), using solvent extraction and standard gas chromatography/mass spectrometry (GC/MS) analysis procedures. This procedure was...

An unusual and persistent contamination of drinking water by cutting oil.

PubMed

Rella, R; Sturaro, A; Parvoli, G; Ferrara, D; Doretti, L

2003-02-01

Drinking water contamination by materials, such as cutting oil, used to set up pipelines is an uncommon but possible event. This paper describes the analytical procedures used to identify the components of that contaminant in drinking water. Volatile and semi-volatile chemical species, responsible for an unpleasant taste and odour, were recognised by solid phase microextraction and GC/MS techniques. Among the volatile compounds, the presence of xylenes, bornyl acetate and diphenyl ether was confirmed by certificate standards and quantified in the most contaminated samples.

A volatile organics concentrator for use in monitoring Space Station water quality

NASA Technical Reports Server (NTRS)

Ehntholt, Daniel J.; Bodek, Itamar; Valentine, James R.; Trabanino, Rudy; Vincze, Johanna E.; Sauer, Richard L.

1990-01-01

The process used to identify, select, and design an approach to the isolation and concentration of volatile organic compounds from a water sample prior to chemical analysis in a microgravity environment is discerned. The trade analysis leading to the recommended volatile organics concentrator (VOC) concept to be tested in a breadboard device is presented. The system covers the areas of gases, volatile separation from water, and water removal/gas chromatograph/mass spectrometer interface. Five options for potential use in the VOC and GC/MS system are identified and ranked, and also nine options are presented for separation of volatiles from the water phase. Seven options for use in the water removal/GC column and MS interface are also identified and included in the overall considerations. A final overall recommendation for breadboard VOC testing is given.

Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

NASA Astrophysics Data System (ADS)

Cao, Li-Ming; Huang, Xiao-Feng; Li, Yuan-Yuan; Hu, Min; He, Ling-Yan

2018-02-01

Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components, and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a thermodenuder aerosol mass spectrometer (TD-AMS) system was deployed to study the volatility of non-refractory submicron particulate matter (PM1) species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7±20.1 µg m-3, with organic aerosol (OA) being the most abundant component (43.2 % of the total mass). The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with a mass fraction remaining (MFR) of 0.57 at 50 °C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 °C), and the volatility had a relatively linear correlation with the TD temperature (from the ambient temperature to 200 °C), with an evaporation rate of 0.45 % °C-1. Five subtypes of OA were resolved from total OA using positive matrix factorization (PMF) for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %), a cooking OA (COA, 20.6 %), a biomass-burning OA (BBOA, 8.9 %), and two oxygenated OAs (OOAs): a less-oxidized OOA (LO-OOA, 39.1 %) and a more-oxidized OOA (MO-OOA, 17.9 %). Different OA factors presented different volatilities, and the volatility sequence of the OA factors at 50 °C was HOA (MFR of 0.56) > LO-OOA (0.70) > COA (0.85) ≈ BBOA (0.87) > MO-OOA (0.99), which was not completely consistent with the sequence of their O / C ratios. The high volatility of HOA implied that it had a high potential to be oxidized to secondary species in the gas phase. The aerosol volatility measurement results in this study provide useful parameters for the modeling work of aerosol evolution in China and are also helpful in understanding the formation mechanisms of secondary aerosols.

Influence of variation in mobile phase pH and solute pK(a) with the change of organic modifier fraction on QSRRs of hydrophobicity and RP-HPLC retention of weakly acidic compounds.

PubMed

Han, Shu-ying; Liang, Chao; Zou, Kuan; Qiao, Jun-qin; Lian, Hong-zhen; Ge, Xin

2012-11-15

The variation in mobile phase pH and ionizable solute dissociation constant (pK(a)) with the change of organic modifier fraction in hydroorganic mobile phase has seemingly been a troublesome problem in studies and applications of reversed phase high performance liquid chromatography (RP-HPLC). Most of the early studies regarding the RP-HPLC of acid-base compounds have to measure the actual pH of the mixed mobile phase rigorously, sometimes bringing difficulties in the practices of liquid chromatographic separation. In this paper, the effect of this variation on the apparent n-octanol/water partition coefficient (K(ow)″) and the related quantitative structure-retention relationship (QSRR) of logK(ow)″ vs. logk(w), the logarithm of retention factor of analytes in neat aqueous mobile phases, was investigated for weakly acidic compounds. This QSRR is commonly used as a classical method for K(ow) measurement by RP-HPLC. The theoretical and experimental derivation revealed that the variation in mobile phase pH and solute pK(a) will not affect the QSRRs of acidic compounds. This conclusion is proved to be suitable for various types of ion-suppressors, i.e., strong acid (perchloric acid), weak acid (acetic acid) and buffer salt (potassium dihydrogen phosphate/phosphoric acid, PBS). The QSRRs of logK(ow)″ vs. logk(w) were modeled by 11 substituted benzoic acids using different types of ion-suppressors in a binary methanol-water mobile phase to confirm our deduction. Although different types of ion-suppressor all can be used as mobile phase pH modifiers, the QSRR model obtained by using perchloric acid as the ion-suppressor was found to have the best result, and the slightly inferior QSRRs were obtained by using acetic acid or PBS as the ion-suppressor. Copyright © 2012 Elsevier B.V. All rights reserved.

Trace elements in primitive meteorites—VII Antarctic unequilibrated ordinary chondrites

NASA Astrophysics Data System (ADS)

Wang, Ming-Sheng; Lipschutz, Michael E.

2007-02-01

We report RNAA results for Co, Au, Sb, Ga, Rb, Cs, Se, Ag, Te, Zn, In, Bi, Tl and Cd (in increasing order of metamorphic mobility) in 22 Antarctic unequilibrated ordinary chondrites (UOC). This brings to 38 the number of UOC for which data for highly volatile elements are known. For elements of lesser mobility (Co to Se, omitting Cs) overall variability in UOC are low, relative standard deviations (one sigma) being no more than a factor of two. For Ag, Te and Zn, relative standard deviations are 2-4×, while for Cs and the four most volatile elements, the variabilities are 8-110×. Elemental abundances do not vary with chemical type (H, L and LL) nor with UOC subtype (3.0-3.9). Contents of all elements reach levels up to, even exceeding, cosmic and all but Cd and the two alkalis, seem unaffected by post-accretionary processes. Contents of highly volatile elements are consistent with the idea that source regions producing contemporary falls and older Antarctic UOC differed in thermal histories. The presence or absence of carbide magnetite assemblages (CMA) generally accords with high or low Cd contents, respectively. This relationship accords with the prior suggestion that CMA formed by alteration of Fe-Ni metal by C-O-H-containing fluids at temperatures <700 K, generated by thermal metamorphism in parent body interiors. The absence of CMA in most UOC (and OC), may indicate that they were subsequently destroyed as metamorphic intensity increased. The high, often supercosmic, Rb and Cs levels in UOC may result from their high solubility in liquid water signalling their redistribution by C-O-H-containing fluid while in the liquid water field. Because of its uniquely high mobility, Cd could have been enriched by the C-O-H fluids and should have been lost from parent regions during later, higher temperature anhydrous metamorphism at temperatures in the 500-600 °C range.

Solvent Additive-Assisted Anisotropic Assembly and Enhanced Charge Transport of π-Conjugated Polymer Thin Films.

PubMed

Jeong, Jae Won; Jo, Gyounglyul; Choi, Solip; Kim, Yoong Ahm; Yoon, Hyeonseok; Ryu, Sang-Wan; Jung, Jaehan; Chang, Mincheol

2018-05-30

Charge transport in π-conjugated polymer films involves π-π interactions within or between polymer chains. Here, we demonstrate a facile solution processing strategy that provides enhanced intra- and interchain π-π interactions of the resultant polymer films using a good solvent additive with low volatility. These increased interactions result in enhanced charge transport properties. The effect of the good solvent additive on the intra- and intermolecular interactions, morphologies, and charge transport properties of poly(3-hexylthiophene) (P3HT) films is systematically investigated. We found that the good solvent additive facilitates the self-assembly of P3HT chains into crystalline fibrillar nanostructures by extending the solvent drying time during thin-film formation. As compared to the prior approach using a nonsolvent additive with low volatility, the solvent blend system containing a good solvent additive results in enhanced charge transport in P3HT organic field-effect transistor (OFET) devices [from ca. 1.7 × 10 -2 to ca. 8.2 × 10 -2 cm 2 V -1 s -1 for dichlorobenzene (DCB) versus 4.4 × 10 -2 cm 2 V -1 s -1 for acetonitrile]. The mobility appears to be maximized over a broad spectrum of additive concentrations (1-7 vol %), indicative of a wide processing window. Detailed analysis results regarding the charge injection and transport characteristics of the OFET devices reveal that a high-boiling-point solvent additive decreases both the contact resistance ( R c ) and channel resistance ( R ch ), contributing to the mobility enhancement of the devices. Finally, the platform presented here is proven to be applicable to alternative good solvent additives with low volatility, such as chlorobenzene (CB) and trichlorobenzene (TCB). Specifically, the mobility enhancement of the resultant P3HT films increases in the order CB (bp 131 °C) < DCB (bp 180 °C) < TCB (bp 214 °C), suggesting that solvent additives with higher boiling points provide resultant films with preferable molecular ordering and morphologies for efficient charge transport.

Measurement of acetates in air using differential ion mobility spectrometer

NASA Astrophysics Data System (ADS)

Szczurek, Andrzej; Maciejewska, Monika; Zajiczek, Żaneta; Maziejuk, Mirosław

2017-11-01

Volatile organic compounds are one of the most important group of air pollutants. Potential health and environmental problems resulting from their emission prompted the requirement for monitoring these species. It motivates development of new measurement techniques which are fast, cost effective, reliable and field deployable. One of novel approaches is ion mobility spectrometry. It dwells on ion separation in electric field, based on differences in ion mobility. Many variants of this method are developed. In this wok, differential ion mobility spectrometry (DMS) was considered in respect of acetate measurements in air. It was demonstrated that DMS offers linear response to methyl, ethyl, propyl and butyl acetate in concentration range from 0.3 ppm to 7 ppm. Positive ions spectrum has to be utilised for this purpose. We showed that fragments of DMS spectrum which secure linearity are compound-specific. The obtained results are promising from the application point of view.

Boost Up Carrier Mobility for Ferroelectric Organic Transistor Memory via Buffering Interfacial Polarization Fluctuation

PubMed Central

Sun, Huabin; Wang, Qijing; Li, Yun; Lin, Yen-Fu; Wang, Yu; Yin, Yao; Xu, Yong; Liu, Chuan; Tsukagoshi, Kazuhito; Pan, Lijia; Wang, Xizhang; Hu, Zheng; Shi, Yi

2014-01-01

Ferroelectric organic field-effect transistors (Fe-OFETs) have been attractive for a variety of non-volatile memory device applications. One of the critical issues of Fe-OFETs is the improvement of carrier mobility in semiconducting channels. In this article, we propose a novel interfacial buffering method that inserts an ultrathin poly(methyl methacrylate) (PMMA) between ferroelectric polymer and organic semiconductor layers. A high field-effect mobility (μFET) up to 4.6 cm2 V−1 s−1 is obtained. Subsequently, the programming process in our Fe-OFETs is mainly dominated by the switching between two ferroelectric polarizations rather than by the mobility-determined charge accumulation at the channel. Thus, the “reading” and “programming” speeds are significantly improved. Investigations show that the polarization fluctuation at semiconductor/insulator interfaces, which affect the charge transport in conducting channels, can be suppressed effectively using our method. PMID:25428665

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

PubMed

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

1999-10-01

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

Volatile Compound-Mediated Interactions between Barley and Pathogenic Fungi in the Soil

PubMed Central

Fiers, Marie; Lognay, Georges; Fauconnier, Marie-Laure; Jijakli, M. Haïssam

2013-01-01

Plants are able to interact with their environment by emitting volatile organic compounds. We investigated the volatile interactions that take place below ground between barley roots and two pathogenic fungi, Cochliobolus sativus and Fusarium culmorum. The volatile molecules emitted by each fungus, by non-infected barley roots and by barley roots infected with one of the fungi or the two of them were extracted by head-space solid phase micro extraction and analyzed by gas chromatography mass spectrometry. The effect of fungal volatiles on barley growth and the effect of barley root volatiles on fungal growth were assessed by cultivating both organisms in a shared atmosphere without any physical contact. The results show that volatile organic compounds, especially terpenes, are newly emitted during the interaction between fungi and barley roots. The volatile molecules released by non-infected barley roots did not significantly affect fungal growth, whereas the volatile molecules released by pathogenic fungi decreased the length of barley roots by 19 to 21.5% and the surface of aerial parts by 15%. The spectrum of the volatiles released by infected barley roots had no significant effect on F. culmorum growth, but decreased C. sativus growth by 13 to 17%. This paper identifies the volatile organic compounds emitted by two pathogenic fungi and shows that pathogenic fungi can modify volatile emission by infected plants. Our results open promising perspectives concerning the biological control of edaphic diseases. PMID:23818966

77 FR 57085 - Mobility Fund Phase I Auction; Release of Files with Recalculated Road Miles for Auction 901...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-17

... FEDERAL COMMUNICATIONS COMMISSION [AU Docket No. 12-25; DA 12-1446] Mobility Fund Phase I Auction... Mobility Fund Phase I support to be offered in Auction 901, which is to be held on September 27, 2012, and the change of the mock auction date from September 25, 2012 to September 21, 2012. DATES: The mock...

Influence of physicochemical parameters and high pressure processing on the volatile compounds of Serrano dry-cured ham after prolonged refrigerated storage.

PubMed

Martínez-Onandi, N; Rivas-Cañedo, A; Picon, A; Nuñez, M

2016-12-01

One hundred and three volatile compounds were detected by solid-phase microextraction followed by gas chromatography-mass spectrometry in 30 ripened Serrano dry-cured hams, submitted or not to high pressure processing (HPP) and afterwards held for 5months at 4°C. The effect of ham physicochemical parameters and HPP (600MPa for 6min) on volatile compounds was assessed. Physicochemical parameters primarily affected the levels of acids, alcohols, alkanes, esters, benzene compounds, sulfur compounds and some miscellaneous compounds. Intramuscular fat content was the physicochemical parameter with the most pronounced effect on the volatile fraction of untreated Serrano ham after refrigerated storage, influencing the levels of 38 volatile compounds while aw, salt content and salt-in-lean ratio respectively influenced the levels of 4, 4 and 5 volatile compounds. HPP treatment affected 21 volatile compounds, resulting in higher levels of alkanes and ketones and lower levels of esters and secondary alcohols, what might affect Serrano ham odor and aroma after 5months of refrigerated storage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multidimensional analysis of cannabis volatile constituents: identification of 5,5-dimethyl-1-vinylbicyclo[2.1.1]hexane as a volatile marker of hashish, the resin of Cannabis sativa L.

PubMed

Marchini, Marie; Charvoz, Céline; Dujourdy, Laurence; Baldovini, Nicolas; Filippi, Jean-Jacques

2014-11-28

The volatile constituents of drug samples derived from Cannabis sativa L. were investigated by means of headspace solid phase microextraction (HS-SPME) and gas chromatography techniques (GC-MS, GC×GC-MS). Samples of cannabis herb and hashish showed clear differences in their volatile chemical profiles, mostly resulting from photo-oxidation processes occurring during the transformation of fresh cannabis herb into hashish. Most unexpectedly, we could demonstrate hashish samples as containing remarkable amounts of a rare and unusual monoterpene - 5,5-dimethyl-1-vinylbicyclo[2.1.1]hexane - among the volatile compounds detected in their headspaces. We gave evidence for the formation of this compound from the light induced rearrangement of β-myrcene during the manufacture of hashish. In view of its high abundance among volatile constituents of cannabis resin and its scarce occurrence in other natural volatile extracts, we propose to rename this specific monoterpene hashishene. Copyright © 2014 Elsevier B.V. All rights reserved.

Ewe's diet (pasture vs grain-based feed) affects volatile profile of cooked meat from light lamb.

PubMed

Almela, Elisabeth; Jordán, María José; Martínez, Cristina; Sotomayor, José Antonio; Bedia, Mario; Bañón, Sancho

2010-09-08

The effects of ewe's diet during gestation and lactation on the volatile compounds profile in cooked meat from light lamb were compared. Two lamb groups from ewes that had been fed pasture (PA) or grain-based concentrate (FE) were tested. Cooked loin mixed with saliva was analyzed by solid phase microextraction, gas chromatography, and mass spectrometry. The fiber coating used was divinylbenzene-carboxen-polydimethylsiloxane. The volatiles detected and quantified were aldehydes, alcohols, ketones, phenols, indole, and sulfur compounds. The ewe's diet strongly affected the volatile compounds profile of the cooked meat. The total volatiles concentration was higher in PA (409 mg kg(-1)) than in FE (201 mg kg(-1)). The major volatiles in PA were phenol, 4-methylphenol, and hexanoic acid, while the major volatile in FE was 3-hydroxy-2-butanone. No branched C8-C9 fatty acids responsible for mutton flavor were detected in either group. The findings suggest that nutritional strategies can be use during gestation and lactation to modify the aroma of light lamb meat in the light of consumer preferences.

Project inspection using mobile technology - phase I : an investigation into existing business processes and areas for improvement using mobile technology.

DOT National Transportation Integrated Search

2013-08-01

As mobile technology becomes widely available and affordable, transportation agencies can use this technology to : streamline operations involved within project inspection. This research, conducted in two phases, identified : opportunities for proces...

Flotation of Magnetite Crystals upon Decompression - A Formation Model for Kiruna-type Iron Oxide-Apatite Deposits

NASA Astrophysics Data System (ADS)

Knipping, J. L.; Simon, A. C.; Fiege, A.; Webster, J. D.; Reich, M.; Barra, F.; Holtz, F.; Oeser-Rabe, M.

2017-12-01

Trace-element characteristics of magnetite from Kiruna-type iron oxide-apatite deposits indicate a magmatic origin. A possible scenario currently considered for the magmatic formation, apart from melt immiscibility, is related to degassing of volatile-rich magmas. Decompression, e.g., induced by magma ascent, results in volatile exsolution and the formation of a magmatic volatile phase. Volatile bubbles are expected to nucleate preferentially on the surface of oxides like magnetite which is due to a relatively low surface tension of oxide-bubble interfaces [1]. The "bulk" density of these magnetite-bubble pairs is typically lower than the surrounding magma and thus, they are expected to migrate upwards. Considering that magnetite is often the liquidus phase in fluid-saturated, oxidized andesitic arc magmas, this process may lead to the formation of a rising magnetite-bubble suspension [2]. To test this hypothesis, complementary geochemical analyses and high pressure experimental studies are in progress. The core to rim Fe isotopic signature of magnetite grains from the Los Colorados deposit in the Chilean Iron Belt was determined by Laser Ablation-MC-ICP-MS. The δ56Fe data reveal a systematic zonation from isotopically heavy Fe (δ56Fe: 0.25 ±0.07 ‰) in the core of magnetite grains to relatively light Fe (δ56Fe: 0.15 ±0.05 ‰) toward grain rims. This variation indicates crystallization of the magnetite cores at early magmatic stages from a silicate melt and subsequent growth of magnetite rims at late magmatic - hydrothermal stages from a free volatile phase. These signatures agree with the core to rim trace-element signatures of the same magnetite grains. The presence of Cl in the exsolved volatile phase and the formation of FeCl2 complexes is expected to enhance the transport of Fe in fluids and the formation of magmatic-hydrothermal magnetite [3]. First experiments (975 °C, 350 to 100 MPa, 0.025 MPa/s) show certain magnetite accumulation only 15 minutes after decompression in the upper part of the experimental products, indicating that magnetite flotation can be an efficient mechanism to separate and accumulate magnetite. [1] Hurwitz and Navon (1994) Earth Planet. Sci. Lett.122, 267-280 [2] Edmonds et al. (2014) Geol. Soc. London, Spec. Pub. 410. [3] Simon et al. (2004) Geochim. Cosmochim. Acta 68, 4905-4914.

Control of disinfection by-products in canned vegetables caused by water used in their processing.

PubMed

Cardador, Maria Jose; Gallego, Mercedes

2017-01-01

Canned vegetables come into contact with sanitizers and/or treated water in industry during several steps (namely washing, sanitising, blanching and filling with sauces or brine solutions) and therefore they can contain disinfection by-products - DBPs). This study focused on the occurrence of trihalomethanes (THMs) and haloacetic acids (HAAs) in a wide variety of canned vegetables (75 samples). For each vegetable, the edible solid and liquid phases of the package were separated and analysed individually. DBPs can be present in both solid (up to eight species) and liquid (up to 11 species) phases, their levels being higher in liquid ones. Volatile THMs predominate in the edible solid phase (up to four species), while HAAs do so in the liquid phase (up to five species) according to their ionic and non-volatile nature. The lowest concentrations of DBPs were found in tomatoes because they were often preserved in their own juice, without water.

Trace element behavior in hydrothermal experiments: Implications for fluid processes at shallow depths in subduction zones

NASA Astrophysics Data System (ADS)

You, C.-F.; Castillo, P. R.; Gieskes, J. M.; Chan, L. H.; Spivack, A. J.

1996-05-01

Chemical evaluation of fluids affected during progressive water-sediment interactions provides critical information regarding the role of slab dehydration and/or crustal recycling in subduction zones. To place some constraints on geochemical processes during sediment subduction, reactions between décollement sediments and synthetic NaCl-CaCl 2 solutions at 25-350°C and 800 bar were monitored in laboratory hydrothermal experiments using an autoclave apparatus. This is the first attempt in a single set of experiments to investigate the relative mobilities of many subduction zone volatiles and trace elements but, because of difficulties in conducting hydrothermal experiments on sediments at high P-T conditions, the experiments could only be designed for a shallow (˜ 10 km) depth. The experimental results demonstrate mobilization of volatiles (B and NH 4) and incompatible elements (As, Be, Cs, Li, Pb, Rb) in hydrothermal fluids at relatively low temperatures (˜ 300°C). In addition, a limited fractionation of light from heavy rare earth elements (REEs) occurs under hydrothermal conditions. On the other hand, the high field strength elements (HFSEs) Cr, Hf, Nb, Ta, Ti, and Zr are not mobile in the reacted fluids. The observed behavior of volatiles and trace elements in hydrothermal fluids is similar to the observed enrichment in As, B, Cs, Li, Pb, Rb, and light REEs and depletion in HFSEs in arc magmas relative to magmas derived directly from the upper mantle. Thus, our work suggests a link between relative mobilities of trace elements in hydrothermal fluids and deep arc magma generation in subduction zones. The experimental results are highly consistent with the proposal that the addition of subduction zone hydrous fluids to the subarc mantle, which has been depleted by previous melting events, can produce the unique characteristics of arc magmas. Moreover, the results suggest that deeply subducted sediments may no longer have the composition necessary to generate the other distinct characteristics, such as the B-δ 11 B and B- 10Be systematics, of arc lavas. Finally, the mobilization of B, Cs, Pb, and light REEs relative to heavy REEs in the hydrothermal fluids fractionate the ratios of B/Be, B/Nb, Cs/Rb, Pb/Ce, La/Ba and LREE/HREE, which behave conservatively during normal magmatic processes. These results demonstrate that the composition of slab-derived fluids has great implications for the recycling of elements; not only in arc magmas but also in mantle plumes.

Particle growth kinetics over the Amazon rainforest

NASA Astrophysics Data System (ADS)

Pinterich, T.; Andreae, M. O.; Artaxo, P.; Kuang, C.; Longo, K.; Machado, L.; Manzi, A. O.; Martin, S. T.; Mei, F.; Pöhlker, C.; Pöhlker, M. L.; Poeschl, U.; Shilling, J. E.; Shiraiwa, M.; Tomlinson, J. M.; Zaveri, R. A.; Wang, J.

2016-12-01

Aerosol particles larger than 100 nm play a key role in global climate by acting as cloud condensation nuclei (CCN). Most of these particles, originated from new particle formation or directly emitted into the atmospheric, are initially too small to serve as CCN. These small particles grow to CCN size mainly through condensation of secondary species. In one extreme, the growth is dictated by kinetic condensation of very low-volatility compounds, favoring the growth of the smallest particles; in the other extreme, the process is driven by Raoult's law-based equilibrium partitioning of semi-volatile organic compound, favoring the growth of larger particles. These two mechanisms can lead to very different production rates of CCN. The growth of particles depends on a number of parameters, including the volatility of condensing species, particle phase, and diffusivity inside the particles, and this process is not well understood in part due to lack of ambient data. Here we examine atmospheric particle growth using high-resolution size distributions measured onboard the DOE G-1 aircraft during GoAmazon campaign, which took place from January 2014 to December 2015 near Manaus, Brazil, a city surrounded by natural forest for over 1000 km in every direction. City plumes are clearly identified by the strong enhancement of nucleation and Aitken mode particle concentrations over the clean background. As the plume traveled downwind, particle growth was observed, and is attributed to condensation of secondary species and coagulation (Fig.1). Observed aerosol growth is modeled using MOSAIC (Model for Simulating Aerosol Interactions and Chemistry), which dynamically partitions multiple compounds to all particle size bins by taking into account compound volatility, gas-phase diffusion, interfacial mass accommodation, particle-phase diffusion, and particle-phase reaction. The results from both wet and dry seasons will be discussed.

Ground-water contamination at an inactive coal and oil gasification plant site, Gas Works Park, Seattle, Washington

USGS Publications Warehouse

Turney, G.L.; Goerlitz, D.F.

1989-01-01

Gas Works Park, in Seattle, Washington, is located on the site of a coal and oil gasification plant that ceased operation in 1956. During operation, many types of wastes, including coal, tar, and oil, accumulated on site. The park soil is presently (1986) contaminated with compounds such as polynuclear aromatic hydrocarbons, volatile organic compounds, trace metals, and cyanide. Analyses of water samples from a network of observation wells in the park indicate that these compounds are also present in the groundwater. Polynuclear aromatic hydrocarbons and volatile organic compounds were identified in groundwater samples in concentrations as large as 200 mg/L. Concentrations of organic compounds were largest where groundwater was in contact with a nonaqueous phase liquid in the soil. Concentrations in groundwater were much smaller where no nonaqueous phase liquid was present, even if the groundwater was in contact with contaminated soils. This condition is attributed to weathering processes at the site, such as dissolution, volatilization, and biodegradation. Soluble, volatile, low-molecular-weight organic compounds are preferentially dissolved from the nonaqueous phase liquid into the groundwater. Where no nonaqueous phase liquid is present, only stained soils containing relatively insoluble, high-molecular-weight compounds remain; therefore, contaminant concentrations in the groundwater are much smaller. Concentrations of organic contaminants in the soils may still remain large. Values of specific conductance were as large as 5,280 microsiemens/cm, well above a background of 242 microsiemens/cm, suggesting large concentrations of minerals in the groundwater. Trace metal concentrations, however , were generally < 0.010 mg/L, and below limits of US EPA drinking water standards. Cyanide was present in groundwater samples from throughout the park, ranging in concentration from 0.01 to 8.6 mg/L. (Author 's abstract)

Evolution of vehicle exhaust particles in the atmosphere.

PubMed

Canagaratna, Manjula R; Onasch, Timothy B; Wood, Ezra C; Herndon, Scott C; Jayne, John T; Cross, Eben S; Miake-Lye, Richard C; Kolb, Charles E; Worsnop, Douglas R

2010-10-01

Aerosol mass spectrometer (AMS) measurements are used to characterize the evolution of exhaust particulate matter (PM) properties near and downwind of vehicle sources. The AMS provides time-resolved chemically speciated mass loadings and mass-weighted size distributions of nonrefractory PM smaller than 1 microm (NRPM1). Source measurements of aircraft PM show that black carbon particles inhibit nucleation by serving as condensation sinks for the volatile and semi-volatile exhaust gases. Real-world source measurements of ground vehicle PM are obtained by deploying an AMS aboard a mobile laboratory. Characteristic features of the exhaust PM chemical composition and size distribution are discussed. PM mass and number concentrations are used with above-background gas-phase carbon dioxide (CO2) concentrations to calculate on-road emission factors for individual vehicles. Highly variable ratios between particle number and mass concentrations are observed for individual vehicles. NRPM1 mass emission factors measured for on-road diesel vehicles are approximately 50% lower than those from dynamometer studies. Factor analysis of AMS data (FA-AMS) is applied for the first time to map variations in exhaust PM mass downwind of a highway. In this study, above-background vehicle PM concentrations are highest close to the highway and decrease by a factor of 2 by 200 m away from the highway. Comparison with the gas-phase CO2 concentrations indicates that these vehicle PM mass gradients are largely driven by dilution. Secondary aerosol species do not show a similar gradient in absolute mass concentrations; thus, their relative contribution to total ambient PM mass concentrations increases as a function of distance from the highway. FA-AMS of single particle and ensemble data at an urban receptor site shows that condensation of these secondary aerosol species onto vehicle exhaust particles results in spatial and temporal evolution of the size and composition of vehicle exhaust PM on urban and regional scales.

Detection of an organic-non volatile compound in variable-contaminated volcanic soil samples via Time Domain Reflectometry (TDR) technique: Preliminary results

NASA Astrophysics Data System (ADS)

comegna, alessandro; coppola, antonio; dragonetti, giovanna; chaali, nesrine; sommella, angelo

2014-05-01

Hydrocarbons may be present in soils as non-aqueous phase liquids (NAPLs), which means that these organic compounds, exist as a separate and immiscible phase with respect to water and air commonly present in the soil. NAPLs, which can be accidentally introduced in the environment (for example by waste disposal sites, industrial spills, gasoline stations, etc), constitutes a serious geo-environmental problem, given the toxicity level and the high mobility. Time domain reflectometry (TDR) has became, over several decades, an important technique for water estimation in soils. In order to expand the potentiality of the TDR technique, the main objective of this study is to explore the capacity of dielectric response to detect the presence of NAPLs in volcanic soils. In laboratory, soil samples were oven dried at 105° C and passed through a 2 mm sieve. Known quantities of soil, water and NAPL (corn oil, a non-volatile and non-toxic organic compound) were mixed and repacked into plastic cylinders (16 cm high and 9.5 cm in diameter); in order to obtain forty different volumetric combinations of water and oil (i.e. θfg = θwater + θNAPL), with θNAPL varying from 0.05 to 0.40 by 0.05 cm3/cm3 increments. Data collected were employed to implement a multiphase mixing model which permitted conversion from a dielectric permittivity domain into a θf domain and vice versa. The results of this study show that, the TDR device is NAPL-sensitive, especially for θf values greater than 0.20. Further works will be built on this initial study, concentrating on improving the dielectric response-database, in order to: i) enhancing the model efficiency in terms of NAPL capability detention, and ii) validating the developed TDR interpretation tool with field results.

Trace element partitioning behavior of coal gangue-fired CFB plant: experimental and equilibrium calculation.

PubMed

Zhang, Yingyi; Nakano, Jinichiro; Liu, Lili; Wang, Xidong; Zhang, Zuotai

2015-10-01

Energy recovery is a promising method for coal gangue utilization, during which the prevention of secondary pollution, especially toxic metal emission, is a significant issue in the development of coal gangue utilization. In the present study, investigation into trace element partitioning behavior from a coal gangue-fired power plant in Shanxi province, China, has been conducted. Besides the experimental analysis, thermodynamic equilibrium calculation was also conducted to help the further understanding on the effect of different parameters. Results showed that Hg, As, Be, and Cd were highly volatile elements in the combustion of coal gangue, which were notably enriched in fly ash and may be emitted into the environment via the gas phase. Cr and Mn were mostly non-volatile and were enriched in the bottom ash. Pb, Co, Zn, Cu, and Ni were semi-volatile elements and were enriched in the fly ash to varying degrees. Equilibrium calculations show that the air/fuel ratio and the presence of Cl highly affect the element volatility. The presence of mineral phases, such as aluminosilicates, depresses the volatility of elements by chemical immobilization and competition in Cl. The coal gangue, fly ash, and bottom ash all passed the toxicity characteristic leaching procedure (TCLP), and their alkalinity buffers the acidity of the solution and contributes to the low solubility of the trace elements.

Development of an analytical method coupling cell membrane chromatography with gas chromatography-mass spectrometry via microextraction by packed sorbent and its application in the screening of volatile active compounds in natural products.

PubMed

Li, Miao; Wang, Sicen; He, Langchong

2015-01-01

Natural products (NPs) are important sources of lead compounds in modern drug discovery. To facilitate the screening of volatile active compounds in NPs, we have developed a new biochromatography method that uses rat vascular smooth muscle cells (VSMC), which are rich in L-type calcium channels (LCC), to prepare the stationary phase. This integrated method, which couples cell membrane chromatography (CMC) with gas chromatography-mass spectrometry (GC-MS) via microextraction by packed sorbent (MEPS) technology, has been termed VSMC/CMC-MEPS-GC-MS. Methodological validation confirmed its specificity, reliability and convenience. Screening results for Radix Angelicae Dahuricae and Fructus Cnidii obtained using VSMC/CMC-MEPS-GC-MS were consistent with those obtained using VSMC/CMC-offline-GC-MS. MEPS connection plays as simplified solid-phase extraction and replaces the uncontrollable evaporation operation in reported offline connections, so our new method is supposed to be more efficient and reliable than the offline ones, especially for compounds that are volatile, thermally unstable or difficult to purify. In application, senkyunolide A and ligustilide were preliminary identified as the volatile active components in Rhizoma Chuanxiong. We have thus confirmed the suitability of VSMC/CMC-MEPS-GC-MS for volatile active compounds screening in NP. Copyright © 2014 Elsevier B.V. All rights reserved.

Italian and Spanish commercial tomato sauces for pasta dressing: study of sensory and head-space profiles by Flash Profiling and solid-phase microextraction-gas chomatography-mass spectrometry.

PubMed

Bendini, Alessandra; Vallverdú-Queralt, Anna; Valli, Enrico; Palagano, Rosa; Lamuela-Raventos, Rosa Maria; Toschi, Tullia Gallina

2017-08-01

The sensory and head-space profiles of Italian and Spanish commercial tomato sauces were investigated. The Flash Profiling method was used to evaluate sensory characteristics. Samples within each set were ranked according to selected descriptors. One hundred volatile compounds were identified by solid-phase microextraction-gas chomatography-mass spectrometry. For Italian samples, the sensory notes of basil/aromatic herbs, acid and cooked tomato were among those perceived most by the assessors, whereas, in Spanish samples, the sensory attributes of garlic/onion and onion/sweet pepper and, in Italian samples, cooked tomato were among those found most frequently. Data were elaborated using multivariate statistical approaches and interesting correlations were observed among the different sensory attributes and related volatile compounds. Spanish samples were characterized by the highest content of volatiles linked to the thermal treatment of tomatoes and to raw and sautéed garlic and onion, whereas the Italian samples were characterized by terpenic compounds typical of basil and volatile molecules derived from fresh tomato. These results confirm the influence of both formulation and production processes on the aromatic profile (sensory attributes and volatile compounds) of tomato products, which is probably related to the different eating habits and culinary traditions in Italy and Spain. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Molecular Composition and Volatility of Organic Aerosol in the Southeastern U.S.: Implications for IEPOX Derived SOA.

PubMed

Lopez-Hilfiker, F D; Mohr, C; D'Ambro, E L; Lutz, A; Riedel, T P; Gaston, C J; Iyer, S; Zhang, Z; Gold, A; Surratt, J D; Lee, B H; Kurten, T; Hu, W W; Jimenez, J; Hallquist, M; Thornton, J A

2016-03-01

We present measurements as part of the Southern Oxidant and Aerosol Study (SOAS) during which atmospheric aerosol particles were comprehensively characterized. We present results utilizing a Filter Inlet for Gases and AEROsol coupled to a chemical ionization mass spectrometer (CIMS). We focus on the volatility and composition of isoprene derived organic aerosol tracers and of the bulk organic aerosol. By utilizing the online volatility and molecular composition information provided by the FIGAERO-CIMS, we show that the vast majority of commonly reported molecular tracers of isoprene epoxydiol (IEPOX) derived secondary organic aerosol (SOA) is derived from thermal decomposition of accretion products or other low volatility organics having effective saturation vapor concentrations <10(-3) μg m(-3). In addition, while accounting for up to 30% of total submicrometer organic aerosol mass, the IEPOX-derived SOA has a higher volatility than the remaining bulk. That IEPOX-SOA, and more generally bulk organic aerosol in the Southeastern U.S. is comprised of effectively nonvolatile material has important implications for modeling SOA derived from isoprene, and for mechanistic interpretations of molecular tracer measurements. Our results show that partitioning theory performs well for 2-methyltetrols, once accretion product decomposition is taken into account. No significant partitioning delays due to aerosol phase or viscosity are observed, and no partitioning to particle-phase water or other unexplained mechanisms are needed to explain our results.

Boiling vapour-type fluids from the Nifonea vent field (New Hebrides Back-Arc, Vanuatu, SW Pacific): Geochemistry of an early-stage, post-eruptive hydrothermal system

NASA Astrophysics Data System (ADS)

Schmidt, Katja; Garbe-Schönberg, Dieter; Hannington, Mark D.; Anderson, Melissa O.; Bühring, Benjamin; Haase, Karsten; Haruel, Christy; Lupton, John; Koschinsky, Andrea

2017-06-01

In 2013, high-temperature vent fluids were sampled in the Nifonea vent field. This field is located within the caldera of a large shield-type volcano of the Vate Trough, a young extensional rift in the New Hebrides back-arc. Hydrothermal venting occurs as clear and black smoker fluids with temperatures up to 368 °C, the hottest temperatures measured so far in the western Pacific. The physico-chemical conditions place the fluids within the two-phase field of NaCl-H2O, and venting is dominated by vapour phase fluids with Cl concentrations as low as 25 mM. The fluid composition, which differs between the individual vent sites, is interpreted to reflect the specific geochemical fluid signature of a hydrothermal system in its initial, post-eruptive stage. The strong Cl depletion is accompanied by low alkali/Cl ratios compared to more evolved hydrothermal systems, and very high Fe/Cl ratios. The concentrations of REY (180 nM) and As (21 μM) in the most Cl-depleted fluid are among the highest reported so far for submarine hydrothermal fluids, whereas the inter-element REY fractionation is only minor. The fluid signature, which has been described here for the first time in a back-arc setting, is controlled by fast fluid passage through basaltic volcanic rocks, with extremely high water-rock ratios and only limited water-rock exchange, phase separation and segregation, and (at least) two-component fluid mixing. Metals and metalloids are unexpectedly mobile in the vapour phase fluids, and the strong enrichments of Fe, REY, and As highlight the metal transport capacity of low-salinity, low-density vapours at the specific physico-chemical conditions at Nifonea. One possible scenario is that the fluids boiled before the separated vapour phase continued to react with fresh glassy lavas. The mobilization of metals is likely to occur by leaching from fresh glass and grain boundaries and is supported by the high water/rock ratios. The enrichment of B and As is further controlled by their high volatility, whereas the strong enrichment of REY is also a consequence of the elevated concentrations in the host rocks. However, a direct contribution of metals such as As from magmatic degassing cannot be ruled out. The different fluid end-member composition of individual vent sites could be explained by mixing of vapour phase fluids with another fluid phase of different water/rock interaction history.

Effects of milk fat, cocoa butter, or selected fat replacers on flavor volatiles of chocolate ice cream.

PubMed

Welty, W M; Marshall, R T; Grün, I U; Ellersieck, M R

2001-01-01

Selected volatile compounds of chocolate ice creams containing 0.6, 4.0, 6.0, or 9.0% milk fat or containing 2.5% milk fat, cocoa butter, or one of three fat replacers (Simplesse, Dairy Lo, or Oatrim) were analyzed by gas chromatography and gas chromatography-mass spectrometry using headspace solid-phase microextraction. The headspace concentration of most of the selected volatile compounds increased with decreasing milk fat concentration. Fat replacers generally increased the concentration of volatiles found in the headspace compared with milk fat or cocoa butter. Few differences in flavor volatiles were found between the ice cream containing milk fat and the ice cream containing cocoa butter. Among the selected volatiles, the concentration of 2,5-dimethyl-3(2-methyl propyl) pyrazine was the most highly correlated (negatively) with the concentration of milk fat, and it best discriminated among ice creams containing milk fat, cocoa butter, or one of the fat replacers.

[Effects of azadirachtin on rice plant volatiles induced by Nilaparvata lugens].

PubMed

Lu, Hai-Yan; Liu, Fang; Zhu, Shu-De; Zhang, Qing

2010-01-01

With the method of solid phase microextraction (SPME), a total of twenty-five volatiles were collected from rice plants induced by Nilaparvata lugens, and after applying azadirachtin fourteen of them were qualitatively identified by gas chromatography coupled by mass spectrometry (GC-MS), mainly of nine kinds of sesquiterpenes. Comparing with healthy rice plants, the plants attacked by N. lugens had more kinds of volatiles, including limonene, linalool, methyl salicylate, unknown 6, unknown 7, zingiberene, nerolidol, and hexadecane. Applying azadirachtin did not result in the production of new kind volatiles, but affected the relative concentrations of the volatiles induced by N. lugens. The proportions of limonene, linalool, methyl salicylate, unknown 6, zingiberene, and hexadecane changed obviously with the concentration of applied azadirachtin, while those of methyl salicylate, unknown 6, unknown 7, zingiberene, and nerolidol changed significantly with the days after azadirachtin application. Azadirachtin concentration, rice variety, and N. lugens density had significant interactions on the relative concentrations of all test N. lugens-induced volatiles.

Characterization of the volatile profile of Antarctic bacteria by using solid-phase microextraction-gas chromatography-mass spectrometry.

PubMed

Romoli, Riccardo; Papaleo, Maria Cristiana; de Pascale, Donatella; Tutino, Maria Luisa; Michaud, Luigi; LoGiudice, Angelina; Fani, Renato; Bartolucci, Gianluca

2011-10-01

Bacteria belonging to the Burkholderia cepacia complex (Bcc) are significant pathogens in Cystic Fibrosis (CF) patients and are resistant to a plethora of antibiotics. In this context, microorganisms from Antarctica are interesting because they produce antimicrobial compounds inhibiting the growth of other bacteria. This is particularly true for bacteria isolated from Antarctic sponges. The aim of this work was to characterize a set of Antarctic bacteria for their ability to produce new natural drugs that could be exploited in the control of infections in CF patients by Bcc bacteria. Hence, 11 bacterial strains allocated to different genera (e.g., Pseudoalteromonas, Arthrobacter and Psychrobacter) were tested for their ability to inhibit the growth of 21 Bcc strains and some other human pathogens. All these bacteria completely inhibited the growth of most, if not all, Bcc strains, suggesting a highly specific activity toward Bcc strains. Experimental evidences showed that the antimicrobial compounds are small volatile organic compounds, and are constitutively produced via an unknown pathway. The microbial volatile profile was obtained by SPME-GC-MS within the m/z interval of 40-450. Solid phase micro extraction technique affords the possibility to extract the volatile compounds in head space with a minimal sample perturbation. Principal component analysis and successive cluster discriminant analysis was applied to evaluate the relationships among the volatile organic compounds with the aim of classifying the microorganisms by their volatile profile. These data highlight the potentiality of Antarctic bacteria as novel sources of antibacterial substances to face Bcc infections in CF patients. Copyright © 2011 John Wiley & Sons, Ltd.

Comparative study of solvation parameter models accounting the effects of mobile phase composition in reversed-phase liquid chromatography.

PubMed

Torres-Lapasió, J R; Ruiz-Angel, M J; García-Alvarez-Coque, M C

2007-09-28

Solvation parameter models relate linearly compound properties with five fundamental solute descriptors (excess molar refraction, dipolarity/polarizability, effective hydrogen-bond acidity and basicity, and McGowan volume). These models are widely used, due to the availability of protocols to obtain the descriptors, good performance, and general applicability. Several approaches to predict retention in reversed-phase liquid chromatography (RPLC) as a function of these descriptors and mobile phase composition are compared, assaying the performance with a set of 146 organic compounds of diverse nature, eluted with acetonitrile and methanol. The approaches are classified in two groups: those that only allow predictions of retention for the mobile phases used to build the models, and those valid at any other mobile phase composition. The first group includes the use of ratios between the regressed coefficients of the solvation models that are assumed to be characteristic for a column/solvent system, and the application of offsets to transfer the retention from a reference mobile phase to any other. Maximal accuracy in predictions corresponded, however, to the approaches in the second group, which were based on models that describe the retention as a function of mobile phase composition (expressed as the solvent volume fraction or a normalised polarity measurement), where the coefficients were made dependent on the solvent descriptors. The study revealed the properties that influence the retention and distinguish the particular behaviour of acetonitrile and methanol in RPLC.

Simultaneous determination of bioactive constituents in Danggui Buxue Tang for quality control by HPLC coupled with a diode array detector, an evaporative light scattering detector and mass spectrometry.

PubMed

Yi, Ling; Qi, Lian-Wen; Li, Ping; Ma, Yi-Han; Luo, Yong-Jing; Li, Hai-Yun

2007-09-01

Danggui Buxue Tang (DBT), a classical traditional Chinese formula comprising Radix Angelicae Sinensis (RAS) and Radix Astragali (RA), has been widely used to treat menopausal irregularity in Chinese women for nearly 800 years. In this study, a comprehensive analytical method of simultaneously determining the main types of bioactive constituents, eighteen in all from the formula, involving flavonoids, saponins, organic acid and some volatile compounds, was developed. This method was based on HPLC coupled to a diode array and evaporative light scattering detectors (HPLC-DAD-ELSD) on a common reverse-phase C(18) column. Liquid chromatography coupled with on-line electrospray ionization mass spectrometry (LC-ESI-MS) was also used to further validate and analyze the constituents. It was found that 0.3% aqueous formic acid and acetonitrile was the optimum mobile phase for gradient elution. This method, which showed good precision and accuracy, was successfully used to quantify the bioactive constituents in six products. As a result, the validated HPLC method, together with the LC-ESI-MS analysis, provided a new basis for assessing the quality of traditional Chinese medicinal compound preparations (TCMCPs) consisting of many bioactive components.

Multiphase mean curvature flows with high mobility contrasts: A phase-field approach, with applications to nanowires

NASA Astrophysics Data System (ADS)

Bretin, Elie; Danescu, Alexandre; Penuelas, José; Masnou, Simon

2018-07-01

The structure of many multiphase systems is governed by an energy that penalizes the area of interfaces between phases weighted by surface tension coefficients. However, interface evolution laws depend also on interface mobility coefficients. Having in mind some applications where highly contrasted or even degenerate mobilities are involved, for which classical phase field models are inapplicable, we propose a new effective phase field approach to approximate multiphase mean curvature flows with mobilities. The key aspect of our model is to incorporate the mobilities not in the phase field energy (which is conventionally the case) but in the metric which determines the gradient flow. We show the consistency of such an approach by a formal analysis of the sharp interface limit. We also propose an efficient numerical scheme which allows us to illustrate the advantages of the model on various examples, as the wetting of droplets on solid surfaces or the simulation of nanowires growth generated by the so-called vapor-liquid-solid method.

Cost-Effective, Ultra-Sensitive Groundwater Monitoring for Site Remediation and Management

DTIC Science & Technology

2015-05-01

Example anion concentrations in groundwater used for feasibility studies. ................... 30 Table 5. Compounds screened in the laboratory for IS2...phase extraction ST storage tank SVOC semivolatile organic compound TCE trichloroethene TPH total petroleum hydrocarbon USEPA U.S. Environmental...Protection Agency UST underground storage tank V volt VOA volatile organic analysis VOC volatile organic compound Technical material

A High Frequency Response Relaxed Eddy Accumulation Flux Measurement System for Sampling Short-Lived Biogenic Volatile Organic Compounds

EPA Science Inventory

A second-generation relaxed eddy accumulation system was built and tested with the capability to measure vertical biogenic volatile organic compound (VOC) fluxes at levels as low as 10 µg C m⁻² hr⁻¹. The system features a continuous, integrated gas-phase ozo...

Optimization of a Solid-Phase Microextraction method for the Gas Chromatography-Mass Spectrometry analysis of blackberry (Rubus ulmifolius Schott) fruit volatiles.

PubMed

D'Agostino, M F; Sanz, J; Sanz, M L; Giuffrè, A M; Sicari, V; Soria, A C

2015-07-01

A Solid-Phase Microextraction method for the Gas Chromatography-Mass Spectrometry analysis of blackberry (Rubus sp.) volatiles has been fully optimized by means of a Box-Behnken experimental design. The optimized operating conditions (Carboxen/Polydimethylsiloxane fiber coating, 66°C, 20 min equilibrium time and 16 min extraction time) have been applied to the characterization for the first time of the volatile composition of Rubus ulmifolius Schott blackberries collected in Italy and Spain. A total of 74 volatiles of different functionality were identified; esters and aliphatic alcohols were the predominant classes in both sample types. Methylbutanal (2.02-25.70%), ethanol (9.84-68.21%), 2,3-butanedione (2.31-14.71%), trans-2-hexenal (0.49-17.49%), 3-hydroxy-2-butanone (0.08-7.39%), 1-hexanol (0.56-16.39%), 1-octanol (0.49-10.86%) and methylbutanoic acid (0.53-21.48%) were the major compounds in most blackberries analyzed. Stepwise multiple regression analysis of semiquantitative data showed that only two variables (ethyl decanoate and ethyl acetate) were necessary for a successful differentiation of blackberries according to their harvest location. Copyright © 2015 Elsevier Ltd. All rights reserved.

Non-volatile resistive switching in the Mott insulator (V1-xCrx)2O3

NASA Astrophysics Data System (ADS)

Querré, M.; Tranchant, J.; Corraze, B.; Cordier, S.; Bouquet, V.; Députier, S.; Guilloux-Viry, M.; Besland, M.-P.; Janod, E.; Cario, L.

2018-05-01

The discovery of non-volatile resistive switching in Mott insulators related to an electric-field-induced insulator to metal transition (IMT) has paved the way for their use in a new type of non-volatile memories, the Mott memories. While most of the previous studies were dedicated to uncover the resistive switching mechanism and explore the memory potential of chalcogenide Mott insulators, we present here a comprehensive study of resistive switching in the canonical oxide Mott insulator (V1-xCrx)2O3. Our work demonstrates that this compound undergoes a non-volatile resistive switching under electric field. This resistive switching is induced by a Mott transition at the local scale which creates metallic domains closely related to existing phases of the temperature-pressure phase diagram of (V1-xCrx)2O3. Our work demonstrates also reversible resistive switching in (V1-xCrx)2O3 crystals and thin film devices. Preliminary performances obtained on 880 nm thick layers with 500 nm electrodes show the strong potential of Mott memories based on the Mott insulator (V1-xCrx)2O3.

Non-aqueous phase liquid spreading during soil vapor extraction

PubMed Central

Kneafsey, Timothy J.; Hunt, James R.

2010-01-01

Many non-aqueous phase liquids (NAPLs) are expected to spread at the air – water interface, particularly under non-equilibrium conditions. In the vadose zone, this spreading should increase the surface area for mass transfer and the efficiency of volatile NAPL recovery by soil vapor extraction (SVE). Observations of spreading on water wet surfaces led to a conceptual model of oil spreading vertically above a NAPL pool in the vadose zone. Analysis of this model predicts that spreading can enhance the SVE contaminant recovery compared to conditions where the liquid does not spread. Experiments were conducted with spreading volatile oils hexane and heptane in wet porous media and capillary tubes, where spreading was observed at the scale of centimeters. Within porous medium columns up to a meter in height containing stagnant gas, spreading was less than ten centimeters and did not contribute significantly to hexane volatilization. Water film thinning and oil film pinning may have prevented significant oil film spreading, and thus did not enhance SVE at the scale of a meter. The experiments performed indicate that volatile oil spreading at the field scale is unlikely to contribute significantly to the efficiency of SVE. PMID:14734243

Preparation of sulfonated graphene/polypyrrole solid-phase microextraction coating by in situ electrochemical polymerization for analysis of trace terpenes.

PubMed

Zhang, Chengjiang; Zhang, Zhuomin; Li, Gongke

2014-06-13

In this study, a novel sulfonated graphene/polypyrrole (SG/PPy) solid-phase microextraction (SPME) coating was prepared and fabricated on a stainless-steel wire by a one-step in situ electrochemical polymerization method. Crucial preparation conditions were optimized as polymerization time of 15min and SG doping amount of 1.5mg/mL. SG/PPy coating showed excellent thermal stability and mechanical durability with a long lifespan of more than 200 stable replicate extractions. SG/PPy coating demonstrated higher extraction selectivity and capacity to volatile terpenes than commonly-used commercial coatings. Finally, SG/PPy coating was practically applied for the analysis of volatile components from star anise and fennel samples. The majority of volatile components identified were terpenes, which suggested the ultra-high extraction selectivity of SG/PPy coating to terpenes during real analytical projects. Four typical volatile terpenes were further quantified to be 0.2-27.4μg/g from star anise samples with good recoveries of 76.4-97.8% and 0.1-1.6μg/g from fennel samples with good recoveries of 80.0-93.1%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison of different methodologies for detailed screening of Taraxacum officinale honey volatiles.

PubMed

Jerković, Igor; Marijanović, Zvonimir; Kranjac, Marina; Radonić, Ani

2015-02-01

Headspace solid-phase microextraction (HS-SPME), ultrasonic solvent extraction (USE) and solid phase extraction (SPE), followed by GC-FID/MS were used for screening of dandelion (Taraxacum officinale Weber) honey headspace, volatiles and semi-volatiles. The obtained results constitute a breakthrough towards screening of dandelion honey since dominant compounds identified in the extracts were not previously reported for this honey type. Nitriles dominated in the headspace, particularly 3-methylpentanenitrile (up to 29.9%) and phenylacetonitrile (up to 20.9%). Lower methyl branched aliphatic acids and norisoprenoids were relevant minor constituents of the headspace. The extracts contained phenylacetic acid (up to 24.0%) and dehydrovomifoliol (up to 19.3%) as predominant compounds, while 3-methylpentanenitrile and phenylacetonitrile were detected in the extracts in minor abundance. Dehydrovomifoliol can be considered more characteristic for dandelion honey in distinction from phenylacetic acid. Low molecular aliphatic acids, benzene derivatives and an array of higher aliphatic compounds were also found in the extracts. The results of SPE/GC-FID/MS were very similar to USE/GC-FID/MS with the solvent dichloromethane. The use of all applied methodologies was relevant for the comprehensive chemical fingerprinting of dandelion honey volatiles.

Kinetics of volatile extraction from carbonaceous chondrites: Dehydration of talc

NASA Technical Reports Server (NTRS)

Bose, Kunal; Ganguly, Jibamitra

1991-01-01

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.

Nitrogen mobility, ammonia volatilization, and estimated leaching loss from long-term manure incorporation in red soil

USDA-ARS?s Scientific Manuscript database

Nitrogen (N) loss from fertilization in agricultural fields has an unavoidable negative impact on the environment, and a better understanding of the major pathways can assist in developing best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic re...

Residual impact of methyl salicylate fumigation at the breaker stage on C6 volatile biopathway in red tomato fruit

USDA-ARS?s Scientific Manuscript database

Flavor, which is comprised of aroma and taste, is an important tomato characteristic. Methyl salicylate (MeSA), acting as a critical mobile signal, plays an important role in tomato stress responses and ripening processes. However, less is studied on the impact of its application at early ripening s...

40 CFR 264.259 - Special requirements for hazardous wastes FO20, FO21, FO22, FO23, FO26, and FO27.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) The volume, physical, and chemical characteristics of the wastes, including their potential to migrate through soil or to volatilize or escape into the atmosphere; (2) The attenuative properties of underlying and surrounding soils or other materials; (3) The mobilizing properties of other materials co-disposed...

77 FR 3681 - Approval and Promulgation of Air Quality Implementation Plans; Minnesota; Regional Haze

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-25

... approach in the BART Guidelines in making a BART determination for a fossil fuel-fired EGU with total... ammonia (NH 3 ), and volatile organic compound (VOCs). Fine particle precursors react in the atmosphere to... standards, low sulfur fuel, and non-road mobile source control programs. The fourth step is to determine...

Use of vancomycin silica stationary phase in packed capillary electrochromatography: III. enantiomeric separation of basic compounds with the polar organic mobile phase.

PubMed

Fanali, Salvatore; Catarcini, Paolo; Quaglia, Maria Giovanna

2002-02-01

The separation of basic compounds into their enantiomers was achieved using capillary electrochromatography in 50 or 75 microm inner diameter (ID) fused-silica capillaries packed with silica a stationary phase derivatized with vancomycin and mobile phases composed of mixtures of polar organic solvents containing 13 mM ammonium acetate. Enantiomer resolution, electroosmotic flow, and the number of theoretical plates were strongly influenced by the type and concentration of the organic solvent. Mobile phases composed of 13 mM ammonium acetate dissolved in mixtures of acetonitrile/methanol, ethanol, n-propanol, or isopropanol were tested and the highest enantioresolutions were achieved using the first mobile phase, allowing the separation of almost all investigated enantiomers (9 from 11 basic compounds). The use of capillaries with different ID (50 and 75 microm ID) packed with the same chiral stationary phase revealed that a higher number of theoretical plates and higher enantioresolution was achieved with the tube with lowest ID.

A comparison of solid-phase microextraction (SPME) with simultaneous distillation-extraction (SDE) for the analysis of volatile compounds in heated beef and sheep fats.

PubMed

Watkins, P J; Rose, G; Warner, R D; Dunshea, F R; Pethick, D W

2012-06-01

A comparison has been made on the application of SPME and SDE for the extraction of volatile compounds from heated beef and sheep fats with separation and measurement by gas chromatography-mass spectrometry. As far as we know, this report represents the first time that such a comparison has been made for the measurement of volatile compounds in heated sheep fat. Approximately 100 compounds (in relatively high abundance) were characterised in the volatile profiles of heated beef and sheep fats using both techniques. Differences were observed in the volatile profiles obtained from each technique, independent of compound class. Rather than rate one technique as superior to another, the techniques can be regarded as complementary to each other. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Nanoparticle growth by particle-phase chemistry

NASA Astrophysics Data System (ADS)

Apsokardu, Michael J.; Johnston, Murray V.

2018-02-01

The ability of particle-phase chemistry to alter the molecular composition and enhance the growth rate of nanoparticles in the 2-100 nm diameter range is investigated through the use of a kinetic growth model. The molecular components included are sulfuric acid, ammonia, water, a non-volatile organic compound, and a semi-volatile organic compound. Molecular composition and growth rate are compared for particles that grow by partitioning alone vs. those that grow by a combination of partitioning and an accretion reaction in the particle phase between two organic molecules. Particle-phase chemistry causes a change in molecular composition that is particle diameter dependent, and when the reaction involves semi-volatile molecules, the particles grow faster than by partitioning alone. These effects are most pronounced for particles larger than about 20 nm in diameter. The modeling results provide a fundamental basis for understanding recent experimental measurements of the molecular composition of secondary organic aerosol showing that accretion reaction product formation increases linearly with increasing aerosol volume-to-surface-area. They also allow initial estimates of the reaction rate constants for these systems. For secondary aerosol produced by either OH oxidation of the cyclic dimethylsiloxane (D5) or ozonolysis of β-pinene, oligomerization rate constants on the order of 10-3 to 10-1 M-1 s-1 are needed to explain the experimental results. These values are consistent with previously measured rate constants for reactions of hydroperoxides and/or peroxyacids in the condensed phase.

Mobile Particulate Emission Measurements of New York City Transit Buses and Other in use Vehicles

NASA Astrophysics Data System (ADS)

Jayne, J. T.; Canagaratna, M.; Herndon, S.; Shorter, J.; Zahniser, M.; Kolb, C.; Williams, L.; Worsnop, D.; Drewnick, F.; Demerjian, K. L.; Lanni, T.

2002-12-01

Emissions from both diesel and gasoline powered motor vehicles are a significant source of particulate (PM2.5) and trace gas pollution, especially in urban environments. Emission characterizations of motor vehicles can be performed using a dynamometer but these studies make fleet characterization impractical. Few studies have been performed which characterize emissions from in-use vehicles using a mobile sampling platform. This work describes application of new technology instrumentation for rapid (1-5 second) and real-time characterization of both gas and particulate emissions from in-use vehicles and is part of the PM2.5 Technology Assessment and Characterization Study in New York (PMTACS-NY). An aerosol mass spectrometer (AMS) and a tunable infrared laser differential absorption spectrometer (TILDAS) system were deployed on the Aerodyne Research mobile laboratory designed to "chase" target vehicles in and around the New York City area and measure their emissions under actual driving conditions. The AMS provides particle size and composition information for volatile and semi-volatile matter (0.03 - 1 um) while the TILDAS system was configured to measure NO, NO2, CO, CH4, SO2 and formaldehyde. In addition to a global positioning system, an ELPI and a condensation particle counter, the mobile laboratory was also equipped with a Licor CO2 monitor to allow emission indices to be computed for the targeted vehicles. Emission indices for both particulate and trace gases correlated with engine type are reported for a representative fraction of the NYC Metropolitan Transit Authority (MTA) bus fleet in an effort to characterize new emission control technologies currently implemented by the NYC MTA.

Emissions of volatile organic compounds (VOCs) from concentrated animal feeding operations (CAFOs): chemical compositions and separation of sources

NASA Astrophysics Data System (ADS)

Yuan, Bin; Coggon, Matthew M.; Koss, Abigail R.; Warneke, Carsten; Eilerman, Scott; Peischl, Jeff; Aikin, Kenneth C.; Ryerson, Thomas B.; de Gouw, Joost A.

2017-04-01

Concentrated animal feeding operations (CAFOs) emit a large number of volatile organic compounds (VOCs) to the atmosphere. In this study, we conducted mobile laboratory measurements of VOCs, methane (CH4) and ammonia (NH3) downwind of dairy cattle, beef cattle, sheep and chicken CAFO facilities in northeastern Colorado using a hydronium ion time-of-flight chemical-ionization mass spectrometer (H3O+ ToF-CIMS), which can detect numerous VOCs. Regional measurements of CAFO emissions in northeastern Colorado were also performed using the NOAA WP-3D aircraft during the Shale Oil and Natural Gas Nexus (SONGNEX) campaign. Alcohols and carboxylic acids dominate VOC concentrations and the reactivity of the VOCs with hydroxyl (OH) radicals. Sulfur-containing and phenolic species provide the largest contributions to the odor activity values and the nitrate radical (NO3) reactivity of VOC emissions, respectively. VOC compositions determined from mobile laboratory and aircraft measurements generally agree well with each other. The high time-resolution mobile measurements allow for the separation of the sources of VOCs from different parts of the operations occurring within the facilities. We show that the emissions of ethanol are primarily associated with feed storage and handling. Based on mobile laboratory measurements, we apply a multivariate regression analysis using NH3 and ethanol as tracers to determine the relative importance of animal-related emissions (animal exhalation and waste) and feed-related emissions (feed storage and handling) for different VOC species. Feed storage and handling contribute significantly to emissions of alcohols, carbonyls, carboxylic acids and sulfur-containing species. Emissions of phenolic species and nitrogen-containing species are predominantly associated with animals and their waste.

Identification of volatile organic compounds emitted by a naturally aged book using solid-phase microextraction/gas chromatography/mass spectrometry.

PubMed

Lattuati-Derieux, Agnès; Bonnassies-Termes, Sylvette; Lavédrine, Bertrand

2004-02-13

Solid-phase microextraction (SPME) coupled to gas chromatography/mass spectrometry (GC/MS) has been applied to the analysis of volatile organic compounds emitted from a naturally aged groundwood pulp paper originating from an old book in order to access the products produced through the decomposition reactions occurring in paper upon ageing. Two different extraction methods were developed and compared: headspace SPME and contact SPME. The influence of few extraction parameters were tested in order to define the best extraction conditions. An optimised non-destructive contact SPME method was elaborated and allowed the characterisation of more than 50 individual constituents.

Determination of volatile compounds in cider apple juices using a covalently bonded ionic liquid coating as the stationary phase in gas chromatography.

PubMed

Pello-Palma, Jairo; González-Álvarez, Jaime; Gutiérrez-Álvarez, María Dolores; Dapena de la Fuente, Enrique; Mangas-Alonso, Juan José; Méndez-Sánchez, Daniel; Gotor-Fernández, Vicente; Arias-Abrodo, Pilar

2017-04-01

A chromatographic method for the separation of volatile compounds in Asturian cider apple juices has been developed. For this separation purpose, a monocationic imidazolium-based ionic liquid bearing a reactive terminal iodine atom was synthesized by a quaternization-anion exchange chemical sequence. Next, the gas chromatography (GC) stationary phase was prepared by covalently linking the imidazolium monolith to the reactive silanol groups of the inner capillary wall at 70 °C. This coated GC column exhibited good thermal stability (290 °C), as well as good efficiency (2000 plates/m) in the separation of volatile compounds from Asturian apple cider juices, and was characterized using the Abraham solvation parameter model. The intra-day and inter-day precision of the chromatographic method was evaluated, obtaining relative standard deviations from 3.7 to 12.9% and from 7.4 to 18.0%, respectively. Furthermore, recoveries from 82.5 to 122% were achieved. Graphical Abstract Covalent bonding of an ionic liquid to inner column wall led to a great improvement of the separation efficiencies of stationary phases in gas chromatography.

Effects of sulfur on lead partitioning during sludge incineration based on experiments and thermodynamic calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Jing-yong, E-mail: www053991@126.com; Huang, Shu-jie; Sun, Shui-yu

2015-04-15

Highlights: • A thermodynamic equilibrium calculation was carried out. • Effects of three types of sulfurs on Pb distribution were investigated. • The mechanism for three types of sulfurs acting on Pb partitioning were proposed. • Lead partitioning and species in bottom ash and fly ash were identified. - Abstract: Experiments in a tubular furnace reactor and thermodynamic equilibrium calculations were conducted to investigate the impact of sulfur compounds on the migration of lead (Pb) during sludge incineration. Representative samples of typical sludge with and without the addition of sulfur compounds were combusted at 850 °C, and the partitioning ofmore » Pb in the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that three types of sulfur compounds (S, Na{sub 2}S and Na{sub 2}SO{sub 4}) added to the sludge could facilitate the volatilization of Pb in the gas phase (fly ash and flue gas) into metal sulfates displacing its sulfides and some of its oxides. The effect of promoting Pb volatilization by adding Na{sub 2}SO{sub 4} and Na{sub 2}S was superior to that of the addition of S. In bottom ash, different metallic sulfides were found in the forms of lead sulfide, aluminosilicate minerals, and polymetallic-sulfides, which were minimally volatilized. The chemical equilibrium calculations indicated that sulfur stabilizes Pb in the form of PbSO{sub 4}(s) at low temperatures (<1000 K). The equilibrium calculation prediction also suggested that SiO{sub 2}, CaO, TiO{sub 2}, and Al{sub 2}O{sub 3} containing materials function as condensed phase solids in the temperature range of 800–1100 K as sorbents to stabilize Pb. However, in the presence of sulfur or chlorine or the co-existence of sulfur and chlorine, these sorbents were inactive. The effect of sulfur on Pb partitioning in the sludge incineration process mainly depended on the gas phase reaction, the surface reaction, the volatilization of products, and the concentration of Si, Ca and Al-containing compounds in the sludge. These findings provide useful information for understanding the partitioning behavior of Pb, facilitating the development of strategies to control the volatilization of Pb during sludge incineration.« less

Measurements of hygroscopicity and volatility of atmospheric ultrafine particles during ultrafine particle formation events at urban, industrial, and coastal sites.

PubMed

Park, Kihong; Kim, Jae-Seok; Park, Seung Ho

2009-09-01

The tandem differential mobility analyzer (TDMA) technique was applied to determine the hygroscopicity and volatility of atmospheric ultrafine particles in three sites of urban Gwangju, industrial Yeosu, and coastal Taean in South Korea. A database for the hygroscopicity and volatility of the known compositions and sizes of the laboratory-generated particles wasfirst constructed for comparison with the measured properties of atmospheric ultrafine particles. Distinct differences in hygroscopicity and volatility of atmospheric ultrafine particles werefound between a "photochemical event" and a "combustion event" as well as among different sites. At the Gwangju site, ultrafine particles in the "photochemical event" were determined to be more hygroscopic (growth factor (GF) = 1.05-1.33) than those in the "combustion event" (GF = 1.02-1.12), but their hygroscopicity was not as high as pure ammonium sulfate or sulfuric acid particles in the laboratory-generated database, suggesting they were internally mixed with less soluble species. Ultrafine particles in the "photochemical event" at the Yeosu site, having a variety of SO2, CO, and VOC emission sources, were more hygroscopic (GF = 1.34-1.60) and had a higher amount of volatile species (47-75%)than those observed at the Gwangju site. Ultrafine particle concentration at the Taean site increased during daylight hours with low tide, having a higher GF (1.34-1.80) than the Gwangju site and a lower amount of volatile species (17-34%) than the Yeosu site. Occasionally ultrafine particles were externally mixed according to their hygroscopicity and volatility, and TEM/EDS data showed that each type of particle had a distinct morphology and elemental composition.

Chemical transport model simulations of organic aerosol in southern California: model evaluation and gasoline and diesel source contributions

NASA Astrophysics Data System (ADS)

Jathar, Shantanu H.; Woody, Matthew; Pye, Havala O. T.; Baker, Kirk R.; Robinson, Allen L.

2017-03-01

Gasoline- and diesel-fueled engines are ubiquitous sources of air pollution in urban environments. They emit both primary particulate matter and precursor gases that react to form secondary particulate matter in the atmosphere. In this work, we updated the organic aerosol module and organic emissions inventory of a three-dimensional chemical transport model, the Community Multiscale Air Quality Model (CMAQ), using recent, experimentally derived inputs and parameterizations for mobile sources. The updated model included a revised volatile organic compound (VOC) speciation for mobile sources and secondary organic aerosol (SOA) formation from unspeciated intermediate volatility organic compounds (IVOCs). The updated model was used to simulate air quality in southern California during May and June 2010, when the California Research at the Nexus of Air Quality and Climate Change (CalNex) study was conducted. Compared to the Traditional version of CMAQ, which is commonly used for regulatory applications, the updated model did not significantly alter the predicted organic aerosol (OA) mass concentrations but did substantially improve predictions of OA sources and composition (e.g., POA-SOA split), as well as ambient IVOC concentrations. The updated model, despite substantial differences in emissions and chemistry, performed similar to a recently released research version of CMAQ (Woody et al., 2016) that did not include the updated VOC and IVOC emissions and SOA data. Mobile sources were predicted to contribute 30-40 % of the OA in southern California (half of which was SOA), making mobile sources the single largest source contributor to OA in southern California. The remainder of the OA was attributed to non-mobile anthropogenic sources (e.g., cooking, biomass burning) with biogenic sources contributing to less than 5 % to the total OA. Gasoline sources were predicted to contribute about 13 times more OA than diesel sources; this difference was driven by differences in SOA production. Model predictions highlighted the need to better constrain multi-generational oxidation reactions in chemical transport models.

Prescribed burning of logging slash in the boreal forest of Finland: emissions and effects on meteorological quantities and soil properties

NASA Astrophysics Data System (ADS)

Virkkula, A.; Levula, J.; Pohja, T.; Aalto, P. P.; Keronen, P.; Schobesberger, S.; Clements, C. B.; Pirjola, L.; Kieloaho, A.-J.; Kulmala, L.; Aaltonen, H.; Patokoski, J.; Pumpanen, J.; Rinne, J.; Ruuskanen, T.; Pihlatie, M.; Manninen, H. E.; Aaltonen, V.; Junninen, H.; Petäjä, T.; Backman, J.; Dal Maso, M.; Nieminen, T.; Olsson, T.; Grönholm, T.; Aalto, J.; Virtanen, T. H.; Kajos, M.; Kerminen, V.-M.; Schultz, D. M.; Kukkonen, J.; Sofiev, M.; De Leeuw, G.; Bäck, J.; Hari, P.; Kulmala, M.

2014-05-01

A prescribed fire experiment was conducted on 26 June 2009 in Hyytiälä, Finland, to study aerosol and trace gas emissions from prescribed fires of slash fuels and the effects of fire on soil properties in a controlled environment. A 0.8 ha forest near the SMEAR II measurement station (Station for Measuring Ecosystem-Atmosphere Relations) was cut clear; some tree trunks, all tree tops and branches were left on the ground and burned. The amount of burned organic material was ~46.8 tons (i.e., ~60 tons ha-1). The flaming phase lasted 2 h 15 min, the smoldering phase 3 h. Measurements were conducted on the ground with both fixed and mobile instrumentation, and in the air from a research aircraft. In the middle of the burning area, CO2 concentration peaked around 2000-3000 ppm above the baseline, and peak vertical flow velocities were ~9 m s-1, as measured with a 10 Hz 3-D sonic anemometer placed within the burn area. In the mobile measurements the peak particle number concentrations were approximately 1-2 × 106 cm-3 in the plume at a distance of 100-200 m from the burn area. On the ground at the SMEAR II station the geometric mean diameter of the mode with the highest concentration was 80 ± 1 nm during the flaming phase and in the middle of the smoldering phase, but, at the end of the smoldering phase, the largest mode was 122 nm. In the volume size distributions, geometric mean diameter of the largest volume mode was 153 nm during the flaming phase and 300 nm during the smoldering phase. The lowest single-scattering albedo of the ground-level measurements was 0.7 in the flaming-phase plume and ~0.9 in the smoldering phase. Elevated concentrations of several volatile organic compounds (VOC) (including acetonitrile, a biomass burning marker) were observed in the smoke plume at ground level. Measurements at the forest floor (i.e., a richly organic layer of soil and debris, characteristic of forested land) showed that VOC fluxes were generally low and consisted mainly of monoterpenes, and VOC flux peaked after the burning. After one year, the fluxes had nearly stabilized close to the level before the burning. The clear-cutting and burning of slash increased the total long-term CO2 release from the soil, and altered the physical, chemical and biological properties of the soil, such as increased the available nitrogen contents of the soil, which in turn, affected the long-term fluxes of greenhouse gases.

Technology breakthroughs in high performance metal-oxide-semiconductor devices for ultra-high density, low power non-volatile memory applications

NASA Astrophysics Data System (ADS)

Hong, Augustin Jinwoo

Non-volatile memory devices have attracted much attention because data can be retained without power consumption more than a decade. Therefore, non-volatile memory devices are essential to mobile electronic applications. Among state of the art non-volatile memory devices, NAND flash memory has earned the highest attention because of its ultra-high scalability and therefore its ultra-high storage capacity. However, human desire as well as market competition requires not only larger storage capacity but also lower power consumption for longer battery life time. One way to meet this human desire and extend the benefits of NAND flash memory is finding out new materials for storage layer inside the flash memory, which is called floating gate in the state of the art flash memory device. In this dissertation, we study new materials for the floating gate that can lower down the power consumption and increase the storage capacity at the same time. To this end, we employ various materials such as metal nanodot, metal thin film and graphene incorporating complementary-metal-oxide-semiconductor (CMOS) compatible processes. Experimental results show excellent memory effects at relatively low operating voltages. Detailed physics and analysis on experimental results are discussed. These new materials for data storage can be promising candidates for future non-volatile memory application beyond the state of the art flash technologies.

Source apportionment of fine particles and its chemical components over the Yangtze River Delta, China during a heavy haze pollution episode

NASA Astrophysics Data System (ADS)

Li, L.; An, J. Y.; Zhou, M.; Yan, R. S.; Huang, C.; Lu, Q.; Lin, L.; Wang, Y. J.; Tao, S. K.; Qiao, L. P.; Zhu, S. H.; Chen, C. H.

2015-12-01

An extremely high PM2.5 pollution episode occurred over the eastern China in January 2013. In this paper, the particulate matter source apportionment technology (PSAT) method coupled within the Comprehensive air quality model with extensions (CAMx) is applied to study the source contributions to PM2.5 and its major components at six receptors (Urban Shanghai, Chongming, Dianshan Lake, Urban Suzhou, Hangzhou and Zhoushan) in the Yangtze River Delta (YRD) region. Contributions from 4 source areas (including Shanghai, South Jiangsu, North Zhejiang and Super-region) and 9 emission sectors (including power plants, industrial boilers and kilns, industrial processing, mobile source, residential, volatile emissions, dust, agriculture and biogenic emissions) to PM2.5 and its major components (sulfate, nitrate, ammonia, organic carbon and elemental carbon) at the six receptors in the YRD region are quantified. Results show that accumulation of local pollution was the largest contributor during this air pollution episode in urban Shanghai (55%) and Suzhou (46%), followed by long-range transport (37% contribution to Shanghai and 44% to Suzhou). Super-regional emissions play an important role in PM2.5 formation at Hangzhou (48%) and Zhoushan site (68%). Among the emission sectors contributing to the high pollution episode, the major source categories include industrial processing (with contributions ranging between 12.7 and 38.7% at different receptors), combustion source (21.7-37.3%), mobile source (7.5-17.7%) and fugitive dust (8.4-27.3%). Agricultural contribution is also very significant at Zhoushan site (24.5%). In terms of the PM2.5 major components, it is found that industrial boilers and kilns are the major source contributor to sulfate and nitrate. Volatile emission source and agriculture are the major contributors to ammonia; transport is the largest contributor to elemental carbon. Industrial processing, volatile emissions and mobile source are the most significant contributors to organic carbon. Results show that the Yangtze River Delta region should focus on the joint pollution control of industrial processing, combustion emissions, mobile source emissions, and fugitive dust. Regional transport of air pollution among the cities are prominent, and the implementation of regional joint prevention and control of air pollution will help to alleviate fine particulate matter concentrations under heavy pollution case significantly.

Antimicrobial activities of the essential oils of various plants against tomato late blight disease agent Phytophthora infestans.

PubMed

Soylu, E Mine; Soylu, Soner; Kurt, Sener

2006-02-01

The aim of this study was to find an alternative to synthetic fungicides currently used in the control of devastating oomycete pathogen Phytophthora infestans, causal agent of late blight disease of tomato. Antifungal activities of essential oils obtained from aerial parts of aromatic plants such as oregano (Origanum syriacum var. bevanii), thyme (Thymbra spicata subsp. spicata), lavender (Lavandula stoechas subsp. stoechas), rosemary (Rosmarinus officinalis), fennel (Foeniculum vulgare), and laurel (Laurus nobilis), were investigated against P. infestans. Both contact and volatile phase effects of different concentrations of the essential oils used were determined by using two in vitro methods. Chemical compositions of the essential oils were also determined by GC-MS analysis. Major compounds found in essential oils of thyme, oregano, rosemary, lavender, fennel and laurel were carvacrol (37.9%), carvacrol (79.8), borneol (20.4%), camphor (20.2%), anethole (82.8%) and 1,8-cineole (35.5%), respectively. All essential oils were found to inhibit the growth of P. infestans in a dose-dependent manner. Volatile phase effect of oregano and thyme oils at 0.3 microg/ml air was found to completely inhibit the growth of P. infestans. Complete growth inhibition of pathogen by essential oil of fennel, rosemary, lavender and laurel was, however, observed at 0.4-2.0 microg/ml air concentrations. For the determination of the contact phase effects of the tested essential oils, oregano, thyme and fennel oils at 6.4 microg/ml were found to inhibit the growth of P. infestans completely. Essential oils of rosemary, lavender and laurel were inhibitory at relatively higher concentrations (12.8, 25.6, 51.2 microg/ml respectively). Volatile phase effects of essential oils were consistently found to be more effective on fungal growth than contact phase effect. Sporangial production was also inhibited by the essential oil tested. Light and scanning electron microscopic (SEM) observation on pathogen hyphae, exposed to both volatile and contact phase of oil, revealed considerable morphological alterations in hyphae such as cytoplasmic coagulation, vacuolations, hyphal shrivelling and protoplast leakage.

Proton transfer reaction mass spectrometry and time intensity perceptual measurement of flavor release from lipid emulsions using trained human subjects.

PubMed

Frank, Damian; Appelqvist, Ingrid; Piyasiri, Udayasika; Wooster, Tim J; Delahunty, Conor

2011-05-11

The effect of the fat component of liquid emulsions on dynamic "in-nose" flavor release was examined using a panel of trained human subjects (n = 6), proton transfer reaction mass spectrometry (PTR-MS), and time intensity (TI) sensory evaluation. A rigorous breathing and consumption protocol was developed, which synchronized subjects' breathing cycles and also the timing of sample introduction. Temporal changes in volatile release were measured in exhaled nostril breath by real-time PTR-MS. Corresponding changes in the perceived odor intensity could also be simultaneously measured using a push button TI device. The method facilitated accurate examination of both "preswallow" and "postswallow" phases of volatile release and perception. Volatile flavor compounds spanning a range of octanol/water partition coefficient (K(o/w)) values (1-1380) were spiked into water (0% fat) or lipid emulsions with various fat contents (2, 5, 10, and 20% fat). Replicate samples for each fat level were consumed according to the consumption protocol by six subjects. Statistical comparisons were made at the individual level and across the group for the effects of changes in the food matrix, such as fat content, on both pre- and postswallow volatile release. Significant group differences in volatile release parameters including area under the concentration curve (AUC) and maximum concentration (I(max)) were measured according to the lipid content of emulsions and volatile K(o/w). In a second experiment, using single compounds (2-heptanone, ethyl butanoate, and ethyl hexanoate), significant decreases in both in-nose volatile release and corresponding perceived odor intensities were measured with increasing fat addition. Overall, the effect of fat on in vivo release conformed to theory; fat had little effect on compounds with low K(o/w) values, but increased for volatiles with higher lipophilicity. In addition, significant pre- and postswallow differences were observed in AUC and I(max), as a result of changing fat levels. In the absence of fat, more than half of the total amount of volatile was released in the preswallow phase. As the content of fat was increased in the emulsion systems, the ratio of volatile released postswallow increased compared to preswallow. These data may provide new insights into why low-fat and high-fat foods are perceived differently.

Configuration of Pluto's Volatile Ices

NASA Astrophysics Data System (ADS)

Grundy, William M.; Binzel, R. P.; Cook, J. C.; Cruikshank, D. P.; Dalle Ore, C. M.; Earle, A. M.; Ennico, K.; Jennings, D. E.; Howett, C. J. A.; Linscott, I. R.; Lunsford, A. W.; Olkin, C. B.; Parker, A. H.; Parker, J. Wm; Protopapa, S.; Reuter, D. C.; Singer, K. N.; Spencer, J. R.; Stern, S. A.; Tsang, C. C. C.; Verbiscer, A. J.; Weaver, H. A.; Young, L. A.; Berry, K.; Buie, M. W.; Stansberry, J. A.

2015-11-01

We report on near-infrared remote sensing by New Horizons' Ralph instrument (Reuter et al. 2008, Space Sci. Rev. 140, 129-154) of Pluto's N2, CO, and CH4 ices. These especially volatile ices are mobile even at Pluto's cryogenic surface temperatures. Sunlight reflected from these ices becomes imprinted with their characteristic spectral absorption bands. The detailed appearance of these absorption features depends on many aspects of local composition, thermodynamic state, and texture. Multiple-scattering radiative transfer models are used to retrieve quantitative information about these properties and to map how they vary across Pluto's surface. Using parameter maps derived from New Horizons observations, we investigate the striking regional differences in the abundances and scattering properties of Pluto's volatile ices. Comparing these spatial patterns with the underlying geology provides valuable constraints on processes actively modifying the planet's surface, over a variety of spatial scales ranging from global latitudinal patterns to more regional and local processes within and around the feature informally known as Sputnik Planum. This work was supported by the NASA New Horizons Project.

ENVIRONMENTALLY SAFE, NO VOC AUTOMOTIVE COATING - PHASE II

EPA Science Inventory

The EPA recognizes that volatile organic compounds (VOCs) must be eliminated from automotive coating formulations to improve worker safety and reduce environmental pollution. The phase I project resulted in the production of a polymer-based coating material that was clear, ...

Things fall apart: Fragmentation reactions in the oxidative aging of organic species

NASA Astrophysics Data System (ADS)

Kroll, J. H.; Isaacman-VanWertz, G. A.; Wilson, K. R.; Daumit, K. E.; Kessler, S. H.; Lim, C. Y.; Worsnop, D. R.

2016-12-01

The atmospheric oxidation of organic compounds involves a wide array of chemical transformations, including functionalization reactions (addition of polar functional groups to the carbon skeleton), fragmentation reactions (formation of lower carbon-number products via C-C bond scission), and accretion reactions (increases in molecular weight by the combination of two chemical species). Each of these reaction classes can lead to large changes in volatility, and hence can have major implications for atmospheric organic aerosol (OA). For example, the formation of OA is predominantly driven by functionalization and accretion reactions, which generally lead to decreases in volatility. Here we describe a series of laboratory studies of the subsequent organic "aging", the multiday oxidation processes that occur after the initial OA formation and growth. In these studies, the multigenerational oxidation of organic compounds in various phases (the gas phase, the condensed OA phase, and the aqueous phase) is carried out within either an environmental chamber or a flow reactor, and monitored using various high-resolution mass spectrometric techniques. In all cases it is found that fragmentation reactions play a major role in the observed aging chemistry, dominated by the formation of small, volatile oxidation products. These results suggest that multi-day oxidative aging processes do not lead to sustained aerosol growth, but rather may serve as a chemical sink for atmospheric OA.

Satellite mobile data service for Canada

NASA Technical Reports Server (NTRS)

Egan, Glenn R.; Sward, David J.

1990-01-01

A commercial mobile satellite system which is to be constructed and operated in Canada is examined. This is done in two phases. First, mobile data services was introduced. Hub equipment and 3000 mobile data terminals were supplied. Over the satellite tests were performed. The mobile data service provides full two way digital messaging automatic vehicle location and fleet management services. The second phase is to construct, launch and make operational the MSAT satellite and associated network control facilities. The implementation is examined of the mobile data service in Canada, including the technical description. Marketing and applications are also examined.

Fluidized bed combustion of high-volatile solid fuels: An assessment of char attrition and volatile matter segregation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chirone, R.; Marzocchella, A.; Salatino, P.

1999-07-01

A simple lumped-parameter model of a bubbling fluidized bed combustor fueled with high-volatile solid fuels is presented. The combustor is divided into three sections: the dense bed, the splashing region and the freeboard. Material balances on fixed carbon, volatile matter and oxygen are set up, taking into account fuel particle fragmentation and attrition, volatile matter segregation as well as postcombustion of both carbon fines and volatiles escaping the bed. A basic assumption of the model is that the combustion pathway that foes from the raw fuel to the combustion products proceeds via the formation of three phases: volatile matter, relativelymore » large non-elutriable char particles and fine char particles of elutriable size. The study is complemented by a simplified thermal balance on the splashing zone taking into account volatiles and elutriated fines postcombustion and radiative and convective heat fluxes to the bed and the freeboard. Results from calculations with either low- or high-volatile solid fuels indicate that low-volatile bituminous coal combustion takes place essentially in the bed mostly via coarse char particles combustion, while high-volatile biomass fuel combustion occurs to comparable extents both in the bed and in the splashing region of the combustor. Depending on the extent of volatile matter segregation with respect to the bed, a significant fraction of the heat is released into the splashing region of the combustor and this results into an increase of temperature in this region. Extensive bed solids recirculation associated to bubble bursting/solids ejection at the bed surface together with effective gas-solids heat transfer promotes thermal feedback from this region to the bed of as much as 90% of the heat release by volatile matter and elutriated fines afterburning.« less

Hydraulic Universal Display Processor System (HUDPS).

DTIC Science & Technology

1981-11-21

emphasis on smart alphanumeric devices in Task II. Volatile and non-volatile memory components were utilized along with the Intel 8748 microprocessor...system. 1.2 TASK 11 Fault display methods for ground support personnel were investigated during Phase II with emphasis on smart alphanumeric devices...CONSIDERATIONS Methods of display fault indication for ground support personnel have been investigated with emphasis on " smart " alphanumeric devices

Modeling Regolith Temperatures and Volatile Ice Processes (Invited)

NASA Astrophysics Data System (ADS)

Mellon, M. T.

2013-12-01

Surface and subsurface temperatures are an important tool for exploring the distribution and dynamics of volatile ices on and within planetary regoliths. I will review thermal-analysis approaches and recent applications in the studies of volatile ice processes. Numerical models of regolith temperatures allow us to examine the response of ices to periodic and secular changes in heat sources such as insolation. Used in conjunction with spatially and temporally distributed remotely-sensed temperatures, numerical models can: 1) constrain the stability and dynamics of volatile ices; 2) define the partitioning between phases of ice, gas, liquid, and adsorbate; and 3) in some instances be used to probe the distribution of ice hidden from view beneath the surface. The vapor pressure of volatile ices (such as water, carbon dioxide, and methane) depends exponentially on temperature. Small changes in temperature can result in transitions between stable phases. Cyclic temperatures and the propagation of thermal waves into the subsurface can produce a strong hysteresis in the population and partitioning of various phases (such as between ice, vapor, and adsorbate) and result in bulk transport. Condensation of ice will also have a pronounced effect on the thermal properties of otherwise loose particulate regolith. Cementing grains at their contacts through ice deposition will increase the thermal conductivity, and may enhance the stability of additional ice. Likewise sintering of grains within a predominantly icy regolith will increase the thermal conductivity. Subsurface layers that result from ice redistribution can be discriminated by remote sensing when combined with numerical modeling. Applications of these techniques include modeling of seasonal carbon dioxide frosts on Mars, predicting and interpreting the subsurface ice distribution on Mars and in Antarctica, and estimating the current depth of ice-rich permafrost on Mars. Additionally, understanding cold trapping ices in regions of the regolith of airless bodies, such as Mercury and the Moon, are aided by numerical modeling of regolith temperatures. Thermally driven sublimation of volatiles (water ice on Mars and more exotic species on icy moons in the outer solar system) can result in terrain degradation and collapse.

A Novel Inlet System for On-line Chemical Analysis of Semi-Volatile Submicron Particulate Matter

NASA Astrophysics Data System (ADS)

Wisthaler, A.; Eichler, P.; Müller, M.

2015-12-01

Semi-volatile organic molecules bound to particles are difficult to measure, especially if they are reactive in nature. Any technique based on aerosol collection onto a substrate generates sampling artifacts due to surface reactions and ad- and desorption of semi-volatile analytes. On-line sampling without sample pre-collection, as for example implemented in the AMS, has greatly reduced many sampling artifacts. AMS measurements of organics do, however, suffer from the drawback that molecular-level information is, in most cases, lost during hard ionization events. As a consequence, only little speciated and thus mechanistically informative data on organic matter is obtained. PTR-ToF-MS is a well-established on-line measurement technique for gas-phase organics. Soft ionization via gas-phase hydronium ions preserves, to a large extent, molecular-level information and thus allows identifying organic compounds at an elemental composition level. We have recently developed a particle inlet system for PTR-ToF-MS instruments (doi:10.5194/amt-8-1353-2015). The CHARON ("Chemical Analysis of Aerosol On-line") inlet consists of a gas-phase denuder, an aerodynamic lens and a thermodesorption unit. In its latest version, it includes a heatable tube upstream of the denuder to form a thermodenuder. Over the last year, the CHARON PTR-ToF-MS system has been successfully used in a series of measurement campaigns to characterize i) POA emitted from a marine diesel engine, ii) SOA generated from the photo-oxidation of toluene, iii) SOA generated from the photo-oxidation of selected amines, iv) ambient aerosol in two major European cities and v) SOA generated from the photo-oxidation of biogenic VOCs. These measurements have demonstrated that the CHARON PTR-ToF-MS system i) generates on-line and real-time elemental composition information of semi-volatile organics in submicron particles (both POA and SOA), ii) detects 80-100 % of the organic mass as measured by the AMS and iii) generates volatility information of semi-volatile organics at an elemental composition level. Selected application examples will be shown.

Effect of the type of oil on the evolution of volatile compounds of taralli during storage.

PubMed

Giarnetti, Mariagrazia; Caponio, Francesco; Paradiso, Vito M; Summo, Carmine; Gomes, Tommaso

2012-03-01

Baking process leads to a huge quantity of newly formed volatile compounds, which play a major role in developing the flavor of the final product. The aim of this work was to investigate on the evolution of the volatile profile of taralli as a function of both the kind of oil used in the dough and the storage time. The volatile compounds from the taralli were extracted by headspace solid-phase microextraction and analyzed by gas-chromatography/mass spectrometry (GC/MS). Forty-four volatile compounds were identified in taralli, most of which produced by thermically induced reactions occurring during baking process, such as volatiles deriving from Maillard reaction and/or sugar degradation and lipid oxidation. The results obtained demonstrated the essential role played by the type of oil on the formation and on the release of volatile compounds. The volatile compounds significantly increased during storage and their individual levels were in most cases significantly lower in taralli made with extra virgin olive oil than in those made with refined oils. Finally, the taralli made with extra virgin olive oil, compared with those prepared with other vegetable oils, showed to be more resistant to oxidation, probably due to the presence of natural antioxidants. © 2012 Institute of Food Technologists®

Rapid differentiation of Chinese hop varieties (Humulus lupulus) using volatile fingerprinting by HS-SPME-GC-MS combined with multivariate statistical analysis.

PubMed

Liu, Zechang; Wang, Liping; Liu, Yumei

2018-01-18

Hops impart flavor to beer, with the volatile components characterizing the various hop varieties and qualities. Fingerprinting, especially flavor fingerprinting, is often used to identify 'flavor products' because inconsistencies in the description of flavor may lead to an incorrect definition of beer quality. Compared to flavor fingerprinting, volatile fingerprinting is simpler and easier. We performed volatile fingerprinting using head space-solid phase micro-extraction gas chromatography-mass spectrometry combined with similarity analysis and principal component analysis (PCA) for evaluating and distinguishing between three major Chinese hops. Eighty-four volatiles were identified, which were classified into seven categories. Volatile fingerprinting based on similarity analysis did not yield any obvious result. By contrast, hop varieties and qualities were identified using volatile fingerprinting based on PCA. The potential variables explained the variance in the three hop varieties. In addition, the dendrogram and principal component score plot described the differences and classifications of hops. Volatile fingerprinting plus multivariate statistical analysis can rapidly differentiate between the different varieties and qualities of the three major Chinese hops. Furthermore, this method can be used as a reference in other fields. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Retention of ionisable compounds on high-performance liquid chromatography XVII. Estimation of the pH variation of aqueous buffers with the change of the methanol fraction of the mobile phase.

PubMed

Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

2007-01-05

The use of methanol-aqueous buffer mobile phases in HPLC is a common election when performing chromatographic separations of ionisable analytes. The addition of methanol to the aqueous buffer to prepare such a mobile phase changes the buffer capacity and the pH of the solution. In the present work, the variation of these buffer properties is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-hydrogencitrate-citrate, and ammonium-ammonia buffers. It is well established that the pH change of the buffers depends on the initial concentration and aqueous pH of the buffer, on the percentage of methanol added, and on the particular buffer used. The proposed equations allow the pH estimation of methanol-water buffered mobile phases up to 80% in volume of organic modifier from initial aqueous buffer pH and buffer concentration (before adding methanol) between 0.001 and 0.01 mol L(-1). From both the estimated pH values of the mobile phase and the estimated pKa of the ionisable analytes, it is possible to predict the degree of ionisation of the analytes and therefore, the interpretation of acid-base analytes behaviour in a particular methanol-water buffered mobile phase.

A weak cation-exchange monolith as stationary phase for the separation of peptide diastereomers by CEC.

PubMed

Ludewig, Ronny; Nietzsche, Sandor; Scriba, Gerhard K E

2011-01-01

A CEC weak cation-exchange monolith has been prepared by in situ polymerization of acrylamide, methylenebisacrylamide and 4-acrylamidobutyric acid in a decanol-dimethylsulfoxide mixture as porogen. The columns were evaluated by SEM and characterized with regard to the separation of diastereomers and α/β-isomers of aspartyl peptides. Column preparation was reproducible as evidenced by comparison of the analyte retention times of several columns prepared simultaneously. Analyte separation was achieved using mobile phases consisting of acidic phosphate buffer and ACN. Under these conditions the peptides migrated due to their electrophoretic mobility but the EOF also contributed as driving force as a function of the pH of the mobile phase due to increasing dissociation of the carboxyl groups of the polymer. Raising the pH of the mobile phase also resulted in deprotonation of the peptides reducing analyte mobility. Due to these mechanisms each pair of diastereomeric peptides displayed the highest resolution at a different pH of the buffer component of the mobile phase. Comparing the weak-cation exchange monolith to an RP monolith and a strong cation-exchange monolith different elution order of some peptide diastereomers was observed, clearly illustrating that interactions with the stationary phase contribute to the CEC separations. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Field Testing Near-IR and Neutron Spectrometer Prospecting: Applications to Resource Prospector on the Moon

NASA Technical Reports Server (NTRS)

Elphic, R. C.; Colaprete, A.; Heldmann, J. L.; Deans, M. C.

2015-01-01

While we know there are volatiles sequestered at the poles of the Moon, the detailed 3-D distribution, abundance, and physical and chemical form are largely unknown. The next giant leap, Resource Prospector (RP), will use landed assets to fully characterize the volatile composition and distribution at scales of tens to hundreds of meters. To achieve this range of scales, mobility is required. Near real-time operation of surface assets is desirable, with a concept of operations very different from that of rovers on Mars. For RP, new operational approaches are required to carry out real-time robotic exploration. The Mojave Volatiles Project (MVP) is a Moon- Mars Analog Mission Activities (MMAMA) program effort aimed at (1) determining effective approaches to operating a real-time but short-duration lunar surface robotic mission, and (2) performing prospecting science in a natural setting, as a test of these approaches. Here we describe some results from the first such test, carried out in the Mojave Desert between 16 and 24 October, 2014. The test site was an alluvial fan just E of the Soda Mountains, SW of Baker, California. This site contains desert pavements, ranging from the late Pleistocene to early-Holocene in age. These pavements are dissected by the ongoing development of washes. A principal objective was to determine the hydration state of different types of desert pavement and bare ground features. The mobility element of the test was the KREX-2 rover, designed and operated by the Intelligent Robotics Group at NASA Ames Research Center.

Slow equilibration of reversed-phase columns for the separation of ionized solutes.

PubMed

Marchand, D H; Williams, L A; Dolan, J W; Snyder, L R

2003-10-10

Reversed-phase columns that have been stored in buffer-free solvents can exhibit pronounced retention-time drift when buffered, low-pH mobile phases are used with ionized solutes. Whereas non-ionized compounds exhibit constant retention times within 20 min of the beginning of mobile phase flow, the retention of ionized compounds can continue to change (by 20% or more) for several hours. If mobile phase pH is changed from low to high and back again, an even longer time may be required before the column reaches equilibration at low pH. The speed of column equilibration for ionized solutes can vary significantly among different reversed-phase columns and is not affected by flow rate.

Combined effect of polarity and pH on the chromatographic behavior of some angiotensin II receptor antagonists and optimization of their determination in pharmaceutical dosage forms.

PubMed

Demiralay, Ebru Cubuk; Cubuk, Burcu; Ozkan, Sibel A; Alsancak, Guleren

2010-11-02

In the present study, the combined effect of mobile phase polarity and pH on retention behavior of some ARA-IIs (irbesartan, losartan, valsartan and telmisartan) is investigated. The linear relationships established between retention factors of the species and the polarity parameter of the mobile phase has proved to predict accurately retention in LC as a function of the acetonitrile content (50%, 55%, 60%, v/v). The suggested model uses the pH value in the acetonitrile-water mixture as mobile phase instead of pH value in water and takes into account the effect of activity coefficients. Moreover, correlation between retention and the mobile phase pH can be established allowing prediction of the retention behavior as a function of the mobile phase pH. The model can be used to estimate the pKa in an acetonitrile percentage between 50% and 60%, at 30 degrees C. The developed method was successfully applied to both the simultaneous separation of these drug-active compounds and individual determination in their commercial pharmaceutical dosage forms.

Optimisation of solid-phase microextraction combined with gas chromatography-mass spectrometry based methodology to establish the global volatile signature in pulp and skin of Vitis vinifera L. grape varieties.

PubMed

Perestrelo, Rosa; Barros, António S; Rocha, Sílvia M; Câmara, José S

2011-09-15

The volatiles (VOCs) and semi-volatile organic compounds (SVOCs) responsible for aroma are mainly present in skin of grape varieties. Thus, the present investigation is directed towards the optimisation of a solvent free methodology based on headspace-solid-phase microextraction (HS-SPME) combined with gas chromatography-quadrupole mass spectrometry (GC-qMS) in order to establish the global volatile composition in pulp and skin of Bual and Bastardo Vitis vinifera L. varieties. A deep study on the extraction-influencing parameters was performed, and the best results, expressed as GC peak area, number of identified compounds and reproducibility, were obtained using 4 g of sample homogenised in 5 mL of ultra-pure Milli-Q water in a 20 mL glass vial with addition of 2g of sodium chloride (NaCl). A divinylbenzene/carboxen/polydimethylsiloxane fibre was selected for extraction at 60°C for 45 min under continuous stirring at 800 rpm. More than 100 VOCs and SVOCs, including 27 monoterpenoids, 27 sesquiterpenoids, 21 carbonyl compounds, 17 alcohols (from which 2 aromatics), 10 C(13) norisoprenoids and 5 acids were identified. The results showed that, for both grape varieties, the levels and number of volatiles in skin were considerably higher than those observed in pulp. According to the data obtained by principal component analysis (PCA), the establishment of the global volatile signature of grape and the relationship between different part of grapes-pulp and skin, may be an useful tool to winemaker decision to define the vinification procedures that improves the organoleptic characteristics of the corresponding wines and consequently contributed to an economic valorization and consumer acceptance. Copyright © 2011 Elsevier B.V. All rights reserved.

Volatile organic compound concentrations in the South Coast Air Basin (CA) during the summers of 1995 and 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zielinska, B.; Harshfield, G.; Fujita, E.

1997-12-31

Volatile organic compounds (VOC) were measured in California`s South Coast Air Basin (SoCAB) during the summers of 1995 and 1996 in order to determine the air quality impacts of the introduction in 1996 of California`s Phase 2 reformulated gasoline (RFG). Over 250 canister and 2,4-dinitrophenylhydrazine (DNPH)-impregnated cartridge samples were collected during each sampling campaign at four sampling sites--two source-dominated sites, a downwind receptor site, and a background site. Canister samples were analyzed for methane, speciated volatile hydrocarbons (C{sub 2}-C{sub 12}), carbon monoxide (CO), carbon dioxide (CO{sub 2}), and methyl tert-butyl ether (MTBE). DNPH were analyzed for C{sub 1}-C{sub 7} carbonylmore » compounds. This paper examines the changes in concentrations of C{sub 2}-C{sub 12} hydrocarbons in the SoCAB resulting from the introduction of Phase 2 RFG with particular emphasis on hydrocarbon species that are most affected by the reformulation.« less

Non-volatile Clocked Spin Wave Interconnect for Beyond-CMOS Nanomagnet Pipelines

PubMed Central

Dutta, Sourav; Chang, Sou-Chi; Kani, Nickvash; Nikonov, Dmitri E.; Manipatruni, Sasikanth; Young, Ian A.; Naeemi, Azad

2015-01-01

The possibility of using spin waves for information transmission and processing has been an area of active research due to the unique ability to manipulate the amplitude and phase of the spin waves for building complex logic circuits with less physical resources and low power consumption. Previous proposals on spin wave logic circuits have suggested the idea of utilizing the magneto-electric effect for spin wave amplification and amplitude- or phase-dependent switching of magneto-electric cells. Here, we propose a comprehensive scheme for building a clocked non-volatile spin wave device by introducing a charge-to-spin converter that translates information from electrical domain to spin domain, magneto-electric spin wave repeaters that operate in three different regimes - spin wave transmitter, non-volatile memory and spin wave detector, and a novel clocking scheme that ensures sequential transmission of information and non-reciprocity. The proposed device satisfies the five essential requirements for logic application: nonlinearity, amplification, concatenability, feedback prevention, and complete set of Boolean operations. PMID:25955353

Electric-field triggered controlled release of bioactive volatiles from imine-based liquid crystalline phases.

PubMed

Herrmann, Andreas; Giuseppone, Nicolas; Lehn, Jean-Marie

2009-01-01

Application of an electric field to liquid crystalline film forming imines with negative dielectric anisotropy, such as N-(4-methoxybenzylidene)-4-butylaniline (MBBA, 1), results in the expulsion of compounds that do not participate in the formation of the liquid crystalline phase. Furthermore, amines and aromatic aldehydes undergo component exchange with the imine by generating constitutional dynamic libraries. The strength of the electric field and the duration of its application to the liquid crystalline film influence the release rate of the expelled compounds and, at the same time, modulate the equilibration of the dynamic libraries. The controlled release of volatile organic molecules with different chemical functionalities from the film was quantified by dynamic headspace analysis. In all cases, higher headspace concentrations were detected in the presence of an electric field. These results point to the possibility of using imine-based liquid crystalline films to build devices for the controlled release of a broad variety of bioactive volatiles as a direct response to an external electric signal.

Comparison of Aroma Character Impact Volatiles of Thummong Leaves ( Litsea petiolata Hook. f.), Mangdana Water Beetle ( Lethocerus indicus), and a Commercial Product as Flavoring Agents in Thai Traditional Cooking.

PubMed

Mahattanatawee, Kanjana; Luanphaisarnnont, Torsak; Rouseff, Russell

2018-03-14

Thummong ( Litsea petiolata Hook. f.) is a tree native to southern Thailand. The leaves of this tree are highly aromatic and used to flavor Thai dishes in place of the traditional water beetle Mangdana ( Lethocerus indicus) for religious and cultural reasons. Total and aroma-active volatiles from both flavoring materials were compared using gas chromatography-olfactory (GC-O) and gas chromatography-mass spectrometry (GC-MS). The volatiles from Thummong leaves and the Mangdana water beetle were collected and concentrated using headspace solid-phase microextraction. A total of 23 and 25 aroma-active volatiles were identified in Thummong leaves and Mangdana, respectively. The major aroma-active volatiles in Thummong leaves consisted of 7 aldehydes, 5 ketones, and 3 esters. In contrast, the aroma-active volatiles in the water beetle consisted of 11 aldehydes, 3 esters, and 2 ketones. Both had ( E)-2-nonenal as the most intense aroma-active volatile. The water beetle character impact volatile ( E)-2-hexenyl acetate was absent in the leaves, but its aroma character was mimicked by 11-dodecen-2-one in the leaves, which was absent in the beetle. In addition, a commercial Mangdana flavoring was examined using GC-O and GC-MS and found to contain only a single aroma-active volatile, hexyl acetate. All three flavoring sources exhibited similar aroma characteristics but were produced from profoundly different aroma-active volatiles.

Characterization of Volatile Sulfur Compounds in Moutai Liquors by Headspace Solid-Phase Microextraction Gas Chromatography-Pulsed Flame Photometric Detection and Odor Activity Value.

PubMed

Chen, Shuang; Sha, Sha; Qian, Michael; Xu, Yan

2017-12-01

This study investigated the aroma contribution of volatile sulfur compounds (VSCs) in Moutai liquors. The VSCs were analyzed using headspace solid-phase microextraction-gas chromatography-pulsed flame photometric detection (HS-SPME-GC-PFPD). The influences of SPME fibers, ethanol content in the sample, pre-incubation time, and extraction temperature and time on the extraction of VSCs were optimized. The VSCs were optimally extracted using a divinylbenzene/carboxen/polydimethylsiloxane fiber, by incubating 10 mL diluted Chinese liquor (5% vol.) with 3 g NaCl at 30 °C for 15 min, followed by a subsequent extraction for 40 min at 30 °C. The optimized method was further validated. A total of 13 VSCs were identified and quantified in Moutai liquors. The aroma contribution of these VSCs were evaluated by their odor activity values (OAVs), with the result that 7 of 13 VSCs had OAVs > 1. In particular, 2-furfurylthiol, methanethiol, dimethyl trisulfide, ethanethiol, and methional had relatively high OAVs and could be the key aroma contributors to Moutai liquors. In this study, a method for analyzing volatile sulfur compounds in Chinese liquors has been developed. This method will allow an in-depth study the aroma contribution of volatile sulfur compounds in Chinese liquors. Seven volatile sulfur compounds were identified as potential key aroma contributors for Moutai liquors, which can help to the quality control of Moutai liquors. © 2017 Institute of Food Technologists®.

Understanding the spreading patterns of mobile phone viruses.

PubMed

Wang, Pu; González, Marta C; Hidalgo, César A; Barabási, Albert-László

2009-05-22

We modeled the mobility of mobile phone users in order to study the fundamental spreading patterns that characterize a mobile virus outbreak. We find that although Bluetooth viruses can reach all susceptible handsets with time, they spread slowly because of human mobility, offering ample opportunities to deploy antiviral software. In contrast, viruses using multimedia messaging services could infect all users in hours, but currently a phase transition on the underlying call graph limits them to only a small fraction of the susceptible users. These results explain the lack of a major mobile virus breakout so far and predict that once a mobile operating system's market share reaches the phase transition point, viruses will pose a serious threat to mobile communications.

Experimental Constraints on Alkali Volatilization during Chondrule Formation: Implications for Early Solar System Heterogeneity

NASA Astrophysics Data System (ADS)

Ustunisik, G. K.; Ebel, D. S.; Nekvasil, H.

2014-12-01

The chemical variability of chondrule volatile element contents provide a wealth of information on the processes that shaped the early solar system and its compositional heterogeneity. An essential observation is that chondrule melts contain very low alkalies and other volatile elements (e.g., Cl). The reason for this depletion is the combined effects of cooling rates (10 to 1000K/h), the small size of chondrules, and their high melting temperatures (~1700 to 2100 K) resulting in extensive loss of volatiles at canonical pressures (e.g., 10-4bar). However, we observe some chondrules with significant concentrations of volatiles (Na, Cl), that differ markedly from chondrules dominated by refractory elements. Could such heterogeneity arise from loss of alkalis and Cl to a gas phase that itself later condenses, thereby yielding variations in volatile enrichments in chondrules? Does Cl enhance volatility of the alkalis to varying extents? Experiments on Cl-bearing and Cl-free melts of equivalent composition for 10 min, 4 h, and 6 h reveal systematic effects of Cl on alkali volatility. Cl-bearing melts lose 48% of initial Na2O, 66% of K2O, 96% of Cl within the first 10 minutes of degassing. Then the amount of alkali loss decreases due to the absence of Cl. Cl-free melts loses only 15% of initial Na2O and 33% K2O. After 4 hours, melts lose 1/3 of initial Na2O and 1/2 of K2O. For both systems, Na2O is more compatible in the melt relative to K2O. Therefore, the vapor given off has a K/Na ratio higher than the melt through time in spite of the much higher initial Na abundance in the melt. Enhanced vaporization of alkalis from Cl-bearing melt suggests that Na and K evaporate more readily as volatile chlorides than as monatomic gases. Cl-free initial melts with normative plagioclase of An50Ab44Or6 evolved into slightly normal zoned ones (An49Ab50Or1) while Cl-bearing initial melts normative to albitic plagioclase (An46Ab50Or4) evolved to reverse zoned ones (An54Ab45Or1). The vapor phase over Cl-bearing chondrule melts may have a bimodal character over time. The heteregeneous volatile contents of chondrules may result from quenching of melt droplets at different stages of repeated heating, chondrule fragment recycling, and recondensation of exsolved volatiles.

40 CFR 264.317 - Special requirements for hazardous wastes FO20, FO21, FO22, FO23, FO26, and FO27.

Code of Federal Regulations, 2011 CFR

2011-07-01

... factors to be considered are: (1) The volume, physical, and chemical characteristics of the wastes, including their potential to migrate through the soil or to volatilize or escape into the atmosphere; (2) The attenuative properties of underlying and surrounding soils or other materials; (3) The mobilizing...

40 CFR 264.231 - Special requirements for hazardous wastes FO20, FO21, FO22, FO23, FO26, and FO27.

Code of Federal Regulations, 2011 CFR

2011-07-01

... chemical characteristics of the wastes, including their potential to migrate through soil or to volatilize or escape into the atmosphere; (2) The attenuative properties of underlying and surrounding soils or other materials; (3) The mobilizing properties of other materials co-disposed with these wastes; and (4...

Selection of Environmentally Friendly Solvents for the Extravehicular Mobility Unit Secondary Oxygen Pack Cold Trap Testing

NASA Technical Reports Server (NTRS)

Steele, John; Chullen, Cinda; Morenz, Jesse; Stephenson, Curtis

2010-01-01

Freon-113(TradeMark) has been used as a chemistry lab sampling solvent at NASA/JSC for EMU (extravehicular Mobility Unit) SOP (Secondary Oxygen Pack) oxygen testing Cold Traps utilized at the USA (United Space Alliance) Houston facility. Similar testing has occurred at the HSWL (Hamilton Sundstrand Windsor Locks) facility. A NASA Executive Order bans the procurement of all ODS (ozone depleting substances), including Freon-113 by the end of 2009. In order to comply with NASA direction, HSWL began evaluating viable solvents to replace Freon-113 . The study and testing effort to find Freon-113 replacements used for Cold Trap sampling is the subject of this paper. Test results have shown HFE-7100 (a 3M fluorinated ether) to be an adequate replacement for Freon-113 as a solvent to remove and measure the non-volatile residue collected in a Cold Trap during oxygen testing. Furthermore, S-316 (a Horiba Instruments Inc. high molecular weight, non-ODS chlorofluorocarbon) was found to be an adequate replacement for Freon-113 as a solvent to reconstitute non-volatile residue removed from a Cold Trap during oxygen testing for subsequent HC (hydrocarbon) analysis via FTIR (Fourier Transform Infrared Spectroscopy).

Method for determining asphaltene stability of a hydrocarbon-containing material

DOEpatents

Schabron, John F; Rovani, Jr., Joseph F

2013-02-05

A method for determining asphaltene stability in a hydrocarbon-containing material having solvated asphaltenes therein is disclosed. In at least one embodiment, it involves the steps of: (a) precipitating an amount of the asphaltenes from a liquid sample of the hydrocarbon-containing material with an alkane mobile phase solvent in a column; (b) dissolving a first amount and a second amount of the precipitated asphaltenes by changing the alkane mobile phase solvent to a final mobile phase solvent having a solubility parameter that is higher than the alkane mobile phase solvent; (c) monitoring the concentration of eluted fractions from the column; (d) creating a solubility profile of the dissolved asphaltenes in the hydrocarbon-containing material; and (e) determining one or more asphaltene stability parameters of the hydrocarbon-containing material.

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR ANALYSIS OF 2-PHASE MULTISORBENT SAMPLERS FOR VOCS (BCO-L-31.0)

EPA Science Inventory

The purpose of this SOP is to describe the methodology for the analysis of certain trace volatile organic compounds (VOCs) in air that are captured on two-phase carbon-based multisorbent tubes packed with Carbotrap (graphitized carbon blacks) and Carbosieve S-III (a carbon molecu...

Analysis of Volatile Markers for Virgin Olive Oil Aroma Defects by SPME-GC/FID: Possible Sources of Incorrect Data.

PubMed

Oliver-Pozo, Celia; Aparicio-Ruiz, Ramón; Romero, Inmaculada; García-González, Diego L

2015-12-09

The need to explain virgin olive oil (VOO) aroma descriptors by means of volatiles has raised interest in applying analytical techniques for trapping and quantitating volatiles. Static headspace sampling with solid phase microextraction (SPME) as trapping material is one of the most applied solutions for analyzing volatiles. The use of an internal standard and the determination of the response factors of the main volatiles seem to guarantee the correct determination of volatile concentrations in VOOs by SPME-GC/FID. This paper, however, shows that the competition phenomena between volatiles in their adsorption to the SPME fiber, inherent in static headspace sampling, may affect the quantitation. These phenomena are more noticeable in the particular case of highly odorant matrices, such as rancid and vinegary VOOs with high intensity of defect. The competition phenomena can modify the measurement sensitivity, which can be observed in volatile quantitation as well as in the recording of internal standard areas in different matrices. This paper analyzes the bias of the peak areas and concentrations of those volatiles that are markers for each sensory defect of VOOs (rancid, vinegary, musty, and fusty) when the intensity and complexity of aroma are increased. Of the 17 volatile markers studied in this work, 10 presented some anomalies in the quantitation in highly odorant matrices due the competition phenomena. However, quantitation was not affected in the concentration ranges at which each volatile marker is typically found in the defective oils they were characteristic of, validating their use as markers.

Volatile aroma compounds in various brewed green teas.

PubMed

Lee, Jeehyun; Chambers, Delores H; Chambers, Edgar; Adhikari, Koushik; Yoon, Youngmo

2013-08-20

This study identifies and semi-quantifies aroma volatiles in brewed green tea samples. The objectives of this study were to identify using a gas chromatograph-mass spectrometer (GC-MS) paired with a headspace solid-phase micro-extraction (HS-SPME) the common volatile compounds that may be responsible for aroma/flavor of the brewed liquor of a range of green tea samples from various countries as consumed and to determine if green teas from the same region have similarities in volatile composition when green tea samples are prepared for consumption. Twenty-four green tea samples from eight different countries were brewed as recommended for consumer brewing. The aroma volatiles were extracted by HS-SPME, separated on a gas chromatograph and identified using a mass spectrometer. Thirty-eight compounds were identified and the concentrations were semi-quantified. The concentrations were lower than those reported by other researchers, probably because this research examined headspace volatiles from brewed tea rather than solvent extraction of leaves. No relationship to country of origin was found, which indicates that other factors have a greater influence than country of origin on aroma.

Effect of hot air drying on volatile compounds of Flammulina velutipes detected by HS-SPME-GC-MS and electronic nose.

PubMed

Yang, Wenjian; Yu, Jie; Pei, Fei; Mariga, Alfred Mugambi; Ma, Ning; Fang, Yong; Hu, Qiuhui

2016-04-01

Volatile compounds are important factors that affect the flavor quality of Flammulina velutipes, but the changes occurring during hot air drying is still unclear. To clarify the dynamic changes of flavor components during hot air drying, comprehensive flavor characterization and volatile compounds of F. velutipes were evaluated using electronic nose technology and headspace solid phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively. Results showed that volatile components in F. velutipes significantly changed during hot air drying according to the principal component analysis and radar fingerprint chart of electronic nose. Volatile compounds of fresh F. velutipes consisted mainly of ketones, aldehydes and alcohols, and 3-octanone was the dominant compound. Drying process could significantly decrease the relative content of ketones and promoted the generation of alcohols, acids, and esters, which became the main volatile compounds of dried F. velutipes. These may provide a theoretical basis for the formation mechanism of flavor substances in dried F. velutipes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Carrier recovery techniques on satellite mobile channels

NASA Technical Reports Server (NTRS)

Vucetic, B.; Du, J.

1990-01-01

An analytical method and a stored channel model were used to evaluate error performance of uncoded quadrature phase shift keying (QPSK) and M-ary phase shift keying (MPSK) trellis coded modulation (TCM) over shadowed satellite mobile channels in the presence of phase jitter for various carrier recovery techniques.

Diffusion-based process for carbon dioxide uptake and isoprene emission in gaseous/aqueous two-phase photobioreactors by photosynthetic microorganisms.

PubMed

Bentley, Fiona K; Melis, Anastasios

2012-01-01

Photosynthesis for the generation of fuels and chemicals from cyanobacteria and microalgae offers the promise of a single host organism acting both as photocatalyst and processor, performing sunlight absorption and utilization, as well as CO(2) assimilation and conversion into product. However, there is a need to develop methods for generating, sequestering, and trapping such bio-products in an efficient and cost-effective manner that is suitable for industrial scale-up and exploitation. A sealed gaseous/aqueous two-phase photobioreactor was designed and applied for the photosynthetic generation of volatile isoprene (C(5)H(8)) hydrocarbons, which operates on the principle of spontaneous diffusion of CO(2) from the gaseous headspace into the microalgal or cyanobacterial-containing aqueous phase, followed by photosynthetic CO(2) assimilation and isoprene production by the transgenic microorganisms. Volatile isoprene hydrocarbons were emitted from the aqueous phase and were sequestered into the gaseous headspace. Periodic replacement (flushing) of the isoprene (C(5)H(8)) and oxygen (O(2)) content of the gaseous headspace with CO(2) allowed for the simultaneous harvesting of the photoproducts and replenishment of the CO(2) supply in the gaseous headspace. Reduction in practice of the gaseous/aqueous two-phase photobioreactor is offered in this work with a fed-batch and a semi-continuous culturing system using Synechocystis sp. PCC 6803 heterologously expressing the Pueraria montana (kudzu) isoprene synthase (IspS) gene. Constitutive isoprene production was observed over 192 h of experimentation, coupled with cyanobacterial biomass accumulation. The diffusion-based process in gaseous/aqueous two-phase photobioreactors has the potential to be applied to other high-value photosynthetically derived volatile molecules, emanating from a variety of photosynthetic microorganisms. Copyright © 2011 Wiley Periodicals, Inc.

Aqueous-phase oxidation of green leaf volatiles by hydroxyl radical as a source of SOA: Product identification from methyl jasmonate and methyl salicylate oxidation

NASA Astrophysics Data System (ADS)

Hansel, Amie K.; Ehrenhauser, Franz S.; Richards-Henderson, Nicole K.; Anastasio, Cort; Valsaraj, Kalliat T.

2015-02-01

Green leaf volatiles (GLVs) are a group of biogenic volatile organic compounds (BVOCs) released into the atmosphere by vegetation. BVOCs produce secondary organic aerosol (SOA) via gas-phase reactions, but little is known of their aqueous-phase oxidation as a source of SOA. GLVs can partition into atmospheric water phases, e.g., fog, mist, dew or rain, and be oxidized by hydroxyl radicals (˙OH). These reactions in the liquid phase also lead to products that have higher molecular weights, increased polarity, and lower vapor pressures, ultimately forming SOA after evaporation of the droplet. To examine this process, we investigated the aqueous, ˙OH-mediated oxidation of methyl jasmonate (MeJa) and methyl salicylate (MeSa), two GLVs that produce aqueous-phase SOA. High performance liquid chromatography/electrospray ionization mass spectrometry (HPLC-ESI-MS) was used to monitor product formation. The oxidation products identified exhibit higher molecular mass than their parent GLV due to either dimerization or the addition of oxygen and hydroxyl functional groups. The proposed structures of potential products are based on mechanistic considerations combined with the HPLC/ESI-MS data. Based on the structures, the vapor pressure and the Henry's law constant were estimated with multiple methods (SPARC, SIMPOL, MPBPVP, Bond and Group Estimations). The estimated vapor pressures of the products identified are significantly (up to 7 orders of magnitude) lower than those of the associated parent compounds, and therefore, the GLV oxidation products may remain as SOA after evaporation of the water droplet. The contribution of the identified oxidation products to SOA formation is estimated based on measured HPLC-ESI/MS responses relative to previous aqueous SOA mass yield measurements.

A Two-Phase Coverage-Enhancing Algorithm for Hybrid Wireless Sensor Networks.

PubMed

Zhang, Qingguo; Fok, Mable P

2017-01-09

Providing field coverage is a key task in many sensor network applications. In certain scenarios, the sensor field may have coverage holes due to random initial deployment of sensors; thus, the desired level of coverage cannot be achieved. A hybrid wireless sensor network is a cost-effective solution to this problem, which is achieved by repositioning a portion of the mobile sensors in the network to meet the network coverage requirement. This paper investigates how to redeploy mobile sensor nodes to improve network coverage in hybrid wireless sensor networks. We propose a two-phase coverage-enhancing algorithm for hybrid wireless sensor networks. In phase one, we use a differential evolution algorithm to compute the candidate's target positions in the mobile sensor nodes that could potentially improve coverage. In the second phase, we use an optimization scheme on the candidate's target positions calculated from phase one to reduce the accumulated potential moving distance of mobile sensors, such that the exact mobile sensor nodes that need to be moved as well as their final target positions can be determined. Experimental results show that the proposed algorithm provided significant improvement in terms of area coverage rate, average moving distance, area coverage-distance rate and the number of moved mobile sensors, when compare with other approaches.

A Two-Phase Coverage-Enhancing Algorithm for Hybrid Wireless Sensor Networks

PubMed Central

Zhang, Qingguo; Fok, Mable P.

2017-01-01

Providing field coverage is a key task in many sensor network applications. In certain scenarios, the sensor field may have coverage holes due to random initial deployment of sensors; thus, the desired level of coverage cannot be achieved. A hybrid wireless sensor network is a cost-effective solution to this problem, which is achieved by repositioning a portion of the mobile sensors in the network to meet the network coverage requirement. This paper investigates how to redeploy mobile sensor nodes to improve network coverage in hybrid wireless sensor networks. We propose a two-phase coverage-enhancing algorithm for hybrid wireless sensor networks. In phase one, we use a differential evolution algorithm to compute the candidate’s target positions in the mobile sensor nodes that could potentially improve coverage. In the second phase, we use an optimization scheme on the candidate’s target positions calculated from phase one to reduce the accumulated potential moving distance of mobile sensors, such that the exact mobile sensor nodes that need to be moved as well as their final target positions can be determined. Experimental results show that the proposed algorithm provided significant improvement in terms of area coverage rate, average moving distance, area coverage–distance rate and the number of moved mobile sensors, when compare with other approaches. PMID:28075365

Mixing of secondary organic aerosols versus relative humidity

PubMed Central

Ye, Qing; Robinson, Ellis Shipley; Ding, Xiang; Ye, Penglin

2016-01-01

Atmospheric aerosols exert a substantial influence on climate, ecosystems, visibility, and human health. Although secondary organic aerosols (SOA) dominate fine-particle mass, they comprise myriad compounds with uncertain sources, chemistry, and interactions. SOA formation involves absorption of vapors into particles, either because gas-phase chemistry produces low-volatility or semivolatile products that partition into particles or because more-volatile organics enter particles and react to form lower-volatility products. Thus, SOA formation involves both production of low-volatility compounds and their diffusion into particles. Most chemical transport models assume a single well-mixed phase of condensing organics and an instantaneous equilibrium between bulk gas and particle phases; however, direct observations constraining diffusion of semivolatile organics into particles containing SOA are scarce. Here we perform unique mixing experiments between SOA populations including semivolatile constituents using quantitative, single-particle mass spectrometry to probe any mass-transfer limitations in particles containing SOA. We show that, for several hours, particles containing SOA from toluene oxidation resist exchange of semivolatile constituents at low relative humidity (RH) but start to lose that resistance above 20% RH. Above 40% RH, the exchange of material remains constant up to 90% RH. We also show that dry particles containing SOA from α-pinene ozonolysis do not appear to resist exchange of semivolatile compounds. Our interpretation is that in-particle diffusion is not rate-limiting to mass transfer in these systems above 40% RH. To the extent that these systems are representative of ambient SOA, we conclude that diffusion limitations are likely not common under typical ambient boundary layer conditions. PMID:27791066

Mixing of secondary organic aerosols versus relative humidity.

PubMed

Ye, Qing; Robinson, Ellis Shipley; Ding, Xiang; Ye, Penglin; Sullivan, Ryan C; Donahue, Neil M

2016-10-24

Atmospheric aerosols exert a substantial influence on climate, ecosystems, visibility, and human health. Although secondary organic aerosols (SOA) dominate fine-particle mass, they comprise myriad compounds with uncertain sources, chemistry, and interactions. SOA formation involves absorption of vapors into particles, either because gas-phase chemistry produces low-volatility or semivolatile products that partition into particles or because more-volatile organics enter particles and react to form lower-volatility products. Thus, SOA formation involves both production of low-volatility compounds and their diffusion into particles. Most chemical transport models assume a single well-mixed phase of condensing organics and an instantaneous equilibrium between bulk gas and particle phases; however, direct observations constraining diffusion of semivolatile organics into particles containing SOA are scarce. Here we perform unique mixing experiments between SOA populations including semivolatile constituents using quantitative, single-particle mass spectrometry to probe any mass-transfer limitations in particles containing SOA. We show that, for several hours, particles containing SOA from toluene oxidation resist exchange of semivolatile constituents at low relative humidity (RH) but start to lose that resistance above 20% RH. Above 40% RH, the exchange of material remains constant up to 90% RH. We also show that dry particles containing SOA from α-pinene ozonolysis do not appear to resist exchange of semivolatile compounds. Our interpretation is that in-particle diffusion is not rate-limiting to mass transfer in these systems above 40% RH. To the extent that these systems are representative of ambient SOA, we conclude that diffusion limitations are likely not common under typical ambient boundary layer conditions.

A novel traveling wave piezoelectric actuated tracked mobile robot utilizing friction effect

NASA Astrophysics Data System (ADS)

Wang, Liang; Shu, Chengyou; Jin, Jiamei; Zhang, Jianhui

2017-03-01

A novel traveling wave piezoelectric-actuated tracked mobile robot with potential application to robotic rovers was proposed and investigated in this study. The proposed tracked mobile robot is composed of a parallelogram-frame-structure piezoelectric transducer with four rings and a metal track. Utilizing the converse piezoelectric and friction effects, traveling waves were propagated in the rings and then the metal track was actuated by the piezoelectric transducer. Compared with traditional tracked mechanisms, the proposed tracked mobile robot has a simpler and more compact structure without lubricant, which eliminates the problem of lubricant volatilization and deflation, thus, it could be operated in the vacuum environment. Dynamic characteristics were simulated and measured to reveal the mechanism of actuating track of the piezoelectric transducer. Experimental investigations of the traveling wave piezoelectric-actuated tracked mobile robot were then carried out, and the results indicated that the robot prototype with a pair of exciting voltages of 460 Vpp is able to achieve a maximum velocity of 57 mm s-1 moving on the foam plate and possesses the obstacle crossing capability with a maximum height of 27 mm. The proposed tracked mobile robot exhibits potential to be the driving system of robotic rovers.

Using a portable ion mobility spectrometer to screen dietary supplements for sibutramine.

PubMed

Dunn, Jamie D; Gryniewicz-Ruzicka, Connie M; Kauffman, John F; Westenberger, Benjamin J; Buhse, Lucinda F

2011-02-20

In response to recent incidents of undeclared sibutramine, an appetite suppressant found in dietary supplements, we developed a method to detect sibutramine using hand-held ion mobility spectrometers with an analysis time of 15 s. Ion mobility spectrometry is a high-throughput and sensitive technique that has been used for illicit drug, explosive, volatile organic compound and chemical warfare detection. We evaluated a hand-held ion mobility spectrometer as a tool for the analysis of supplement extracts containing sibutramine. The overall instrumental limit of detection of five portable ion mobility spectrometers was 2 ng of sibutramine HCl. When sample extractions containing 30 ng/μl or greater of sibutramine were analyzed, saturation of the ionization chamber of the spectrometer occurred and the instrument required more than three cleaning cycles to remove the drug. Hence, supplement samples suspected of containing sibutramine should be prepared at concentrations of 2-20 ng/μl. To obtain this target concentration range for products containing unknown amounts of sibutramine, we provided a simple sample preparation procedure, allowing the U.S. Food and Drug Administration or other agencies to screen products using the portable ion mobility spectrometer. Published by Elsevier B.V.

Mobile, stationary and mixed phase tracers: consequences to sea ice biogeochemistry

NASA Astrophysics Data System (ADS)

Jeffery, N.; Elliott, S.; Hunke, E. C.; Deal, C.; Jin, M.

2016-02-01

Models of brine motion in sea ice have offered mechanisms for transporting biogeochemical compounds vertically within the ice and between the ice-ocean interface. In these models, sea ice microstructure and/or gross physical properties determine the resupply of nitrate, for example, to sympagic algae and that resupply, in large part, constrains sea ice primary production. The assumption of brine transport models is that the transported matter exists in a purely mobile phase within the ice brine channels. As a result, non-reacting, mobile phase tracers evolve like salinity in dynamic sea ice. Field and laboratory observations indicate that this is a good approximation for the primary algal macronutrients - nitrate, silicate and phosphate, but clear deviations are evident for ammonium, micronutrients such as iron, humic substances, algal bi-products such as gels and extracellular polysaccharides, and the algae themselves. This wide range of biogeochemical matter resists brine motion and is present in both the mobile and stationary phases, i.e. these tracers are "mixed" with respect to their transport phases. Although the precise mechanism for this resistance may be due to attachment by frustules, "stickiness" of the material surface, adsorption, or, in the case of microorganisms, active motility, a key common element in all cases is the presence of the ice matrix. In this presentation we investigate the consequences of mixed phase tracers in sea ice on algal concentrations, vertical distributions, and the potential accumulation of biogeochemical matter within the ice. We assume that sea ice growth promotes retention to the stationary phase, while melt and the disintegration of the ice matrix promotes release into the mobile phase. By varying the retention and release timescales of this formulation, we retrieve the purely mobile and maximal accumulation limits.

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR USE OF THE ACTIVE VOC SAMPLER FOR THE COLLECTION OF AIRBORNE VOCS AT FIXED INDOOR AND OUTDOOR SITES (UA-F-11.1)

EPA Science Inventory

The purpose of this SOP is to describe the methods used to collect indoor and outdoor air samples for the determination of selected volatile organic compounds (VOC's) using a pump to draw air through a Carbotrap Sampler. Volatile organic compounds (VOCs) present in the air are p...

Volatile Transport by Volcanic Plumes on Earth, Venus and Mars

NASA Technical Reports Server (NTRS)

Glaze, Lori S.; Self, Stephen; Baloga, Steve; Stofan, Ellen R.

2012-01-01

Explosive volcanic eruptions can produce sustained, buoyant columns of ash and gas in the atmosphere (Fig. 1). Large flood basalt eruptions may also include significant explosive phases that generate eruption columns. Such eruptions can transport volcanic volatiles to great heights in the atmosphere. Volcanic eruption columns can also redistribute chemical species within the atmosphere by entraining ambient atmosphere at low altitudes and releasing those species at much higher altitudes.

Solid-phase microextraction method development for headspace analysis of volatile flavor compounds.

PubMed

Roberts, D D; Pollien, P; Milo, C

2000-06-01

Solid-phase microextraction (SPME) fibers were evaluated for their ability to adsorb volatile flavor compounds under various conditions with coffee and aqueous flavored solutions. Experiments comparing different fibers showed that poly(dimethylsiloxane)/divinylbenzene had the highest overall sensitivity. Carboxen/poly(dimethylsiloxane) was the most sensitive to small molecules and acids. As the concentrations of compounds increased, the quantitative linear range was exceeded as shown by competition effects with 2-isobutyl-3-methoxypyrazine at concentrations above 1 ppm. A method based on a short-time sampling of the headspace (1 min) was shown to better represent the equilibrium headspace concentration. Analysis of coffee brew with a 1-min headspace adsorption time was verified to be within the linear range for most compounds and thus appropriate for relative headspace quantification. Absolute quantification of volatiles, using isotope dilution assays (IDA), is not subject to biases caused by excess compound concentrations or complex matrices. The degradation of coffee aroma volatiles during storage was followed by relative headspace measurements and absolute quantifications. Both methods gave similar values for 3-methylbutanal, 4-ethylguaiacol, and 2,3-pentanedione. Acetic acid, however, gave higher values during storage upon relative headspace measurements due to concurrent pH decreases that were not seen with IDA.

Crystallization of rhenium salts in a simulated low-activity waste borosilicate glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riley, Brian J.; McCloy, John S.; Goel, Ashutosh

2013-04-01

This study presents a new method for looking at the solubility of volatile species in simulated low-activity waste glass. The present study looking at rhenium salts is also applicable to real applications involving radioactive technetium salts. In this synthesis method, oxide glass powder is mixed with the volatiles species, vacuum-sealed in a fused quartz ampoule, and then heat-treated under vacuum in a furnace. This technique restricts the volatile species to the headspace above the melt but still within the sealed ampoule, thus maximizing the volatile concentration in contact with the glass. Various techniques were used to measure the solubility ofmore » rhenium in glass and include energy dispersive spectroscopy, wavelength dispersive spectroscopy, laser ablation inductively-coupled plasma mass spectroscopy, and inductively-coupled plasma optical emission spectroscopy. The Re-solubility in this glass was determined to be ~3004 parts per million Re atoms. Above this concentration, the salts separated out of the melt as inclusions and as a low viscosity molten salt phase on top of the melt observed during and after cooling. This salt phase was analyzed with X-ray diffraction, scanning electron microscopy as well as some of the other aforementioned techniques and identified to be composed of alkali perrhenate and alkali sulfate.« less

Controlling the volatility of the written optical state in electrochromic DNA liquid crystals

NASA Astrophysics Data System (ADS)

Liu, Kai; Varghese, Justin; Gerasimov, Jennifer Y.; Polyakov, Alexey O.; Shuai, Min; Su, Juanjuan; Chen, Dong; Zajaczkowski, Wojciech; Marcozzi, Alessio; Pisula, Wojciech; Noheda, Beatriz; Palstra, Thomas T. M.; Clark, Noel A.; Herrmann, Andreas

2016-05-01

Liquid crystals are widely used in displays for portable electronic information display. To broaden their scope for other applications like smart windows and tags, new material properties such as polarizer-free operation and tunable memory of a written state become important. Here, we describe an anhydrous nanoDNA-surfactant thermotropic liquid crystal system, which exhibits distinctive electrically controlled optical absorption, and temperature-dependent memory. In the liquid crystal isotropic phase, electric field-induced colouration and bleaching have a switching time of seconds. Upon transition to the smectic liquid crystal phase, optical memory of the written state is observed for many hours without applied voltage. The reorientation of the DNA-surfactant lamellar layers plays an important role in preventing colour decay. Thereby, the volatility of optoelectronic state can be controlled simply by changing the phase of the material. This research may pave the way for developing a new generation of DNA-based, phase-modulated, photoelectronic devices.

Combined SEM/AVS and attenuation of concentration models for the assessment of bioavailability and mobility of metals in sediments of Sepetiba Bay (SE Brazil).

PubMed

Ribeiro, Andreza Portella; Figueiredo, Ana Maria Graciano; dos Santos, José Osman; Dantas, Elizabeth; Cotrim, Marycel Elena Barboza; Figueira, Rubens Cesar Lopes; Silva Filho, Emmanoel V; Wasserman, Julio Cesar

2013-03-15

This study proposes a new methodology to study contamination, bioavailability and mobility of metals (Cd, Cu, Ni, Pb, and Zn) using chemical and geostatistics approaches in marine sediments of Sepetiba Bay (SE Brazil). The chemical model of SEM (simultaneously extracted metals)/AVS (acid volatile sulfides) ratio uses a technique of cold acid extraction of metals to evaluate their bioavailability, and the geostatistical model of attenuation of concentrations estimates the mobility of metals. By coupling the two it was observed that Sepetiba Port, the urban area of Sepetiba and the riverine discharges may constitute potential sources of metals to Sepetiba Bay. The metals are concentrated in the NE area of the bay, where they tend to have their lowest mobility, as shown by the attenuation model, and are not bioavailable, as they tend to associate with sulfide and organic matter originated in the mangrove forests of nearby Guaratiba area. Copyright © 2013 Elsevier Ltd. All rights reserved.

A complementary mobile phase approach based on the peak count concept oriented to the full resolution of complex mixtures.

PubMed

Ortín, A; Torres-Lapasió, J R; García-Álvarez-Coque, M C

2011-08-26

Situations of minimal resolution are often found in liquid chromatography, when samples that contain a large number of compounds, or highly similar in terms of structure and/or polarity, are analysed. This makes full resolution with a single separation condition (e.g., mobile phase, gradient or column) unfeasible. In this work, the optimisation of the resolution of such samples in reversed-phase liquid chromatography is approached using two or more isocratic mobile phases with a complementary resolution behaviour (complementary mobile phases, CMPs). Each mobile phase is dedicated to the separation of a group of compounds. The CMPs are selected in such a way that, when the separation is considered globally, all the compounds in the sample are satisfactorily resolved. The search of optimal CMPs can be carried out through a comprehensive examination of the mobile phases in a selected domain. The computation time of this search has been reported to be substantially reduced by application of a genetic algorithm with local search (LOGA). A much simpler approach is here described, which is accessible to non-experts in programming, and offers solutions of the same quality as LOGA, with a similar computation time. The approach makes a sequential search of CMPs based on the peak count concept, which is the number of peaks exceeding a pre-established resolution threshold. The new approach is described using as test sample a mixture of 30 probe compounds, 23 of them with an ionisable character, and the pH and organic solvent contents as experimental factors. Copyright © 2011 Elsevier B.V. All rights reserved.

Phase II Historic Resources Survey Archaeological Testing of Site 9FU416 Fulton County, Georgia

DTIC Science & Technology

2003-06-01

Archaeological Park, Moundville, Alabama ) for final curation. 6 Phase 11 Testing 9FUJ 416 Chapter 3. Environmental and Cultural Overview Human...Corps of Engineers, Mobile District PO Box 2288 Mobile, Alabama 36628-0001 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING...MONITORING AGENCY REPORT NUMBER US Army Corps of Engineers, Mobile District PO Box 2288 Mobile, Alabama 36628-0001 1I. SUPPLEMENTARY NOTES DISTIR 11IT!O N

Ammonium fluoride as a mobile phase additive in aqueous normal phase chromatography.

PubMed

Pesek, Joseph J; Matyska, Maria T

2015-07-03

The use of ammonium fluoride as a mobile phase additive in aqueous normal phase chromatography with silica hydride-based stationary phases and mass spectrometry detection is evaluated. Retention times, peak shape, efficiency and peak intensity are compared to the more standard additives formic acid and ammonium formate. The test solutes were NAD, 3-hydroxyglutaric acid, α-ketoglutaric acid, p-aminohippuric acid, AMP, ATP, aconitic acid, threonine, N-acetyl carnitine, and 3-methyladipic acid. The column parameters are assessed in both the positive and negative ion detection modes. Ammonium fluoride is potentially an aggressive mobile phase additive that could have detrimental effects on column lifetime. Column reproducibility is measured and the effects of switching between different additives are also tested. Copyright © 2015 Elsevier B.V. All rights reserved.

[Changes in pelvic organ mobility and ligamentous laxity during pregnancy and postpartum. Review of literature and prospects].

PubMed

Gachon, B; Desseauve, D; Fradet, L; Decatoire, A; Lacouture, P; Pierre, F; Fritel, X

2016-06-01

The role of pregnancy in pelvic floor disorders occurrence remains poorly known. It might exist a link between changes in ligamentous laxity and changes in pelvic organ mobility during this period. Our objective was to conduct a non-systematic review of literature about changes in pelvic organ mobility as well as in ligamentous laxity during pregnancy and postpartum. From the PubMed, Medline, Cochrane Library and Web of Science database we have selected works which pertains clinical assessment of pelvic organ mobility (pelvic organ prolapse quantification), ultrasound assessment of levator hiatus and urethral mobility, ligamentous laxity assessment during pregnancy and postpartum. Clinical assessments performed in these works show an increase of pelvic organ mobility and perineal distension during pregnancy followed by a recovery phase during postpartum. Pelvic floor imaging shows an increase of levator hiatus area and urethral mobility during pregnancy then a recovery phase in postpartum. Different authors also report an increase of ligamentous laxity (upper and lower limbs) during pregnancy followed by a decrease phase in postpartum. Pelvic organ mobility, ligamentous laxity, levator hiatus and urethral mobility change in a similarly way during pregnancy (increase of mobility or distension) and postpartum (recovery). 3. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Enantiomeric separation of 2-arylpropionic acid nonsteroidal anti-inflammatory drugs by HPLC with hydroxypropyl-beta-cyclodextrin as chiral mobile phase additive.

PubMed

Ye, Jincui; Yu, Wenying; Chen, Guosheng; Shen, Zhengrong; Zeng, Su

2010-08-01

The enantio-separations of eight 2-arylpropionic acid nonsteroidal anti-inflammatory drugs (2-APA NSAIDs) were established using reversed-phase high-performance liquid chromatography with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) as chiral mobile phase additive for studying the stereoselective skin permeation of suprofen, ketoprofen, naproxen, indoprofen, fenoprofen, furbiprofen, ibuprofen and carprofen. The effects of the mobile phase composition, concentration of HP-beta-CD and column temperature on retention and enantioselective separation were investigated. With 2-APA NSAIDs as acidic analytes, the retention times and resolutions of the enantiomers were strongly related to the pH of the mobile phase. In addition, both the concentration of HP-beta-CD and temperature had a great effect on retention time, but only a slight or almost no effect on resolutions of the analytes. Enantioseparations were achieved on a Shimpack CLC-ODS (150 x 4.6 mm i.d., 5 microm) column. The mobile phase was a mixture of methanol and phosphate buffer (pH 4.0-5.5, 20 mM) containing 25 mM HP-beta-CD. This method was flexible, simple and economically advantageous over the use of chiral stationary phase, and was successfully applied to the enantioselective determination of the racemic 2-APA NSAIDs in an enantioselective skin permeation study.

Pinot noir wine volatile and anthocyanin composition under different levels of vine fruit zone leaf removal.

PubMed

Feng, Hui; Skinkis, Patricia A; Qian, Michael C

2017-01-01

The impacts of fruit zone leaf removal on volatile and anthocyanin compositions of Pinot noir wine were investigated over two growing seasons. Wine volatiles were analyzed by multiple techniques, including headspace solid phase microextraction-GC-MS (HS-SPME-GC-MS), headspace-GC-FID (HS-GC-FID) and stir bar sorptive extraction-GC-MS (SBSE-GC-MS). Fruit zone leaf removal affected the concentration of many grape-derived volatile compounds such as terpene alcohols and C13-norisoprenoids in wine, although the degree of impact depended on the vintage year and severity of leaf removal. Fruit zone leaf removal resulted in greater concentrations of linalool, α-terpineol and β-damascenone but had no impact on other terpene alcohols or β-ionone. Fruit zone leaf removal had no consistent impact on C6 alcohols, volatile phenols, lactones, fermentation-derived alcohols, acids, or most esters. Fruit zone leaf removal increased anthocyanins in final wine. Copyright © 2016 Elsevier Ltd. All rights reserved.

Trichomes and chemical composition of the volatile oil of Trichogonia cinerea (Gardner) R. M. King & H. Rob. (Eupatorieae, Asteraceae).

PubMed

Fernandes, Yanne S; Trindade, Luma M P; Rezende, Maria Helena; Paula, José R; Gonçalves, Letícia A

2016-03-01

Trichogonia cinerea is endemic to Brazil and occurs in areas of cerrado and campo rupestre. In this study, we characterized the glandular and non-glandular trichomes on the aerial parts of this species, determined the principal events in the development of the former, and identified the main constituents of the volatile oil produced in its aerial organs. Fully expanded leaves, internodes, florets, involucral bracts, and stem apices were used for the characterization of trichomes. Leaves, internodes, florets, and involucral bracts were examined by light microscopy and scanning electron microscopy, whereas stem apices were examined only by light microscopy. Branches in the reproductive phase were used for the extraction and determination of the composition of the volatile oil. The species has three types of glandular trichomes, biseriate vesicular, biseriate pedunculate, and multicellular uniseriate, which secrete volatile oils and phenolic compounds. The major components identified in the volatile oil were 3,5-muuroladiene (39.56%) and butylated hydroxytoluene (13.07%).

SDE and SPME Analysis of Flavor Compounds in Jin Xuan Oolong Tea.

PubMed

Sheibani, Ershad; Duncan, Susan E; Kuhn, David D; Dietrich, Andrea M; O'Keefe, Sean F

2016-02-01

Simultaneous distillation-extraction (SDE) and solid phase micro extraction (SPME) are procedures used for the isolation of flavor compounds in foods. The purpose of this study was to optimize SDE conditions (solvent and time) and to compare SDE with SPME for the isolation of flavor compounds in Jin Xuan oolong tea using GC-MS and GC-O. The concentration of volatile compounds isolated with diethyl ether was higher (P < 0.05) than for dichloromethane and concentration was higher at 40 min (P < 0.05) than 20 or 60 min extractions. For SDE, 128 volatiles were identified using GC-MS and 45 aroma active compounds using GC-O. Trans-nerolidol was the most abundant compound in oolong tea. The number of volatiles identified using GC-MS was lower in SPME than SDE. For SPME, 59 volatiles and 41 aroma active compounds were identified. The composition of the volatiles isolated by the 2 methods differed considerably but provided complementary information. © 2016 Institute of Food Technologists®

Determination of volatile marker compounds in raw ham using headspace-trap gas chromatography.

PubMed

Bosse Née Danz, Ramona; Wirth, Melanie; Konstanz, Annette; Becker, Thomas; Weiss, Jochen; Gibis, Monika

2017-03-15

A simple, reliable and automated method was developed and optimized for qualification and quantification of aroma-relevant volatile marker compounds of North European raw ham using a headspace (HS)-Trap gas chromatography-mass spectrometry (GC-MS) and GC-flame ionization detector (FID) analysis. A total of 38 volatile compounds were detected with this HS-Trap GC-MS method amongst which the largest groups were ketones (12), alcohols (8), hydrocarbons (7), aldehydes (6) and esters (3). The HS-Trap GC-FID method was optimized for the parameters: thermostatting time and temperature, vial and desorption pressure, number of extraction cycles and salt addition. A validation for 13 volatile marker compounds with limits of detection in ng/g was carried out. The optimized method can serve as alternative to conventional headspace and solid phase micro extraction methods and allows users to determine volatile compounds in raw hams making it of interest to industrial and academic meat scientists. Copyright © 2016 Elsevier Ltd. All rights reserved.

Volatile organic compounds released by blowfly larvae and pupae: new perspectives in forensic entomology.

PubMed

Frederickx, C; Dekeirsschieter, J; Brostaux, Y; Wathelet, J-P; Verheggen, F J; Haubruge, E

2012-06-10

To evaluate postmortem intervals (PMIs), one should take into account the determined age of necrophagous flies present on the cadaver. However, PMI determination needs further improvement, and rapid and accurate approaches have therefore to be developed. While previous studies have focussed on insect cuticular hydrocarbons, here we explore the volatile profile released by larvae and pupae of Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae). We monitored changes in volatile compounds daily, by headspace solid-phase microextraction, followed by gas chromatography-mass spectrometry. Branched and unbranched hydrocarbons, alcohols, esters and acids were identified, and the volatile profile was shown to vary, in both composition and quantity, with the age of the larva/pupa under investigation. We concluded, based on the analysis of the released volatile organic compounds, that it is possible to increase the accuracy of the estimated PMI, through improved estimation of the age of blowflies present on the cadaver. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Predominant yeasts in Chinese traditional sourdough and their influence on aroma formation in Chinese steamed bread.

PubMed

Liu, Tongjie; Li, Yang; Sadiq, Faizan A; Yang, Huanyi; Gu, Jingsi; Yuan, Lei; Lee, Yuan Kun; He, Guoqing

2018-03-01

A total of 105 yeast isolates was obtained from 15 sourdough samples collected from different regions in China and subjected to random amplified polymorphic DNA (RAPD) analysis. Six species were identified including Pichia membranifaciens, which has not previously been reported in Chinese sourdoughs. Different species of yeast were used in single-culture fermentation to make Chinese steamed bread (CSB). The volatiles of the CSB were captured by solid-phase microextraction method, separated and identified by gas chromatography-mass spectrometry. In total, 41 volatile compounds were found in all the steamed breads. All CSBs showed a similar volatile profile; however, significant differences in the quantity of some volatile compounds were seen among the CSB fermented by different yeast species. A partial least squares discriminant analysis showed that the CSBs could be separated by their characteristic volatile profiles. The study suggested that the aromatic properties of CSB are determined by the yeast used. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of two headspace sampling techniques for the analysis of off-flavour volatiles from oat based products.

PubMed

Cognat, Claudine; Shepherd, Tom; Verrall, Susan R; Stewart, Derek

2012-10-01

Two different headspace sampling techniques were compared for analysis of aroma volatiles from freshly produced and aged plain oatcakes. Solid phase microextraction (SPME) using a Carboxen-Polydimethylsiloxane (PDMS) fibre and entrainment on Tenax TA within an adsorbent tube were used for collection of volatiles. The effects of variation in the sampling method were also considered using SPME. The data obtained using both techniques were processed by multivariate statistical analysis (PCA). Both techniques showed similar capacities to discriminate between the samples at different ages. Discrimination between fresh and rancid samples could be made on the basis of changes in the relative abundances of 14-15 of the constituents in the volatile profiles. A significant effect on the detection level of volatile compounds was observed when samples were crushed and analysed by SPME-GC-MS, in comparison to undisturbed product. The applicability and cost effectiveness of both methods were considered. Copyright © 2012 Elsevier Ltd. All rights reserved.

Firm size distribution and mobility of the top 500 firms in China, the United States and the world

NASA Astrophysics Data System (ADS)

Guo, Jinzhong; Xu, Qi; Chen, Qinghua; Wang, Yougui

2013-07-01

This paper considers the macroscopic and microscopic statistical features of the top 500 firms in China, the United States and the world, denoted as China 500 (CH500), Fortune 500 (US500) and Fortune Global 500 (FG500). From a macroscopic perspective, the firm size distribution of each category, when measured by revenue, is steadily distributed over the observed period, even during periods of financial crises. As is evidenced by the Gini coefficient, divergences between firm scales are most significant for the CH500. From a microscopic perspective, the underlying micro-dynamics are volatile and often turbulent due to the exit and entry of firms as well as shifts in their revenues and ranks. Such fluctuations, or mobility, are visualized in rank/revenue/share clocks. We also propose a revenue/rank/share mobility index that is a quantitative measurement of mobility. Among these, we find that the share mobility acts as an effective indicator of economic status; where there is a share mobility spike, there is an ailing economy. The share mobility indexes indicate that the 2008 Financial Crisis had little impact on the Chinese economy, while it triggered violent changes in the top 500 firms in the United States and the world.

Modeling Ozone in the Eastern U.S. using a Fuel-Based Mobile Source Emissions Inventory.

PubMed

McDonald, Brian C; McKeen, Stuart A; Cui, Yu Yan; Ahmadov, Ravan; Kim, Si-Wan; Frost, Gregory J; Pollack, Ilana B; Peischl, Jeff; Ryerson, Thomas B; Holloway, John S; Graus, Martin; Warneke, Carsten; Gilman, Jessica B; de Gouw, Joost A; Kaiser, Jennifer; Keutsch, Frank N; Hanisco, Thomas F; Wolfe, Glenn M; Trainer, Michael

2018-06-22

Recent studies suggest overestimates in current U.S. emission inventories of nitrogen oxides (NO x = NO + NO 2 ). Here, we expand a previously developed fuel-based inventory of motor-vehicle emissions (FIVE) to the continental U.S. for the year 2013, and evaluate our estimates of mobile source emissions with the U.S. Environmental Protection Agency's National Emissions Inventory (NEI) interpolated to 2013. We find that mobile source emissions of NO x and carbon monoxide (CO) in the NEI are higher than FIVE by 28% and 90%, respectively. Using a chemical transport model, we model mobile source emissions from FIVE, and find consistent levels of urban NO x and CO as measured during the Southeast Nexus (SENEX) Study in 2013. Lastly, we assess the sensitivity of ozone (O 3 ) over the Eastern U.S. to uncertainties in mobile source NO x emissions and biogenic volatile organic compound (VOC) emissions. The ground-level O 3 is sensitive to reductions in mobile source NO x emissions, most notably in the Southeastern U.S. and during O 3 exceedance events, under the revised standard proposed in 2015 (>70 ppb, 8 h maximum). This suggests that decreasing mobile source NO x emissions could help in meeting more stringent O 3 standards in the future.

Mercury's Crater-Hosted Hollows: Chalcogenide Pryo-Thermokarst, and Permafrost Analogs on Earth, Mars, and Titan

NASA Astrophysics Data System (ADS)

Kargel, Jeffrey

2013-04-01

MESSENGER has acquired stunning images of pitted, light-toned and variegated light/dark terrains located primarily on the floors—probably impact-melt sheets—of many of Mercury's large craters. Termed "hollows", the pitted terrains are geomorphologically similar to some on Mars formed by sublimation of ice-rich permafrost and to lowland thermokarst on Earth formed by permafrost thaw; to "swiss cheese" terrain forming by sublimation of frozen CO2 at the Martian South Pole; and to suspected hydrocarbon thermokarst at Titan's poles. I shall briefly review some analogs on these other worlds. The most plausible explanation for Mercury's hollows is terrain degradation involving melting or sublimation of heterogeneous chalcogenide and sulfosalt mineral assemblages. I refer to these Mercurian features as pyrothermokarst; the etymological redundancy distinguishes the conditions and mineral agents from the ice-related features on Earth and Mars, though some of the physical processes may be similar. Whereas ice and sulfur have long been suspected and ice recently was discovered in permanently shadowed craters of Mercury's polar regions, the hollows occur down to the equator, where neither ice nor sulfur is plausible. The responsible volatiles must be only slightly volatile on the surface and/or in the upper crust of Mercury's low to middle latitudes at 400-800 K, but they must be capable of either melting or sublimating on geologically long time scales. Under prevailing upper crustal and surface temperatures, chalcophile-rich "permafrost" can undergo either desulfidation or melting reactions that could cause migration or volume changes of the permafrost, and hence lead to collapse and pitting. I propose the initial emplacement of crater-hosted chalcogenides, sulfosalts and related chalcophile materials such as pnictides, in impact-melt pools (involving solid-liquid and silicate-sulfide fractionation) and further differentiation by associated dry or humid fumaroles (solid-vapor and liquid-vapor fractionation and recondensation). Key phase transitions can occur in the temperature range of Mercury's surface and upper crust. Vapor-solid, vapor-liquid, and solid-liquid transitions of the heated materials resulted in migration and loss of volatiles and anatectic liquids, causing collapse pits to form. Seasonal heating near perihelion may work together with geothermal flux or early impact heating to drive off volatiles and produce the pits. In some cases, local recondensation of moderately volatile materials may have occurred on the rims of the pits; some volatiles may have been transported to the polar regions or lost by exospheric escape. Impacts by comets may have caused local oxidation and formation of oxygenated salts and other minerals, whose local recondensation from fumarole gases can explain the light-toned layers and light-toned rims of many pits. Plating of native volatile metals and semi-metals may also account for some light-toned deposits. Large contrasts in thermal conductivity as well as local topographic shading and latitude controls may result in large differences in element mobility and mineral assemblages. Pyrothermokarst on Mercury may be more chemically heterogeneous and complex in its development than any other thermokarst in the Solar System. Validation of this model would require a future mission with high-resolution multispectral imaging and neutral/ion detection.

Ionic liquid as a mobile phase additive in high-performance liquid chromatography for the simultaneous determination of eleven fluorescent whitening agents in paper materials.

PubMed

Wang, Qing; Chen, Xianbo; Qiu, Bin; Zhou, Liang; Zhang, Hui; Xie, Juan; Luo, Yan; Wang, Bin

2016-04-01

In the present study, 11 4,4'-diaminostilbene-2,2'-disulfonic acid based fluorescent whitening agents with different numbers of sulfonic acid groups were separated by using an ionic liquid as a mobile phase additive in high-performance liquid chromatography with fluorescence detection. The effects of ionic liquid concentration, pH of mobile phase B, and composition of mobile phase A on the separation of fluorescent whitening agents were systematically investigated. The ionic liquid tetrabutylammonium tetrafluoroborate is superior to tetrabutylammomnium bromide for the separation of the fluorescent whitening agents. The optimal separation conditions were an ionic liquid concentration at 8 mM and the pH of mobile phase B at 8.5 with methanol as mobile phase A. The established method exhibited low limits of detection (0.04-0.07 ng/mL) and wide linearity ranges (0.30-20 ng/mL) with high linear correlation coefficients from 0.9994 to 0.9998. The optimized procedure was applied to analyze target analytes in paper samples with satisfactory results. Eleven target analytes were quantified, and the recoveries of spiked paper samples were in the range of 85-105% with the relative standard deviations from 2.1 to 5.1%. The obtained results indicated that the method was efficient for detection of 11 fluorescent whitening agents. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of a mixed-model stationary phase derived from glutamine for HPLC separation of structurally different biologically active compounds: HILIC and reversed-phase applications.

PubMed

Aral, Tarık; Aral, Hayriye; Ziyadanoğulları, Berrin; Ziyadanoğulları, Recep

2015-01-01

A novel mixed-mode stationary phase was synthesised starting from N-Boc-glutamine, aniline and spherical silica gel (4 µm, 60 Å). The prepared stationary phase was characterized by IR and elemental analysis. The new stationary phase bears an embedded amide group into phenyl ring, highly polar a terminal amide group and non-polar groups (phenyl and alkyl groups). At first, this new mixed-mode stationary phase was used for HILIC separation of four nucleotides and five nucleosides. The effects of different separation conditions, such as pH value, mobile phase and temperature, on the separation process were investigated. The optimum separation for nucleotides was achieved using HILIC isocratic elution with aqueous mobile phase and acetonitrile with 20°C column temperature. Under these conditions, the four nucleotides could be separated and detected at 265 nm within 14 min. Five nucleosides were separated under HILIC isocratic elution with aqueous mobile phase containing pH=3.25 phosphate buffer (10mM) and acetonitrile with 20°C column temperature and detected at 265 nm within 14 min. Chromatographic parameters as retention factor, selectivity, theoretical plate number and peak asymmetry factor were calculated for the effect of temperature and water content in mobile phase on the separation process. The new column was also tested for nucleotides and nucleosides mixture and six analytes were separated in 10min. The chromatographic behaviours of these polar analytes on the new mixed-model stationary phase were compared with those of HILIC columns under similar conditions. Further, phytohormones and phenolic compounds were separated in order to see influence of the new stationary phase in reverse phase conditions. Eleven plant phytohormones were separated within 13 min using RP-HPLC gradient elution with aqueous mobile phase containing pH=2.5 phosphate buffer (10mM) and acetonitrile with 20°C column temperature and detected at 230 or 278 nm. The best separation conditions for seven phenolic compounds was also achieved using reversed-phase HPLC gradient elution with aqueous mobile phase containing pH=2.5 phosphate buffer (10mM) and acetonitrile with 20°C column temperature and seven phenolic compounds could be separated and detected at 230 nm within 16 min. Copyright © 2014 Elsevier B.V. All rights reserved.

Electronic transport in smectic liquid crystals

NASA Astrophysics Data System (ADS)

Shiyanovskaya, I.; Singer, K. D.; Twieg, R. J.; Sukhomlinova, L.; Gettwert, V.

2002-04-01

Time-of-flight measurements of transient photoconductivity have revealed bipolar electronic transport in phenylnaphthalene and biphenyl liquid crystals (LC), which exhibit several smectic mesophases. In the phenylnaphthalene LC, the hole mobility is significantly higher than the electron mobility and exhibits different temperature and phase behavior. Electron mobility in the range ~10-5 cm2/V s is temperature activated and remains continuous at the phase transitions. However, hole mobility is nearly temperature independent within the smectic phases, but is very sensitive to smectic order, 10-3 cm2/V s in the smectic-B (Sm-B) and 10-4 cm2/V s in the smectic-A (Sm-A) mesophases. The different behavior for holes and electron transport is due to differing transport mechanisms. The electron mobility is apparently controlled by rate-limiting multiple shallow trapping by impurities, but hole mobility is not. To explain the lack of temperature dependence for hole mobility within the smectic phases we consider two possible polaron transport mechanisms. The first mechanism is based on the hopping of Holstein small polarons in the nonadiabatic limit. The polaron binding energy and transfer integral values, obtained from the model fit, turned out to be sensitive to the molecular order in smectic mesophases. A second possible scenario for temperature-independent hole mobility involves the competion between two different polaron mechanisms involving so-called nearly small molecular polarons and small lattice polarons. Although the extracted transfer integrals and binding energies are reasonable and consistent with the model assumptions, the limited temperature range of the various phases makes it difficult to distinguish between any of the models. In the biphenyl LCs both electron and hole mobilities exhibit temperature activated behavior in the range of 10-5 cm2/V s without sensitivity to the molecular order. The dominating transport mechanism is considered as multiple trapping in the impurity sites. Temperature-activated mobility was treated within the disorder formalism, and activation energy and width of density of states have been calculated.

Enhanced hydrophobicity and volatility of submicron aerosols under severe emission control conditions in Beijing

NASA Astrophysics Data System (ADS)

Wang, Yuying; Zhang, Fang; Li, Zhanqing

2017-04-01

A series of strict emission control measures were implemented in Beijing and the surrounding seven provinces to ensure good air quality during the 2015 China Victory Day parade, rendering a unique opportunity to investigate anthropogenic impact of aerosol properties. Submicron aerosol hygroscopicity and volatility were measured during and after the control period using a hygroscopic and volatile tandem differential mobility analyzer (H/V-TDMA) system. Three periods, namely, the control clean period (Clean1), the non-control clean period (Clean2), and the non-control pollution period (Pollution), were selected to study the effect of the emission control measures on aerosol hygroscopicity and volatility. Aerosol particles became more hydrophobic and volatile due to the emission control measures. The hygroscopicity parameter (κ) of 40-200 nm particles decreased by 32.0%-8.5% during the Clean1 period relative to the Clean2 period, while the volatile shrink factor (SF) of 40-300 nm particles decreased by 7.5%-10.5%. The emission controls also changed the diurnal variation patterns of both the probability density function of κ (κ-PDF) and the probability density function of SF (SF-PDF). During Clean1 the κ-PDF showed one nearly-hydrophobic (NH) mode for particles in the nucleation mode, which was likely due to the dramatic reduction in industrial emissions of inorganic trace gases. Compared to the Pollution period, particles observed during the Clean1 and Clean2 periods exhibited a more significant non-volatile (NV) mode throughout the day, suggesting a more externally-mixed state particularly for the 150 nm particles. Aerosol hygroscopicities increased as particle sizes increased, with the greatest increases seen during the Pollution period. Accordingly, the aerosol volatility became weaker (i.e., SF increased) during the Clean1 and Clean2 periods, but no apparent trend was observed during the Pollution period. Based on a correlation analysis of the number fractions of NH and NV particles, we found that a higher number fraction of hydrophobic and volatile particles during the emission control period.

Major Volatiles from MSL SAM Evolved Gas Analyses: Yellowknife Bay Through Lower Mount Sharp

NASA Technical Reports Server (NTRS)

McAdam, A. C.; Archer, P. D., Jr.; Sutter, B.; Franz, H. B.; Eigenbrode, J. L.; Ming, D. W.; Morris, R. V.; Niles, P. B.; Stern, J. C.; Freissinet, C.;

Rapid Screening of Volatile Organic Compounds from Aframomum danielli Seeds Using Headspace Solid Phase Microextraction Coupled to Gas Chromatography Mass Spectrometry

PubMed Central

Njobeh, Patrick B.; Gbashi, Sefater; Adegoke, Gabriel O.; Dubery, Ian A.

2018-01-01

Volatile organic compounds (VOCs) derived from plants have been used in the fragrance industry since time immemorial. Herein we report on the rapid screening of VOCs from seeds of ripe Aframomum danielli (family, Zingiberaceae) using a polydimethylsiloxane fibre headspace solid phase microextraction coupled to a gas chromatography mass spectrometry (SPME-GC/MS) instrument. Portions of 0.25, 0.35, and 0.50 g of ground sample were weighed and extraction of volatile organic compounds (VOCs) was achieved using a 100 μm polydimethylsiloxane solid phase microextraction (PDMS SPME) fibre, with the equilibrium time of 40 minutes and extraction temperature of 50°C; the following compounds with their respective relative abundances were obtained as the top ten most abundant and annotated ones using NIST, Wiley, and Fragrances Libraries: eucalyptol (58%); β-pinene (22%); α-pinene (7.5%); α-terpineol (4%), α-terpinyl acetate (2%); α-bergamotene (1%); pinocarveol (0.39%); α-copaene (0.35%); caryophyllene (0.34); and β-bisabolene (0.31%). These compounds have been reported elsewhere in the literature and listed in the Fragrances Library, incorporated into the Saturn QP2020 GCMS Solution® software used for their analysis. PMID:29849643

Lunar sample analysis. [X-ray photoemission and Auger spectroscopy of lunar glass

NASA Technical Reports Server (NTRS)

Housley, R. M.; Grant, R. W.; Cirlin, E. H.

1979-01-01

The surface composition of two samples from the highly shocked, glass-coated lunar basalt (12054) and from four glass-coated fragments from the 1-2 mm (14161) fines were examined by X-ray photoemission spectroscopy to determine whether the agglutination process itself is responsible for the difference between their surface and bulk compositions. Auger electron spectroscopy of glass balls from the 15425 and 74001 fines were analyzed to understand the nature, extent, and behavior of volatile phases associated with lunar volcanism. Initial results indicate that (1) volatiles, in the outer few atomic layers sampled, vary considerably from ball to ball; (2) variability over the surface of individual balls is smaller; (3) the dominant volatiles on the balls are S and Zn; and (4) other volatiles commonly observed are P, Cl, and K.

Test and Recommendation of Flight-forward Resistive Temperature Detector for Resource Prospector Mission

NASA Technical Reports Server (NTRS)

Hinricher, Jesse

2014-01-01

The Resource Prospector Mission (RPM) is an in-situ resource utilization (ISRU) technology demonstration mission planned to launch in 2018. The mission will use the Regolith and Environment Science & Oxygen and Lunar Volatile Extraction (RESOLVE) Payload to prospect for lunar volatiles such as water, oxygen, and carbon dioxide. These compounds will validate ISRU capability. The payload, particularly the Lunar Advanced Volatile Analysis (LAVA) subsystem, requires numerous temperature measurements to accurately control on-board heaters that keep the volatiles in the vapor phase to allow quantification and prevent the clogging of delivery lines. Previous spaceflight missions have proven that Resistive Temperature Detector (RTD) failure impedes mission success. The research resulted in a recommendation for a flight-forward RTD. The recommendation was based on accuracy, consistency, and ease of installation of RTDs procured from IST, QTI, and Honeywell.

Test and Recommendation of Flight-Forward Resistive Temperature Detector for Resource Prospector Mission

NASA Technical Reports Server (NTRS)

Hinricher, Jesse John

2012-01-01

The Resource Prospector Mission (RPM) is an in-situ resource utilization (ISRU) technology demonstration mission planned to launch in 2018. The mission will use the Regolith and Environment Science & Oxygen and Lunar Volatile Extraction (RESOLVE) Payload to prospect for lunar volatiles such as water, oxygen, and carbon dioxide. These compounds will validate ISRU capability. The payload, particularly the Lunar Advanced Volatile Analysis (LAVA) subsystem, requires numerous temperature measurements to accurately control on-board heaters that keep the volatiles in the vapor phase to allow quantification and prevent the clogging of delivery lines. Previous spaceflight missions have proven that Resistive Temperature Detector (RTD) failure impedes mission success. The research resulted in a recommendation for a flight-forward RTD. The recommendation was based on accuracy, consistency, and ease of installation of RTDs procured from IST, QTI, and Honeywell.

GAS- AND SOLID-PHASE PARTITIONING OF PCDDS/FS ON MSWI FLY ASH AND THE EFFECTS OF SAMPLING

EPA Science Inventory

Semi-volatile organic compounds (SOCs), including polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/Fs), are partitioned as gas-phase and particle-bound products of many industrial combustion processes. This gas/particle partitioning of SOCs has severe implications on both ...

The gas phase origin of complex organic molecules precursors in prestellar cores

NASA Astrophysics Data System (ADS)

Bacmann, A.; Faure, A.

2015-05-01

Complex organic molecules (COMs) have long been observed in the warm regions surrounding nascent protostars. The recent discovery of oxygen-bearing COMs like methyl formate or dimethyl ether in prestellar cores (Bacmann et al. [2]), where gas and dust temperatures rarely exceed 10-15 K, has challenged the previously accepted models according to which COM formation relied on the diffusion of heavy radicals on warm (˜30 K) grains. Following these detections, new questions have arisen: do non-thermal processes play a role in increasing radical mobility or should new gas-phase routes be explored? The radicals involved in the formation of the aforementioned COMs, HCO and CH3O represent intermediate species in the grain-surface synthesis of methanol which proceeds via successive hydrogenations of CO molecules in the ice. We present here observations of methanol and its grain-surface precursors HCO, H2CO, CH3O in a sample of prestellar cores and derive their relative abundances. We find that the relative abundances HCO:H2CO:CH3O:CH3OH are constant across the core sample, close to 10:100:1:100. Our results also show that the amounts of HCO and CH3O are consistent with a gas-phase synthesis of these species from H2CO and CH3OH via radical-neutral or ion-molecule reactions followed by dissociative recombinations. Thus, while grain chemistry is necessary to explain the abundances of the parent volatile CH3OH, and possibly H2CO, the reactive species HCO and CH3O might be daughter molecules directly produced in the gas-phase.

Volatiles emitted by Carya illinoinensis (Wang.) K. Koch as a prelude for semiochemical investigations to focus on Acrobasis nuxvorella Nuenzig (Lepidoptera: Pyralidae).

PubMed

Corella-Madueño, Maria A; Harris, Marvin K; Fu-Castillo, Agustin A; Martínez-Téllez, Miguel A; Valenzuela-Soto, Elisa M; Gálvez-Ruiz, Juan C; Vargas-Arispuro, Irasema

2011-12-01

Plant volatiles have complex intra- and interspecific effects in the environment that include plant/herbivore interactions. Identifying the quantity and quality of volatiles produced by a plant is needed to aid the process of determining which chemicals are exerting what effects and then examining whether these effects can be manipulated to benefit society. The qualitative characterization of volatile compounds emitted by pecan, Carya illinoinensis (Wang.) K. Koch, was begun in order to establish a database for investigating how these volatiles affect Acrobasis nuxvorella Nuenzig, a monophagous pest of pecan. Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry was used for the analysis of the volatile constituents of pecan during three phenological stages (dormant buds, intact new shoot growth and intact nutlets) of the Western Schley and Wichita cultivars. About 111 distinct compounds were identified from the two cultivars, accounting for ∼99% of the headspace volatiles. The chromatographic profiles of both varieties revealed variations in the volatile composition and proportion between cultivars, with a predominance of terpene hydrocarbons, of the sesquiterpenes class, as well as monoterpenes. The significantly higher responsiveness recorded for the larvae of A. nuxvorella to C. illinoinensis shoots indicates that the larvae may be activated by terpenes emanating from the new shoot growth. This is the first study that has examined volatiles of pecan in Mexico. Copyright © 2011 Society of Chemical Industry.

A rapid space-resolved solid-phase microextraction method as a powerful tool to determine contaminants in wine based on their volatility.

PubMed

Liu, Min; Peng, Qing-Qing; Chen, Yu-Feng; Tang, Qian; Feng, Qing

2015-06-01

A novel space-resolved solid phase microextraction (SR-SPME) technique was developed to facilitate simultaneously analyte monitoring within heterogeneous samples. Graphene (G) and graphene oxide (GO) were coated separately to the segmented fibers which were successfully used for the solid-phase microextraction of two contaminants with dramatically different volatility: 2,4,6-trichloroanisole (TCA) and dibutyl phthalate (DBP). The space-resolved fiber showed good precision (5.4%, 6.8%), low detection limits (0.3ng/L, 0.3ng/L), and wide linearity (1.0-250.0ng/L, 1.0-250.0ng/L) under the optimized conditions for TCA and DBP, respectively. The method was applied to simultaneous analysis of the two contaminates with satisfactory recoveries, which were 96.96% and 98.20% for wine samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Nitrous oxide from aerated dairy manure slurries: Effects of aeration rates and oxic/anoxic phasing.

PubMed

Molodovskaya, Marina; Singurindy, Olga; Richards, Brian K; Steenhuis, Tammo S

2008-12-01

Small-scale laboratory research was conducted to compare the effects of different aeration rates and oxic/anoxic phasing on nitrous oxide (N(2)O) formation from dairy manure slurries. Manure slurry samples were incubated in triplicate for three-weeks under a range of continuous sweep gas flows (0.01-0.23L min(-1)kg(-1) slurry) with and without oxygen (air and dinitrogen gas). The net release of N(2)O-N was affected by both aeration rates and oxic/anoxic conditions, whereas ammonia volatilization depended mainly on gas flow rates. Maximum N(2)O-N losses after three-weeks incubation were 4.2% of total slurry N. Major N losses (up to 50% of total slurry N) were caused by ammonia volatilization that increased with increasing gas flow rates. The lowest nitrous oxide and ammonia production was observed from low flow phased oxic/anoxic treatment.

Experimental Measurements of the Effects of Photo-chemical Oxidation on Aerosol Emissions in Aircraft Exhaust

NASA Astrophysics Data System (ADS)

Miracolo, M. A.; Presto, A. A.; Hennigan, C. J.; Nguyen, N.; Ranjan, M.; Reeder, A.; Lipsky, E.; Donahue, N. M.; Robinson, A. L.

2009-12-01

Many military and commercial airfields are located in non-attainment areas for particulate matter (PM2.5), but the contribution of emissions from in-use aircraft to local and regional PM2.5 concentrations is uncertain. In collaboration with the Pennsylvania Air National Guard 171st Air Refueling Wing, the Carnegie Mellon University (CMU) Mobile Laboratory was deployed to measure fresh and aged emissions from a CFM56-2B1 gas-turbine engine mounted on a KC-135 Stratotanker airframe. The CFM-56 family of engine powers many different types of military and civilian aircraft, including the Boeing 737 and several Airbus models. It is one of the most widely deployed models of engines in the world. The goal of this work was to measure the gas-particle partitioning of the fresh emissions at atmospherically relevant conditions and to investigate the effect of atmospheric oxidation on aerosol loadings as the emissions age. Emissions were sampled from an inlet installed one meter downstream of the engine exit plane and transferred into a portable smog chamber via a heated inlet line. Separate experiments were conducted at different engine loads ranging from ground idle to take-off rated thrust. During each experiment, some diluted exhaust was added to the chamber and the volatility of the fresh emissions was then characterized using a thermodenuder. After this characterization, the chamber was exposed to either ambient sunlight or UV lights to initiate photochemical oxidation, which produced secondary aerosol and ozone. A suite of gas and particle-phase instrumentation was used to characterize the evolution of the gas and particle-phase emissions, including an aerosol mass spectrometer (AMS) to measure particle size and composition distributions. Fresh emissions of fine particles varied with engine load with peak emission factors at low and high loads. At high engine loads, the fresh emissions were dominated by black carbon; at low loads volatile organic carbon emissions were dominant. At low loads, photo-oxidation increased aerosol loadings in the chamber by a factor of fifty. We attribute this substantial secondary organic aerosol (SOA) production to oxidation of low-volatility organic vapors emitted under low loads. At higher loads, we see more modest secondary aerosol production from both organics and inorganics. Therefore secondary aerosol production can substantially exceed the direct aerosol emissions from aircraft. The results underscore the dramatic effects that photo-oxidation has on aerosol emissions from aircraft.

Power and spectrally efficient M-ARY QAM schemes for future mobile satellite communications

NASA Technical Reports Server (NTRS)

Sreenath, K.; Feher, K.

1990-01-01

An effective method to compensate nonlinear phase distortion caused by the mobile amplifier is proposed. As a first step towards the future use of spectrally efficient modulation schemes for mobile satellite applications, we have investigated effects of nonlinearities and the phase compensation method on 16-QAM. The new method provides about 2 dB savings in power for 16-QAM operation with cost effective amplifiers near saturation and thereby promising use of spectrally efficient linear modulation schemes for future mobile satellite applications.

The effect of dry and wet deposition of condensable vapors on secondary organic aerosols concentrations over the continental US

NASA Astrophysics Data System (ADS)

Knote, C.; Hodzic, A.; Jimenez, J. L.

2015-01-01

The effect of dry and wet deposition of semi-volatile organic compounds (SVOCs) in the gas phase on the concentrations of secondary organic aerosol (SOA) is reassessed using recently derived water solubility information. The water solubility of SVOCs was implemented as a function of their volatility distribution within the WRF-Chem regional chemistry transport model, and simulations were carried out over the continental United States for the year 2010. Results show that including dry and wet removal of gas-phase SVOCs reduces annual average surface concentrations of anthropogenic and biogenic SOA by 48 and 63% respectively over the continental US. Dry deposition of gas-phase SVOCs is found to be more effective than wet deposition in reducing SOA concentrations (-40 vs. -8% for anthropogenics, and -52 vs. -11% for biogenics). Reductions for biogenic SOA are found to be higher due to the higher water solubility of biogenic SVOCs. The majority of the total mass of SVOC + SOA is actually deposited via the gas phase (61% for anthropogenics and 76% for biogenics). Results are sensitive to assumptions made in the dry deposition scheme, but gas-phase deposition of SVOCs remains crucial even under conservative estimates. Considering reactivity of gas-phase SVOCs in the dry deposition scheme was found to be negligible. Further sensitivity studies where we reduce the volatility of organic matter show that consideration of gas-phase SVOC removal still reduces average SOA concentrations by 31% on average. We consider this a lower bound for the effect of gas-phase SVOC removal on SOA concentrations. A saturation effect is observed for Henry's law constants above 108 M atm-1, suggesting an upper bound of reductions in surface level SOA concentrations by 60% through removal of gas-phase SVOCs. Other models that do not consider dry and wet removal of gas-phase SVOCs would hence overestimate SOA concentrations by roughly 50%. Assumptions about the water solubility of SVOCs made in some current modeling systems (H* = H* (CH3COOH); H* = 105 M atm-1; H* = H* (HNO3)) still lead to an overestimation of 35%/25%/10% compared to our best estimate.

Formation and evolution of molecular products in α-pinene secondary organic aerosol.

PubMed

Zhang, Xuan; McVay, Renee C; Huang, Dan D; Dalleska, Nathan F; Aumont, Bernard; Flagan, Richard C; Seinfeld, John H

2015-11-17

Much of our understanding of atmospheric secondary organic aerosol (SOA) formation from volatile organic compounds derives from laboratory chamber measurements, including mass yield and elemental composition. These measurements alone are insufficient to identify the chemical mechanisms of SOA production. We present here a comprehensive dataset on the molecular identity, abundance, and kinetics of α-pinene SOA, a canonical system that has received much attention owing to its importance as an organic aerosol source in the pristine atmosphere. Identified organic species account for ∼58-72% of the α-pinene SOA mass, and are characterized as semivolatile/low-volatility monomers and extremely low volatility dimers, which exhibit comparable oxidation states yet different functionalities. Features of the α-pinene SOA formation process are revealed for the first time, to our knowledge, from the dynamics of individual particle-phase components. Although monomeric products dominate the overall aerosol mass, rapid production of dimers plays a key role in initiating particle growth. Continuous production of monomers is observed after the parent α-pinene is consumed, which cannot be explained solely by gas-phase photochemical production. Additionally, distinct responses of monomers and dimers to α-pinene oxidation by ozone vs. hydroxyl radicals, temperature, and relative humidity are observed. Gas-phase radical combination reactions together with condensed phase rearrangement of labile molecules potentially explain the newly characterized SOA features, thereby opening up further avenues for understanding formation and evolution mechanisms of α-pinene SOA.

Analysis of honeybush tea (Cyclopia spp.) volatiles by comprehensive two-dimensional gas chromatography using a single-stage thermal modulator.

PubMed

Ntlhokwe, Gaalebalwe; Tredoux, Andreas G J; Górecki, Tadeusz; Edwards, Matthew; Vestner, Jochen; Muller, Magdalena; Erasmus, Lené; Joubert, Elizabeth; Christel Cronje, J; de Villiers, André

2017-07-01

The applicability of comprehensive two-dimensional gas chromatography (GC×GC) using a single-stage thermal modulator was explored for the analysis of honeybush tea (Cyclopia spp.) volatile compounds. Headspace solid phase micro-extraction (HS-SPME) was used in combination with GC×GC separation on a non-polar × polar column set with flame ionisation (FID) detection for the analysis of fermented Cyclopia maculata, Cyclopia subternata and Cyclopia genistoides tea infusions of a single harvest season. Method optimisation entailed evaluation of the effects of several experimental parameters on the performance of the modulator, the choice of columns in both dimensions, as well as the HS-SPME extraction fibre. Eighty-four volatile compounds were identified by co-injection of reference standards. Principal component analysis (PCA) showed clear differentiation between the species based on their volatile profiles. Due to the highly reproducible separations obtained using the single-stage thermal modulator, multivariate data analysis was simplified. The results demonstrate both the complexity of honeybush volatile profiles and the potential of GC×GC separation in combination with suitable data analysis techniques for the investigation of the relationship between sensory properties and volatile composition of these products. The developed method therefore offers a fast and inexpensive methodology for the profiling of honeybush tea volatiles. Graphical abstract Surface plot obtained for the GC×GC-FID analysis of honeybush tea volatiles.