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Full-Text Articles in Chemistry
Infrared Spectroscopy Of The Nitrogenase Mofe Protein Under Electrochemical Control: Potential-Triggered Co Binding, P. Paengnakorn, Philip A. Ash, Sudipta K. Shaw, Karamatullah Danyal, T. Chen, Dennis R. Dean, Lance C. Seefeldt, Kylie A. Vincent
Infrared Spectroscopy Of The Nitrogenase Mofe Protein Under Electrochemical Control: Potential-Triggered Co Binding, P. Paengnakorn, Philip A. Ash, Sudipta K. Shaw, Karamatullah Danyal, T. Chen, Dennis R. Dean, Lance C. Seefeldt, Kylie A. Vincent
Chemistry and Biochemistry Faculty Publications
We demonstrate electrochemical control of the nitrogenase MoFe protein, in the absence of Fe protein or ATP, using europium(III/II) polyaminocarboxylate complexes as electron transfer mediators. This allows the potential dependence of proton reduction and inhibitor (CO) binding to the active site FeMo-cofactor to be established. Reduction of protons to H2 is catalyzed by the wild type MoFe protein and Β-98Tyr→His and Β-99Phe→His variants of the MoFe protein at potentials more negative than -800 mV (vs. SHE), with greater electrocatalytic proton reduction rates observed for the variants compared to the wild type protein. Electrocatalytic proton reduction is strongly …
Emissions Of Nitrogen-Containing Organic Compounds From The Burning Of Herbaceous And Arboraceous Biomass: Fuel Composition Dependence And The Variability Of Commonly Used Nitrile Tracers, Matthew M. Coggon, Patrick R. Veres, Bin Yuan, Abigail Koss, Carsten Warneke, Jessica B. Gilman, Brian M. Lerner, Jeff Peischl, Kenneth C. Aikin, Chelsea E. Stockwell, Lindsay E. Hatch, Thomas B. Ryerson, James M. Roberts, Robert J. Yokelson, Joost A. De Gouw
Emissions Of Nitrogen-Containing Organic Compounds From The Burning Of Herbaceous And Arboraceous Biomass: Fuel Composition Dependence And The Variability Of Commonly Used Nitrile Tracers, Matthew M. Coggon, Patrick R. Veres, Bin Yuan, Abigail Koss, Carsten Warneke, Jessica B. Gilman, Brian M. Lerner, Jeff Peischl, Kenneth C. Aikin, Chelsea E. Stockwell, Lindsay E. Hatch, Thomas B. Ryerson, James M. Roberts, Robert J. Yokelson, Joost A. De Gouw
Chemistry and Biochemistry Faculty Publications
Volatile organic compounds (VOCs) emitted from residential wood and crop residue burning were measured in Colorado, U.S. When compared to the emissions from crop burning, residential wood burning exhibited markedly lower concentrations of acetonitrile, a commonly used biomass burning tracer. For both herbaceous and arboraceous fuels, the emissions of nitrogen-containing VOCs (NVOCs) strongly depend on the fuel nitrogen content; therefore, low NVOC emissions from residential wood burning result from the combustion of low-nitrogen fuel. Consequently, the emissions of compounds hazardous to human health, such as HNCO and HCN, and the formation of secondary pollutants, such as ozone generated by NOx, …
Field Measurements Of Trace Gases And Aerosols Emitted By Peat Fires In Central Kalimantan, Indonesia, During The 2015 El Niño, Chelsea E. Stockwell, Thilina Jayarathne, Mark A. Cochrane, Kevin C. Ryan, Erianto I. Putra, Bambang H. Saharjo, Ati D. Nurhayati, Israr Albar, Donald R. Blake, Isobel J. Simpson, Elizabeth A. Stone, Robert J. Yokelson
Field Measurements Of Trace Gases And Aerosols Emitted By Peat Fires In Central Kalimantan, Indonesia, During The 2015 El Niño, Chelsea E. Stockwell, Thilina Jayarathne, Mark A. Cochrane, Kevin C. Ryan, Erianto I. Putra, Bambang H. Saharjo, Ati D. Nurhayati, Israr Albar, Donald R. Blake, Isobel J. Simpson, Elizabeth A. Stone, Robert J. Yokelson
Chemistry and Biochemistry Faculty Publications
Peat fires in Southeast Asia have become a major annual source of trace gases and particles to the regional-global atmosphere. The assessment of their influence on atmospheric chemistry, climate, air quality, and health has been uncertain partly due to a lack of field measurements of the smoke characteristics. During the strong 2015 El Niño event we deployed a mobile smoke sampling team in the Indonesian province of Central Kalimantan on the island of Borneo and made the first, or rare, field measurements of trace gases, aerosol optical properties, and aerosol mass emissions for authentic peat fires burning at various depths …
Nepal Ambient Monitoring And Source Testing Experiment (Namaste): Emissions Of Trace Gases And Light-Absorbing Carbon From Wood And Dung Cooking Fires, Garbage And Crop Residue Burning, Brick Kilns, And Other Sources, Chelsea E. Stockwell, Ted J. Christian, J. Douglas Goetz, Thilina Jayarathne, Prakash V. Bhave, Puppala S. Praveen, Sagar Adhikari, Rashmi Maharjan, Peter F. Decarlo, Elizabeth A. Stone, Eri Saikawa, Donald R. Blake, Isobel J. Simpson, Robert J. Yokelson, Arnico K. Panday
Nepal Ambient Monitoring And Source Testing Experiment (Namaste): Emissions Of Trace Gases And Light-Absorbing Carbon From Wood And Dung Cooking Fires, Garbage And Crop Residue Burning, Brick Kilns, And Other Sources, Chelsea E. Stockwell, Ted J. Christian, J. Douglas Goetz, Thilina Jayarathne, Prakash V. Bhave, Puppala S. Praveen, Sagar Adhikari, Rashmi Maharjan, Peter F. Decarlo, Elizabeth A. Stone, Eri Saikawa, Donald R. Blake, Isobel J. Simpson, Robert J. Yokelson, Arnico K. Panday
Chemistry and Biochemistry Faculty Publications
The Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE) campaign took place in and around the Kathmandu Valley and in the Indo-Gangetic Plain (IGP) of southern Nepal during April 2015. The source characterization phase targeted numerous important but undersampled (and often inefficient) combustion sources that are widespread in the developing world such as cooking with a variety of stoves and solid fuels, brick kilns, open burning of municipal solid waste (a.k.a. trash or garbage burning), crop residue burning, generators, irrigation pumps, and motorcycles. NAMaSTE produced the first, or rare, measurements of aerosol optical properties, aerosol mass, and detailed trace gas …
Interactions Of Nucleic Acid Bases With Temozolomide. Stacked, Perpendicular, And Coplanar Heterodimers, Okuma Emile Kasende, Steve Scheiner
Interactions Of Nucleic Acid Bases With Temozolomide. Stacked, Perpendicular, And Coplanar Heterodimers, Okuma Emile Kasende, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
Temozolomide (TMZ) was paired with each of the five nucleic acid bases, and the potential energy surface searched for all minima, in the context of dispersion-corrected density functional theory and MP2 methods. Three types of arrangements were observed, with competitive stabilities. Coplanar H-bonding structures, reminiscent of Watson–Crick base pairs were typically the lowest in energy, albeit by a small amount. Also very stable were perpendicular arrangements that included one or more H-bonds. The two monomers were stacked approximately parallel to one another in the third category, some of which contained weak and distorted H-bonds. Dispersion was found to be a …
Monitoring The Charge Distribution During Proton And Sodium Ion Conduction Along Chains Of Water Molecules And Protein Residues, Steve Scheiner
Monitoring The Charge Distribution During Proton And Sodium Ion Conduction Along Chains Of Water Molecules And Protein Residues, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
Quantum calculations are used to determine the level of delocalization of the charge of a cation as it translates along a chain of water molecules or glycine residues. Charge dispersal is monitored via the molecular electrostatic potential and the dipole moment of the entire system. The positive charge is largely localized on the water molecule on which the proton is situated, but becomes more intense and extended as the proton moves along the chain. The positive charge is more delocalized in protonated polyglycine, where it extends over at least an entire residue. Displacement of the proton along the chain intensifies …
Parameterization Of Single-Scattering Albedo (Ssa) And Absorption Ångström Exponent (Aae) With Ec/Oc For Aerosol Emissions From Biomass Burning, Rudra P. Pokhrel, Nick L. Wagner, Justin M. Langridge, Daniel A. Lack, Thilina Jayarathne, Elizabeth A. Stone, Chelsea E. Stockwell, Robert J. Yokelson, Shane M. Murphy
Parameterization Of Single-Scattering Albedo (Ssa) And Absorption Ångström Exponent (Aae) With Ec/Oc For Aerosol Emissions From Biomass Burning, Rudra P. Pokhrel, Nick L. Wagner, Justin M. Langridge, Daniel A. Lack, Thilina Jayarathne, Elizabeth A. Stone, Chelsea E. Stockwell, Robert J. Yokelson, Shane M. Murphy
Chemistry and Biochemistry Faculty Publications
Single-scattering albedo (SSA) and absorption Ångström exponent (AAE) are two critical parameters in determining the impact of absorbing aerosol on the Earth's radiative balance. Aerosol emitted by biomass burning represent a significant fraction of absorbing aerosol globally, but it remains difficult to accurately predict SSA and AAE for biomass burning aerosol. Black carbon (BC), brown carbon (BrC), and non-absorbing coatings all make substantial contributions to the absorption coefficient of biomass burning aerosol. SSA and AAE cannot be directly predicted based on fuel type because they depend strongly on burn conditions. It has been suggested that SSA can be effectively parameterized …
Ice-Nucleating Particle Emissions From Biomass Combustion And The Potential Importance Of Soot Aerosol, E. J.T. Levin, G. R. Mcmeeking, P. J. Demott, C. S. Mccluskey, C. M. Carrico, S. Nakao, T. Jayarathne, E. A. Stone, C. E. Stockwell, R. J. Yokelson, S. M. Kreidenweis
Ice-Nucleating Particle Emissions From Biomass Combustion And The Potential Importance Of Soot Aerosol, E. J.T. Levin, G. R. Mcmeeking, P. J. Demott, C. S. Mccluskey, C. M. Carrico, S. Nakao, T. Jayarathne, E. A. Stone, C. E. Stockwell, R. J. Yokelson, S. M. Kreidenweis
Chemistry and Biochemistry Faculty Publications
Ice-nucleating particles (INPs) are required for initial ice crystal formation in clouds at temperatures warmer than about -36°C and thus play a crucial role in cloud and precipitation formation. Biomass burning has been found to be a source of INPs in previous studies and is also a major contributor to atmospheric black carbon (BC) concentrations. This study focuses on isolating the BC contribution to the INP population associated with biomass combustion. Emissions of condensation mode INPs from a number of globally relevant biomass fuels were measured at -30°C and above water saturation as fires progressed from ignition to extinguishment in …
Agricultural Fires In The Southeastern U.S. During Seac4Rs: Emissions Of Trace Gases And Particles And Evolution Of Ozone, Reactive Nitrogen, And Organic Aerosol, Xiaoxi Liu, Y. Zhang, L. G. Huey, R. J. Yokelson, Y. Wang, J. L. Jimenez, P. Campuzano-Jost, A. J. Beyersdorf, D. R. Blake, Y. Choi, J. M. St. Clair, J. D. Crounse, D. A. Day, G. S. Diskin, A. Ried, S. R. Hall, T. F. Hanisco, L. E. King, S. Meinardi, T. Mikoviny, B. B. Palm, J. Peischl, A. E. Perring, I. B. Pollack, T. B. Ryerson, G. Sachse, J. P. Schwarz, I. J. Simpson, D. J. Tanner, K. L. Thornhil, K. Ullmann, R. J. Weber, P. O. Wennberg
Agricultural Fires In The Southeastern U.S. During Seac4Rs: Emissions Of Trace Gases And Particles And Evolution Of Ozone, Reactive Nitrogen, And Organic Aerosol, Xiaoxi Liu, Y. Zhang, L. G. Huey, R. J. Yokelson, Y. Wang, J. L. Jimenez, P. Campuzano-Jost, A. J. Beyersdorf, D. R. Blake, Y. Choi, J. M. St. Clair, J. D. Crounse, D. A. Day, G. S. Diskin, A. Ried, S. R. Hall, T. F. Hanisco, L. E. King, S. Meinardi, T. Mikoviny, B. B. Palm, J. Peischl, A. E. Perring, I. B. Pollack, T. B. Ryerson, G. Sachse, J. P. Schwarz, I. J. Simpson, D. J. Tanner, K. L. Thornhil, K. Ullmann, R. J. Weber, P. O. Wennberg
Chemistry and Biochemistry Faculty Publications
Emissions from 15 agricultural fires in the southeastern U.S. were measured from the NASA DC-8 research aircraft during the summer 2013 Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. This study reports a detailed set of emission factors (EFs) for 25 trace gases and 6 fine particle species. The chemical evolution of the primary emissions in seven plumes was examined in detail for ~1.2 h. A Lagrangian plume cross-section model was used to simulate the evolution of ozone (O3), reactive nitrogen species, and organic aerosol (OA). Observed EFs are generally consistent with previous …
Rapidly Evolving Ultrafine And Fine Mode Biomass Smoke Physical Properties: Comparing Laboratory And Field Results, Christian M. Carrico, Anthony J. Prenni, Sonia M. Kreidenweis, Ezra J.T. Levin, Christina S. Mccluskey, Paul J. Demott, Gavin R. Mcmeeking, Shunsuke Nakao, Chelsea Stockwell, Robert J. Yokelson
Rapidly Evolving Ultrafine And Fine Mode Biomass Smoke Physical Properties: Comparing Laboratory And Field Results, Christian M. Carrico, Anthony J. Prenni, Sonia M. Kreidenweis, Ezra J.T. Levin, Christina S. Mccluskey, Paul J. Demott, Gavin R. Mcmeeking, Shunsuke Nakao, Chelsea Stockwell, Robert J. Yokelson
Chemistry and Biochemistry Faculty Publications
Combining field and laboratory results, we present biomass smoke physical properties. We report sub-0.56 µm diameter (Dp) particle sizing (fast mobility particle sizer, FMPS) plus light absorption and scattering at 870nm (photoacoustic extinctiometer). For Dp<200 >nm, the FMPS characterized sizing within ±20% compared to standards. As compared to the traditional scanning mobility particle sizer, the FMPS responded most accurately to single-mode polydispersions with mean Dp<200 >nm, which characterized the smoke sampled here. Smoke was measured from laboratory fresh emissions (seconds to hours old), the High Park Fire (hours to<1 >day), and from regional biomass burning (several days). During a High …
Planning, Implementation, And Scientific Goals Of The Studies Of Emissions And Atmospheric Composition, Clouds And Climate Coupling By Regional Surveys (Seac4Rs) Field Mission, Owen B. Toon, Hal Maring, Jack Dibb, Richard Ferrare, Daniel J. Jacob, Eric J. Jensen, Z. Johnny Luo, Gerald G. Mace, Laura L. Pan, Lenny Pfister, Karen H. Rosenlof, Jens Redemann, Jeffrey S. Reid, Hanwant B. Singh, Anne M. Thompson, Robert Yokelson, Patrick Minnis, Gao Chen, Kenneth W. Jucks, Alex Pszenny
Planning, Implementation, And Scientific Goals Of The Studies Of Emissions And Atmospheric Composition, Clouds And Climate Coupling By Regional Surveys (Seac4Rs) Field Mission, Owen B. Toon, Hal Maring, Jack Dibb, Richard Ferrare, Daniel J. Jacob, Eric J. Jensen, Z. Johnny Luo, Gerald G. Mace, Laura L. Pan, Lenny Pfister, Karen H. Rosenlof, Jens Redemann, Jeffrey S. Reid, Hanwant B. Singh, Anne M. Thompson, Robert Yokelson, Patrick Minnis, Gao Chen, Kenneth W. Jucks, Alex Pszenny
Chemistry and Biochemistry Faculty Publications
The Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) fieldmission based at Ellington Field, Texas, during August and September 2013 employed the most comprehensive airborne payload to date to investigate atmospheric composition over North America. The NASA ER-2, DC-8, and SPEC Inc. Learjet flew 57 science flights fromthe surface to 20 km. The ER-2 employed seven remote sensing instruments as a satellite surrogate and eight in situ instruments. The DC-8 employed 23 in situ and five remote sensing instruments for radiation, chemistry, and microphysics. The Learjet used 11 instruments to explore cloud microphysics. SEAC4RS …
A Disease Spectrum For Itpa Variation: Advances In Biochemical And Clinical Research, Nicholas E. Burgis
A Disease Spectrum For Itpa Variation: Advances In Biochemical And Clinical Research, Nicholas E. Burgis
Chemistry and Biochemistry Faculty Publications
Human ITPase (encoded by the ITPA gene) is a protective enzyme which acts to exclude noncanonical (deoxy) nucleoside triphosphates ((d)NTPs) such as (deoxy)inosine 5′-triphosphate ((d)ITP), from (d)NTP pools. Until the last few years, the importance of ITPase in human health and disease has been enigmatic. In 2009, an article was published demonstrating that ITPase deficiency in mice is lethal. All homozygous null offspring died before weaning as a result of cardiomyopathy due to a defect in the maintenance of quality ATP pools. More recently, a whole exome sequencing project revealed that very rare, severe human ITPA mutation results in early …