Chemistry Commons^™

Structure Of The Photochemical Reaction Path Populated Via Promotion Of Cf2i2 Into Its First Excited State, Patrick Z. El-Khoury, Alexander N. Tarnovsky, Igor Schapiro, Mikhail N. Ryazantsev, Massimo Olivucci

Chemistry Faculty Publications

The photochemical reaction path following the promotion of CF2I2 into its lowest-lying excited electronic singlet state has been modeled using ab initio multiconfigurational quantum chemical calculations. It is found that a conical intersection drives the electronically excited CF2I2* species either to the CF2I + I radical pair or back to the starting CF2I2 structure. The structures of the computed relaxation pathways explain the photoproduct selectivity previously observed in the gas phase. Furthermore, the results provide the basis for explaining the condensed-phase photochemistry of CF2I2.

Proteomic And Phospho-Proteomic Profile Of Human Platelets In Basal, Resting State: Insights Into Integrin Signaling, Amir H. Qureshi, Vineet Chaoji, Dony Maiguel, Mohd Hafeez Faridi, Constantinos J. Barth, Saeed M. Salem, Mudita Singhal, Darren Stoub, Bryan Krastins, Mitsunori Ogihara, Mohammed J. Zaki, Vineet Gupta

Faculty Work Comprehensive List

During atherogenesis and vascular inflammation quiescent platelets are activated to increase the surface expression and ligand affinity of the integrin αIIbβ3 via inside-out signaling. Diverse signals such as thrombin, ADP and epinephrine transduce signals through their respective GPCRs to activate protein kinases that ultimately lead to the phosphorylation of the cytoplasmic tail of the integrin αIIbβ3 and augment its function. The signaling pathways that transmit signals from the GPCR to the cytosolic domain of the integrin are not well defined. In an effort to better understand these pathways, we employed a combination of proteomic profiling and computational analyses of isolated …

Lipid-Protein Interactions Probed By Electron Crystallography, Steve L. Reichow, Tamir Gonen

Chemistry Faculty Publications and Presentations

Electron crystallography is arguably the only electron cryomicroscopy (cryoEM) technique able to deliver an atomic-resolution structure of membrane proteins embedded in the lipid-bilayer. In the electron crystallographic structures of the light driven ion pump, bacteriorhodopsin, and the water channel, aquaporin-0, sufficiently high resolution was obtained and both lipid and protein were visualized, modeled and described in detail. An extensive network of lipid-protein interactions mimicking native membranes is established and maintained in two-dimensional (2D) crystalline vesicles used for structural analysis by electron crystallography. Lipids are tightly integrated into the protein's architecture where they can affect the function, structure, quaternary assembly and …

Unlv Magazine, Matthew K. Jacobsen, Holly Ivy De Vore, Lisa Arth, Cate Weeks, Greg Lacour, Tony Allen, Afsha Bawany, Barbara Cloud, Gian Galassi, Phil Hagen, Karyn S. Hollingsworth, Michelle Mouton, Erin O'Donnell

UNLV Magazine

No abstract provided.

An Expeditious Synthesis Of 3-Amino B-Lactams Derived From Polyaromatic Compounds, Gildardo Rivera, Debasish Bandyopadhyay, Sonam Jaggi, R. Christopher Gonzales, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

A simple an effective method for the synthesis of a few trans 3-amino B-lactams derived from polyaromatic compounds has been accomplished via the deprotection of phthalimido groups with ethylene diamine.

Solvent Dependent Morphologies In Thiol-Ene Photopolymerization: A Facile Route To Synthesis Of Resorcinarene Nanocapsules, Zaharoula Marie Kalaitzis

Chemistry & Biochemistry Theses & Dissertations

Synthesis of morphologically distinct polymeric nanostructures is vital for their wide ranging applications from nanomedicine to material science. Among various polymeric nanostructures, nanocapsules in particular have attracted a lot of attention as nanoreactors and drug delivery vehicles in nanomedicine. Often, synthesis of nanocapsules is achieved by template-based approaches. A direct, template-free method for the fabrication of nanocapsules and a variety of other morphologically distinct polymeric architectures was developed. The photopolymerization of a resorcinarene thiol-ene surfactant in various solvents lead to the formation of nanocapsules, nanoparticles, fibers, distorted honeycomb-like lattices, and sheets. The progress of the polymerization reaction and the morphology …

Development Of Chemometric Models And Calibration Transfer For Rapid Diesel And Jet Fuel Analysis Using Near Infrared Spectroscopy, Christopher Matthew Larkin

Chemistry & Biochemistry Theses & Dissertations

Fuel quality assurance and analysis, as it pertains to the United States armed forces, is crucial for maintaining operability and upholding safety regulations with respect to fuel class. Currently a great amount of effort, money and manpower are dedicated to this task as fuel analysis takes place in off-site laboratories where quality assessment and property determination is performed manually by highly qualified lab technicians. This presents the military with a logistics problem with respect to refueling, transport, and fuel storage as the typical tum-around time is 1-2 weeks. In this thesis it has been demonstrated that near-infrared spectroscopy, in conjunction …

Hierarchical Subject Inter-Relations In Physical Chemistry, Carl W. David

Chemistry Education Materials

Students mystified by the progression of topics in Physical Chemistry may gain insight into their path through the material if acquainted with the diagrams presented and discussed herein.

Pore Size Characterization Of Monolithic Capillary Columns Using Capillary Flow Porometry, Yan Fang

Theses and Dissertations

A simple capillary flow porometer (CFP) was assembled for pore structure characterization of monolithic capillary liquid chromatography columns based on ASTM standard F316-86. Determination of differential pressures and flow rates through dry and wet samples provided the necessary information to determine the through-pore throat diameter, bubble point pore diameter, mean flow pore diameter, and pore distribution. Unlike measurements in bulk using traditional techniques to provide indirect information about the pore properties of monolithic columns, monoliths can be characterized in their original chromatographic forms with this system. The performance of the new CFP was first evaluated by characterizing the pore size …

The Α,Α-Difluorinated Phosphonate L-Pser-Analogue: An Accessible Chemical Tool For Studying Kinase-Dependent Signal Transduction In Vitro, And In Living Cells, Kaushik Panigrahi, Marijean Eggen, Jun-Ho Maeng, Quanrong Shen, David B. Berkowitz

David Berkowitz Publications

This overview focuses on the (α,α-difluoromethylene)phosphonate mimic of phosphoserine (pCF₂Ser) and its application to the study of kinase-mediated signal transduction – pathways of great interest to drug development. The most versatile modes of access to these chemical biological tools are discussed, organized by method of PCF₂-C bond. The pCF₂-Ser mimic may be site-specifically incorporated into peptides (SPPS) and proteins (expressed protein ligation). This isopolar, dianionic pSer mimic results in a “constitutive phosphorylation” phenotype, and is seen to support native protein-protein interactions that depend upon serine phosphorylation. Signal transduction pathways studied with this chemical biological …

Succination Of Thiol Groups In Adipose Tissue Proteins In Diabetes: Succination Inhibits Polymerization And Secretion Of Adiponectin, Norma Frizzell, Mathur Rajesh, Matthew J. Jepson, Ryoji Nagai, James A. Carson, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

S-(2-Succinyl)cysteine (2SC) is formed by reaction of the Krebs cycle intermediate fumarate with cysteine residues in protein, a process termed succination of protein. Both fumarate and succination of proteins are increased in adipocytes cultured in high glucose medium (Nagai, R., Brock, J. W., Blatnik, M., Baatz, J. E., Bethard, J., Walla, M. D., Thorpe, S. R., Baynes, J. W., and Frizzell, N. (2007) J. Biol. Chem. 282, 34219-34228). We show here that succination of protein is also increased in epididymal, mesenteric, and subcutaneous adipose tissue of diabetic (db/db) mice and that adiponectin is a major target for succination in both …

Identification And Structural Analysis Of A Novel Carboxysome Shell Protein With Implications For Metabolite Transport, Michael G. Klein, Peter Zwart, Sarah C. Bag By, Fei Cai, Sallie W. Chisolm, Sabine Heinhorst, Gordon C. Cannon, Cheryl A. Kerfeld

Faculty Publications

Bacterial microcompartments (BMCs) are polyhedral bodies, composed entirely of proteins, that function as organelles in bacteria; they promote subcellular processes by encapsulating and co-localizing targeted enzymes with their substrates. The best-characterized BMC is the carboxysome, a central part of the carbon-concentrating mechanism that greatly enhances carbon fixation in cyanobacteria and some chemoautotrophs. Here we report the first structural insights into the carboxysome of Prochlorococcus, the numerically dominant cyanobacterium in the world's oligotrophic oceans. Bioinformatic methods, substantiated by analysis of gene expression data, were used to identify a new carboxysome shell component, CsoS1D, in the genome of Prochlorococcus strain MED4; …

Gas Phase Chiral Recognition, Characterization Of Porous Polymer Monolith Nanospray Ionization, And The Negative Mode Crafti Method Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, Nannan Fang

Theses and Dissertations

Our group has been studying chiral recognition in gas phase using mass spectrometry for more than 10 years. We are interested in gas phase studies of fundamental interactions because the gas phase avoids complications and masking effects that may arise upon solvation. Therefore, the results of gas phase experiments can be directly compared with those of high-level computational studies. In chapter 2, I studied the roles of hydrogen bonding and pi stacking in gas phase chiral recognition between aromatic crown molecules and aromatic amines. High affinity between host and guest doesn't necessarily result in better recognition. If the affinity is …

A Spectral Time-Domain Method For Computational Electrodynamics, James V. Lambers

Faculty Publications

We present a new approach to the numerical solution of Maxwell’s equations in the case of spatially‐varying electric permittivity and/or magnetic permeability, based on Krylov subspace spectral (KSS) methods. KSS methods for scalar equations compute each Fourier coefficient of the solution using techniques developed by Gene Golub and Gérard Meurant for approximating elements of functions of matrices by Gaussian quadrature in the spectral, rather than physical, domain. We show how they can be generalized to coupled systems of equations, such as Maxwell’s equations, by choosing appropriate basis functions that, while induced by this coupling, still allow efficient and robust computation …

Progress Toward The Synthesis Of A Truncated Ergoline, Ryan D. Enck, Matthew Hart

Student Summer Scholars Manuscripts

Many people are diagnosed with thyroid related disorders, and many more are unaware of their existing thyroid problems. T1AM, a naturally occurring metabolite of the thyroid hormone (TH), has been shown to activate the Trace Amine Associated Receptor 1 (TAAR1) and exhibits effects that oppose those of the TH. It is, therefore, likely that there is regulatory relationship between T1AM and the TH. In order to better understand this relationship, a compound must be developed that will effectively block TAAR1. Previously our lab has examined the two different mirror images of apomorphine. One of the mirror images inhibited and the …

Combined Mössbauer Spectral And Density Functional Theory Determination Of The Magnetic Easy-Axis In Two High-Spin Iron(Ii) 2-Pyrazinecarboxylate Complexes, Gary J. Long, Stefania Tanase, Françoise Remacle, Ganga Periyasamy, Fernande Grandjean

Chemistry Faculty Research & Creative Works

A combination of density functional theory (DFT) calculations and Mössbauer spectroscopy has been used to determine that the magnetic easy-axis is coincident with its crystallography c-axis in [Fe(pca) 2(py)2] · py, where pac is the 2- pyrazinecarboxylate ligand. This easy-axis bisects the approximately axial O-Fe-O coordination axes of molecules adjacent to each other along the c-axis. in {[Fe(pca)2(H₂O)]-H₂O) n the easy magnetic axis is not coincident with any of its crystallographic axes nor with the Fe-O(water) coordination axis, but is coincident with one of the Fe ... Fe axes in the crystal structure. the DFT calculations, …

Manipulating Self-Assembly In Silver(I) Complexes Of 1,3-Di-N-Pyrazolylorganyls, Brendan J. Liddle, Daniel Hall, Sergey V. Lindeman, Mark D. Smith, James R. Gardinier

Chemistry Faculty Research and Publications

Three di-N-pyrazolylorganyls with different conformational flexibilities in the three-atom organyl spacers have been prepared, and the self-assembly properties with AgBF₄ have been studied both in solution and in the solid state. All ligands give low-coordinate silver(I) centers that are capable of participating in multiple noncovalent interactions, but only the rigid 1,8-dipyrazolylnaphthalene ligand promotes very short Ag−Ag contacts.

Spectroscopic Investigation Of The Anatase-To-Rutile Transformation Of Sol-Gel Synthesised Tio2 Photocatalysts, Nicholas Nolan, Suresh Pillai, Michael Seery

Articles

Among the three major phases in titania, anatase is reported to be a better photocatalytically active phase. Anatase to rutile transformations, under normal conditions, usually occurs at a temperatue range of 600- 700 °C. Various chemical additives have previously been employed to extend the anatase transition to higher temperatures. Effect of employing various concentrations of formic acid and water on phase transition has systematically been studied by XRD, FTIR and Raman spectroscopy. A considerably higher anatase phase (41%) has been obtained at 800 ºC and 10% anatase composition is retained after annealing the materials at 900 ºC for the optimised …

Compendium Of Polymer Terminology And Nomenclature: Iupac Recommendations, 2008 (Book Review), Jeffrey H. Glans

Chemistry & Physics Faculty Publications

Book review by Jeffrey Glans.

Polymer Division, International Union of Pure and Applied Chemistry. Compendium of Polymer Terminology and Nomenclature: IUPAC Recommendations, 2008. Royal Society of Chemistry, 2009.

Apoptotic And Chemotherapeutic Properties Of Iron (Iii)-Salophene In An Ovarian Cancer Animal Model, Thilo S. Lange, Carolyn Mccourt, Rakesh K. Singh, Kyu Kwang Kim, Ajay P. Singh, Brian S. Luisi, Onur Alptürk, Robert M. Strongin, Laurent Brard

Chemistry Faculty Publications and Presentations

The cytotoxicity of organometallic compounds iron(III)-, cobalt(III)-, manganese(II)-, and copper(II)-salophene (-SP) on platinum-resistant ovarian cancer cell lines was compared. Fe-SP displayed selective cytotoxicity (IC(50) at ~1 muM) against SKOV-3 and OVCAR-3 cell lines while Co-SP caused cytotoxic effects only at higher concentrations (IC(50) at 60 muM) and Cu-SP effects were negligible. High cytotoxicity of Mn-SP (30-60 muM) appeared to be nonspecific because the Mn-chloride salt reduced cell viability similarly. The effect of Fe-SP at 1 muM proved to be ovarian cancer cell selective when compared to a panel of cell lines derived from different tumors. The first irreversible step in …

Theoretical Studies Of 2,3 -Sigmatropic Rearrangements Of Allylic Selenoxides And Selenimides, Craig A. Bayse, Sonia Antony

Chemistry & Biochemistry Faculty Publications

Density-functional theory is used to model the endo and exo transition states for [2,3]-sigmatropic rearrangement of allylic aryl-selenoxides and -selenimides. The endo transition state is generally preferred for selenoxides if there is no substitution at the 2 position of the allyl group. Based upon the relative energies of the endo and exo transition states, enantioselectivity of rearrangements is expected to be greatest for molecules with substitutions at the 1- or (E)-3- position of the allyl group. Ortho substitution of a nitro group on the ancillary selenoxide phenyl ring reduces the activation barriers, increases the difference between the endo and exo …

Interface Slippage Study Between Polyamide 12 And Ethylene Butene Copolymer Melt In Capillary Extrusion, Jinhai Yang, James L. White

Faculty Publications

Extrusion of a polyamide 12 (PA12) material through a capillary die coated with an ethylene butene copolymer (EBM) was studied. The EBM coated die significantly increased the flow rates of the PA12 melt compared to a clean die at the same extrusion pressure. Introducing a maleic anhydride grafted ethylene-octene copolymer (EOM-g-MAH) into the EBM suppressed the effect. This behavior seems only explained by significant interface slippage between PA12 and EBM melts, which could be eliminated by introducing covalent chemical bonds across the interface. A mathematical analysis was carried out to calculate the interface slippage. The shear stress where slippage began …

Chemically Decorated Boron-Nitride Nanoribbons, Xiao-Jun Wu, Men-Hao Wu, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Motivated by recent studies of graphenen nanoribbons (GNRs), we explored electronic properties of pure and chemically modified boron nitride nanoribbons (BNNRs) using the density functional theory method. Pure BNNRs with both edges fully saturated by hydrogen are semiconducting with wide band gaps. Values of the band gap depend on the width and the type of edge. The chemical decoration of BNNRs’ edges with four different functional groups, including -F, -Cl, -OH, and -NO₂, was investigated. The band-gap modulation by chemical decoration may be exploited for nanoelectronic applications.

Experimental And Theoretical Investigation Of Molecular Field Effects By Polarization-Resolved Resonant Inelastic X-Ray Scattering, Stephane Carniato, Renaud Guillemin, Wayne C. Stolte, Loic Journel, Richard Taieb, Dennis W. Lindle, Marc Simon

Chemistry and Biochemistry Faculty Research

We present a combined theoretical and experimental study of molecular field effects on molecular core levels. Polarization-dependent resonant inelastic x-ray scattering is observed experimentally after resonant K-shell excitation of CF₃Cl and HCl. We explain the linear dichroism observed in spin-orbit level intensities as due to molecular field effects, including singlet-triplet exchange, and interpret this behavior in terms of population differences in the 2p_x,y,z inner-shell orbitals. We investigate theoretically the different factors that can affect the electronic populations and the dynamical R dependence of the spin-orbit ratio. Finally, the results obtained are used to interpret the L-shell …

Decarbonylation Reaction Of [Os3(Co)10(Μ-H)(Μ-Sn2C4H5)]: X-Ray Structures Of The Two Isomers Of [Os3(Co)9(Μ-H)(Μ3-Η2-Sn2C4H5)], Shishir Ghosh, Shariff E. Kabir, Mansura Khatun, Daniel T. Haworth, Sergey V. Lindeman, Tasneem Siddiquee, Dennis W. Bennett

Chemistry Faculty Research and Publications

The thermal reaction of [Os₃(CO)₁₀(μ-H)(μ-SN₂C₄H₅)] (1) at 110 °C afforded the new compound [Os₃(CO)₉(μ-H)(μ ₃-η ²-SN₂C₄H₅)] (2) in 84% yield. Compound 2 exists as two isomers, which differ in the disposition of the bridging hydride ligand. Both of the isomers of 2 have been characterized by a combination of elemental analysis, infrared and ¹H NMR spectroscopic data together with single crystal X-ray crystallography. The isomers …

Fabrication Of Polyvinyl Alcohol Arrays And The Direct Electrochemistry Of Adsorbed Cytochrome C, Yu-Hua Qin, Ruo-Kun Jia, Qing-Juan Wei, Li Ma, Xiao-Hui Guan, Nan Lv

Journal of Electrochemistry

Regular polyvinyl alcohol arrays were prepared with porous polystyrene films by a self-assembly method. Cyt c immobilized on PVA microlens arrays modified glassy carbon electrodes gave a pair of stable,well-defined and quasi-reversible cyclic voltammetric peaks at about 0.072 V (vs. Ag/AgCl) in 0.1 mol/L PBS buffer (pH = 6.89) solution. The effects of scan rate,pH and concentration of buffers on the electrochemical behaviors of Cyt c were studied in detail. The apparent heterogeneous electron transfer rate constant (k⁰) was evaluated to be 2.98×10^-6 cm·s^-1.

Synthesis And Characterization For A New Organic Cathode Material Of Lithium-Ion Batteries——Poly Sulfurized Chloranilic Acid(Psca), Kai Liu, Jian-Ming Zheng, Gui-Ming Zhong, Yong Yang

Journal of Electrochemistry

A new organic cathode material,poly sulfurized chloranilic acid(PSCA),has been successfully synthesized for lithium-ion batteries. 13C solid state NMR and FTIR results indicated that the chorine in chronailic acid was substituted by sulfur after sulfurization. The electrochemical measurements showed that the initial discharge capacity of PSCA was up to 287.6 mAh/g,and 169.9 mAh/g still remained after 100 cycles when cycled between 1.5～3.6 V at the current density of 15 mA/g.

Silicon Silver Composite Materials For Li-Ion Batteries, Lian-Bang Wang, Xiao-Bo Dai, Xin-Yan Zhu, Xin-Biao Mao, Chun-An Ma

Journal of Electrochemistry

properties of the composites were determined by charge-discharge tests and cyclic voltammetry. The composite composed of Si∶Ag with an atomic ratio of 1∶1 (sample 1#) showed good cyclic stability and charge-discharge reversibility. The reversible capacity of the composite (sample 1#) was remained over 300 mAh·g^-1 after 50 cycles. Experimental results showed that controlling the potential range of charge-discharge processes could enhance the cyclic performance of alloy materials.

Synergism Of Complex Additives Of Dtab+Ktl For Zinc Corrosion Inhibition In Koh Solutions, Sheng-Zhou Lin, Zeng-Xin Cai, Gui-Sheng Wang, He-Bing Zhou, Wei-Shan Li

Journal of Electrochemistry

The electrochemical behaviors of Zn in 3mol/L KOH solution containing several kinds of inhibitors were investigated by weight-loss,electrochemical methods and SEM. The results showed that both the single ad-ditive and the mixed additives can suppress the corrosion of zinc in 3 mol/LKOH solution. And the inhibition ef-feciency of the mixed additives is higher than that of any single additive because of the synergistic effect between KTL and DTAB. The adsorption of DTAB on the surface of zinc has been enhanced in the presence of KTL.

A Study On The Lifepo4/Mwcnts Cathode Materials For Li-Ion Batteries, You-Yi Peng, Hai-Yan Zhang, Chun-Hua He, Wei Xie, Zhi-Feng Zeng

Journal of Electrochemistry

The LiFePO₄/MWCNTs composite was synthesized by ball milling,then the composite electrode was assembled into button lithium-ion batteries.The structure and morphology of the samples,the electrochemical performance of the electrodes were investigated by ways of X-ray diffraction,scanning electron microscopy,cyclic voltammetry and charge-discharge capacity tests. The electrochemical performance of the composite electrodes with different MWNTs contents were studied. The results indicated that the composite electrode containing 10% MWCNTs(by mass)exhibited the most excellent electrochemical performance with the initial charge-discharge capacities of 139 mAh·g^-1,128.5 mAh·g^-1,respectively,and a Kulun efficiency of 92.4% at 0.1C rate under room temperature.Compared to the electrodes …