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- Biomass burning (12)
- Oxygenated organic compounds (5)
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- NBO (4)
- Savanna fires (4)
- AIM (3)
- ITP (3)
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- Molecular electrostatic potential (3)
- Nanomagnetism (3)
- Relaxation times (3)
- Smoke (3)
- Viscosity (3)
- Ammonia (2)
- Anti-inflammatory agents (2)
- Biomass fires (2)
- Coercive force (2)
- Colorectal cancer (2)
- Copper (2)
- DFT (2)
- Diet therapy (2)
- Ferromagnetic resonance (2)
- Gases (2)
- Hydrogen bonds (2)
- Hydrological modeling (2)
- ITPA (2)
Articles 1 - 30 of 193
Full-Text Articles in Chemistry
Relation Between Halogen Bond Strength And Ir And Nmr Spectroscopic Markers, Akhtam Amonov, Steve Scheiner
Relation Between Halogen Bond Strength And Ir And Nmr Spectroscopic Markers, Akhtam Amonov, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
The relationship between the strength of a halogen bond (XB) and various IR and NMR spectroscopic quantities is assessed through DFT calculations. Three different Lewis acids place a Br or I atom on a phenyl ring; each is paired with a collection of N and O bases of varying electron donor power. The weakest of the XBs display a C–X bond contraction coupled with a blue shift in the associated frequency, whereas the reverse trends occur for the stronger bonds. The best correlations with the XB interaction energy are observed with the NMR shielding of the C atom directly bonded …
C···O And Si···O Tetrel Bonds: Substituent Effects And Transfer Of The Sif3 Group, Zhihao Niu, Qiaozhuo Wu, Qingzhong Li, Steve Scheiner
C···O And Si···O Tetrel Bonds: Substituent Effects And Transfer Of The Sif3 Group, Zhihao Niu, Qiaozhuo Wu, Qingzhong Li, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
The tetrel bond (TB) between 1,2-benzisothiazol-3-one-2-TF3-1,1-dioxide (T = C, Si) and the O atom of pyridine-1-oxide (PO) and its derivatives (PO-X, X = H, NO2, CN, F, CH3, OH, OCH3, NH2, and Li) is examined by quantum chemical means. The Si···O TB is quite strong, with interaction energies approaching a maximum of nearly 70 kcal/mol, while the C···O TB is an order of magnitude weaker, with interaction energies between 2.0 and 2.6 kcal/mol. An electron-withdrawing substituent on the Lewis base weakens this TB, while an electron-donating group has the opposite …
Arginine-178 Is An Essential Residue For Itpa Function, Nicholas E. Burgis, Caitlin April, Kandise Vanwormer
Arginine-178 Is An Essential Residue For Itpa Function, Nicholas E. Burgis, Caitlin April, Kandise Vanwormer
Chemistry and Biochemistry Faculty Publications
The inosine triphosphate pyrophosphatase (ITPA) enzyme plays a critical cellular role by removing noncanonical nucleoside triphosphates from nucleotide pools. One of the first pathological ITPA mutants identified is R178C (rs746930990), which causes a fatal infantile encephalopathy, termed developmental and epileptic encephalopathy 35 (DEE 35). The accumulation of noncanonical nucleotides such as inosine triphosphate (ITP), is suspected to affect RNA and/or interfere with normal nucleotide function, leading to development of DEE 35. Molecular dynamics simulations have shown that the very rare R178C mutation does not significantly perturb the overall structure of the protein, but results in a high level of structural …
Rapid Evolution Of Aerosol Particles And Their Optical Properties Downwind Of Wildfires In The Western Us, Lawrence I. Kleinman, Arthur J. Sedlacek, Kouji Adachi, Peter R. Buseck, Sonya Collier, Manvendra K. Dubey, Anna L. Hodshire, Ernie Lewis, Timothy B. Onasch, Jeffery R. Pierce, John Shilling, Stephen R. Springston, Jian Wang, Qi Zhang, Shan Zhou, Robert J. Yokelson
Rapid Evolution Of Aerosol Particles And Their Optical Properties Downwind Of Wildfires In The Western Us, Lawrence I. Kleinman, Arthur J. Sedlacek, Kouji Adachi, Peter R. Buseck, Sonya Collier, Manvendra K. Dubey, Anna L. Hodshire, Ernie Lewis, Timothy B. Onasch, Jeffery R. Pierce, John Shilling, Stephen R. Springston, Jian Wang, Qi Zhang, Shan Zhou, Robert J. Yokelson
Chemistry and Biochemistry Faculty Publications
During the first phase of the Biomass Burn Operational Project (BBOP) field campaign, conducted in the Pacific Northwest, the DOE G-1 aircraft was used to follow the time evolution of wildfire smoke from near the point of emission to locations 2-3.5 h downwind. In nine flights we made repeated transects of wildfire plumes at varying downwind distances and could thereby follow the plume's time evolution. On average there was little change in dilution-normalized aerosol mass concentration as a function of downwind distance. This consistency hides a dynamic system in which primary aerosol particles are evaporating and secondary ones condensing. Organic …
Aerosol Mass And Optical Properties, Smoke Influence On O3, And High No3 Production Rates In A Western U.S. City Impacted By Wildfires, Vanessa Selimovic, Robert J. Yokelson, Gavin R. Mcmeeking, Sarah Coefield
Aerosol Mass And Optical Properties, Smoke Influence On O3, And High No3 Production Rates In A Western U.S. City Impacted By Wildfires, Vanessa Selimovic, Robert J. Yokelson, Gavin R. Mcmeeking, Sarah Coefield
Chemistry and Biochemistry Faculty Publications
Evaluating our understanding of smoke from wild and prescribed fires can benefit from downwind measurements that include inert tracers to test production and transport and reactive species to test chemical mechanisms. We characterized smoke from fires in coniferous forest fuels for >1,000 hr over two summers (2017 and 2018) at our Missoula, Montana, surface station and found a narrow range for key properties. ΔPM2.5/ΔCO was 0.1070 ± 0.0278 (g/g) or about half the age-independent ratios obtained at free troposphere elevations (0.2348 ± 0.0326). The average absorption Ångström exponent across both years was 1.84 ± 0.18, or about half the values …
The Nitrogen Budget Of Laboratory-Simulated Western Us Wildfires During The Firex 2016 Fire Lab Study, James M. Roberts, Chelsea E. Stockwell, Robert J. Yokelson, Joost De Gouw, Yong Liu, Vanessa Selimovic, Abigail R. Koss, Kanako Sekimoto, Matthew M. Coggon, Bin Yuan, Kyle J. Zarzana, Steven S. Brown, Cristina Santin, Stefan H. Doerr, Carsten Warneke
The Nitrogen Budget Of Laboratory-Simulated Western Us Wildfires During The Firex 2016 Fire Lab Study, James M. Roberts, Chelsea E. Stockwell, Robert J. Yokelson, Joost De Gouw, Yong Liu, Vanessa Selimovic, Abigail R. Koss, Kanako Sekimoto, Matthew M. Coggon, Bin Yuan, Kyle J. Zarzana, Steven S. Brown, Cristina Santin, Stefan H. Doerr, Carsten Warneke
Chemistry and Biochemistry Faculty Publications
Reactive nitrogen (Nr, defined as all nitrogencontaining compounds except for N2 and N2O) is one of the most important classes of compounds emitted from wildfire, as Nr impacts both atmospheric oxidation processes and particle formation chemistry. In addition, several Nr compounds can contribute to health impacts from wildfires. Understanding the impacts of wildfire on the atmosphere requires a thorough description of Nr emissions. Total reactive nitrogen was measured by catalytic conversion to NO and detection by NO-O3 chemiluminescence together with individual Nr species during a series of laboratory fires of fuels characteristic of western US wildfires, conducted as part of …
Comparison Of Accelerated Solvent Extraction (Ase) And Energized Dispersive Guided Extraction (Edge) For The Analysis Of Pesticides In Leaves, Ashlie D. Kinross, Kimberly J. Hageman, William J. Doucette, Alexandria L. Foster
Comparison Of Accelerated Solvent Extraction (Ase) And Energized Dispersive Guided Extraction (Edge) For The Analysis Of Pesticides In Leaves, Ashlie D. Kinross, Kimberly J. Hageman, William J. Doucette, Alexandria L. Foster
Chemistry and Biochemistry Faculty Publications
Various techniques have been evaluated for the extraction and cleanup of pesticides from environmental samples. In this work, a Selective Pressurized Liquid Extraction (SPLE) method for pesticides was developed using a Thermo Fisher Scientific Accelerated Solvent Extraction (ASE) system. This instrument was compared to the newly introduced (2017) extraction instrument, the Energized Dispersive Guided Extraction (EDGE) system, which combines Pressurized Liquid Extraction (PLE) and dispersive Solid Phase Extraction (dSPE). We first optimized the SPLE method using the ASE instrument for pesticide extraction from alfalfa leaves using layers of Florisil and graphitized carbon black (GCB) downstream of the leaf homogenate in …
Influence Of Adjuvants On Pesticide Soil-Air Partition Coefficients: Laboratory Measurements And Predicted Effects On Volatilization, Supta Das, Kimberly J. Hageman
Influence Of Adjuvants On Pesticide Soil-Air Partition Coefficients: Laboratory Measurements And Predicted Effects On Volatilization, Supta Das, Kimberly J. Hageman
Chemistry and Biochemistry Faculty Publications
A solid-phase fugacity meter was used to measure the soil–air partition coefficients of three semivolatile pesticides (chlorpyrifos, pyrimethanil, and trifluralin) in the absence of additional adjuvants (Ksoil–air,AI), as part of commercial formulations (Ksoil–air,formulation), and as formulation mixtures with an additional spray adjuvant added (Ksoil–air,formulation+spray adjuvant). Chlorpyrifos Ksoil–air,formulation values were also measured over 15–30 °C, allowing for the change in internal energy of the phase transfer reaction (Δsoil–airU) to be calculated and compared to the Δsoil–airU for Ksoil–air,AI from the literature. Measured Ksoil–air values …
N3-Ligated Nickel(Ii) Diketonate Complexes: Synthesis, Characterization And Evaluation Of O2 Reactivity, Josiah G. D. Elsberg, Austin Peterson, Amy L. Fuller, Lisa M. Berreau
N3-Ligated Nickel(Ii) Diketonate Complexes: Synthesis, Characterization And Evaluation Of O2 Reactivity, Josiah G. D. Elsberg, Austin Peterson, Amy L. Fuller, Lisa M. Berreau
Chemistry and Biochemistry Faculty Publications
Interest in O2-dependent aliphatic carbon–carbon (C–C) bond cleavage reactions of first row divalent metal diketonate complexes stems from the desire to further understand the reaction pathways of enzymes such as DKE1 and to extract information to develop applications in organic synthesis. A recent report of O2-dependent aliphatic C–C bond cleavage at ambient temperature in Ni(II) diketonate complexes supported by a tridentate nitrogen donor ligand [(MBBP)Ni(PhC(O)CHC(O)Ph)]Cl (7-Cl; MBBP = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine) in the presence of NEt3 spurred our interest in further examining the chemistry of such complexes. A series of new TERPY-ligated Ni(II) diketonate complexes of the …
Modeling The Alkaline Hydrolysis Of Diaryl Sulfate Diesters: A Mechanistic Study, Klaudia Szeler, Nicholas H. Williams, Alvan C. Hengge, Shina C. Kamerlin
Modeling The Alkaline Hydrolysis Of Diaryl Sulfate Diesters: A Mechanistic Study, Klaudia Szeler, Nicholas H. Williams, Alvan C. Hengge, Shina C. Kamerlin
Chemistry and Biochemistry Faculty Publications
Phosphate and sulfate esters have important roles in regulating cellular processes. However, while there has been substantial experimental and computational investigation of the mechanisms and the transition states involved in phosphate ester hydrolysis, there is far less work on sulfate ester hydrolysis. Here, we report a detailed computational study of the alkaline hydrolysis of diaryl sulfate diesters, using different DFT functionals as well as mixed implicit/explicit solvation with varying numbers of explicit water molecules. We consider the impact of the computational model on computed linear free-energy relationships (LFER) and the nature of the transition states (TS) involved. We obtain good …
Ambient Air Quality In The Kathmandu Valley, Nepal, During The Pre-Monsoon: Concentrations And Sources Of Particulate Matter And Trace Gases, Md Robiul Islam, Thilina Jayarathne, Isobel J. Simpson, Benjamin Werden, John Maben, Ashley Gilbert, Puppala S. Praveen, Sagar Adhikari, Arnico K. Panday, Maheswar Rupakheti, Donald R. Blake, Robert J. Yokelson, Peter F. Decarlo, William C. Keene, Elizabeth A. Stone
Ambient Air Quality In The Kathmandu Valley, Nepal, During The Pre-Monsoon: Concentrations And Sources Of Particulate Matter And Trace Gases, Md Robiul Islam, Thilina Jayarathne, Isobel J. Simpson, Benjamin Werden, John Maben, Ashley Gilbert, Puppala S. Praveen, Sagar Adhikari, Arnico K. Panday, Maheswar Rupakheti, Donald R. Blake, Robert J. Yokelson, Peter F. Decarlo, William C. Keene, Elizabeth A. Stone
Chemistry and Biochemistry Faculty Publications
The Kathmandu Valley in Nepal is a bowl-shaped urban basin that experiences severe air pollution that poses health risks to its 3.5 million inhabitants. As part of the Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE), ambient air quality in the Kathmandu Valley was investigated from 11 to 24 April 2015, during the premonsoon season. Ambient concentrations of fine and coarse particulate matter (PM2:5 and PM10, respectively), online PM1, inorganic trace gases (NH3, HNO3, SO2, and HCl), and carbon-containing gases (CO2, CO, CH4, and 93 nonmethane volatile organic compounds; NMVOCs) were quantified at a semi-urban location near the center of …
Molecular Composition And Photochemical Lifetimes Of Brown Carbon Chromophores In Biomass Burning Organic Aerosol, Lauren T. Fleming, Peng Lin, James M. Roberts, Vanessa Selimovic, Robert Yokelson, Julia Laskin, Alexander Laskin, Sergey A. Nizkorodov
Molecular Composition And Photochemical Lifetimes Of Brown Carbon Chromophores In Biomass Burning Organic Aerosol, Lauren T. Fleming, Peng Lin, James M. Roberts, Vanessa Selimovic, Robert Yokelson, Julia Laskin, Alexander Laskin, Sergey A. Nizkorodov
Chemistry and Biochemistry Faculty Publications
To better understand the effects of wildfires on air quality and climate, it is important to assess the occurrence of chromophoric compounds in smoke and characterize their optical properties. This study explores the molecular composition of light-absorbing organic aerosol, or brown carbon (BrC), sampled at the Missoula Fire Sciences laboratory as a part of the FIREX Fall 2016 lab intensive. A total of 12 biomass fuels from different plant types were tested, including gymnosperm (coniferous) and angiosperm (flowering) plants and different ecosystem components such as duff, litter, and canopy. Emitted biomass burning organic aerosol (BBOA) particles were collected onto Teflon …
Dominant Negative Effects By Inactive Spa47 Mutants Inhibit T3ss Function And Shigella Virulence, Jamie L. Burgess, Heather B. Case, R. Alan Burgess, Nicholas E. Dickenson
Dominant Negative Effects By Inactive Spa47 Mutants Inhibit T3ss Function And Shigella Virulence, Jamie L. Burgess, Heather B. Case, R. Alan Burgess, Nicholas E. Dickenson
Chemistry and Biochemistry Faculty Publications
Type three secretion systems (T3SS) are complex nano-machines that evolved to inject bacterial effector proteins directly into the cytoplasm of eukaryotic cells. Many high-priority human pathogens rely on one or more T3SSs to cause disease and evade host immune responses, underscoring the need to better understand the mechanisms through which T3SSs function and their role(s) in supporting pathogen virulence. We recently identified the Shigella protein Spa47 as an oligomerization-activated T3SS ATPase that fuels the T3SS and supports overall Shigella virulence. Here, we provide both in vitro and in vivo characterization of Spa47 oligomerization and activation in the presence and absence …
Structural Dynamics Of Inosine Triphosphate Pyrophosphatase (Itpa) Protein And Two Clinically Relevant Mutants: Molecular Dynamics Simulations, Yao Houndonougbo, Bethany Pugh, Kandise Vanwormer, Caitlin April, Nicholas Burgis
Structural Dynamics Of Inosine Triphosphate Pyrophosphatase (Itpa) Protein And Two Clinically Relevant Mutants: Molecular Dynamics Simulations, Yao Houndonougbo, Bethany Pugh, Kandise Vanwormer, Caitlin April, Nicholas Burgis
Chemistry and Biochemistry Faculty Publications
The inosine triphosphate pyrophosphatase (ITPA) protein is responsible for removing noncanonical purine nucleoside triphosphates from intracellular nucleotide pools. Absence of ITPA results in genomic instability and increased levels of inosine in DNA and RNA. The proline to threonine substitution at position 32 (P32T) affects roughly 15% of the global population and can modulate treatment outcomes for cancer, lupus, and hepatitis C patients. The substitution of arginine with cysteine at position 178 (R178C) is extremely uncommon and has only been reported in a small cohort of early infantile encephalopathy patients suggesting that a functional ITPA protein is required for life in …
Oh Chemistry Of Non-Methane Organic Gases (Nmogs) Emitted From Laboratory And Ambient Biomass Burning Smoke: Evaluating The Influence Of Furans And Oxygenated Aromatics On Ozone And Secondary Nmog Formation, Matthew M. Coggon, Christopher Y. Lim, Abigail R. Koss, Kanako Sekimoto, Bin Yuan, Jessica B. Gilman, David H. Hagan, Vanessa Selimovic, Kyle J. Zarzana, Steven S. Brown, James M Roberts, Markus Müller, Robert Yokelson, Armin Wisthaler, Jordan E. Krechmer, Jose L. Jimenez, Christopher Cappa, Jesse H. Kroll, Joost De Gouw, Carsten Warneke
Oh Chemistry Of Non-Methane Organic Gases (Nmogs) Emitted From Laboratory And Ambient Biomass Burning Smoke: Evaluating The Influence Of Furans And Oxygenated Aromatics On Ozone And Secondary Nmog Formation, Matthew M. Coggon, Christopher Y. Lim, Abigail R. Koss, Kanako Sekimoto, Bin Yuan, Jessica B. Gilman, David H. Hagan, Vanessa Selimovic, Kyle J. Zarzana, Steven S. Brown, James M Roberts, Markus Müller, Robert Yokelson, Armin Wisthaler, Jordan E. Krechmer, Jose L. Jimenez, Christopher Cappa, Jesse H. Kroll, Joost De Gouw, Carsten Warneke
Chemistry and Biochemistry Faculty Publications
Chamber oxidation experiments conducted at the Fire Sciences Laboratory in 2016 are evaluated to identify important chemical processes contributing to the hydroxy radical (OH) chemistry of biomass burning non-methane organic gases (NMOGs). Based on the decay of primary carbon measured by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS), it is confirmed that furans and oxygenated aromatics are among the NMOGs emitted from western United States fuel types with the highest reactivities towards OH. The oxidation processes and formation of secondary NMOG masses measured by PTR-ToF-MS and iodide-clustering time-of-flight chemical ionization mass spectrometry (I-CIMS) is interpreted using a box model employing …
Isotopic Characterization Of Nitrogen Oxides (NoX), Nitrous Acid (Hono), And Nitrate (PNo3-) From Laboratory Biomass Burning During Firex, Jiajue Chai, David J. Miller, Eric Scheuer, Jack Dibb, Vanessa Selimovic, Robert Yokelson, Kyle K. Zarzana, Steven Brown, Abigail R. Koss, Carsten Warneke, Meredith Hastings
Isotopic Characterization Of Nitrogen Oxides (NoX), Nitrous Acid (Hono), And Nitrate (PNo3-) From Laboratory Biomass Burning During Firex, Jiajue Chai, David J. Miller, Eric Scheuer, Jack Dibb, Vanessa Selimovic, Robert Yokelson, Kyle K. Zarzana, Steven Brown, Abigail R. Koss, Carsten Warneke, Meredith Hastings
Chemistry and Biochemistry Faculty Publications
New techniques have recently been developed and applied to capture reactive nitrogen species, including nitrogen oxides (NOx D NOCNO2), nitrous acid (HONO), nitric acid (HNO3), and particulate nitrate (pNO3 ), for accurate measurement of their isotopic composition. Here, we report – for the first time – the isotopic composition of HONO from biomass burning (BB) emissions collected during the Fire Influence on Regional to Global Environments Experiment (FIREX, later evolved into FIREX-AQ) at the Missoula Fire Science Laboratory in the fall of 2016. We used our newly developed annular denuder system (ADS), which was verified to completely capture HONO associated …
Theoretical Studies Of Ir And Nmr Spectral Changes Induced By Sigma-Hole Hydrogen, Halogen, Chalcogen, Pnicogen, And Tetrel Bonds In A Model Protein Environment, Mariusz Michalczyk, Wiktor Zierkiewicz, Rafał Wysokiński, Steve Scheiner
Theoretical Studies Of Ir And Nmr Spectral Changes Induced By Sigma-Hole Hydrogen, Halogen, Chalcogen, Pnicogen, And Tetrel Bonds In A Model Protein Environment, Mariusz Michalczyk, Wiktor Zierkiewicz, Rafał Wysokiński, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
Various types of σ-hole bond complexes were formed with FX, HFY, H2FZ, and H3FT (X = Cl, Br, I; Y = S, Se, Te; Z = P, As, Sb; T = Si, Ge, Sn) as Lewis acid. In order to examine their interactions with a protein, N-methylacetamide (NMA), a model of the peptide linkage was used as the base. These noncovalent bonds were compared by computational means with H-bonds formed by NMA with XH molecules (X = F, Cl, Br, I). In all cases, the A–F bond, which lies opposite the base and is responsible for …
Anisotropic Singlet Fission In Single Crystalline Hexacene, Dezheng Sun, Gang-Hua Deng, Bolei Xu, Enshi Xu, Xia Li, Yajing Wu, Yuqin Qian, Yu Zhong, Colin Nuckolls, Avetik R. Harutyunyan, Hai-Lung Dai, Gugang Chen, Hanning Chen, Yi Rao
Anisotropic Singlet Fission In Single Crystalline Hexacene, Dezheng Sun, Gang-Hua Deng, Bolei Xu, Enshi Xu, Xia Li, Yajing Wu, Yuqin Qian, Yu Zhong, Colin Nuckolls, Avetik R. Harutyunyan, Hai-Lung Dai, Gugang Chen, Hanning Chen, Yi Rao
Chemistry and Biochemistry Faculty Publications
Singlet fission is known to improve solar energy utilization by circumventing the Shockley-Queisser limit. The two essential steps of singlet fission are the formation of a correlated triplet pair and its subsequent quantum decoherence. However, the mechanisms of the triplet pair formation and decoherence still remain elusive. Here we examined both essential steps in single crystalline hexacene and discovered remarkable anisotropy of the overall singlet fission rate along different crystal axes. Since the triplet pair formation emerges on the same timescale along both crystal axes, the quantum decoherence is likely responsible for the directional anisotropy. The distinct quantum decoherence rates …
Spectroscopic Description Of The E1 State Of Mo Nitrogenase Based On Mo And Fe X‑Ray Absorption And MöSsbauer Studies, Casey Van Stappen, Roman Davydov, Zhi-Yong Yang, Ruixi Fan, Yisong Guo, Eckhard Bill, Lance C. Seefeldt, Brian M. Hoffman, Serena Debeer
Spectroscopic Description Of The E1 State Of Mo Nitrogenase Based On Mo And Fe X‑Ray Absorption And MöSsbauer Studies, Casey Van Stappen, Roman Davydov, Zhi-Yong Yang, Ruixi Fan, Yisong Guo, Eckhard Bill, Lance C. Seefeldt, Brian M. Hoffman, Serena Debeer
Chemistry and Biochemistry Faculty Publications
Mo nitrogenase (N2ase) utilizes a two-component protein system, the catalytic MoFe and its electron-transfer partner FeP, to reduce atmospheric dinitrogen (N2) to ammonia (NH3). The FeMo cofactor contained in the MoFe protein serves as the catalytic center for this reaction and has long inspired model chemistry oriented toward activating N2. This field of chemistry has relied heavily on the detailed characterization of how Mo N2ase accomplishes this feat. Understanding the reaction mechanism of Mo N2ase itself has presented one of the most challenging problems in bioinorganic chemistry because of the ephemeral nature of its …
Nepal Ambient Monitoring And Source Testing Experiment (Namaste): Emissions Of Particulate Matter And Sulfur Dioxide From Vehicles And Brick Kilns And Their Impacts On Air Quality In The Kathmandu Valley, Nepal, Min Zhong, Eri Saikawa, Alexander Avramov, Chen Chen, Boya Sun, Wenlu Ye, William C. Keene, Robert J. Yokelson, Thilina Jayarathne, Elizabeth A. Stone, Maheswar Rupakheti, Arnico K. Panday
Nepal Ambient Monitoring And Source Testing Experiment (Namaste): Emissions Of Particulate Matter And Sulfur Dioxide From Vehicles And Brick Kilns And Their Impacts On Air Quality In The Kathmandu Valley, Nepal, Min Zhong, Eri Saikawa, Alexander Avramov, Chen Chen, Boya Sun, Wenlu Ye, William C. Keene, Robert J. Yokelson, Thilina Jayarathne, Elizabeth A. Stone, Maheswar Rupakheti, Arnico K. Panday
Chemistry and Biochemistry Faculty Publications
Air pollution is one of the most pressing environmental issues in the Kathmandu Valley, where the capital city of Nepal is located. We estimated emissions from two of the major source types in the valley (vehicles and brick kilns) and analyzed the corresponding impacts on regional air quality. First, we estimated the on-road vehicle emissions in the valley using the International Vehicle Emissions (IVE) model with local emissions factors and the latest available data for vehicle registration. We also identified the locations of the brick kilns in the Kathmandu Valley and developed an emissions inventory for these kilns using emissions …
Consumption Of Black Raspberries Altered The Composition Of The Fecal Microbiome In Mice Fed A Western Type Diet (Or04-01-19), Abby D. Benninghoff, Sumira Phatak, Korry Hintze
Consumption Of Black Raspberries Altered The Composition Of The Fecal Microbiome In Mice Fed A Western Type Diet (Or04-01-19), Abby D. Benninghoff, Sumira Phatak, Korry Hintze
Chemistry and Biochemistry Faculty Publications
Dietary strategies to reduce colonic inflammation and promote gut homeostasis may markedly reduce the risk of colitis-associated colorectal cancer. Previously, we showed that dietary supplementation with black raspberries significantly suppressed colitis and colon tumorigenesis promoted by the consumption a Western type diet in mice. In this study, our goal was to assess the impact of consumption of the TWD with and without black raspberry supplementation on the composition of the fecal microbiome over the course of disease development.
Dietary Intervention With Black Raspberries To Reduce Colitis Symptoms In Mice Fed Either Standard Ain93g Diet Or The Total Western Diet (P05-021-19), Daphne Michelle Rodriguez Jimenez, Michaela Brubaker, Elizabeth Park, Canyon Neal, Korry Hintze, Abby D. Benninghoff
Dietary Intervention With Black Raspberries To Reduce Colitis Symptoms In Mice Fed Either Standard Ain93g Diet Or The Total Western Diet (P05-021-19), Daphne Michelle Rodriguez Jimenez, Michaela Brubaker, Elizabeth Park, Canyon Neal, Korry Hintze, Abby D. Benninghoff
Chemistry and Biochemistry Faculty Publications
Approximately 1.4 million people suffer from inflammatory bowel disease, which is a major risk factor for developing colitis associated colorectal cancer (CAC). Dietary interventions with the goal to reduce colon inflammation and encourage gut microbiome homeostasis may be a strategy to reduce the risk of CAC. The antioxidants and anti-inflammatory compounds present in black raspberries (BRB) have demonstrated protective effects in the colon epithelium and may alter the composition of the gut microbiome. Previously, we showed that dietary supplementation with black raspberries significantly suppressed colitis and colon tumorigenesis promoted by the consumption of a Western type diet in mice. The …
Interactions Of (My) 6 (M = Zn, Cd; Y = O, S, Se) Quantum Dots With N-Bases, Mariusz Michalczyk, Wiktor Zierkiewicz, Steve Scheiner
Interactions Of (My) 6 (M = Zn, Cd; Y = O, S, Se) Quantum Dots With N-Bases, Mariusz Michalczyk, Wiktor Zierkiewicz, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
(MY)6 clusters, with M = Zn and Cd and Y = O, S, Se, form double-layer drum-like structures containing M–Y covalent bonds. The positive regions near the M atoms attract the N atom of both NH3 and NMe3 so as to form a noncovalent M···N bond. This bond is quite strong, with interaction energies exceeding 35 kcal/mol. The bond strength diminishes with reduced electronegativity of the Y atom (O > S > Se) and is stronger for M = Zn than for Cd. Trimethylation of the base enhances the bond strength. The interaction is dominated by the electrostatic component …
Production Of Secondary Organic Aerosol During Aging Of Biomass Burning Smoke From Fresh Fuels And Its Relationship To Voc Precursors, A. T. Ahern, E. S. Robinson, D. S. Tkacik, R. Saleh, L. E. Hatch, K. C. Barsanti, C. E. Stockwell, R. J. Yokelson, A. A. Presto, A. L. Robinson, R. C. Sullivan, N. M. Donahue
Production Of Secondary Organic Aerosol During Aging Of Biomass Burning Smoke From Fresh Fuels And Its Relationship To Voc Precursors, A. T. Ahern, E. S. Robinson, D. S. Tkacik, R. Saleh, L. E. Hatch, K. C. Barsanti, C. E. Stockwell, R. J. Yokelson, A. A. Presto, A. L. Robinson, R. C. Sullivan, N. M. Donahue
Chemistry and Biochemistry Faculty Publications
After smoke from burning biomass is emitted into the atmosphere, chemical and physical processes change the composition and amount of organic aerosol present in the aged, diluted plume. During the fourth Fire Lab at Missoula Experiment, we performed smog-chamber experiments to investigate formation of secondary organic aerosol (SOA) and multiphase oxidation of primary organic aerosol (POA). We simulated atmospheric aging of diluted smoke from a variety of biomass fuels while measuring particle composition using high-resolution aerosol mass spectrometry. We quantified SOA formation using a tracer ion for low-volatility POA as a reference standard (akin to a naturally occurring internal standard). …
In Situ Measurements Of Trace Gases, Pm, And Aerosol Optical Properties During The 2017 Nw Us Wildfire Smoke Event, Vanessa Selimovic, Robert J. Yokelson, Gavin R. Mcmeeking, Sarah Coefield
In Situ Measurements Of Trace Gases, Pm, And Aerosol Optical Properties During The 2017 Nw Us Wildfire Smoke Event, Vanessa Selimovic, Robert J. Yokelson, Gavin R. Mcmeeking, Sarah Coefield
Chemistry and Biochemistry Faculty Publications
In mid-August through mid-September of 2017 a major wildfire smoke and haze episode strongly impacted most of the NW US and SW Canada. During this period our ground-based site in Missoula, Montana, experienced heavy smoke impacts for ∼ 500h (up to 471μ-3 hourly average PM2.5). We measured wildfire trace gases, PM2.5 (particulate matter ≤2.5μm in diameter), and black carbon and submicron aerosol scattering and absorption at 870 and 401nm. This may be the most extensive real-time data for these wildfire smoke properties to date. Our range of trace gas ratios for δNH3 δCO and δC2H4 δCO confirmed that the smoke …
Molecular Rotation In 3 Dimensions At An Air/Water Interface Using Femtosecond Time Resolved Sum Frequency Generation, Yi Rao, Yuqin Qian, Gang-Hua Deng, Ashlie Kinross, Nicholas J. Turro, Kenneth B. Eisenthal
Molecular Rotation In 3 Dimensions At An Air/Water Interface Using Femtosecond Time Resolved Sum Frequency Generation, Yi Rao, Yuqin Qian, Gang-Hua Deng, Ashlie Kinross, Nicholas J. Turro, Kenneth B. Eisenthal
Chemistry and Biochemistry Faculty Publications
This paper presents the first study of the rotations of rigid molecules in 3 dimensions at the air/water interface, using the femtosecond time resolved sum frequency generation (SFG) technique. For the purpose of this research, the aromatic dye molecule C153 was chosen as an example of a molecule having two functional groups that are SFG active, one being the hydrophilic −−C==O group and the other the hydrophobic −−CF3 group. From polarized SFG measurements, the orientations of the two chromophores with respect to the surface normal were obtained. On combining these results with the known relative orientation of the two …
Transition State Interactions In A Promiscuous Enzyme: Sulfate And Phosphate Monoester Hydrolysis By Pseudomonas Aeruginosa Arylsulfatase, Bert Van Loo, Ryan Berry, Usa Boonyuen, Mark F. Mohamed, Marko Golicnik, Alvan C. Hengge, Florian Hollfelder
Transition State Interactions In A Promiscuous Enzyme: Sulfate And Phosphate Monoester Hydrolysis By Pseudomonas Aeruginosa Arylsulfatase, Bert Van Loo, Ryan Berry, Usa Boonyuen, Mark F. Mohamed, Marko Golicnik, Alvan C. Hengge, Florian Hollfelder
Chemistry and Biochemistry Faculty Publications
Pseudomonas aeruginosa arylsulfatase (PAS) hydrolyses sulfate and, promiscuously, phosphate monoesters. Enzyme-catalyzed sulfate transfer is crucial to a wide variety of biological processes, but detailed studies of the mechanistic contributions to its catalysis are lacking. We present linear free energy relationships (LFERs) and kinetic isotope effects (KIEs) of PAS and active site mutants that suggest a key role for leaving group (LG) stabilization. In LFERs PASWT has a much less negative Brønsted coefficient (ßleaving group obs-Enz=-0.33) than the uncatalyzed reaction (ßleaving group obs=-1.81). This situation is diminished when cationic active site groups are exchanged for alanine. …
Catalytic Mechanism For The Conversion Of Salicylate Into Catechol By The Flavin-Dependent Monooxygenase Salicylate Hydroxylase, Débora M. A. Costa, Stefanya V. Gómez, Simara S. De Araújo, Mozart S. Pereira, Rosemeire B. Alves, Denize C. Favaro, Alvan C. Hengge, Ronaldo A. P. Nagem, Tiago A. S. Brandão
Catalytic Mechanism For The Conversion Of Salicylate Into Catechol By The Flavin-Dependent Monooxygenase Salicylate Hydroxylase, Débora M. A. Costa, Stefanya V. Gómez, Simara S. De Araújo, Mozart S. Pereira, Rosemeire B. Alves, Denize C. Favaro, Alvan C. Hengge, Ronaldo A. P. Nagem, Tiago A. S. Brandão
Chemistry and Biochemistry Faculty Publications
Salicylate hydroxylase (NahG) is a flavin-dependent monooxygenase that catalyzes the decarboxylative hydroxylation of salicylate into catechol in the naphthalene degradation pathway in Pseudomonas putida G7. We explored the mechanism of action of this enzyme in detail using a combination of structural and biophysical methods. NahG shares many structural and mechanistic features with other versatile flavin-dependent monooxygenases, with potential biocatalytic applications. The crystal structure at 2.0 Å resolution for the apo form of NahG adds a new snapshot preceding the FAD binding in flavin-dependent monooxygenases. The kcat/Km for the salicylate reaction catalyzed by the holo form is …
Speciated And Total Emission Factors Of Particulate Organics From Burning Western Us Wildland Fuels And Their Dependence On Combustion Efficiency, Coty N. Jen, Lindsay E. Hatch, Vanessa Selimovic, Robert J. Yokelson, Robert Weber, Arantza E. Fernandez, Nathan M. Kreisberg, Kelley C. Barsanti, Allen H. Goldstein
Speciated And Total Emission Factors Of Particulate Organics From Burning Western Us Wildland Fuels And Their Dependence On Combustion Efficiency, Coty N. Jen, Lindsay E. Hatch, Vanessa Selimovic, Robert J. Yokelson, Robert Weber, Arantza E. Fernandez, Nathan M. Kreisberg, Kelley C. Barsanti, Allen H. Goldstein
Chemistry and Biochemistry Faculty Publications
Western US wildlands experience frequent and large-scale wildfires which are predicted to increase in the future. As a result, wildfire smoke emissions are expected to play an increasing role in atmospheric chemistry while negatively impacting regional air quality and human health. Understanding the impacts of smoke on the environment is informed by identifying and quantifying the chemical compounds that are emitted during wildfires and by providing empirical relationships that describe how the amount and composition of the emissions change based upon different fire conditions and fuels. This study examined particulate organic compounds emitted from burning common western US wildland fuels …
Dual Geometry Schemes In Tetrel Bonds: Complexes Between Tf4(T = Si, Ge, Sn) And Pyridine Derivatives, Wiktor Zierkiewicz, Mariusz Michalczyk, Rafał Wysokiński, Steve Scheiner
Dual Geometry Schemes In Tetrel Bonds: Complexes Between Tf4(T = Si, Ge, Sn) And Pyridine Derivatives, Wiktor Zierkiewicz, Mariusz Michalczyk, Rafał Wysokiński, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
When an N-base approaches the tetrel atom of TF4(T = Si, Ge, Sn) the latter moleculedeforms from a tetrahedral structure in the monomer to a trigonal bipyramid. The base can situateitself at either an axial or equatorial position, leading to two different equilibrium geometries.The interaction energies are considerably larger for the equatorial structures, up around 50 kcal/mol,which also have a shorter R(T··N) separation. On the other hand, the energy needed to deform thetetrahedral monomer into the equatorial structure is much higher than the equivalent deformationenergy in the axial dimer. When these two opposite trends are combined, it is the axial …