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Chemistry Faculty Publications

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Articles 901 - 930 of 1129

Full-Text Articles in Chemistry

Sensing Of Antipyretic Carboxylates By Simple Chromogenic Calix[4]Pyrroles, Ryuhei Nishiyabu, Pavel Anzenbacher Jr. Jun 2005

Sensing Of Antipyretic Carboxylates By Simple Chromogenic Calix[4]Pyrroles, Ryuhei Nishiyabu, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

We present a simple, two- or three-step method for the synthesis of chromogenic octamethylcalix[4]pyrrole-based (OMCP) sensors for anions. Electrophilic aromatic substitution allows for converting the pyrrole moieties of OMCP into a dye. The formation of a sensor-anion complex results in partial charge transfer and a dramatic change in color. The absorption (UV-vis) and NMR titration experiments show that the chromogenic OMCPs sense anions administered as aqueous solutions, even at high ionic strength ( approximately 0.1 M NaCl), while displaying selectivity for pyrophosphate and carboxylate anions. The experiments with polyurethane sensor films show a strong response for aqueous carboxylates, such as …

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Cu(I) Luminescence From The Tetranuclear Cu4s4 Cofactor Of A Synthetic 4-Helix Bundle, Olesya A. Kharenko, David C. Kennedy, Borries Demeler, Michael J. Maroney, Michael Y. Ogawa Jun 2005

Cu(I) Luminescence From The Tetranuclear Cu4s4 Cofactor Of A Synthetic 4-Helix Bundle, Olesya A. Kharenko, David C. Kennedy, Borries Demeler, Michael J. Maroney, Michael Y. Ogawa

Chemistry Faculty Publications

The addition of Cu(I) to the random-coil peptide, C16C19-GGY, produces a self-organized, metal-bridged 4-helix bundle which displays an intense room-temperature luminescence at 600 nm. Emission, UV, and CD titrations along with X-ray absorption studies indicate that the luminescent cofactor is likely a Cu4S4 cluster in which each Cu atom is bridged by the side chains of two cysteine residues and has terminal N/O ligation.

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Radiolytic Damage To Freeze-Dried Human Amniotic Membrane, Chester C. Deocaris, Lucille B. Abad, Erwin P. Enriquez, Zenaida M. De Guzman, Ann A. Aliganga, Marianne B. Tangonan, Mitos M. Tolentino, Luzviminda V. Ignacio, Custer C. Deocaris Jun 2005

Radiolytic Damage To Freeze-Dried Human Amniotic Membrane, Chester C. Deocaris, Lucille B. Abad, Erwin P. Enriquez, Zenaida M. De Guzman, Ann A. Aliganga, Marianne B. Tangonan, Mitos M. Tolentino, Luzviminda V. Ignacio, Custer C. Deocaris

Chemistry Faculty Publications

Radiation-sterilization at 25 and 35 kGy of freeze-dried human amniotic membranes caused degradative effects in the biologic dressing. The decrease in pH and increase in UV absorption showed that radiation may have caused possible radiolytic changes in this biomaterial. Total nitrogen content, tensile strength, and [H3]water-retention capacity of the irradiated membranes remained invariable. Molecular topography analysis by atomic force microscopy showed radiation-induced defrayment of the collagen fibers, the major structural protein in amnion.

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An Investigation Of The Chemistry Of Ship Emission Plumes During Itct 2002, G. Chen, L. G. Huey, M. Trainer, D. Nicks, J. Corbett, T. Ryerson, D. Parrish, J. A. Neuman, J. Nowak, D. Tanner, J. Holloway, C. Brock, J. Crawford, J. R. Olson, A. Sullivan, R. Weber, S. Schauffler, Stephen G. Donnelly Ph.D., E. Atlas, J. Roberts, F. Flocke, G. Hübler, F. Fehsenfeld May 2005

An Investigation Of The Chemistry Of Ship Emission Plumes During Itct 2002, G. Chen, L. G. Huey, M. Trainer, D. Nicks, J. Corbett, T. Ryerson, D. Parrish, J. A. Neuman, J. Nowak, D. Tanner, J. Holloway, C. Brock, J. Crawford, J. R. Olson, A. Sullivan, R. Weber, S. Schauffler, Stephen G. Donnelly Ph.D., E. Atlas, J. Roberts, F. Flocke, G. Hübler, F. Fehsenfeld

Chemistry Faculty Publications

A ship emission plume experiment was conducted about 100 km off the California coast during the NOAA Intercontinental Transport and Chemical Transformation (ITCT) 2K2 airborne field campaign. Measurements of chemical species were made from the NOAA WP-3D aircraft in eight consecutive transects of a ship plume around midday during 2.5 hours of flight. The measured species include NOx, HNO3, peroxyacetylnitrate (PAN), SO2, H2SO4, O3, CO, CO2, nonmethane hydrocarbons (NMHC), and particle number and size distributions. Observations demonstrate a NOx lifetime of ∼1.8 hours inside the ship plume compared to ∼6.5 hours (at noontime) in the moderately polluted background marine boundary …

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Dispiro-1,2,4-Trioxane Analogues Of A Prototype Dispiro-1,2,4-Trioxolane: Mechanistic Comparators For Artemisinin In The Context Of Reaction Pathways With Iron(Ii), Yuanqing Tang, Yuxiang Dong, Xiaofang Wang, Kamaraj Sriraghavan, James K. Wood, Jonathan L. Vennerstrom May 2005

Dispiro-1,2,4-Trioxane Analogues Of A Prototype Dispiro-1,2,4-Trioxolane: Mechanistic Comparators For Artemisinin In The Context Of Reaction Pathways With Iron(Ii), Yuanqing Tang, Yuxiang Dong, Xiaofang Wang, Kamaraj Sriraghavan, James K. Wood, Jonathan L. Vennerstrom

Chemistry Faculty Publications

Single electron reduction of the 1,2,4-trioxane heterocycle of artemisinin (1) forms primary and secondary carbon-centered radicals. The complex structure of 1 does not lend itself to a satisfactory dissection of the electronic and steric effects that influence the formation and subsequent reaction of these carbon-centered free radicals. To help demarcate these effects, we characterized the reactions of achiral dispiro-1,2,4-trioxolane 4 and dispiro-1,2,4-trioxanes 5−7 with ferrous bromide and 4-oxo-TEMPO. Our results suggest a small preference for attack of Fe(II) on the nonketal peroxide oxygen atom of 1. For 4, but not for 5 and 6 …

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Hinge-Like Motions In Rna Kink-Turns: The Role Of The Second A-Minor Motif And Nominally Unpaired Bases, Neocles B. Leontis, Filip Rázga, Jaroslav Koča, Jiří Šponer May 2005

Hinge-Like Motions In Rna Kink-Turns: The Role Of The Second A-Minor Motif And Nominally Unpaired Bases, Neocles B. Leontis, Filip Rázga, Jaroslav Koča, Jiří Šponer

Chemistry Faculty Publications

Kink-turn (K-turn) motifs are asymmetric internal loops found at conserved positions in diverse RNAs, with sharp bends in phosphodiester backbones producing V-shaped structures. Explicit-solvent molecular dynamics simulations were carried out for three K-turns from 23S rRNA, i. e., Kt-38 located at the base of the A-site. nger, Kt-42 located at the base of the L7/L12 stalk, and Kt-58 located in domain III, and for the K-turn of human U4 snRNA. The simulations reveal hinge-like K-turn motions on the nanosecond timescale. The first conserved A-minor interaction between the K-turn stems is entirely stable in all simulations. The angle between the helical …

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Synthesis, Structural Studies And Desilylation Reactions Of Some N-2-(Trimethylsilyl)Ethyl-N-Nitrosocarbamates, Arpitha Thakkalapally, Vladimir Benin May 2005

Synthesis, Structural Studies And Desilylation Reactions Of Some N-2-(Trimethylsilyl)Ethyl-N-Nitrosocarbamates, Arpitha Thakkalapally, Vladimir Benin

Chemistry Faculty Publications

The present report describes the preparation and characterization of several N-2-(trimethylsilyl)ethyl-N-nitrosocarbamates, designed as precursors to thermally unstable secondary N-nitrosocarbamate anions via fluoride-assisted cleavage. X-ray structural studies demonstrate that the core N-nitrosocarbamate moiety has a nearly planar geometry, with an s-E orientation at the N–N bond. DFT calculations (B3LYP/6-31+G(d)) reproduce accurately the structural features of the title compounds and detailed conformational analysis at the same level of theory addresses the long-standing issue of preferred geometries for three classes of related structures: N-nitrosocarbamates, N-nitrosoureas and N-nitrosoamides. Desilylation studies demonstrate that both the …

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Preparation, Structural Characterization, And Dynamic Properties Investigation Of Permalloy Antidot Arrays, Scott Whittenburg, Charles J. O'Connor May 2005

Preparation, Structural Characterization, And Dynamic Properties Investigation Of Permalloy Antidot Arrays, Scott Whittenburg, Charles J. O'Connor

Chemistry Faculty Publications

Regular nanosized structures are considered to be promising materials for magnetic information storage media with high density of information. Recently attention was paid to static and dynamic magnetic properties arising from dimensional confinement in such nanostructures. Here we present an investigation of permalloy antidot arrays of different thicknesses. Thin permalloy films of thickness ranging from 10 to 500 nm were deposited on anoporous Al2O3 membranes with a pore size of 100 nm. It was found that additional ferromagnetic resonance peaks appear for film thicknesses below 100 nm, while films with larger thicknesses show resonance properties similar to continuous films. A …

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Double-Stranded Rna-Dependent Protein Kinase (Pkr) Is Downregulated By Phorbol Ester, Yan Zhou, Barbara I. Chase, Mark Whitmore, Bryan R.G. Williams, Aimin Zhou Apr 2005

Double-Stranded Rna-Dependent Protein Kinase (Pkr) Is Downregulated By Phorbol Ester, Yan Zhou, Barbara I. Chase, Mark Whitmore, Bryan R.G. Williams, Aimin Zhou

Chemistry Faculty Publications

The double-stranded RNA-dependent protein kinase (PKR) is one of the key mediators of interferon (IFN) action against certain viruses. PKR also plays an important role in signal transduction and immunomodulation. Understanding the regulation of PKR activity is important for the use of PKR as a tool to discover and develop novel therapeutics for viral infections, cancer and immune dysfunction. We found that phorbol 12-myristate 13-acetate (PMA), a potent activator of protein kinase C (PKC), decreased the level of autophosphorylated PKR in a dose- and time-dependent manner in IFN-treated mouse fibroblast cells. Polyinosinic–polycytidylic acid (poly I:C) treatment enhanced the activity of …

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Magnetic Characterization Of Nanocrystalline Nickel Ferrite Films Processed By A Spin-Spraying Method, Gabriel Caruntu, I Dumitru, Bush Gg, Daniela Caruntu, Charles J. O'Connor Mar 2005

Magnetic Characterization Of Nanocrystalline Nickel Ferrite Films Processed By A Spin-Spraying Method, Gabriel Caruntu, I Dumitru, Bush Gg, Daniela Caruntu, Charles J. O'Connor

Chemistry Faculty Publications

Highly crystalline nickel ferrite films with different chemical compositions were processed via the spin-spraying method and their morphological, structural and magnetic properties were subsequently investigated. Regardless of the chemical composition, films with variable thicknesses are constructed by 200–400 nm spherical grains grown in the direction normal to the substrate surface. Magnetization measurements show that the spinel ferrite films present a hysteretic behaviour at room temperature with a randomly oriented in-plane easy axis and an anisotropy constant K1 ≈ −2.5 × 104 erg cm−3 Furthermore, the absence of an angular dependence of the coercivity for the in-plane measurement of …

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Simulations Of Proton Order And Disorder In Ice Ih, Steven W. Rick Mar 2005

Simulations Of Proton Order And Disorder In Ice Ih, Steven W. Rick

Chemistry Faculty Publications

Computer simulations of ice Ih with different proton orientations are presented. Simulations of proton disordered ice are carried out using a Monte Carlo method which samples over proton degree of freedom, allowing for the calculation of the dielectric constant and for the examination of the degree of proton disorder. Simulations are also presented for two proton ordered structures of ice Ih, the ferroelectric Cmc21 structure or ice XI and the antiferroelectric Pna21 structure. These simulations indicate that a transition to a proton ordered phase occurs at low temperatures (below 80 K). The …

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Green Photoluminescence From Platinum(Ii) Complexes Bearing Silylacetylide Ligands, Fei Hua, Solen Kinayyigit, John R. Cable, Felix Castellano Feb 2005

Green Photoluminescence From Platinum(Ii) Complexes Bearing Silylacetylide Ligands, Fei Hua, Solen Kinayyigit, John R. Cable, Felix Castellano

Chemistry Faculty Publications

The synthesis, structural characterization, photoluminescence properties, and density functional theory analysis of three Pt(II) diimine complexes, Pt(dbbpy)(CdropCR)(2) [dbbpy = 4,4'-di(tert-butyl-2,2'-bipyridine; R = -SiMe3, -CdropC-SiMe3, or -t-Bu], are presented. The Pt(dbbpy)(CdropC-tBu)(2) complex serves as a carbon-based ligand structure for which the photophysical properties of the two silicon-bearing complexes are compared in dichloromethane. Pt(dbbpy)(CdropC-SiMe3)(2) and Pt(dbbpy)(CdropC-CdropC-SiMe3)(2) display visible absorptions with strong green emission (lambda(emmax) = 526 and 524 nm, respectively) while Pt(dbbpy)(CdropCt-Bu)(2) displays efficient, long-lived yellow emission (lambda(emmax) = 557 nm). Direct side by side comparisons of Pt(dbbpy)(CdropC-SiMe3)(2) and Pt(dbbpy)(CdropC-t-Bu)(2) suggest that the difference in excited state energy results from the relative …

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Mass Spectrometric And Computational Study Of Snpb In The Gas Phase, G Gigli, Giovanni Meloni, M Carrozzino Jan 2005

Mass Spectrometric And Computational Study Of Snpb In The Gas Phase, G Gigli, Giovanni Meloni, M Carrozzino

Chemistry Faculty Publications

The SnPb molecule has been identified in a Knudsen effusion mass spectrometry experiment. The direct dissociation reaction and two isomolecular exchange reactions involving the Sn(2) and Pb(2) molecules have been studied, in the 1426-1705 K range of temperatures, using both second and third law procedures. The D(degree)0(SnPb,g) has been derived, for the first time, as (122.6+/-4.0) kJ mol(-1). Density functional and ab initio calculations up to the coupled clusters level of theory were also performed. In addition, the anion dissociation energy D(degree)0(SnPb(-),g) of (179.2+/-4.2) kJ mol(-1) was determined using the D(degree)0(SnPb,g) mass spectrometric value derived in this investigation and literature …

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Gallium Oxide And Dioxide: Investigation Of The Ground And Low-Lying Electronic States Via Anion Photoelectron Spectroscopy, Giovanni Meloni, S M. Sheehan, D M. Neumark Jan 2005

Gallium Oxide And Dioxide: Investigation Of The Ground And Low-Lying Electronic States Via Anion Photoelectron Spectroscopy, Giovanni Meloni, S M. Sheehan, D M. Neumark

Chemistry Faculty Publications

The GaO and GaO2 molecules were investigated using negative ion photoelectron spectroscopy. All the photoelectron spectra showed vibrationally resolved progressions. With the aid of electronic structure calculations and Franck-Condon spectral simulations, different molecular parameters and energetics of GaO-/GaO and GaO2-/GaO2 were determined, including the electron affinity of GaO, the vibrational frequency of GaO-, and the term energy, spin-orbit splitting, and vibrational frequency for the first excited A 2PiOmega state of GaO. The GaO2- photoelectron spectra comprised three bands assigned as transitions from the linear X 1Sigma(g)+ ground state of GaO2- to three linear neutral states: the A 2Pi(g), B 2Pi(u), …

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Recurrent Structural Rna Motifs, Isostericity Matrices And Sequence Alignments, Neocles B. Leontis, Aurélie Lescoute, Christian Massire, Eric Westhof Jan 2005

Recurrent Structural Rna Motifs, Isostericity Matrices And Sequence Alignments, Neocles B. Leontis, Aurélie Lescoute, Christian Massire, Eric Westhof

Chemistry Faculty Publications

The occurrences of two recurrent motifs in ribosomal RNA sequences, the Kink-turn and the C-loop, are examined in crystal structures and systematically compared with sequence alignments of rRNAs from the three kingdoms of life in order to identify the range of the structural and sequence variations. Isostericity Matrices are used to analyze structurally the sequence variations of the characteristic non-Watson-Crick base pairs for each motif. We show that Isostericity Matrices for non-Watson-Crick base pairs provide important tools for deriving the sequence signatures of recurrent motifs, for scoring and refining sequence alignments, and for determining whether motifs are conserved throughout evolution. …

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Potential Energy Surface Of The Reaction Of Imidazole With Peroxynitrite: Density Functional Theory Study, Valentin Gogonea Jan 2005

Potential Energy Surface Of The Reaction Of Imidazole With Peroxynitrite: Density Functional Theory Study, Valentin Gogonea

Chemistry Faculty Publications

This article presents a theoretical investigation of the reaction mechanism of imidazole nitration by peroxynitrite using density functional theory calculations. Understanding this reaction mechanism will help in elucidating the mechanism of guanine nitration by peroxynitrite, which is one of the assumed chemical pathways for damaging DNA in cells. This work focuses on the analysis of the potential energy surface (PES) for this reaction in the gas phase. Calculations were carried out using Hartree–Fock (HF) and density functional theory (DFT) Hamiltonians with double-zeta basis sets ranging from 6-31G(d) to 6-31++G(d,p), and the triple-zeta basis set 6-311G(d). The computational results reveal that …

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A Regularized And Renormalized Electrostatic Coupling Hamiltonian For Hybrid Quantum-Mechanical–Molecular-Mechanical Calculations, Pradip K. Biswas, Valentin Gogonea Jan 2005

A Regularized And Renormalized Electrostatic Coupling Hamiltonian For Hybrid Quantum-Mechanical–Molecular-Mechanical Calculations, Pradip K. Biswas, Valentin Gogonea

Chemistry Faculty Publications

We describe a regularized and renormalized electrostatic coupling Hamiltonian for hybrid quantum-mechanical (QM)–molecular-mechanical (MM) calculations. To remedy the nonphysical QM/MM Coulomb interaction at short distances arising from a point electrostatic potential (ESP) charge of the MM atom and also to accommodate the effect of polarized MM atom in the coupling Hamiltonian, we propose a partial-wave expansion of the ESP charge and describe the effect of a s-wave expansion, extended over the covalent radius rc, of the MM atom. The resulting potential describes that, at short distances, large scale cancellation of Coulomb interaction arises intrinsically from the localized expansion of the …

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Gas-Phase Chemical Characteristics Of Asian Emission Plumes Observed During Itct 2k2 Over The Eastern North Pacific Ocean, J. B. Nowak, D. D. Parrish, J. A. Neuman, J. S. Holloway, O. R. Cooper, T. B. Ryerson, Jr K. Nicks, F. Flocke, J. M. Roberts, E. Atlas, J. A. De Gouw, Stephen G. Donnelly Ph.D., E. Dunlea, G. Hübler, L. G. Huey, S. Schauffler, D. J. Tanner, C. Warneke, F. C. Fehsenfeld Dec 2004

Gas-Phase Chemical Characteristics Of Asian Emission Plumes Observed During Itct 2k2 Over The Eastern North Pacific Ocean, J. B. Nowak, D. D. Parrish, J. A. Neuman, J. S. Holloway, O. R. Cooper, T. B. Ryerson, Jr K. Nicks, F. Flocke, J. M. Roberts, E. Atlas, J. A. De Gouw, Stephen G. Donnelly Ph.D., E. Dunlea, G. Hübler, L. G. Huey, S. Schauffler, D. J. Tanner, C. Warneke, F. C. Fehsenfeld

Chemistry Faculty Publications

The gas-phase chemical characteristics of emission plumes transported from Asia across the Pacific Ocean observed during the Intercontinental Transport and Chemical Transformation experiment in 2002 (ITCT 2K2) are described. Plumes measured in the troposphere from an aircraft were separated from the background air in data analysis using 1-s measurements of carbon monoxide (CO), total reactive nitrogen (NOy), and other gasphase species along with back trajectory analysis. On the basis of these measurements, Asian transport plumes with CO mixing ratios greater than 150 ppbv were observed on seven flights. Correlations between 1-s observations of CO, ozone (O3), and NOy are used …

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Changes In The Photochemical Environment Of The Temperate North Pacific Troposphere In Response To Increased Asian Emissions, D. D. Parrish, E. J. Dunlea, E. L. Atlas, S. Schauffler, Stephen G. Donnelly Ph.D., V. Stroud, A. H. Goldstein, D. B. Millet, M. Mckay, D. A. Jaffe, H. U. Price, P. G. Hess, F. Flocke, J. M. Roberts Dec 2004

Changes In The Photochemical Environment Of The Temperate North Pacific Troposphere In Response To Increased Asian Emissions, D. D. Parrish, E. J. Dunlea, E. L. Atlas, S. Schauffler, Stephen G. Donnelly Ph.D., V. Stroud, A. H. Goldstein, D. B. Millet, M. Mckay, D. A. Jaffe, H. U. Price, P. G. Hess, F. Flocke, J. M. Roberts

Chemistry Faculty Publications

Measurements during the Intercontinental Transport and Chemical Transformation 2002 (ITCT 2K2) field study characterized the springtime, eastern Pacific ozone distribution at two ground sites, from the National Oceanic and Atmospheric Administration WP-3D aircraft, and from a light aircraft operated by the University of Washington. D. Jaffe and colleagues compared the 2002 ozone distribution with measurements made in the region over the two previous decades and show that average ozone levels over the eastern midlatitude Pacific have systematically increased by ∼10 ppbv in the last two decades. Here we provide substantial evidence that a marked change in the photochemical environment in …

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Multiscale Simulations Of Tropospheric Chemistry In The Eastern Pacific And On The U.S. West Coast During Spring 2002, Youhua Tang, Gregory R. Carmichael, Larry W. Horowitz, Itsushi Uno, Jung Hun Woo, David G. Streets, Donald Dabdub, Gakuji Kurata, Adrian Sandu, James Allan, Elliot Atlas, Frank Flocke, Lewis Gregory Huey, Roger O. Jakoubek, Dylan B. Millet, Patricia K. Quinn, James M. Roberts, Douglas R. Worsnop, Allen Goldstein, Stephen G. Donnelly Ph.D., Sue Schauffler, Verity Stroud, Kristen Johnson, Melody A. Avery, Hanwant B. Singh, Eric C. Apel Dec 2004

Multiscale Simulations Of Tropospheric Chemistry In The Eastern Pacific And On The U.S. West Coast During Spring 2002, Youhua Tang, Gregory R. Carmichael, Larry W. Horowitz, Itsushi Uno, Jung Hun Woo, David G. Streets, Donald Dabdub, Gakuji Kurata, Adrian Sandu, James Allan, Elliot Atlas, Frank Flocke, Lewis Gregory Huey, Roger O. Jakoubek, Dylan B. Millet, Patricia K. Quinn, James M. Roberts, Douglas R. Worsnop, Allen Goldstein, Stephen G. Donnelly Ph.D., Sue Schauffler, Verity Stroud, Kristen Johnson, Melody A. Avery, Hanwant B. Singh, Eric C. Apel

Chemistry Faculty Publications

Regional modeling analysis for the Intercontinental Transport and Chemical Transformation 2002 (ITCT 2K2) experiment over the eastern Pacific and U.S. West Coast is performed using a multiscale modeling system, including the regional tracer model Chemical Weather Forecasting System (CFORS), the Sulfur Transport and Emissions Model 2003 (STEM-2K3) regional chemical transport model, and an off-line coupling with the Model of Ozone and Related Chemical Tracers (MOZART) global chemical transport model. CO regional tracers calculated online in the CFORS model are used to identify aircraft measurement periods with Asian influences. Asian-influenced air masses measured by the National Oceanic and Atmospheric Administration (NOAA) …

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Chemical Composition Of Air Masses Transported From Asia To The U.S. West Coast During Itct 2k2: Fossil Fuel Combustion Versus Biomass-Burning Signatures, J. A. De Gouw, O. R. Cooper, C. Warneke, P. K. Hudson, F. C. Fehsenfeld, J. S. Holloway, G. Hübler, Jr K. Nicks, J. B. Nowak, D. D. Parrish, T. B. Ryerson, E. L. Atlas, Stephen G. Donnelly Ph.D., S. M. Schauffler, V. Stroud, K. Johnson, G. R. Carmichael, D. G. Streets Dec 2004

Chemical Composition Of Air Masses Transported From Asia To The U.S. West Coast During Itct 2k2: Fossil Fuel Combustion Versus Biomass-Burning Signatures, J. A. De Gouw, O. R. Cooper, C. Warneke, P. K. Hudson, F. C. Fehsenfeld, J. S. Holloway, G. Hübler, Jr K. Nicks, J. B. Nowak, D. D. Parrish, T. B. Ryerson, E. L. Atlas, Stephen G. Donnelly Ph.D., S. M. Schauffler, V. Stroud, K. Johnson, G. R. Carmichael, D. G. Streets

Chemistry Faculty Publications

As part of the Intercontinental Transport and Chemical Transformation experiment in 2002 (ITCT 2K2), a National Oceanic and Atmospheric Administration (NOAA) WP-3D research aircraft was used to study the long-range transport of Asian air masses toward the west coast of North America. During research flights on 5 and 17 May, strong enhancements of carbon monoxide (CO) and other species were observed in air masses that had been transported from Asia. The hydrocarbon composition of the air masses indicated that the highest CO levels were related to fossil fuel use. During the flights on 5 and 17 May and other days, …

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Manganese Oxide Thin Films Prepared By Nonaqueous Sol-Gel Processing: Preferential Formation Of Birnessite, Stanton Ching, Steven M. Hughes, Timothy P. Gray, Eric J. Welch Dec 2004

Manganese Oxide Thin Films Prepared By Nonaqueous Sol-Gel Processing: Preferential Formation Of Birnessite, Stanton Ching, Steven M. Hughes, Timothy P. Gray, Eric J. Welch

Chemistry Faculty Publications

High quality manganese oxide thin films with smooth surfaces and even thicknesses have been prepared with a nonaqueous sol–gel process involving reduction of tetraethylammonium permanganate in methanol. Spin-coated films have been cast onto soft glass, quartz, and Ni foil substrates, with two coats being applied for optimum crystallization. The addition of alkali metal cations as dopants results in exclusive formation of the layered birnessite phase. By contrast, analogous reactions in bulk sol–gel reactions yield birnessite, tunneled, and spinel phases depending on the dopant cation. XRD patterns confirm the formation of well-crystallized birnessite. SEM images of Li-, Na-, and K–birnessite reveal …

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Electrical Properties And Raman Scattering Study Of Single Crystal Cs2nb4o11, Jianjun Liu, E. P. Kharitonova, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy Nov 2004

Electrical Properties And Raman Scattering Study Of Single Crystal Cs2nb4o11, Jianjun Liu, E. P. Kharitonova, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy

Chemistry Faculty Publications

We studied temperature dependence of complex capacitance, impedance, and polarized Raman spectra of single crystal Cs2Nb4O11. First, we observed a sharp-shaped peak at 165 oC in the complex capacitance, then found drastic changes in the Raman spectra in the same temperature range. Utilizing the pseudosymmetry search of structure space group, we attributed the observed anomalies to a structural change from the room temperature orthorhombic Pnn2 to another or- thorhombic Imm2. We also measured room temperature polarized Raman spectra in different symmetries of normal vibrations and assigned high wavenumber Raman bands to the internal vibrations of NbO6 octahedra and NbO4 …

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Long-Residency Hydration, Cation Binding, And Dynamics Of Loop E/Helix Iv Rrna-L25 Protein Complex, Neocles B. Leontis, Kamila Réblová, Nad'a Špačková, Jaroslav Koča, Jiří Šponer Nov 2004

Long-Residency Hydration, Cation Binding, And Dynamics Of Loop E/Helix Iv Rrna-L25 Protein Complex, Neocles B. Leontis, Kamila Réblová, Nad'a Špačková, Jaroslav Koča, Jiří Šponer

Chemistry Faculty Publications

Molecular dynamics simulations of RNA-protein complex between Escherichia coli loop E/helix IV (LE/HeIV) rRNA and L25 protein reveal a qualitative agreement between the experimental and simulated structures. The major groove of LE is a prominent rRNA cation-binding site. Divalent cations rigidify the LE major groove geometry whereas in the absence of divalent cations LE extensively interacts with monovalent cations via inner-shell binding. The HeIV region shows bistability of its major groove explaining the observed differences between x-ray and NMR structures. In agreement with the experiments, the simulations suggest that helix-alpha1 of L25 is the least stable part of the protein. …

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Ultra-Fast Formation Of Stable Nanoparticle Film Assemblies, Dan Sheibley, Renee Szymanik, Michael C. Leopold Oct 2004

Ultra-Fast Formation Of Stable Nanoparticle Film Assemblies, Dan Sheibley, Renee Szymanik, Michael C. Leopold

Chemistry Faculty Publications

Novel assembled films of monolayer-protected clusters (MPCs) can be grown on gold and glass substrates with a 20-fold higher efficiency than established procedures. Thick MPC films grown using this new method, which can easily be scaled up or automated, are extremely stable and have properties identical to traditionally formed nanoparticle films, including unique quantized double layer charging effects. This new procedure for growing nanoparticle films shares the versatility of the traditional method but exhibits accelerated growth attributed to highly efficient sorption and mobility of metal ion linkers within swelled films and improved mass transfer of nanoparticles to assembly sites. Concentration …

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9-Ethyl-3-Methyl-1, 6-Dinitrocarbazole, Erol Asker, John Masnovi Sep 2004

9-Ethyl-3-Methyl-1, 6-Dinitrocarbazole, Erol Asker, John Masnovi

Chemistry Faculty Publications

No abstract provided.

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Phospholipid Scramblase 1 Potentiates The Antiviral Activity Of Interferon, Beihua Dong, Quansheng Zhou, Ji Zhao, Aimin Zhou, Ronald N. Harty, Santanu Bose, Amiya Banerjee, Roger Slee, Jeanna Guenther, Bryan R.G. Williams, Therese Wiedmer, Peter J. Sims, Robert H. Silverman Sep 2004

Phospholipid Scramblase 1 Potentiates The Antiviral Activity Of Interferon, Beihua Dong, Quansheng Zhou, Ji Zhao, Aimin Zhou, Ronald N. Harty, Santanu Bose, Amiya Banerjee, Roger Slee, Jeanna Guenther, Bryan R.G. Williams, Therese Wiedmer, Peter J. Sims, Robert H. Silverman

Chemistry Faculty Publications

Phospholipid scramblase 1 (PLSCR1) is an interferon (IFN)- and growth factor-inducible, calcium-binding protein that either inserts into the plasma membrane or binds DNA in the nucleus depending on its state of palmyitoylation. In certain hematopoietic cells, PLSCR1 is required for normal maturation and terminal differentiation from progenitor cells as regulated by select growth factors, where it promotes recruitment and activation of Src kinases. PLSCR1 is a substrate of Src (and Abl) kinases, and transcription of the PLSCR1 gene is regulated by the same growth factor receptor pathways in which PLSCR1 potentiates afferent signaling. The marked transcriptional upregulation of PLSCR1 by …

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Synthesis And Characterization Of Nanocrystalline Zinc Ferrite, Gabriel Caruntu, Charles J. O'Connor Sep 2004

Synthesis And Characterization Of Nanocrystalline Zinc Ferrite, Gabriel Caruntu, Charles J. O'Connor

Chemistry Faculty Publications

We report on the synthesis of highly uniform, single phase zinc ferrite films prepared through a single step low temperature reaction by the liquid phase deposition (LPD) method. X-ray diffraction, TGA and EDX
measurements support the assumption that the as-deposited films are constituted from a mixture of crystallized FeOOH and amorphous Zn(OH)2. Upon heat treatment in air at 600 uC for one hour the intermediates are subsequently converted into the corresponding zinc ferrites. The films with adjustable chemical compositions are identified as having a spinel-type crystal structure and present a spherical or rod-like microstructure, depending on the Zn content. The …

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Eliminating Absorbing Interference Using The H-Point Standard Addition Method: Case Of Griess Assay In The Presence Of Interferent Heme Enzymes Such As Nos, Perera N. Indika, Mekki Bayachou Aug 2004

Eliminating Absorbing Interference Using The H-Point Standard Addition Method: Case Of Griess Assay In The Presence Of Interferent Heme Enzymes Such As Nos, Perera N. Indika, Mekki Bayachou

Chemistry Faculty Publications

Standard calibration methods used to determine trace analytes usually yield significant deviations from the actual analyte value in the presence of interferents in the assay media. These deviations become of particular concern when the concentration of the analyte is low, and when the results are used to draw mechanistic or kinetic conclusions, for instance in enzyme structure-function studies. In these circumstances, the H-point standard addition method (HPSAM) provides superior precision and accuracy. This method is developed here for the case of the spectrophotometric Griess assay used to determine nitrite in various enzymology investigations, such as nitrite determination in studies of …

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Novel Chromium(Vi) Catalyzed Oxidation Of N-Alkylamides To Imides With Periodic Acid, Mark L. Trudell Jun 2004

Novel Chromium(Vi) Catalyzed Oxidation Of N-Alkylamides To Imides With Periodic Acid, Mark L. Trudell

Chemistry Faculty Publications

A novel and practical procedure for preparation of imides is described using chromium(VI) oxide to catalyze the oxidation of N-alkylamides with periodic acid in the presence of acetic anhydride in acetonitrile.

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