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Articles 61 - 90 of 140

Full-Text Articles in Biochemistry

Aerosol Single Scattering Albedo Dependence On Biomass Combustion Efficiency: Laboratory And Field Studies, Shang Liu, Allison C. Aiken, Caleb Arata, Manvendra K. Dubey, C. Stockwell, Robert Yokelson, Elizabeth A. Stone, Thilina Jayarathne, Allen L. Robinson, Paul J. Demott, Sonia M. Kreidenweis Jan 2014

Aerosol Single Scattering Albedo Dependence On Biomass Combustion Efficiency: Laboratory And Field Studies, Shang Liu, Allison C. Aiken, Caleb Arata, Manvendra K. Dubey, C. Stockwell, Robert Yokelson, Elizabeth A. Stone, Thilina Jayarathne, Allen L. Robinson, Paul J. Demott, Sonia M. Kreidenweis

Chemistry and Biochemistry Faculty Publications

Single scattering albedo (ω) of fresh biomass burning (BB) aerosols produced from 92 controlled laboratory combustion experiments of 20 different woods and grasses was analyzed to determine the factors that control the variability in ω. Results show that ω varies strongly with fire-integrated modified combustion efficiency (MCEFI)—higher MCEFI results in lower ω values and greater spectral dependence of ω. A parameterization of ω as a function of MCEFI for fresh BB aerosols is derived from the laboratory data and is evaluated by field observations from two wildfires. The parameterization suggests that MCEFI explains 60% of …

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Laboratory Characterization Of Pm Emissions From Combustion Of Wildland Biomass Fuels, S. Hosseini, S. P. Urbanski, P. Dixit, L. Qi, I. R. Burling, Robert J. Yokelson, T. J. Johnson, M. Shrivastava, H. S. Jung, D. R. Weise, J. W. Miller, D. R. Cocker Iii Sep 2013

Laboratory Characterization Of Pm Emissions From Combustion Of Wildland Biomass Fuels, S. Hosseini, S. P. Urbanski, P. Dixit, L. Qi, I. R. Burling, Robert J. Yokelson, T. J. Johnson, M. Shrivastava, H. S. Jung, D. R. Weise, J. W. Miller, D. R. Cocker Iii

Chemistry and Biochemistry Faculty Publications

[1] Particle emissions from open burning of southwestern (SW) and southeastern (SE) U.S. fuel types during 77 controlled laboratory burns are presented. The fuels include SW vegetation types: ceanothus, chamise/scrub oak, coastal sage scrub, California sagebrush, manzanita, maritime chaparral, masticated mesquite, oak savanna, and oak woodland, as well as SE vegetation types: 1 year, 2 year rough, pocosin, chipped understory, understory hardwood, and pine litter. The SW fuels burned at higher modified combustion efficiency (MCE) than the SE fuels resulting in lower particulate matter mass emission factor. Particle mass distributions for six fuels and particle number emission for all fuels …

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Pitfalls With The Use Of Enhancement Ratios Or Normalized Excess Mixing Ratios Measured In Plumes To Characterize Pollution Sources And Aging, Robert J. Yokelson, Meinrat O. Andreae, S. K. Akagi Aug 2013

Pitfalls With The Use Of Enhancement Ratios Or Normalized Excess Mixing Ratios Measured In Plumes To Characterize Pollution Sources And Aging, Robert J. Yokelson, Meinrat O. Andreae, S. K. Akagi

Chemistry and Biochemistry Faculty Publications

Normalized excess mixing ratios (NEMRs), also known as enhancement ratios, are a common way to characterize plumes of pollution in atmospheric research. As single-source pollutant plumes disperse in the atmosphere, they are diluted by mixing with the adjacent background air. Changes in the composition of this background air can cause large changes to the NEMR that is subsequently measured by remote-sensing, airborne, or ground-based instruments. This scenario is common when boundary layer plumes enter the free troposphere and could also impact long-range transport or plumes near the top of the troposphere. We provide a context for these issues and an …

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Role Of Resonance-Enhanced Multiphoton Excitation In High-Harmonic Generation Of N-2: A Time-Dependent Density-Functional-Theory Study, Xi Chu, Gerrit C. Groenenboom Jan 2013

Role Of Resonance-Enhanced Multiphoton Excitation In High-Harmonic Generation Of N-2: A Time-Dependent Density-Functional-Theory Study, Xi Chu, Gerrit C. Groenenboom

Chemistry and Biochemistry Faculty Publications

A minimum at similar to 39 eV is observed in the high-harmonic-generation spectra of N-2 for several laser intensities and frequencies. This minimum appears to be invariant for different molecular orientations. We reproduce this minimum for a set of laser parameters and orientations in time-dependent density-functional-theory calculations, which also render orientation-dependent maxima at 23-26 eV. Photon energies of these maxima overlap with ionization potentials of excited states observed in photoelectron spectra. Time profile analysis shows that these maxima are caused by resonance-enhanced multiphoton excitation. We propose a four-step mechanism, in which an additional excitation step is added to the well-accepted …

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Coupling Field And Laboratory Measurements To Estimate The Emission Factors Of Identified And Unidentified Trace Gases For Prescribed Fires, Robert J. Yokelson, I. R. Burling, J. Gilman, C. Warneke, C. Stockwell, J. De Gouw, S. K. Akagi, S. P. Urbanski, P. Veres, J. M. Roberts, W. C. Kuster, J. Reardon, David W. T. Griffith, T. J. Johnson, S. Hosseini, J. W. Miller, D. R. Cocker Iii, H. Jung, D. R. Weise Jan 2013

Coupling Field And Laboratory Measurements To Estimate The Emission Factors Of Identified And Unidentified Trace Gases For Prescribed Fires, Robert J. Yokelson, I. R. Burling, J. Gilman, C. Warneke, C. Stockwell, J. De Gouw, S. K. Akagi, S. P. Urbanski, P. Veres, J. M. Roberts, W. C. Kuster, J. Reardon, David W. T. Griffith, T. J. Johnson, S. Hosseini, J. W. Miller, D. R. Cocker Iii, H. Jung, D. R. Weise

Chemistry and Biochemistry Faculty Publications

An extensive program of experiments focused on biomass burning emissions began with a laboratory phase in which vegetative fuels commonly consumed in prescribed fires were collected in the southeastern and southwestern US and burned in a series of 71 fires at the US Forest Service Fire Sciences Laboratory in Missoula, Montana. The particulate matter (PM2.5) emissions were measured by gravimetric filter sampling with subsequent analysis for elemental carbon (EC), organic carbon (OC), and 38 elements. The trace gas emissions were measured by an open-path Fourier transform infrared (OP-FTIR) spectrometer, proton-transfer-reaction mass spectrometry (PTRMS), proton-transfer ion-trap mass spectrometry (PIT-MS), negative-ion proton-transfer …

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Measurements Of Reactive Trace Gases And Variable O-3 Formation Rates In Some South Carolina Biomass Burning Plumes, S. K. Akagi, Robert J. Yokelson, I. R. Burling, S. Meinardi, Isobel J. Simpson, Donald R. Blake, G. R. Mcmeeking, A. Sullivan, T. Lee, S. Kreidenweis, S. P. Urbanski, J. Reardon, David W. T. Griffith, T. J. Johnson, D. R. Weise Jan 2013

Measurements Of Reactive Trace Gases And Variable O-3 Formation Rates In Some South Carolina Biomass Burning Plumes, S. K. Akagi, Robert J. Yokelson, I. R. Burling, S. Meinardi, Isobel J. Simpson, Donald R. Blake, G. R. Mcmeeking, A. Sullivan, T. Lee, S. Kreidenweis, S. P. Urbanski, J. Reardon, David W. T. Griffith, T. J. Johnson, D. R. Weise

Chemistry and Biochemistry Faculty Publications

In October-November 2011 we measured trace gas emission factors from seven prescribed fires in South Carolina (SC), US, using two Fourier transform infrared spectrometer (FTIR) systems and whole air sampling (WAS) into canisters followed by gas-chromatographic analysis. A total of 97 trace gas species were quantified from both airborne and ground-based sampling platforms, making this one of the most detailed field studies of fire emissions to date. The measurements include the first emission factors for a suite of monoterpenes produced by heating vegetative fuels during field fires. The first quantitative FTIR observations of limonene in smoke are reported along with …

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Time-Dependent Density-Functional-Theory Calculation Of High-Order-Harmonic Generation Of H-2, Xi Chu, Gerrit C. Groenenboom May 2012

Time-Dependent Density-Functional-Theory Calculation Of High-Order-Harmonic Generation Of H-2, Xi Chu, Gerrit C. Groenenboom

Chemistry and Biochemistry Faculty Publications

The observation of the isotope effect in the high-order-harmonic generation (HHG) of H-2 presents a challenge for time-dependent density-functional-theory (TDDFT) methods, since this effect is related to the dynamics of the ion created in the tunneling ionization step of HHG and it depends on the harmonic order. As an initial step toward describing this effect within current computational capacity, we benchmark a method in which the nuclear and electronic degrees of freedom are separated and both treated quantum mechanically. For the electrons two TDDFT formalisms are adopted. Although the ion-dynamics effect is not described in our method, it reproduces the …

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The Nucleotide Exchange Factor Ric-8a Is A Chaperone For The Conformationally Dynamic Nucleotide-Free State Of G Alpha I1, Celestine J. Thomas, Klara Briknarova, Jonathan K. Hilmer, Navid Movahed, Brian Bothner, John P. Sumida, Gregory G. Tall, Stephen R. Sprang Aug 2011

The Nucleotide Exchange Factor Ric-8a Is A Chaperone For The Conformationally Dynamic Nucleotide-Free State Of G Alpha I1, Celestine J. Thomas, Klara Briknarova, Jonathan K. Hilmer, Navid Movahed, Brian Bothner, John P. Sumida, Gregory G. Tall, Stephen R. Sprang

Chemistry and Biochemistry Faculty Publications

Heterotrimeric G protein alpha subunits are activated upon exchange of GDP for GTP at the nucleotide binding site of G alpha, catalyzed by guanine nucleotide exchange factors (GEFs). In addition to transmembrane G protein-coupled receptors (GPCRs), which act on G protein heterotrimers, members of the family cytosolic proteins typified by mammalian Ric-8A are GEFs for Gi/q/12/13-class G alpha subunits. Ric-8A binds to G alpha.GDP, resulting in the release of GDP. The Ric-8A complex with nucleotide-free G alpha i1 is stable, but dissociates upon binding of GTP to G alpha i1. To gain insight into the mechanism of Ric-8A-catalyzed GDP release …

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Quantifying The Flux Of Caco3 And Organic Carbon From The Surface Ocean Using In Situ Measurements Of O-2, N-2, Pco(2), And Ph, Steven Emerson, Christopher Sabine, Meghan F. Cronin, Richard Feely, Sarah E. Cullison Gray, Michael Degrandpre Jul 2011

Quantifying The Flux Of Caco3 And Organic Carbon From The Surface Ocean Using In Situ Measurements Of O-2, N-2, Pco(2), And Ph, Steven Emerson, Christopher Sabine, Meghan F. Cronin, Richard Feely, Sarah E. Cullison Gray, Michael Degrandpre

Chemistry and Biochemistry Faculty Publications

Ocean acidification from anthropogenic CO2 has focused our attention on the importance of understanding the rates and mechanisms of CaCO3 formation so that changes can be monitored and feedbacks predicted. We present a method for determining the rate of CaCO3 production using in situ measureme nts of fCO(2) and pH in surface waters of the eastern subarctic Pacific Ocean. These quantities were determined on a surface mooring every 3 h for a period of about 9 months in 2007 at Ocean Station Papa (50 degrees N, 145 degrees W). We use the data in a simple surface ocean, mass balance …

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The Fire Inventory From Ncar (Finn): A High Resolution Global Model To Estimate The Emissions From Open Burning, C. Wiedinmyer, S. K. Akagi, Robert J. Yokelson, L. K. Emmons, J. A. Al-Saadi, J. J. Orlando, A. J. Soja Jan 2011

The Fire Inventory From Ncar (Finn): A High Resolution Global Model To Estimate The Emissions From Open Burning, C. Wiedinmyer, S. K. Akagi, Robert J. Yokelson, L. K. Emmons, J. A. Al-Saadi, J. J. Orlando, A. J. Soja

Chemistry and Biochemistry Faculty Publications

The Fire INventory from NCAR version 1.0 (FINNv1) provides daily, 1 km resolution, global estimates of the trace gas and particle emissions from open burning of biomass, which includes wildfire, agricultural fires, and prescribed burning and does not include biofuel use and trash burning. Emission factors used in the calculations have been updated with recent data, particularly for the non-methane organic compounds (NMOC). The resulting global annual NMOC emission estimates are as much as a factor of 5 greater than some prior estimates. Chemical speciation profiles, necessary to allocate the total NMOC emission estimates to lumped species for use by …

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Emission Factors For Open And Domestic Biomass Burning For Use In Atmospheric Models, S. K. Akagi, Robert J. Yokelson, C. Wiedinmyer, M. Alvarado, J. S. Reid, T. Karl, J. D. Crounse, P. O. Wennberg Jan 2011

Emission Factors For Open And Domestic Biomass Burning For Use In Atmospheric Models, S. K. Akagi, Robert J. Yokelson, C. Wiedinmyer, M. Alvarado, J. S. Reid, T. Karl, J. D. Crounse, P. O. Wennberg

Chemistry and Biochemistry Faculty Publications

Biomass burning (BB) is the second largest source of trace gases and the largest source of primary fine carbonaceous particles in the global troposphere. Many recent BB studies have provided new emission factor (EF) measurements. This is especially true for non-methane organic compounds (NMOC), which influence secondary organic aerosol (SOA) and ozone formation. New EF should improve regional to global BB emissions estimates and therefore, the input for atmospheric models. In this work we present an up-to-date, comprehensive tabulation of EF for known pyrogenic species based on measurements made in smoke that has cooled to ambient temperature, but not yet …

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Airborne And Ground-Based Measurements Of The Trace Gases And Particles Emitted By Prescribed Fires In The United States, I. R. Burling, Robert J. Yokelson, S. K. Akagi, S. P. Urbanski, C. E. Wold, David W. T. Griffith, T. J. Johnson, J. Reardon, D. R. Weise Jan 2011

Airborne And Ground-Based Measurements Of The Trace Gases And Particles Emitted By Prescribed Fires In The United States, I. R. Burling, Robert J. Yokelson, S. K. Akagi, S. P. Urbanski, C. E. Wold, David W. T. Griffith, T. J. Johnson, J. Reardon, D. R. Weise

Chemistry and Biochemistry Faculty Publications

We have measured emission factors for 19 trace gas species and particulate matter (PM2.5) from 14 prescribed fires in chaparral and oak savanna in the southwestern US, as well as conifer forest understory in the southeastern US and Sierra Nevada mountains of California. These are likely the most extensive emission factor field measurements for temperate biomass burning to date and the only published emission factors for temperate oak savanna fuels. This study helps to close the gap in emissions data available for temperate zone fires relative to tropical biomass burning. We present the first field measurements of the biomass burning …

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Trace Gas And Particle Emissions From Open Biomass Burning In Mexico, Robert J. Yokelson, I. R. Burling, S. P. Urbanski, E. Atlas, K. Adachi, P. R. Buseck, C. Wiedinmyer, S. K. Akagi, D. W. Toohey, C. E. Wold Jan 2011

Trace Gas And Particle Emissions From Open Biomass Burning In Mexico, Robert J. Yokelson, I. R. Burling, S. P. Urbanski, E. Atlas, K. Adachi, P. R. Buseck, C. Wiedinmyer, S. K. Akagi, D. W. Toohey, C. E. Wold

Chemistry and Biochemistry Faculty Publications

We report airborne measurements of emission factors (EF) for trace gases and PM(2.5) made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to EF measured late in the African dry season they were at least 1.7 times larger for NO(x), NH(3), H(2), and most non-methane organic compounds. Our measurements suggest that urban deposition and high windspeed may also be associated with significantly elevated NOx …

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Boreal Forest Fire Emissions In Fresh Canadian Smoke Plumes: C-1-C-10 Volatile Organic Compounds (Vocs), Co2, Co, No2, No, Hcn And Ch3cn, Isobel J. Simpson, S. K. Akagi, B. Barletta, N. J. Blake, Y. Choi, G. S. Diskin, A. Fried, H. E. Fuelberg, S. Meinardi, F. S. Rowland, S. A. Vay, A. J. Weinheimer, P. O. Wennberg, P. Wiebring, A. Wisthaler, M. Yang, Robert J. Yokelson, Donald R. Blake Jan 2011

Boreal Forest Fire Emissions In Fresh Canadian Smoke Plumes: C-1-C-10 Volatile Organic Compounds (Vocs), Co2, Co, No2, No, Hcn And Ch3cn, Isobel J. Simpson, S. K. Akagi, B. Barletta, N. J. Blake, Y. Choi, G. S. Diskin, A. Fried, H. E. Fuelberg, S. Meinardi, F. S. Rowland, S. A. Vay, A. J. Weinheimer, P. O. Wennberg, P. Wiebring, A. Wisthaler, M. Yang, Robert J. Yokelson, Donald R. Blake

Chemistry and Biochemistry Faculty Publications

Boreal regions comprise about 17% of the global land area, and they both affect and are influenced by climate change. To better understand boreal forest fire emissions and plume evolution, 947 whole air samples were collected aboard the NASA DC-8 research aircraft in summer 2008 as part of the ARCTAS-B field mission, and analyzed for 79 non-methane volatile organic compounds (NMVOCs) using gas chromatography. Together with simultaneous measurements of CO2, CO, CH4, CH2O, NO2, NO, HCN and CH3CN, these measurements represent the most comprehensive assessment of trace gas emissions from boreal forest fires to date. Based on 105 air samples …

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Measurements Of Gas‐Phase Inorganic And Organic Acids From Biomass Fires By Negative‐Ion Proton‐Transfer Chemical‐Ionization Mass Spectrometry, P. Veres, James M. Roberts, I. R. Burling, C. Warneke, Joost De Gouw, Robert J. Yokelson Dec 2010

Measurements Of Gas‐Phase Inorganic And Organic Acids From Biomass Fires By Negative‐Ion Proton‐Transfer Chemical‐Ionization Mass Spectrometry, P. Veres, James M. Roberts, I. R. Burling, C. Warneke, Joost De Gouw, Robert J. Yokelson

Chemistry and Biochemistry Faculty Publications

[1] Emissions from 34 laboratory biomass fires were investigated at the combustion facility of the U.S. Department of Agriculture Fire Sciences Laboratory in Missoula, Montana. Gas-phase organic and inorganic acids were quantified using negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS), open-path Fourier transform infrared spectroscopy (OP-FTIR), and proton-transfer-reaction mass spectrometry (PTR-MS). NI-PT-CIMS is a novel technique that measures the mass-to-charge ratio (m/z) of ions generated from reactions of acetate (CH3C(O)O−) ions with inorganic and organic acids. The emission ratios for various important reactive acids with respect to CO were determined. Emission ratios for isocyanic acid (HNCO), 1,2 …

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Measurement Of Hono, Hnco, And Other Inorganic Acids By Negative-Ion Proton-Transfer Chemical-Ionization Mass Spectrometry (Ni-Pt-Cims): Application To Biomass Burning Emissions, J. M. Roberts, P. Veres, C. Warneke, J. A. Neuman, R. A. Washenfelder, S. S. Brown, M. Baasandorj, J. B. Burkholder, I. R. Burling, T. J. Johnson, Robert J. Yokelson, J. De Gouw Jul 2010

Measurement Of Hono, Hnco, And Other Inorganic Acids By Negative-Ion Proton-Transfer Chemical-Ionization Mass Spectrometry (Ni-Pt-Cims): Application To Biomass Burning Emissions, J. M. Roberts, P. Veres, C. Warneke, J. A. Neuman, R. A. Washenfelder, S. S. Brown, M. Baasandorj, J. B. Burkholder, I. R. Burling, T. J. Johnson, Robert J. Yokelson, J. De Gouw

Chemistry and Biochemistry Faculty Publications

A negative-ion proton-transfer chemical ionization mass spectrometric technique (NI-PT-CIMS), using acetate as the reagent ion, was applied to the measurement of volatile inorganic acids of atmospheric interest: hydrochloric (HCl), nitrous (HONO), nitric (HNO(3)), and isocyanic (HNCO) acids. Gas phase calibrations through the sampling inlet showed the method to be intrinsically sensitive (6-16 cts/pptv), but prone to inlet effects for HNO(3) and HCl. The ion chemistry was found to be insensitive to water vapor concentrations, in agreement with previous studies of carboxylic acids. The inlet equilibration times for HNCO and HONO were 2 to 4s, allowing for measurement in biomass burning …

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Trace Gas And Particle Emissions From Domestic And Industrial Biofuel Use And Garbage Burning In Central Mexico, Ted J. Christian, Robert Yokelson, B. Cardenas, L. T. Molina, G. Engling, S. C. Hsu Jan 2010

Trace Gas And Particle Emissions From Domestic And Industrial Biofuel Use And Garbage Burning In Central Mexico, Ted J. Christian, Robert Yokelson, B. Cardenas, L. T. Molina, G. Engling, S. C. Hsu

Chemistry and Biochemistry Faculty Publications

In central Mexico during the spring of 2007 we measured the initial emissions of 12 gases and the aerosol speciation for elemental and organic carbon (EC, OC), anhydrosugars, Cl(-), NO(3)(-), and 20 metals from 10 cooking fires, four garbage fires, three brick making kilns, three charcoal making kilns, and two crop residue fires. Global biofuel use has been estimated at over 2600 Tg/y. With several simple case studies we show that cooking fires can be a major, or the major, source of several gases and fine particles in developing countries. Insulated cook stoves with chimneys were earlier shown to reduce …

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Laboratory Measurements Of Trace Gas Emissions From Biomass Burning Of Fuel Types From The Southeastern And Southwestern United States, I. R. Burling, Robert J. Yokelson, David W. T. Griffith, T. J. Johnson, P. Veres, J. M. Roberts, C. Warneke, S. P. Urbanski, J. Reardon, D. R. Weise, Wei Min Hao, J. De Gouw Jan 2010

Laboratory Measurements Of Trace Gas Emissions From Biomass Burning Of Fuel Types From The Southeastern And Southwestern United States, I. R. Burling, Robert J. Yokelson, David W. T. Griffith, T. J. Johnson, P. Veres, J. M. Roberts, C. Warneke, S. P. Urbanski, J. Reardon, D. R. Weise, Wei Min Hao, J. De Gouw

Chemistry and Biochemistry Faculty Publications

Vegetation commonly managed by prescribed burning was collected from five southeastern and southwestern US military bases and burned under controlled conditions at the US Forest Service Fire Sciences Laboratory in Missoula, Montana. The smoke emissions were measured with a large suite of state-of-the-art instrumentation including an open-path Fourier transform infrared (OP-FTIR) spectrometer for measurement of gas-phase species. The OP-FTIR detected and quantified 19 gas-phase species in these fires: CO2, CO, CH4, C2H2, C2H4, C3H6, HCHO, HCOOH, CH3OH, CH3COOH, furan, H2O, NO, NO2, HONO, NH3, HCN, HCl, and SO2. Emission factors for these species are presented for each vegetation type burned. …

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Evolution Of Trace Gases And Particles Emitted By A Chaparral Fire In California, S. K. Akagi, J. S. Craven, J. W. Taylor, G. R. Mcmeeking, Robert J. Yokelson, I. R. Burling, S. P. Urbanski, C. E. Wold, J. H. Seinfeld, H. Coe, M. J. Alvarado, D. R. Weise Jan 2010

Evolution Of Trace Gases And Particles Emitted By A Chaparral Fire In California, S. K. Akagi, J. S. Craven, J. W. Taylor, G. R. Mcmeeking, Robert J. Yokelson, I. R. Burling, S. P. Urbanski, C. E. Wold, J. H. Seinfeld, H. Coe, M. J. Alvarado, D. R. Weise

Chemistry and Biochemistry Faculty Publications

Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 hectare prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009. We also measured physical and chemical changes that occurred in the isolated down-wind plume in the first similar to 4 h after emission. The measurements were carried out onboard a Twin Otter aircraft outfitted with an airborne Fourier transform infrared …

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Louisiana: A Model For Advancing Regional E-Research Through Cyberinfrastructure, Daniel S. Katz, Gabrielle Allen, Ricardo Cortez, Carolina Cruz-Neira, Raju Gottumukkala, Zeno D. Greenwood, Les Guice, Shantenu Jha, Ramsesh Kolluru, Tevfik Kosar, Lonnie Leger, Honggao Liu, Charlie Mcmahon, Jarek Nabrzyski, Bety Rodriguez-Milla, Ed Seidel, Greg Speyrer, Michael Stubblefield, Brian Voss, Scott L. Whittenburg Jun 2009

Louisiana: A Model For Advancing Regional E-Research Through Cyberinfrastructure, Daniel S. Katz, Gabrielle Allen, Ricardo Cortez, Carolina Cruz-Neira, Raju Gottumukkala, Zeno D. Greenwood, Les Guice, Shantenu Jha, Ramsesh Kolluru, Tevfik Kosar, Lonnie Leger, Honggao Liu, Charlie Mcmahon, Jarek Nabrzyski, Bety Rodriguez-Milla, Ed Seidel, Greg Speyrer, Michael Stubblefield, Brian Voss, Scott L. Whittenburg

Chemistry and Biochemistry Faculty Publications

Louisiana researchers and universities are leading a concentrated, collaborative effort to advance statewide e-Research through a new cyberinfrastructure: computing systems, data storage systems, advanced instruments and data repositories, visualization environments and people, all linked together by software programs and high-performance networks. This effort has led to a set of interlinked projects that have started making a significant difference in the state, and has created an environment that encourages increased collaboration, leading to new e-Research. This paper describes the overall effort, the new projects and environment and the results to date.

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Loop Dynamics Of The Extracellular Domain Of Human Tissue Factor And Activation Of Factor Viia, Agnese S. Minazzo, Reuben C. Darlington, J. B. A. Ross Jan 2009

Loop Dynamics Of The Extracellular Domain Of Human Tissue Factor And Activation Of Factor Viia, Agnese S. Minazzo, Reuben C. Darlington, J. B. A. Ross

Chemistry and Biochemistry Faculty Publications

In the crystal structure of the complex between the soluble extracellular domain of tissue factor (sTF) and activesite- inhibited VIIa, residues 91 and 92 in the Pro79-Pro92 loop of sTF interact with the catalytic domain of VIIa. It is not known, however, whether this loop has a role in allosteric activation of VIIa. Time-resolved fluorescence anisotropy measurements of probes covalently bound to sTF mutants E84C and T121C show that binding uninhibited Factor VIIa affects segmental motions in sTF. Glu84 resides in the Pro79-Pro92 loop, and Thr121 resides in the turn between the …

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Emissions From Biomass Burning In The Yucatan, Robert J. Yokelson, J. D. Crounse, P. F. Decarlo, T. Karl, S. P. Urbanski, E. Atlas, T. Campos, Y. Shinozuka, V. Kasputin, A. D. Clarke, A. Weinheimer, D. J. Knapp, D. D. Montzka, J. Holloway, P. Weibring, F. Flocke, W. Zheng, D. Toohey, P. O. Wennberg, C. Wiedinmyer, L. Mauldin, A. Fried, D. Richter, J. Walega, J. L. Jimenez, K. Adachi, P. R. Buseck, S. R. Hall, R. Shetter Jan 2009

Emissions From Biomass Burning In The Yucatan, Robert J. Yokelson, J. D. Crounse, P. F. Decarlo, T. Karl, S. P. Urbanski, E. Atlas, T. Campos, Y. Shinozuka, V. Kasputin, A. D. Clarke, A. Weinheimer, D. J. Knapp, D. D. Montzka, J. Holloway, P. Weibring, F. Flocke, W. Zheng, D. Toohey, P. O. Wennberg, C. Wiedinmyer, L. Mauldin, A. Fried, D. Richter, J. Walega, J. L. Jimenez, K. Adachi, P. R. Buseck, S. R. Hall, R. Shetter

Chemistry and Biochemistry Faculty Publications

In March 2006 two instrumented aircraft made the first detailed field measurements of biomass burning (BB) emissions in the Northern Hemisphere tropics as part of the MILAGRO project. The aircraft were the National Center for Atmospheric Research C-130 and a University of Montana/US Forest Service Twin Otter. The initial emissions of up to 49 trace gas or particle species were measured from 20 deforestation and crop residue fires on the Yucatan peninsula. This included two trace gases useful as indicators of BB (HCN and acetonitrile) and several rarely, or never before, measured species: OH, peroxyacetic acid, propanoic acid, hydrogen peroxide, …

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Biomass Burning And Urban Air Pollution Over The Central Mexican Plateau, J. D. Crounse, P. F. Decarlo, Donald R. Blake, L. K. Emmons, T. L. Campos, E. C. Apel, A. D. Clarke, A. J. Weinheimer, D. C. Mccabe, Robert J. Yokelson, J. L. Jimenez, P. O. Wennberg Jan 2009

Biomass Burning And Urban Air Pollution Over The Central Mexican Plateau, J. D. Crounse, P. F. Decarlo, Donald R. Blake, L. K. Emmons, T. L. Campos, E. C. Apel, A. D. Clarke, A. J. Weinheimer, D. C. Mccabe, Robert J. Yokelson, J. L. Jimenez, P. O. Wennberg

Chemistry and Biochemistry Faculty Publications

Observations during the 2006 dry season of highly elevated concentrations of cyanides in the atmosphere above Mexico City (MC) and the surrounding plains demonstrate that biomass burning (BB) significantly impacted air quality in the region. We find that during the period of our measurements, fires contribute more than half of the organic aerosol mass and submicron aerosol scattering, and one third of the enhancement in benzene, reactive nitrogen, and carbon monoxide in the outflow from the plateau. The combination of biomass burning and anthropogenic emissions will affect ozone chemistry in the MC outflow.

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Arbuscular Mycorrhizal Fungi: Factors Affecting Soil Organic Matter Storage, Carl Lee Rosier Jan 2009

Arbuscular Mycorrhizal Fungi: Factors Affecting Soil Organic Matter Storage, Carl Lee Rosier

Graduate Student Theses, Dissertations, & Professional Papers

Arbuscular mycorrhizal fungi (AMF) are soil fungi forming symbiotic associations with majority of land plants. AMF alter soil organic matter (SOM) directly through stabilization of soil aggregates and indirectly providing a path in which plant fixed C02 is transferred below-ground. Understanding contributions of AMF to SOM via protein production and stabilization of soil aggregates will greatly aid our understanding of soil carbon sequestration, nutrient cycling and mitigation of soil erosion. The work presented in chapter 2 challenges the glomalin extraction process and assesses the accuracy of the Bradford and monoclonal-antibody ELISA detection methods. My results clarify the contribution of glomalin …

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Molecular-Orientation-Dependent Ac Stark Effect And Its Impact On Multiphoton Processes, Xi Chu Oct 2008

Molecular-Orientation-Dependent Ac Stark Effect And Its Impact On Multiphoton Processes, Xi Chu

Chemistry and Biochemistry Faculty Publications

We study the dependence of the ac Stark shifts of electronic energies on the molecular orientation relative to the polarization direction of an incident intense laser field, using a three-dimensional non-Hermitian Floquet method and H(2)+ as a model system. Simultaneously, we also study the orientation-dependent high-order harmonic generation (HHG) and multiphoton ionization (MPI). We find that with the presence of near-one-photon resonance, the Stark effect strongly mixes electronic states of different symmetries to create quasienergy states (QESs). The orientation dependence of multiphoton processes, in which these QESs play an important role, becomes complex. Population transfer is better achieved with aligned …

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The Tropical Forest And Fire Emissions Experiment: Laboratory Fire Measurements And Synthesis Of Campaign Data, Robert J. Yokelson, Ted J. Christian, T. G. Karl, Alex Guenther Jan 2008

The Tropical Forest And Fire Emissions Experiment: Laboratory Fire Measurements And Synthesis Of Campaign Data, Robert J. Yokelson, Ted J. Christian, T. G. Karl, Alex Guenther

Chemistry and Biochemistry Faculty Publications

As part of the Tropical Forest and Fire Emissions Experiment (TROFFEE), tropical forest fuels were burned in a large. biomass-fire simulation facility and the smoke was characterized with open-path Fourier transform infrared spectroscopy (FTIR), proton-transfer reaction mass spectrometry (PTR-MS), gas chromatography (GC), GC/PTR-MS, and filter sampling of the particles. In most cases, about one-third of the fuel chlorine ended up in the particles and about one-half remained in the ash. About 50% of the mass of non-methane organic compounds (NMOC) emitted by these fires could be identified with the available instrumentation. The lab fire emission factors (EF, g compound emitted …

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The Tropical Forest And Fire Emissions Experiment: Method Evaluation Of Volatile Organic Compound Emissions Measured By Ptr-Ms, Ftir, And Gc From Tropical Biomass Burning, T. G. Karl, Ted J. Christian, Robert J. Yokelson, Paulo Artaxo, Wei Min Hao, Alex Guenther Nov 2007

The Tropical Forest And Fire Emissions Experiment: Method Evaluation Of Volatile Organic Compound Emissions Measured By Ptr-Ms, Ftir, And Gc From Tropical Biomass Burning, T. G. Karl, Ted J. Christian, Robert J. Yokelson, Paulo Artaxo, Wei Min Hao, Alex Guenther

Chemistry and Biochemistry Faculty Publications

Volatile Organic Compound (VOC) emissions from fires in tropical forest fuels were quantified using Proton-Transfer-Reaction Mass Spectrometry (PTRMS), Fourier Transform Infrared Spectroscopy (FTIR) and gas chromatography (GC) coupled to PTRMS (GC-PTR-MS). We investigated VOC emissions from 19 controlled laboratory fires at the USFS (United States Forest Service) Fire Sciences Laboratory and 16 fires during an intensive airborne field campaign during the peak of the burning season in Brazil in 2004. The VOC emissions were dominated by oxygenated VOCs (OVOC) (OVOC/NMHC similar to 4:1, NMHC: non-methane hydrocarbons) The specificity of the PTR-MS instrument, which measures the mass to charge ratio of …

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The Tropical Forest And Fire Emissions Experiment: Trace Gases Emitted By Smoldering Logs And Dung From Deforestation And Pasture Fires In Brazil, Ted J. Christian, Robert J. Yokelson, João A. Carvalho, David W.T. Griffith, Ernesto C. Alvarado, José Carlos Santos, Turibio Gomes Soares Neto, Carlos A.Gurgel Veras, Wei Min Hao Sep 2007

The Tropical Forest And Fire Emissions Experiment: Trace Gases Emitted By Smoldering Logs And Dung From Deforestation And Pasture Fires In Brazil, Ted J. Christian, Robert J. Yokelson, João A. Carvalho, David W.T. Griffith, Ernesto C. Alvarado, José Carlos Santos, Turibio Gomes Soares Neto, Carlos A.Gurgel Veras, Wei Min Hao

Chemistry and Biochemistry Faculty Publications

Earlier work showed that Amazonian biomass burning produces both lofted and initially unlofted emissions in large amounts. A mobile, Fourier transform infrared spectrometer (FTIR) measured the unlofted emissions of 17 trace gases from residual smoldering combustion (RSC) of logs as part of the Tropical Forest and Fire Emissions Experiment (TROFFEE) during the 2004 Amazonian dry season. The RSC emissions were highly variable and the few earlier RSC measurements lay near the high end of combustion efficiency observed in this study. Fuel consumption by RSC was ∼5% of total for a planned deforestation fire. Much regional RSC probably occurs in the …

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The Tropical Forest And Fire Emissions Experiment: Emission, Chemistry, And Transport Of Biogenic Volatile Organic Compounds In The Lower Atmosphere Over Amazonia, Thomas Karl, Alex Guenther, Robert J. Yokelson, Jim Greenberg, Mark Potosnak, Donald R. Blake, Paulo Artaxo Sep 2007

The Tropical Forest And Fire Emissions Experiment: Emission, Chemistry, And Transport Of Biogenic Volatile Organic Compounds In The Lower Atmosphere Over Amazonia, Thomas Karl, Alex Guenther, Robert J. Yokelson, Jim Greenberg, Mark Potosnak, Donald R. Blake, Paulo Artaxo

Chemistry and Biochemistry Faculty Publications

Airborne and ground-based mixing ratio and flux measurements using eddy covariance (EC) and for the first time the mixed layer gradient (MLG) and mixed layer variance (MLV) techniques are used to assess the impact of isoprene and monoterpene emissions on atmospheric chemistry in the Amazon basin. Average noon isoprene (7.8 +/- 2.3 mg/m(2)/h) and monoterpene fluxes (1.2 +/- 0.5 mg/m(2)/h)compared well between ground and airborne measurements and are higher than fluxes estimated in this region during other seasons. The biogenic emission model, Model of Emissions of Gases and Aerosols from Nature (MEGAN), estimates fluxes that are within the model and …

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Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Vovk, Donald J. Scherer Ii, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg, Zachary Davis, Jin-Seung Jung May 2007

Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Vovk, Donald J. Scherer Ii, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg, Zachary Davis, Jin-Seung Jung

Chemistry and Biochemistry Faculty Publications

Arrays consisting of nanosized stripes of Permalloy with different length-to-width ratios have been fabricated using electron beam nanolithography, magnetron sputtering, and lift-off process. These stripes have a thickness of , a width of , and different lengths ranging from . The stripes are separated by a distance of . Magnetization hysteresis loops were measured using a superconducting quantum interference device susceptometer. Microwave absorption at was determined by means of ferromagnetic resonance technique. The dependence of the resonant field on the angle between the nanostructure and the in-plane dc magnetic field indicates the presence of uniaxial magnetic anisotropy associated with the …

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