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Articles 181 - 210 of 384
Full-Text Articles in Chemistry
Interactions Between Thiourea And Imines. Prelude To Catalysis, Vincent De Paul Nzuwah-Nziko, Steve Scheiner
Interactions Between Thiourea And Imines. Prelude To Catalysis, Vincent De Paul Nzuwah-Nziko, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
The interaction between thiourea and a series of imines was examined via high-level ab initio calculations. For each imine, there is a set of stable complexes that represent minima on the potential energy surface. One type is characterized by a pair of symmetric NH···N hydrogen bonds (HBs), with both NH groups of thiourea approaching the imine N from above and below its molecular plane. Another geometry category combines a linear NH···N with a CH···S HB. A third, which is less stable, has the S approaching the imine’s CH2 group, and a stacking arrangement is present in the fourth. Interaction energies …
Dissection Of The Factors Affecting Formation Of A Ch∙∙∙O H-Bond. A Case Study, Steve Scheiner
Dissection Of The Factors Affecting Formation Of A Ch∙∙∙O H-Bond. A Case Study, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
Quantum calculations are used to examine how various constituent components of a large molecule contribute to the formation of an internal CH∙∙∙O H-bond. Such a bond is present in the interaction between two amide units, connected together by a series of functional groups. Each group is removed one at a time, so as to monitor the effect of each upon the H-bond, and thereby learn the bare essentials that are necessary for its formation, as well as how its presence affects the overall molecular structure. Also studied is the perturbation caused by change in the length of the aliphatic chain …
Biomass Burning Emissions And Potential Air Quality Impacts Of Volatile Organic Compounds And Other Trace Gases From Temperate Fuels Common In The United States, J. B. Gilman, B. M. Lerner, W. C. Kuster, P. D. Goldan, C. Warneke, P. R. Veres, J. M. Roberts, J. A. De Gouw, I. R. Burling, Robert Yokelson
Biomass Burning Emissions And Potential Air Quality Impacts Of Volatile Organic Compounds And Other Trace Gases From Temperate Fuels Common In The United States, J. B. Gilman, B. M. Lerner, W. C. Kuster, P. D. Goldan, C. Warneke, P. R. Veres, J. M. Roberts, J. A. De Gouw, I. R. Burling, Robert Yokelson
Chemistry and Biochemistry Faculty Publications
A comprehensive suite of instruments was used to quantify the emissions of over 200 organic gases, including methane and volatile organic compounds (VOCs), and 9 inorganic gases from 56 laboratory burns of 18 different biomass fuel types common in the southeastern, southwestern, or northern United States. A gas chromatograph-mass spectrometer (GC-MS) provided extensive chemical detail of discrete air samples collected during a laboratory burn and was complemented by real-time measurements of organic and inorganic species via an open-path Fourier transform infrared spectrometer (OP-FTIR) and 3 different chemical ionization-mass spectrometers. These measurements were conducted in February 2009 at the U.S. Department …
Comparison Of Ch∙∙O, Sh∙∙O, Chalcogen, And Tetrel Bonds Formed By Neutral And Cationic Sulfur-Containing Compounds, Steve Scheiner
Comparison Of Ch∙∙O, Sh∙∙O, Chalcogen, And Tetrel Bonds Formed By Neutral And Cationic Sulfur-Containing Compounds, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
The ability of neutral and charged S-compounds to form different sorts of noncovalent bonds is examined by ab initio calculations. Neutrals are represented by CH3SH and fluoro substituted FSCH3; cations are (CH3)3S+, CH3SH2+, and FHSCH3+. Each is paired with N-methylacetamide (NMA) whose O atom serves as common electron donor. Charged species engage in much stronger noncovalent bonds than do the neutral molecules, by as much as an order of magnitude. The strongest noncovalent bond for any system is a O∙∙SF chalcogen bond wherein the O lies directly opposite a S-F covalent bond, amounting to as much as 39 kcal/mol. Second …
Competitive Halide Binding By Halogen Versus Hydrogen Bonding: Bis-Triazole Pyridinium, Binod Nepal, Steve Scheiner
Competitive Halide Binding By Halogen Versus Hydrogen Bonding: Bis-Triazole Pyridinium, Binod Nepal, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
The binding of F-, Cl-, Br-, and I- anions by bis‐triazole‐pyridine (BTP) was examined by quantum chemical calculations. There is one H atom on each of the two triazole rings that chelate the halide via H bonds. These H atoms were replaced by halogens Cl, Br, and I, thus substituting H bonds by halogen bonds. I substitution strongly enhances the binding; Br has a smaller effect, and Cl weakens the interaction. The strength of the interaction is sensitive to the overall charge on the BTP, rising as the binding agent becomes singly and then doubly positively charged. The strongest preference …
A Structurally-Tunable 3-Hydroxyflavone Motif For Visible Light-Induced Carbon Monoxide-Releasing Molecules (Corms), Stacey N. Anderson, Jason M. Richards, Hector J. Esquer, Abby D. Benninghoff, Atta M. Arif, Lisa M. Berreau
A Structurally-Tunable 3-Hydroxyflavone Motif For Visible Light-Induced Carbon Monoxide-Releasing Molecules (Corms), Stacey N. Anderson, Jason M. Richards, Hector J. Esquer, Abby D. Benninghoff, Atta M. Arif, Lisa M. Berreau
Chemistry and Biochemistry Faculty Publications
Molecules that can be used to deliver a controlled amount of carbon monoxide (CO) have the potential to facilitate investigations into the roles of this gaseous molecule in biology and advance therapeutic treatments. This has led to the development of light-induced CO-releasing molecules (photoCORMs). A goal in this field of research is the development of molecules that exhibit a combination of controlled CO release, favorable biological properties (e.g., low toxicity and trackability in cells), and structural tunability to affect CO release. Herein, we report a new biologically-inspired organic photoCORM motif that exhibits several features that are desirable in a next-generation …
Regioselectivity Of The Interaction Of Temozolomide With Borane And Boron Trifluoride, Okuma Emile Kasende, Jules Tshishimbi Muya, Steve Scheiner
Regioselectivity Of The Interaction Of Temozolomide With Borane And Boron Trifluoride, Okuma Emile Kasende, Jules Tshishimbi Muya, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
MP2 and B3LYP calculations are used to predict the most favorable site of temozolomide toward BH3 and BF3 which are classical Lewis acids. Binding energies, charge transfers, and bond length perturbations of the temozolomide in various complexes indicate that the N12 atom is the preferred attack site for BH3, while BF3 prefers the O17 atom. The interactions are quite strong, as much as 100 kJ/mol for BH3 and more than 60 kJ/mol for BF3. The molecular electrostatic potential surrounding temozolomide is most negative around the O atoms, which is unable to explain the energetic order of binding of the Lewis …
Investigating The Links Between Ozone And Organic Aerosol Chemistry In A Biomass Burning Plume From A Prescribed Fire In California Chaparral, M. J. Alvarado, C. R. Lonsdale, Robert Yokelson, Sheryl Kashi Akagi, H. Coe, J. S. Craven, E. V. Fischer, G. R. Mcmeeking, J. H. Seinfeld, T. Soni, J. W. Taylor, D. R. Weise, C. E. Wold
Investigating The Links Between Ozone And Organic Aerosol Chemistry In A Biomass Burning Plume From A Prescribed Fire In California Chaparral, M. J. Alvarado, C. R. Lonsdale, Robert Yokelson, Sheryl Kashi Akagi, H. Coe, J. S. Craven, E. V. Fischer, G. R. Mcmeeking, J. H. Seinfeld, T. Soni, J. W. Taylor, D. R. Weise, C. E. Wold
Chemistry and Biochemistry Faculty Publications
Within minutes after emission, complex photochemistry in biomass burning smoke plumes can cause large changes in the concentrations of ozone (O3) and organic aerosol (OA). Being able to understand and simulate this rapid chemical evolution under a wide variety of conditions is a critical part of forecasting the impact of these fires on air quality, atmospheric composition, and climate. Here we use version 2.1 of the Aerosol Simulation Program (ASP) to simulate the evolution of O3 and secondary organic aerosol (SOA) within a young biomass burning smoke plume from the Williams prescribed fire in chaparral, which was sampled over …
Revealing Important Nocturnal And Day-To-Day Variations In Fire Smoke Emissions Through A Multiplatform Inversion, Pablo E. Saide, David A. Peterson, Arlindo Da Silva, Bruce Anderson, Luke D. Ziemba, Glenn Diskin, Glen Sachse, Johnathan Hair, Carolyn Butler, Marta Fenn, Jose L. Jimenez, Pedro Campuzano-Jost, Anne E. Perring, Joshua P. Schwarz, Milos Z. Markovic, Phil Russell, Jens Redemann, Yohei Shinozuka, David G. Streets, Fang Yan, Jack Dibb, Robert Yokelson, O. Brian Toon, Edward Hyer, Gregory R. Carmichael
Revealing Important Nocturnal And Day-To-Day Variations In Fire Smoke Emissions Through A Multiplatform Inversion, Pablo E. Saide, David A. Peterson, Arlindo Da Silva, Bruce Anderson, Luke D. Ziemba, Glenn Diskin, Glen Sachse, Johnathan Hair, Carolyn Butler, Marta Fenn, Jose L. Jimenez, Pedro Campuzano-Jost, Anne E. Perring, Joshua P. Schwarz, Milos Z. Markovic, Phil Russell, Jens Redemann, Yohei Shinozuka, David G. Streets, Fang Yan, Jack Dibb, Robert Yokelson, O. Brian Toon, Edward Hyer, Gregory R. Carmichael
Chemistry and Biochemistry Faculty Publications
We couple airborne, ground-based, and satellite observations; conduct regional simulations; and develop and apply an inversion technique to constrain hourly smoke emissions from the Rim Fire, the third largest observed in California, USA. Emissions constrainedwithmultiplatform data show notable nocturnal enhancements (sometimes over a factor of 20), correlate better with daily burned area data, and are a factor of 2–4 higher than a priori estimates, highlighting the need for improved characterization of diurnal profiles and day-to-day variability when modeling extreme fires. Constraining only with satellite data results in smaller enhancements mainly due to missing retrievals near the emissions source, suggesting that …
The Infrared Spectrum Of The He-C2d2 Complex, N. Moazzen-Ahmadi, A. R. W. Mckellar, Berta Fernandez, David Farrelly
The Infrared Spectrum Of The He-C2d2 Complex, N. Moazzen-Ahmadi, A. R. W. Mckellar, Berta Fernandez, David Farrelly
Chemistry and Biochemistry Faculty Publications
Spectra of the helium-acetylene complex are elusive because this weakly bound system lies close to the free rotor limit. Previously, limited assignments of He–C2D2 transitions in the R(0) region of the ν3 fundamental band (≈2440 cm−1) were published. Here, new He–C2D2 infrared spectra of this band are obtained using a tunable optical parametric oscillator laser source to probe a pulsed supersonic slit jet expansion from a cooled nozzle, and the analysis is extended to the weaker and more difficult P(1) and R(1) regions. A term value approach is used to obtain a consistent set of “experimental” energy levels. …
Identification And Quantification Of Gaseous Organic Compounds Emitted From Biomass Burning Using Two-Dimensional Gas Chromatography–Time-Of-Flight Mass Spectrometry, L. E. Hatch, W. Luo, J. F. Pankow, Robert Yokelson, C. Stockwell, K. C. Barsanti
Identification And Quantification Of Gaseous Organic Compounds Emitted From Biomass Burning Using Two-Dimensional Gas Chromatography–Time-Of-Flight Mass Spectrometry, L. E. Hatch, W. Luo, J. F. Pankow, Robert Yokelson, C. Stockwell, K. C. Barsanti
Chemistry and Biochemistry Faculty Publications
The current understanding of secondary organic aerosol (SOA) formation within biomass burning (BB) plumes is limited by the incomplete identification and quantification of the non-methane organic compounds (NMOCs) emitted from such fires. Gaseous organic compounds were collected on sorbent cartridges during laboratory burns as part of the fourth Fire Lab at Missoula Experiment (FLAME-4) and analyzed by two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC-ToFMS). The sensitivity and resolving power of GC x GC-ToFMS allowed the acquisition of the most extensive data set of BB NMOCs to date, with measurements from 708 positively or tentatively identified compounds. Estimated emission factors …
Intramolecular S···O Chalcogen Bond As Stabilizing Factor In Geometry Of Substituted Phenyl-Sf3 Molecules, Vincent De Paul Nziko, Steve Scheiner
Intramolecular S···O Chalcogen Bond As Stabilizing Factor In Geometry Of Substituted Phenyl-Sf3 Molecules, Vincent De Paul Nziko, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
Density functional methods are used to examine the geometries and energetics of molecules containing a phenyl ring joined to the trigonal bipyramidal SF3 framework. The phenyl ring has a strong preference for an equatorial position. This preference remains when one or two ether -CH2OCH3 groups are added to the phenyl ring, ortho to SF3, wherein an apical structure lies nearly 30 kcal/mol higher in energy. Whether equatorial or apical, the molecule is stabilized by a S···O chalcogen bond, sometimes augmented by CH···F or CH···O H-bonds. The strength of the intramolecular S···O bond is estimated to lie in the range between …
Characterization Of Biomass Burning Emissions From Cooking Fires, Peat, Crop Residue, And Other Fuels With High-Resolution Proton-Transfer-Reaction Time-Of-Flight Mass Spectrometry, C. Stockwell, P. Veres, J. Williams
Characterization Of Biomass Burning Emissions From Cooking Fires, Peat, Crop Residue, And Other Fuels With High-Resolution Proton-Transfer-Reaction Time-Of-Flight Mass Spectrometry, C. Stockwell, P. Veres, J. Williams
Chemistry and Biochemistry Faculty Publications
We deployed a high-resolution proton-transferreaction time-of-flight mass spectrometer (PTR-TOF-MS) to measure biomass-burning emissions from peat, crop residue, cooking fires, and many other fire types during the fourth Fire Lab at Missoula Experiment (FLAME-4) laboratory campaign. A combination of gas standard calibrations and composition sensitive, mass-dependent calibration curves was applied to quantify gas-phase non-methane organic compounds (NMOCs) observed in the complex mixture of fire emissions. We used several approaches to assign the best identities to most major “exact masses”, including many high molecular mass species. Using these methods, approximately 80–96% of the total NMOC mass detected by the PTR-TOFMS and Fourier …
Observations And Analysis Of Organic Aerosol Evolution In Some Prescribed Fire Smoke Plumes, A. A. May, T. Lee, G. R. Mcmeeking, Sheryl Kashi Akagi, A. P. Sullivan, S. P. Urbanski, Robert Yokelson, S. M. Kreidenweis
Observations And Analysis Of Organic Aerosol Evolution In Some Prescribed Fire Smoke Plumes, A. A. May, T. Lee, G. R. Mcmeeking, Sheryl Kashi Akagi, A. P. Sullivan, S. P. Urbanski, Robert Yokelson, S. M. Kreidenweis
Chemistry and Biochemistry Faculty Publications
Open biomass burning is a significant source of primary air pollutants such as particulate matter and non-methane organic gases. However, the physical and chemical atmospheric processing of these emissions during transport is poorly understood. Atmospheric 5 transformations of biomass burning emissions have been investigated in environmental chambers, but there have been limited opportunities to investigate these transformations in the atmosphere. In this study, we deployed a suite of real-time instrumentation on a Twin Otter aircraft to sample smoke from prescribed fires in South Carolina, conducting measurements at both the source and downwind to character10 ize smoke evolution with atmospheric aging. …
Tetrel, Chalcogen, And Ch⋅⋅O Hydrogen Bonds In Complexes Pairing Carbonyl-Containing Molecules With 1, 2, And 3 Molecules Of Co2, L. M. Azofra, Steve Scheiner
Tetrel, Chalcogen, And Ch⋅⋅O Hydrogen Bonds In Complexes Pairing Carbonyl-Containing Molecules With 1, 2, And 3 Molecules Of Co2, L. M. Azofra, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
The complexes formed by H2CO, CH3CHO, and (CH3)2CO with 1, 2, and 3 molecules of CO2 are studied by ab initio calculations. Three different types of heterodimers are observed, most containing a tetrel bond to the C atom of CO2, and some supplemented by a CH⋅⋅O H-bond. One type of heterodimer is stabilized by an anti-parallel arrangement of the C=O bonds of the two molecules. The binding energies are enhanced by methyl substitution on the carbonyl, and vary between 2.4 and 3.5 kcal/mol. Natural bond orbital analysis identifies a prime source of interaction as charge transfer into the π*(CO) antibonding …
Impact Of Detergent On The Biophysical Properties And Immune Response Of The Ipadb Fusion Protein, A Candidate Subunit Vaccine Against Shigella Spp., X. Chen, S. P. Choudhari, F. J. Martinez-Becerra, J. H. Kim, N. E. Dickenson, R. T. Toth, S. B. Joshi, J. C. Greenwood, J. D. Clements, W. D. Picking, C. R. Middaugh, W. L. Picking
Impact Of Detergent On The Biophysical Properties And Immune Response Of The Ipadb Fusion Protein, A Candidate Subunit Vaccine Against Shigella Spp., X. Chen, S. P. Choudhari, F. J. Martinez-Becerra, J. H. Kim, N. E. Dickenson, R. T. Toth, S. B. Joshi, J. C. Greenwood, J. D. Clements, W. D. Picking, C. R. Middaugh, W. L. Picking
Chemistry and Biochemistry Faculty Publications
Shigella spp. are causative agents of bacillary dysentery, a human illness with high global morbidity levels, particularly among elderly and infant populations. Shigella infects via the fecal-oral route, and its virulence is dependent upon a type III secretion system (T3SS). Two components of the exposed needle tip complex of the Shigella T3SS, invasion plasmid antigen D (IpaD) and IpaB, have been identified as broadly protective antigens in the mouse lethal pneumonia model. A recombinant fusion protein (DB fusion) was created by joining the coding sequences of IpaD and IpaB. The DB fusion is coexpressed with IpaB's cognate chaperone, IpgC, for …
Electrodeposited Cobalt-Phosphorous-Derived Films As Competent Bifunctional Catalysts For Overall Water Splitting, Nan Jiang, Bo You, Meili Sheng, Yujie Sun
Electrodeposited Cobalt-Phosphorous-Derived Films As Competent Bifunctional Catalysts For Overall Water Splitting, Nan Jiang, Bo You, Meili Sheng, Yujie Sun
Chemistry and Biochemistry Faculty Publications
One of the challenges to realize large-scale water splitting is the lack of active and low-cost electrocatalysts for its two half reactions: H2 and O2 evolution reactions (HER and OER). Herein, we report that cobalt-phosphorous-derived films (Co-P) can act as bifunctional catalysts for overall water splitting. The as-prepared Co-P films exhibited remarkable catalytic performance for both HER and OER in alkaline media, with a current density of 10 mAcm¢2 at overpotentials of ¢94 mV for HER and 345 mV for OER and Tafel slopes of 42 and 47 mV/dec, respectively. They can be employed as catalysts on both anode and …
Fe Protein-Independent Substrate Reduction By Nitrogenase Mofe Protein Variants, Karamatullah Danyal, Andrew J. Rasmussen, Stephen M. Keable, Boyd S. Inglet, Studipta Shaw, Oleg A. Zadvornyy, Simon Duval, Dennis R. Dean, Simone Raugei, John W. Peters, Lance C. Seefeldt
Fe Protein-Independent Substrate Reduction By Nitrogenase Mofe Protein Variants, Karamatullah Danyal, Andrew J. Rasmussen, Stephen M. Keable, Boyd S. Inglet, Studipta Shaw, Oleg A. Zadvornyy, Simon Duval, Dennis R. Dean, Simone Raugei, John W. Peters, Lance C. Seefeldt
Chemistry and Biochemistry Faculty Publications
The reduction of substrates catalyzed by nitrogenase normally requires nucleotide-dependent Fe protein delivery of electrons to the MoFe protein, which contains the active site FeMo cofactor. Here, it is reported that independent substitution of three amino acids (β- 98Tyr→His, α-64Tyr→His, and β-99Phe→His) located between the P cluster and FeMo cofactor within the MoFe protein endows it with the ability to reduce protons to H2, azide to ammonia, and hydrazine to ammonia without the need for Fe protein or ATP. Instead, electrons can be provided by the low-potential reductant polyaminocarboxylate-ligated Eu(II) (Em values of −1.1 to −0.84 V vs the normal …
Chalcogen Bonds In Complexes Of Soxy (X, Y = F, Cl) With Nitrogen Bases, Luis Miguel Azofra, Ibon Alkorta, Steve Scheiner
Chalcogen Bonds In Complexes Of Soxy (X, Y = F, Cl) With Nitrogen Bases, Luis Miguel Azofra, Ibon Alkorta, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
SOF2, SOFCl, and SOCl2 were each paired with a series of N bases. The potential energy surface of the binary complexes were characterized by MP2 calculations with double and triple-ξ basis sets, extrapolated to complete sets. The most stable configurations contained a S···N chalcogen bond with interaction energies as high as 6.8 kcal/mol. These structures are stabilized by a Nlp→σ*(S−Z) electron transfer (Z = O, F, Cl), complemented by Coulombicattraction of N to theσ-hole opposite the Z atom. N···S−F and N···S−Cl chalcogen bonds are stronger than N···S = O interactions.Formation of each chalcogen bond elongates all of the internalcovalent bonds …
Investigating The Links Between Ozone And Organic Aerosol Chemistry In A Biomass Burning Plume From A Prescribed Fire In California Chaparral, M. J. Alvarado, C. R. Lonsdale, Robert Yokelson, S. K. Akagi, H. Coe, J. S. Craven, E. V. Fischer, G. R. Mcmeeking, J. H. Seinfeld, T. Soni, J. W. Taylor, D. R. Weise, C. E. Wold
Investigating The Links Between Ozone And Organic Aerosol Chemistry In A Biomass Burning Plume From A Prescribed Fire In California Chaparral, M. J. Alvarado, C. R. Lonsdale, Robert Yokelson, S. K. Akagi, H. Coe, J. S. Craven, E. V. Fischer, G. R. Mcmeeking, J. H. Seinfeld, T. Soni, J. W. Taylor, D. R. Weise, C. E. Wold
Chemistry and Biochemistry Faculty Publications
Within minutes after emission, rapid, complex photochemistry within a biomass burning smoke plume can cause large changes in the concentrations of ozone (O3) and organic aerosol (OA). Being able to understand and simulate this rapid chemical evolution under a wide variety of conditions is a critical part of forecasting the impact of these fires on air quality, atmospheric composition, and climate. Here we use version 2.1 of the Aerosol Simulation Program (ASP) to simulate the evolution of O3 and secondary organic aerosol (SOA) within a young biomass burning smoke plume from the Williams prescribed burn in chaparral, …
Synthesis And Characterization Of Polymer (Sulfonated Poly-Ether-Ether-Ketone) Based Nanocomposite (H-Boron Nitride) Membrane For Hydrogen Storage, Naresh Muthu, S. Rajashabala, R. Kannan
Synthesis And Characterization Of Polymer (Sulfonated Poly-Ether-Ether-Ketone) Based Nanocomposite (H-Boron Nitride) Membrane For Hydrogen Storage, Naresh Muthu, S. Rajashabala, R. Kannan
Chemistry and Biochemistry Faculty Publications
The development of light weight and compact hydrogen storage materials is still prerequisite to fuel-cell technology to be fully competitive. The present experimental study reports the hydrogen storage capability of sulfonated poly-ether-ether-ketone (SPEEK)-hexagonal boron nitride (h-BN) (SPEEK-h-BN) nanocomposite membranes. The nanocomposite membranes are prepared by considering various amount of h-BN (0, 1, 3 and 5 wt. %) by phase inversion technique. The degree of sulfonation of the PEEK (SPEEK) is found to be 65% by Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy. Hydrogen adsorption studies have been carried out using a Seiverts-like hydrogenation setup. The membranes are characterized …
Antifungal Amphiphilic Aminoglycoside K20: Bioactivities And Mechanism Of Action, Sanjib K. Shrestha, Cheng-Wei Tom Chang, Nicole Meissner, John Oblad, Jaya P. Shrestha, Kevin N. Sorensen, Michelle M. Grilley, Jon Y. Takemoto
Antifungal Amphiphilic Aminoglycoside K20: Bioactivities And Mechanism Of Action, Sanjib K. Shrestha, Cheng-Wei Tom Chang, Nicole Meissner, John Oblad, Jaya P. Shrestha, Kevin N. Sorensen, Michelle M. Grilley, Jon Y. Takemoto
Chemistry and Biochemistry Faculty Publications
K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20′s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were determined. Effects on Cryptococcus neoformans H-99 infectivity were determined with a preventive murine lung infection model. The antifungal mechanism of action was studied using intact fungal cells, yeast lipid mutants, and small unilamellar lipid …
Designed Supramolecular Filamentous Peptides: Balance Of Nanostructure, Cytotoxicity And Antimicrobial Activity, Dawei Xu, Linhai Jiang, Anju Singh, Derek Dustin, Miao Yang, Ling Liu, Reidar Lund, Timothy J. Sellati, He Dong
Designed Supramolecular Filamentous Peptides: Balance Of Nanostructure, Cytotoxicity And Antimicrobial Activity, Dawei Xu, Linhai Jiang, Anju Singh, Derek Dustin, Miao Yang, Ling Liu, Reidar Lund, Timothy J. Sellati, He Dong
Chemistry and Biochemistry Faculty Publications
This work demonstrates a design strategy to optimize antimicrobial peptides with an ideal balance of minimal cytotoxicity, enhanced stability, potent cell penetration and effective antimicrobial activity, which hold great promise for the treatment of intracellular microbial infections and potentially systemic anti-infective therapy.
Cold Magnetically Trapped 2DG Scandium Atoms. I. Interaction Potential, Tijs Karman, Xi Chu, Gerrit C. Groenenboom
Cold Magnetically Trapped 2DG Scandium Atoms. I. Interaction Potential, Tijs Karman, Xi Chu, Gerrit C. Groenenboom
Chemistry and Biochemistry Faculty Publications
We present a first principles description of the interaction of two ground-state scandium atoms. Scandium has a 2Dg ground state. Thirty molecular states correlate to the lowest dissociation limit of the dimer. In the short range, potential energy curves are calculated using second-order n-electron valence state perturbation theory. The first-order long-range interaction is calculated at the complete active space self-consistent field level. We determine the second-order long-range dispersion interaction from atomic dynamic polarizabilities at imaginary frequencies. These polarizabilities are calculated using time-dependent density functional theory. We merge the short-range approach with the long-range model to obtain a physical …
Aerosol Emissions From Prescribed Fires In The United States: A Synthesis Of Laboratory And Aircraft Measurements, A. A. May, G. R. Mcmeeking, T. Lee, J. W. Taylor, J. S. Craven, I. R. Burling, A. P. Sullivan, Sheryl Kashi Akagi, J. L. Collett Jr., M. Flynn, H. Coe, S. P. Urbanski, J. H. Seinfeld, Robert Yokelson, S. M. Kreidenweis
Aerosol Emissions From Prescribed Fires In The United States: A Synthesis Of Laboratory And Aircraft Measurements, A. A. May, G. R. Mcmeeking, T. Lee, J. W. Taylor, J. S. Craven, I. R. Burling, A. P. Sullivan, Sheryl Kashi Akagi, J. L. Collett Jr., M. Flynn, H. Coe, S. P. Urbanski, J. H. Seinfeld, Robert Yokelson, S. M. Kreidenweis
Chemistry and Biochemistry Faculty Publications
Aerosol emissions from prescribed fires can affect air quality on regional scales. Accurate representation of these emissions in models requires information regarding the amount and composition of the emitted species.Wemeasured a suite of submicron particulatematter species in young plumes emitted from prescribed fires (chaparral and montane ecosystems in California; coastal plain ecosystem in South Carolina) and from open burning of over 15 individual plant species in the laboratory. We report emission ratios and emission factors for refractory black carbon (rBC) and submicron nonrefractory aerosol and compare field and laboratory measurements to assess the representativeness of our laboratory-measured emissions. Laboratory measurements …
Airborne Characterization Of Smoke Marker Ratios From Prescribed Burning, A. P. Sullivan, A. A. May, T. Lee, G. R. Mcmeeking, S. M. Kreidenweis, S. K. Akagi, Robert Yokelson, S. P. Urbanski, J. L. Collett Jr.
Airborne Characterization Of Smoke Marker Ratios From Prescribed Burning, A. P. Sullivan, A. A. May, T. Lee, G. R. Mcmeeking, S. M. Kreidenweis, S. K. Akagi, Robert Yokelson, S. P. Urbanski, J. L. Collett Jr.
Chemistry and Biochemistry Faculty Publications
A Particle-Into-Liquid Sampler – Total Organic Carbon (PILS-TOC) and fraction collector system was flown aboard a Twin Otter aircraft sampling prescribed burning emissions in South Carolina in November 2011 to obtain smoke marker measurements. The fraction collector provided 2 min time-integrated offline samples for carbohydrate (i.e., smoke markers levoglucosan, mannosan, and galactosan) analysis by high-performance anion-exchange chromatography with pulsed amperometric detection. Each fire location appeared to have a unique 1levoglucosan /1water-soluble organic carbon (WSOC) ratio (RF01/RF02/RF03/RF05 = 0.163± 0.007 μg C μg−1 C, RF08 = 0.115 ± 0.011 μg C μg−1 C, RF09A = 0.072 ± 0.028 μgC μg−1 C, …
Trace Gas Emissions From Combustion Of Peat, Crop Residue, Domestic Biofuels, Grasses, And Other Fuels: Configuration And Fourier Transform Infrared (Ftir) Component Of The Fourth Fire Lab At Missoula Experiment (Flame-4), C. E. Stockwell, R. J. Yokelson, S. M. Kreidenweis, A. L. Robinson, P. J. Demott, R. C. Sullivan, J. Reardon, K. C. Ryan, D. W.T. Griffith, L. Stevens
Trace Gas Emissions From Combustion Of Peat, Crop Residue, Domestic Biofuels, Grasses, And Other Fuels: Configuration And Fourier Transform Infrared (Ftir) Component Of The Fourth Fire Lab At Missoula Experiment (Flame-4), C. E. Stockwell, R. J. Yokelson, S. M. Kreidenweis, A. L. Robinson, P. J. Demott, R. C. Sullivan, J. Reardon, K. C. Ryan, D. W.T. Griffith, L. Stevens
Chemistry and Biochemistry Faculty Publications
During the fourth Fire Lab at Missoula Experiment (FLAME-4, October-November 2012) a large variety of regionally and globally significant biomass fuels was burned at the US Forest Service Fire Sciences Laboratory in Missoula, Montana. The particle emissions were characterized by an extensive suite of instrumentation that measured aerosol chemistry, size distribution, optical properties, and cloud-nucleating properties. The trace gas measurements included high-resolution mass spectrometry, one-and two-dimensional gas chromatography, and open-path Fourier transform infrared (OP-FTIR) spectroscopy. This paper summarizes the overall experimental design for FLAME-4-including the fuel properties, the nature of the burn simulations, and the instrumentation employed-and then focuses on …
The Interplay Between Charge Transfer, Rehybridization, And Atomic Charges In The Internal Geometry Of Subunits In Noncovalent Interactions, Steve Scheiner
The Interplay Between Charge Transfer, Rehybridization, And Atomic Charges In The Internal Geometry Of Subunits In Noncovalent Interactions, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
When a noncovalent bond is formed, there is frequently some charge transfer from one subunit to the other. The interaction also causes changes in the atomic charges and hybridization patterns of bonding orbitals. The manner in which these various effects combine to cause elongations or contractions of bonds within the individual subunits is examined. In both the cases of CH···O H-bonds and P···N pnicogen bonds, the bond length changes are consistent with the guiding principles generally known as Bent’s rules.
Identification And Quantification Of Gaseous Organic Compounds Emitted From Biomass Burning Using Two-Dimensional Gas Chromatography/Time-Of-Flight Mass Spectrometry, L. E. Hatch, W. Luo, J. F. Pankow, Robert Yokelson, C. Stockwell, K. C. Barsanti
Identification And Quantification Of Gaseous Organic Compounds Emitted From Biomass Burning Using Two-Dimensional Gas Chromatography/Time-Of-Flight Mass Spectrometry, L. E. Hatch, W. Luo, J. F. Pankow, Robert Yokelson, C. Stockwell, K. C. Barsanti
Chemistry and Biochemistry Faculty Publications
The current understanding of secondary organic aerosol (SOA) formation within biomass burning (BB) plumes is limited by the incomplete identification and quantification of the non-methane organic compounds (NMOCs) emitted from such fires. Gaseous organic compounds were collected on sorbent cartridges during laboratory burns as part of the fourth Fire Lab at Missoula Experiment (FLAME-4), with analysis by two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC/TOFMS). The sensitivity and resolving power of GC×GC/TOFMS allowed the acquisition of the most extensive data set of BB NMOCs to date, with measure ments for 722 positively or tentatively identified compounds. Estimated emission factors (EFs) are presented …
Cyanide Toxicokinetics: The Behavior Of Cyanide, Thiocyanate And 2-Amino-2-Thiazoline-4-Carboxylic Acid In Multiple Animal Models, Raj K. Bhandari, Robert P. Oda, Ilona Petrikovics, David E. Thompson, Matthew Brenner, Sari B. Mahon, Vikhyat S. Bebarta, Gary A. Rockwood, Brian A. Logue
Cyanide Toxicokinetics: The Behavior Of Cyanide, Thiocyanate And 2-Amino-2-Thiazoline-4-Carboxylic Acid In Multiple Animal Models, Raj K. Bhandari, Robert P. Oda, Ilona Petrikovics, David E. Thompson, Matthew Brenner, Sari B. Mahon, Vikhyat S. Bebarta, Gary A. Rockwood, Brian A. Logue
Chemistry and Biochemistry Faculty Publications
Cyanide causes toxic effects by inhibiting cytochrome c oxidase, resulting in cellular hypoxia and cytotoxic anoxia, and can eventually lead to death. Cyanide exposure can be verified by direct analysis of cyanide concentrations or analyzing its metabolites, including thiocyanate (SCN−) and 2-amino-2-thiazoline-4-carboxylic acid (ATCA) in blood. To determine the behavior of these markers following cyanide exposure, a toxicokinetics study was performed in three animal models: (i) rats (250–300 g), (ii) rabbits (3.5–4.2 kg) and (iii) swine (47–54 kg). Cyanide reached a maximum in blood and declined rapidly in each animal model as it was absorbed, distributed, metabolized and …