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J. Ruther - One of the best experts on this subject based on the ideXlab platform.
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emission of herbivore induced Volatiles in absence of a herbivore response of zea mays to Green Leaf Volatiles and terpenoids
Zeitschrift für Naturforschung C, 2005Co-Authors: J. Ruther, Benjamin FurstenauAbstract:Green Leaf Volatiles (GLV), a series of saturated and monounsaturated six-carbon aldehydes, alcohols, and esters are emitted by plants upon mechanical damage. Evidence is increasing that intact plants respond to GLV by activating their own defense mechanisms, thus suggesting that they function in plant-plant communication. The present paper demonstrates that exposure of maize plants to naturally occurring GLV, including (Z)-3-, (E)-2- and saturated derivatives, induce the emission of volatile blends typically associated with herbivory. Position or configuration of a double bond, but not the functional group of the GLV influenced the strength of the emissions. (Z)-3-Configured compounds elicited stronger responses than (E)-2- and saturated derivatives. The response to (Z)-3-hexen-1-ol increased linearly with the dose between 200 and 1000 nmol per plant. Not only the naturally occurring (E)-2-hexenal, but also (E)-2-pentenal and (E)-2-heptenal induced maize plants, although to a lesser extend. Externally applied terpenoids [(3E)-4,8-dimethyl-1,3,7-nonatriene, β-caryophyllene, and (E)-β-farnesene] did not significantly increase the total amount of inducible Volatiles in maize. Of three tested maize cultivars Delprim and Pactol responded much stronger than Attribut. Recovery experiments in the presence and absence of maize plants demonstrated that large proportions of externally applied GLV were assimilated by the plants, whereas (3E)-4,8-dimethyl-1,3,7-nonatriene was recovered in much higher amounts. The results furthermore suggested that plants converted a part of the assimilated Leaf aldehydes and alcohols to the respective acetates. We propose that GLV not only can alert neighboring plants, but may facilitate intra-plant information transfer and can help mediate the systemic defense response in a plant.
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the scent of food and defence Green Leaf Volatiles and toluquinone as sex attractant mediate mate finding in the european cockchafer melolontha melolontha
Ecology Letters, 2002Co-Authors: Andreas Reinecke, J. Ruther, Monika HilkerAbstract:Mate finding in the European cockchafer, Melolontha melolontha, has been investigated in the field. Our data suggest that mainly males show flight activity at dusk. In a landing cage bioassay, male cockchafers preferred cages baited with females over cages baited with males. Gas chromatographic analysis of beetle extracts with electronantennographic detection revealed the presence of electrophysiologically active compounds, among them toluquinone. In funnel trap bioassays none of these compounds was attractive towards males per se. A mixture of Green Leaf Volatiles (GLV) mimicking the bouquet of mechanically damaged leaves was highly attractive to M. melolontha males. The attractiveness of the same GLV mixture was synergistically enhanced when toluquinone was added to the lure. GLV attract males to damaged leaves. Toluquinone as a sex pheromone indicates the presence of conspecific females and synergistically enhances the attractiveness of GLV.
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Retention index database for identification of general Green Leaf Volatiles in plants by coupled capillary gas chromatography−mass spectrometry
Journal of Chromatography A, 2000Co-Authors: J. RutherAbstract:A series of ubiquitously occurring saturated and monounsaturated six-carbon aldehydes, alcohols and esters thereof is summarised as ‘Green Leaf Volatiles’ (GLVs). The present study gives a comprehensive data collection of retention indices of 35 GLVs on commonly used non-polar DB-5, mid-polar DB-1701, and polar DB-Wax stationary phases. Seventeen commercially not available compounds were synthesised. Thus, the present study allows reliable identification of most known GLV in natural plant volatile samples. Applications revealed the presence of several seldom reported GLVs in headspace samples of mechanically damaged plant leaves of Carpinus betulus and Fagus sylvatica.
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retention index database for identification of general Green Leaf Volatiles in plants by coupled capillary gas chromatography mass spectrometry
Journal of Chromatography A, 2000Co-Authors: J. RutherAbstract:A series of ubiquitously occurring saturated and monounsaturated six-carbon aldehydes, alcohols and esters thereof is summarised as ‘Green Leaf Volatiles’ (GLVs). The present study gives a comprehensive data collection of retention indices of 35 GLVs on commonly used non-polar DB-5, mid-polar DB-1701, and polar DB-Wax stationary phases. Seventeen commercially not available compounds were synthesised. Thus, the present study allows reliable identification of most known GLV in natural plant volatile samples. Applications revealed the presence of several seldom reported GLVs in headspace samples of mechanically damaged plant leaves of Carpinus betulus and Fagus sylvatica.
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Retention index database for identification of general Green Leaf Volatiles in plants by coupled capillary gas chromatography-mass spectrometry
Journal of Chromatography A, 2000Co-Authors: J. RutherAbstract:A series of ubiquitously occurring saturated and monounsaturated six- carbon aldehydes, alcohols and esters thereof is summarised as 'Green Leaf Volatiles' (GLVs). The present study gives a comprehensive data collection of retention indices of 35 GLVs on commonly used non-polar DB-5, mid-polar DB- 1701, and polar DB-Wax stationary phases. Seventeen commercially not available compounds were synthesised. Thus, the present study allows reliable identification of most known GLV in natural plant volatile samples. Applications revealed the presence of several seldom reported GLVs in headspace samples of mechanically damaged plant leaves of Carpinus betulus and Fagus sylvatica. (C) 2000 Elsevier Science B.V.
Joseph C Dickens - One of the best experts on this subject based on the ideXlab platform.
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Green Leaf Volatiles enhance sex attractant pheromone of the tobacco budworm heliothis virescens lep noctuidae
Chemoecology, 1993Co-Authors: Joseph C Dickens, J W Smith, Douglas M LightAbstract:Components of the Green Leaf volatile complex (Z-3-hexenyl acetate andE-2-hexenyl acetate) were shown to enhance responses of tobacco budworm,Heliothis virescens, males to the sex attractant pheromone of conspecific females in the field. The results are discussed with regard to Green Leaf Volatiles which enhance the attractant pheromone of a cohabiting species, and serve as attractants of a parasitoid of conspecific larvae.
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Host-plant Green-Leaf Volatiles synergize the synthetic sex pheromones of the corn earworm and codling moth (Lepidoptera)
CHEMOECOLOGY, 1993Co-Authors: Douglas M Light, Joseph C Dickens, Robert A. Flath, Ronald G. Buttery, Frank G. Zalom, Richard E. Rice, Eric B. JangAbstract:The capture of adult male moths in female sex pheromone traps of two key agricultural pests, the corn earworm ( Helicoverpa zea ) and the codling moth ( Cydia pomonella ), is enhanced or synergized by a certain group of host-plant Volatiles, the “Green-Leaf Volatiles” (GLVs). Since female adults of both species call and release their sex pheromones while perched upon the leaves of their host-plants, the volatile constituents from the leaves of a number of host-plants were compared. Sex pheromone traps containing one of the prominent Leaf Volatiles of certain H. zea hosts, (Z)-3-hexenyl acetate, not only significantly increased the capture of H. zea males but were preferred over traps baited only with sex pheromone. Similarly, traps baited with synthetic sex pheromome of C. pomonella plus a blend of GLVs captured significantly more males than traps baited only with sex pheromone. Since male moths are not captured in traps baited only with these GLVs, it appears that these GLVs act as pheromone synergists which increase or enhance the attraction or arrestment of male moths in pheromone traps.
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selectively fluorinated analogs reveal differential olfactory reception and inactivation of Green Leaf Volatiles in insects
Journal of Chemical Ecology, 1993Co-Authors: Joseph C Dickens, Glenn D Prestwich, Chi Shing Ng, J H VisserAbstract:The role of the alkyl terminus of Green Leaf volatile (GLV) molecules in olfactory reception and inactivation was examined in three diverse insect species: the beet armyworm,Spodoptera exigua (Lepidoptera); the Colorado potato beetle,Leptinotarsa decemlineata (Coleoptera); and the desert locust,Schistocerca gregaria (Orthoptera), using selectively fluorinated analogs of GLVs and electroantennograms (EAGs). When only the magnitude of the depolarization of the EAG is considered (a measure of reception), the order of effectiveness was 1-hexanol (6:OH)=(Z)-3-6:OH > 5,5,6,6,6-pentafluoro-(Z)-3-6:OH =5,5-difluoro-(Z)-3-6:OH ≫ 5,5,6,6,6-pentafluoro-6: OH. Percent recovery of the EAG (a measure of inactivation) was greater for the pentafluoro-(Z)-3-6: OH analog than for the difluoro-(Z)-3-6: OH analog. Our results show that the alkyl end of GLV molecules plays an important role not only in reception, but also inactivation processes in insect olfaction. Furthermore, specificities of these two processes may differ.
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Green Leaf Volatiles interrupt aggregation pheromone response in bark beetles infesting southern pines
Cellular and Molecular Life Sciences, 1992Co-Authors: Joseph C Dickens, R F Billings, T L PayneAbstract:Green Leaf Volatiles were shown to interrupt responses to aggregation pheromones of three species of bark beetles (Coleoptera: Scolytidae) which infest pines in the southern United States [the southern pine beetle,Dendroctonus frontalis Zimm.; the four-spined engraver,Ips avulsus (Eichhoff); and the five-spined engraver,Ips grandicollis (Eichhoff)]. The order of effectiveness of the compounds tested for each species was hexanal>hexanal+hexan-1-ol>hexan-1-ol. Neither hexanal, hexan-1-ol nor hexanal+hexan-1-ol was as effective in interrupting pheromone responses ofD. frontalis as verbenone, a known inhibitor of this species. Other than interspecific chemical signals, this is the first report of an interruptant forIps species, and the only report of a pheromone interruptant active for bothIps andDendroctonus species.
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enhancement of insect pheromone responses by Green Leaf Volatiles
Naturwissenschaften, 1990Co-Authors: Joseph C Dickens, Douglas M Light, Eric B. Jang, A R AlfordAbstract:verfahren wird fiir jede Beaufort-St/irkestufe und jedes Jahrzehnt durchgefiihrt, so dab man als Funktion der Zeit far jede Beaufort-St/irke einen Betrag des Luftdruckgradienten erh/ilt. Diesen kann man, etwa mit der heute am besten bestimmten Skala [5], auf Windgeschwindigkeit umrechnen. Damit ist die Umrechnung der Beaufort-St/irkeSch/itzungen friiherer Jahrzehnte auf Windgeschwindigkeiten m6glich. Es sei noch darauf hingewiesen, dab unsere Methode unabh/ingig yon der H~iufigkeitsverteilung des Windes in einem Seegebiet ist, da sie getrennt ftir jede Beaufort-Stufe durchgeftihrt wird. Die sich in einem Gebiet nach der Rekonstruktion ergebenden Wind~inderungen kOnnen daher als lokale Klima/inderungen angesehen werden. Als Beispiel wird hier die rekonstruierte Zeitreihe des Windes aus dem Feld vor der brasilianischen Kiiste wiedergegeben (Fig. 3). W/ihrend man von 1880 bis 1940 eine Zunahme um 0,5 m/s findet, ist nach 1950 praktisch kein von Null verschiedener Trend festzustellen. Diese Aussage gilt speziell fiir das Eingegangen am 17. Oktober 1989
Francisco R Hung - One of the best experts on this subject based on the ideXlab platform.
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Green Leaf Volatiles on atmospheric air water interfaces a combined experimental and molecular simulation study
Journal of Chemical & Engineering Data, 2014Co-Authors: Thilanga P Liyanaarachchi, Zenghui Zhang, Harsha Vempati, Amie K Hansel, Christopher Stevens, Andrew T Pham, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are a family of oxygenated hydrocarbons emitted in large quantities by plants, especially those under mechanical stress or damage. GLVs can significantly contribute to the formation of secondary organic aerosols (SOAs) by reacting with oxidants in atmospheric water droplets (fog, mist, and rain). Here we investigated the properties of four GLVs, 2-methyl-3-buten-2-ol (MBO), methyl salicylate (MeSA), cis-3-hexen-1-ol (HxO), and cis-3-hexenylacetate (HxAc) in air/water systems at 298 K using a combination of experiments and molecular simulations. Good agreement between simulation and experimental results of the 1-octanol/water partition coefficients and the free energy of hydration of the GLVs ensure the suitability of our molecular models for these systems; likewise, surface concentrations determined from experimental measurements of the surface tensions of these systems compared favorably against trends determined from molecular simulations. Our simulations indicate that all fo...
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Green Leaf Volatiles on Atmospheric Air/Water Interfaces: A Combined Experimental and Molecular Simulation Study
Journal of Chemical & Engineering Data, 2014Co-Authors: Thilanga P. Liyana-arachchi, Zenghui Zhang, Harsha Vempati, Amie K Hansel, Christopher Stevens, Andrew T Pham, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are a family of oxygenated hydrocarbons emitted in large quantities by plants, especially those under mechanical stress or damage. GLVs can significantly contribute to the formation of secondary organic aerosols (SOAs) by reacting with oxidants in atmospheric water droplets (fog, mist, and rain). Here we investigated the properties of four GLVs, 2-methyl-3-buten-2-ol (MBO), methyl salicylate (MeSA), cis-3-hexen-1-ol (HxO), and cis-3-hexenylacetate (HxAc) in air/water systems at 298 K using a combination of experiments and molecular simulations. Good agreement between simulation and experimental results of the 1-octanol/water partition coefficients and the free energy of hydration of the GLVs ensure the suitability of our molecular models for these systems; likewise, surface concentrations determined from experimental measurements of the surface tensions of these systems compared favorably against trends determined from molecular simulations. Our simulations indicate that all fo...
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molecular simulations of Green Leaf Volatiles and atmospheric oxidants on air water interfaces
Physical Chemistry Chemical Physics, 2013Co-Authors: Thilanga P Liyanaarachchi, Amie K Hansel, Christopher Stevens, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are oxygenated hydrocarbons that are emitted by plants, especially under stress conditions such as mechanical damage and local weather changes. GLVs can react with photochemically-generated oxidants (e.g., OH radicals) in atmospheric water drops, and contribute to the formation of secondary organic aerosols (SOAs). Here we investigated the adsorption of a gas phase GLV, 2-methyl-3-buten-2-ol (MBO) and OH radicals on atmospheric air/water interfaces using classical molecular dynamics (MD) simulations and potential of mean force (PMF) calculations. Our models can reproduce experimental values of the free energy of hydration of MBO and ˙OH, as well as 1-octanol/water partition coefficients of MBO determined experimentally in this study. Both MBO and ˙OH have a strong thermodynamic incentive to remain at the air/water interface, with their density profiles overlapping significantly at the interface. These results suggest that chemical reactions between MBO and ˙OH are more likely to take place at the interface, rather than inside the bulk of water droplets or in the vapor phase. We found a significant number of contacts between MBO and ˙OH in our simulations, which could lead to reactions between these two species.
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Molecular simulations of Green Leaf Volatiles and atmospheric oxidants on air/water interfaces
Physical Chemistry Chemical Physics, 2013Co-Authors: Thilanga P. Liyana-arachchi, Amie K Hansel, Christopher Stevens, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are oxygenated hydrocarbons that are emitted by plants, especially under stress conditions such as mechanical damage and local weather changes. GLVs can react with photochemically-generated oxidants (e.g., OH radicals) in atmospheric water drops, and contribute to the formation of secondary organic aerosols (SOAs). Here we investigated the adsorption of a gas phase GLV, 2-methyl-3-buten-2-ol (MBO) and OH radicals on atmospheric air/water interfaces using classical molecular dynamics (MD) simulations and potential of mean force (PMF) calculations. Our models can reproduce experimental values of the free energy of hydration of MBO and ˙OH, as well as 1-octanol/water partition coefficients of MBO determined experimentally in this study. Both MBO and ˙OH have a strong thermodynamic incentive to remain at the air/water interface, with their density profiles overlapping significantly at the interface. These results suggest that chemical reactions between MBO and ˙OH are more likely to take place at the interface, rather than inside the bulk of water droplets or in the vapor phase. We found a significant number of contacts between MBO and ˙OH in our simulations, which could lead to reactions between these two species.
Kalliat T Valsaraj - One of the best experts on this subject based on the ideXlab platform.
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aqueous phase oxidation of Green Leaf Volatiles by hydroxyl radical as a source of soa product identification from methyl jasmonate and methyl salicylate oxidation
Atmospheric Environment, 2015Co-Authors: Amie K Hansel, Franz S Ehrenhauser, Nicole K Richardshenderson, Cort Anastasio, Kalliat T ValsarajAbstract:Abstract 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.
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aqueous oxidation of Green Leaf Volatiles by hydroxyl radical as a source of soa kinetics and soa yields
Atmospheric Environment, 2014Co-Authors: Nicole K Richardshenderson, Amie K Hansel, Kalliat T Valsaraj, Cort AnastasioAbstract:Abstract Green Leaf Volatiles (GLVs) are a class of oxygenated hydrocarbons released from vegetation, especially during mechanical stress or damage. The potential for GLVs to form secondary organic aerosol (SOA) via aqueous-phase reactions is not known. Fog events over vegetation will lead to the uptake of GLVs into water droplets, followed by aqueous-phase reactions with photooxidants such as the hydroxyl radical (OH). In order to determine if the aqueous oxidation of GLVs by OH can be a significant source of secondary organic aerosol, we studied the partitioning and reaction of five GLVs: cis-3-hexen-1-ol, cis-3-hexenyl acetate, methyl salicylate, methyl jasmonate, and 2-methyl-3-butene-2-ol. For each GLV we measured the kinetics of aqueous oxidation by OH, and the corresponding SOA mass yield. The second-order rate constants for GLVs with OH were all near diffusion controlled, (5.4–8.6) × 109 M−1 s−1 at 298 K, and showed a small temperature dependence, with an average activation energy of 9.3 kJ mol−1 Aqueous-phase SOA mass yields ranged from 10 to 88%, although some of the smaller values were not statistically different from zero. Methyl jasmonate was the most effective aqueous-phase SOA precursor due to its larger Henry's law constant and high SOA mass yield (68 ± 8%). While we calculate that the aqueous-phase SOA formation from the five GLVs is a minor source of aqueous-phase SOA, the availability of other GLVs, other oxidants, and interfacial reactions suggest that GLVs overall might be a significant source of SOA via aqueous reactions.
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Green Leaf Volatiles on atmospheric air water interfaces a combined experimental and molecular simulation study
Journal of Chemical & Engineering Data, 2014Co-Authors: Thilanga P Liyanaarachchi, Zenghui Zhang, Harsha Vempati, Amie K Hansel, Christopher Stevens, Andrew T Pham, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are a family of oxygenated hydrocarbons emitted in large quantities by plants, especially those under mechanical stress or damage. GLVs can significantly contribute to the formation of secondary organic aerosols (SOAs) by reacting with oxidants in atmospheric water droplets (fog, mist, and rain). Here we investigated the properties of four GLVs, 2-methyl-3-buten-2-ol (MBO), methyl salicylate (MeSA), cis-3-hexen-1-ol (HxO), and cis-3-hexenylacetate (HxAc) in air/water systems at 298 K using a combination of experiments and molecular simulations. Good agreement between simulation and experimental results of the 1-octanol/water partition coefficients and the free energy of hydration of the GLVs ensure the suitability of our molecular models for these systems; likewise, surface concentrations determined from experimental measurements of the surface tensions of these systems compared favorably against trends determined from molecular simulations. Our simulations indicate that all fo...
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Green Leaf Volatiles on Atmospheric Air/Water Interfaces: A Combined Experimental and Molecular Simulation Study
Journal of Chemical & Engineering Data, 2014Co-Authors: Thilanga P. Liyana-arachchi, Zenghui Zhang, Harsha Vempati, Amie K Hansel, Christopher Stevens, Andrew T Pham, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are a family of oxygenated hydrocarbons emitted in large quantities by plants, especially those under mechanical stress or damage. GLVs can significantly contribute to the formation of secondary organic aerosols (SOAs) by reacting with oxidants in atmospheric water droplets (fog, mist, and rain). Here we investigated the properties of four GLVs, 2-methyl-3-buten-2-ol (MBO), methyl salicylate (MeSA), cis-3-hexen-1-ol (HxO), and cis-3-hexenylacetate (HxAc) in air/water systems at 298 K using a combination of experiments and molecular simulations. Good agreement between simulation and experimental results of the 1-octanol/water partition coefficients and the free energy of hydration of the GLVs ensure the suitability of our molecular models for these systems; likewise, surface concentrations determined from experimental measurements of the surface tensions of these systems compared favorably against trends determined from molecular simulations. Our simulations indicate that all fo...
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molecular simulations of Green Leaf Volatiles and atmospheric oxidants on air water interfaces
Physical Chemistry Chemical Physics, 2013Co-Authors: Thilanga P Liyanaarachchi, Amie K Hansel, Christopher Stevens, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are oxygenated hydrocarbons that are emitted by plants, especially under stress conditions such as mechanical damage and local weather changes. GLVs can react with photochemically-generated oxidants (e.g., OH radicals) in atmospheric water drops, and contribute to the formation of secondary organic aerosols (SOAs). Here we investigated the adsorption of a gas phase GLV, 2-methyl-3-buten-2-ol (MBO) and OH radicals on atmospheric air/water interfaces using classical molecular dynamics (MD) simulations and potential of mean force (PMF) calculations. Our models can reproduce experimental values of the free energy of hydration of MBO and ˙OH, as well as 1-octanol/water partition coefficients of MBO determined experimentally in this study. Both MBO and ˙OH have a strong thermodynamic incentive to remain at the air/water interface, with their density profiles overlapping significantly at the interface. These results suggest that chemical reactions between MBO and ˙OH are more likely to take place at the interface, rather than inside the bulk of water droplets or in the vapor phase. We found a significant number of contacts between MBO and ˙OH in our simulations, which could lead to reactions between these two species.
Amie K Hansel - One of the best experts on this subject based on the ideXlab platform.
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aqueous phase oxidation of Green Leaf Volatiles by hydroxyl radical as a source of soa product identification from methyl jasmonate and methyl salicylate oxidation
Atmospheric Environment, 2015Co-Authors: Amie K Hansel, Franz S Ehrenhauser, Nicole K Richardshenderson, Cort Anastasio, Kalliat T ValsarajAbstract:Abstract 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.
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aqueous oxidation of Green Leaf Volatiles by hydroxyl radical as a source of soa kinetics and soa yields
Atmospheric Environment, 2014Co-Authors: Nicole K Richardshenderson, Amie K Hansel, Kalliat T Valsaraj, Cort AnastasioAbstract:Abstract Green Leaf Volatiles (GLVs) are a class of oxygenated hydrocarbons released from vegetation, especially during mechanical stress or damage. The potential for GLVs to form secondary organic aerosol (SOA) via aqueous-phase reactions is not known. Fog events over vegetation will lead to the uptake of GLVs into water droplets, followed by aqueous-phase reactions with photooxidants such as the hydroxyl radical (OH). In order to determine if the aqueous oxidation of GLVs by OH can be a significant source of secondary organic aerosol, we studied the partitioning and reaction of five GLVs: cis-3-hexen-1-ol, cis-3-hexenyl acetate, methyl salicylate, methyl jasmonate, and 2-methyl-3-butene-2-ol. For each GLV we measured the kinetics of aqueous oxidation by OH, and the corresponding SOA mass yield. The second-order rate constants for GLVs with OH were all near diffusion controlled, (5.4–8.6) × 109 M−1 s−1 at 298 K, and showed a small temperature dependence, with an average activation energy of 9.3 kJ mol−1 Aqueous-phase SOA mass yields ranged from 10 to 88%, although some of the smaller values were not statistically different from zero. Methyl jasmonate was the most effective aqueous-phase SOA precursor due to its larger Henry's law constant and high SOA mass yield (68 ± 8%). While we calculate that the aqueous-phase SOA formation from the five GLVs is a minor source of aqueous-phase SOA, the availability of other GLVs, other oxidants, and interfacial reactions suggest that GLVs overall might be a significant source of SOA via aqueous reactions.
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Green Leaf Volatiles on atmospheric air water interfaces a combined experimental and molecular simulation study
Journal of Chemical & Engineering Data, 2014Co-Authors: Thilanga P Liyanaarachchi, Zenghui Zhang, Harsha Vempati, Amie K Hansel, Christopher Stevens, Andrew T Pham, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are a family of oxygenated hydrocarbons emitted in large quantities by plants, especially those under mechanical stress or damage. GLVs can significantly contribute to the formation of secondary organic aerosols (SOAs) by reacting with oxidants in atmospheric water droplets (fog, mist, and rain). Here we investigated the properties of four GLVs, 2-methyl-3-buten-2-ol (MBO), methyl salicylate (MeSA), cis-3-hexen-1-ol (HxO), and cis-3-hexenylacetate (HxAc) in air/water systems at 298 K using a combination of experiments and molecular simulations. Good agreement between simulation and experimental results of the 1-octanol/water partition coefficients and the free energy of hydration of the GLVs ensure the suitability of our molecular models for these systems; likewise, surface concentrations determined from experimental measurements of the surface tensions of these systems compared favorably against trends determined from molecular simulations. Our simulations indicate that all fo...
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Green Leaf Volatiles on Atmospheric Air/Water Interfaces: A Combined Experimental and Molecular Simulation Study
Journal of Chemical & Engineering Data, 2014Co-Authors: Thilanga P. Liyana-arachchi, Zenghui Zhang, Harsha Vempati, Amie K Hansel, Christopher Stevens, Andrew T Pham, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are a family of oxygenated hydrocarbons emitted in large quantities by plants, especially those under mechanical stress or damage. GLVs can significantly contribute to the formation of secondary organic aerosols (SOAs) by reacting with oxidants in atmospheric water droplets (fog, mist, and rain). Here we investigated the properties of four GLVs, 2-methyl-3-buten-2-ol (MBO), methyl salicylate (MeSA), cis-3-hexen-1-ol (HxO), and cis-3-hexenylacetate (HxAc) in air/water systems at 298 K using a combination of experiments and molecular simulations. Good agreement between simulation and experimental results of the 1-octanol/water partition coefficients and the free energy of hydration of the GLVs ensure the suitability of our molecular models for these systems; likewise, surface concentrations determined from experimental measurements of the surface tensions of these systems compared favorably against trends determined from molecular simulations. Our simulations indicate that all fo...
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molecular simulations of Green Leaf Volatiles and atmospheric oxidants on air water interfaces
Physical Chemistry Chemical Physics, 2013Co-Authors: Thilanga P Liyanaarachchi, Amie K Hansel, Christopher Stevens, Franz S Ehrenhauser, Kalliat T Valsaraj, Francisco R HungAbstract:Green Leaf Volatiles (GLVs) are oxygenated hydrocarbons that are emitted by plants, especially under stress conditions such as mechanical damage and local weather changes. GLVs can react with photochemically-generated oxidants (e.g., OH radicals) in atmospheric water drops, and contribute to the formation of secondary organic aerosols (SOAs). Here we investigated the adsorption of a gas phase GLV, 2-methyl-3-buten-2-ol (MBO) and OH radicals on atmospheric air/water interfaces using classical molecular dynamics (MD) simulations and potential of mean force (PMF) calculations. Our models can reproduce experimental values of the free energy of hydration of MBO and ˙OH, as well as 1-octanol/water partition coefficients of MBO determined experimentally in this study. Both MBO and ˙OH have a strong thermodynamic incentive to remain at the air/water interface, with their density profiles overlapping significantly at the interface. These results suggest that chemical reactions between MBO and ˙OH are more likely to take place at the interface, rather than inside the bulk of water droplets or in the vapor phase. We found a significant number of contacts between MBO and ˙OH in our simulations, which could lead to reactions between these two species.
