Physical Sciences and Mathematics Commons^™

On The Vertical And Adiabatic Excitation Energies Of The 21a(G), State Of Trans-1,3-Butadiene, Jason Lappe '00, Robert J. Cave

All HMC Faculty Publications and Research

The excitation energy to the 2¹A_g state of trans-1,3-butadiene is examined using a variety of ab initio electronic structure techniques. While analogous states have been shown to be the lowest singlet excited states for all longer polyenes, for butadiene the position of the 2¹A_g state relative to the HOMO → LUMO excitation (1¹B_u) has been difficult to establish theoretically. We employ a variety of methods (CASSCF, CASPT2, MRSDCI, QDVPT) to examine both the vertical and adiabatic excitation energies for this state. At the ground-state geometry, the vertical excitation energies …

Friction Of (110) Diamond In The Presence Of Small Hydrocarbon Molecule, Catherine Manning

Honors Theses

Molecular dynamic simulations have been used to explore the friction between two (110) diamond surfaces in sliding contact. In general, when a third-body hydrocarbon molecule is placed between two computer generated diamond surfaces in sliding contact, the result is a reduction of friction as the load iH increased compared to the same surfaces in the absence of third-body molecules. The size, shape, and alignment of the third-body hydrocarbon molecules play an essential role in the reduction of friction. Results for a system with ethane presented as a third-body molecule will be compared to previous theoretical studies as well as existing …

(N2o)2⋅So2: Rotational Spectrum And Structure Of The First Van Der Waals Trimer Containing Sulfur Dioxide, Rebecca A. Peebles, Robert L. Kuczkowski

Faculty Research and Creative Activity

No abstract provided.

(N2o)2⋅So2: Rotational Spectrum And Structure Of The First Van Der Waals Trimer Containing Sulfur Dioxide, Rebecca Peebles, Robert Kuczkowski

Faculty Research and Creative Activity

No abstract provided.

Chemical Oxidation Of Mtbe Under O2-Rich And O2-Limited Environments Coupled With Biological Degradation Of Oxidation Byproducts, J. Sutherland, B. Panka, Craig D. Adams, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The H2O2/UV Advanced Oxidation Process (AOP) Was Investigated to Determine Byproduct Formation under Different Experimental Conditions (PH, Alkalinity, and H2O2/UV Dose). a Key Factor in the Efficiency of the AOP Was the Dissolved Oxygen Concentration. Gas Chromatography/mass Spectrometry (GC/MS) Analysis Was Used to Identify Byproducts Resulting from Oxidation under Oxygen-Rich and Oxygen-Limited Conditions. Resultant Oxidation Byproducts Were Analyzed for their Susceptibility to Biological Degradation. Biodegradation Rate Constants Were Determined and Modeled for the Primary Byproducts of the Advanced Oxidation Process. Inhibition Resulting from the Presence of Multiple Byproducts in a Biological System Was Investigated as Well. Effects of Process Parameters …

Enantiomeric High-Performance Liquid Chromatographic Separation Of Β- Substituted Tryptophan Analogues, G. Török, A. Péter, E. Vékes, J. Sápi, M. Laronze, J. Y. Laronze, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

The high-performance liquid chromatographic enantioresolution of β- substituted tryptophan analogues by direct and indirect methods is reported. The direct separation was carried out on chiral crown ether-bonded, on the macrocyclic antibiotic teicoplanin-bonded or on different derivatized β- cyclodextrin-bonded phases. The indirect resolution was achieved by applying pre-column derivatization with the chiral reagents 1-fluoro-2,4- dinitrophenyl-5-L-alanine amide (FDAA) and 2,3,4,6-tetra-O-acetyl-β-D- glucopyranosyl isothiocyanate (GITC). In the separation of all four isomers of the analytes, the indirect methods seemed to be more efficient than the direct methods. In most cases, the FDAA derivatives of the stereoisomers could be separated with better selectivity in methanol-containing …

In-Situ Frequency-Dependent Electromagnetic Sensing For Monitoring Physical And Chemical Attributes During Chemical Processing, Jeffrey David Rogozinski

Dissertations, Theses, and Masters Projects

The objective of this research was to develop an in-situ sensing technique that monitors the molecular-level response of ions and dipoles to an applied electric field in order to characterize the changes in state of a polymer resin during chemical processing. This technique needs to be capable of monitoring the reaction progress not only in the laboratory setting but also in-situ in the processing tool or reaction environment. Frequency Dependent Electromagnetic Sensing (FDEMS) was selected for this task.;This dissertation investigates the applicability of FDEMS to monitoring two types of processing methods: reactive and batch reactor. The reactive processing system examined …

A Study Of The Aging Of Polyamide-11 Based On Molecular Weight Measurements, Yao Lin

Dissertations, Theses, and Masters Projects

No abstract provided.

Reaction Of Alpine-Borane With Aldehydes: Reactivity Rate Assessment By Observation Of The Disappearance Of The Carbonyl N - Pi* Peak By Uv-Visible Spectroscopy, Layla Bland, Michael J. Panigot

Journal of the Arkansas Academy of Science

Due to an unexpectedly difficult reduction of indole-3-carbaldehyde and of isobutyraldehyde using the chiral reducing agent Alpine-Borane, the reactivity of several aliphatic, aromatic, and unsaturated aldehydes was investigated. This was done in order to determine whether there was a relationship between aldehyde structure and reduction rate. It was found that aliphatic aldehydes and aromatic aldehydes with no strongly electron-donating groups on the arene ring reduced faster than unsaturated aldehydes.

Preparation Of An Electrophilic 3-Methylindole Derivative: Difficulties In Forming A Stable, Suitable Material For The Preparation Of Tryptophan, Jason Boggs, Mariah Mcmasters, Robert W. Curley Jr., Michael J. Panigot

Journal of the Arkansas Academy of Science

In an attempt to prepare stereoselectively beta-deuterated tryptophan, N-protected indole-3-methanol compounds were prepared with model studies being done on undeuterated material. Conversion of these compounds to electrophilic species proved exceptionally difficult and resulted in very low yields or recovered starting material only. A summary of the current results utilizing N-tosyl indole-3-methanol will be presented as well as efforts using N-Boc indole-3-methanol.

The Dehydrochlorination Mechanism Of The Internal Allylic Chloride Structure In Poly(Vinyl Chloride), Lynda B. Payne

Dissertations, Theses, and Masters Projects

No abstract provided.

Equilibrium And Kinetic Studies Of Isomerization Of (Co)5w[Η1-Pph2ch2p(P-Tol)2] And (Co)5w[Η1-P(P-Tol)2ch2pph2], Deliang Chen

Masters Theses

Unsymmetrical diphosphine tungsten complexes, (CO)₅W[η¹-PPh₂CH₂P(p-tol)₂] and (CO)₅W[η¹-P(p-tol)₂CH₂PPh₂], were prepared from (CO)₅W(NH₂Ph) and Ph₂PCH₂P(p-tol)₂. Two approaches were successfully used to synthesize Ph₂PCH₂P(p-tol)₂. The first utilized PPh₂CH₂Cl, prepared from PPh₂H, CH₂Cl₂, and KOH under phase transfer conditions, from which Ph₂PCH₂P(p-tol)₂ was …

A Time Resolved Laser Spectroscopy Study Of Resonance Energy Transfer Between Tb(Iii) And An Organic Dye: 6-Hydroxy-5-[(2-Methoxy-5-Methyl-4-Sulfophenyl)Azo]-2-Naphthalenesulfonic Acid Disodium Salt, Ronald Wesley Tennis

Masters Theses

Intermolecular energy transfer is a process of crucial importance to photochemistry and photophysics. Complexed lanthanide ions are well suited as energy transfer donors because they display dependable absorption and luminescence qualities with narrow rare-earthion emission in addition to relatively long excited-state lifetimes.

This project used a pulsed nitrogen laser and high speed digital techniques to study energy transfer dynamics between excited state Tb(acac)₃ and an ionic organic dye called Red 40. Luminescence decay profiles of excited terbium atoms in the presence of the quencher were measured in both high and low viscosity solvents. The effects of solvent viscosity and …

Activation Of P38 Mitogen-Activated Protein Kinase And C-Jun Nh2-Terminal Kinase By Double-Stranded Rna And Encephalomyocarditis Virus: Involvement Of Rnase L, Protein Kinase R, And Alternative Pathways, Mihail S. Iordanov, Jayashree M. Paranjape, Aimin Zhou, John Wong, Bryan R.G. Williams, Eliane F. Meurs, Robert H. Silverman, Bruce E. Magun

Chemistry Faculty Publications

Double-stranded RNA (dsRNA) accumulates in virus-infected mammalian cells and signals the activation of host defense pathways of the interferon system. We describe here a novel form of dsRNA-triggered signaling that leads to the stimulation of the p38 mitogen-activated protein kinase (p38 MAPK) and the c-Jun NH2-terminal kinase (JNK) and of their respective activators MKK3/6 and SEK1/MKK4. The dsRNA-dependent signaling to p38 MAPK was largely intact in cells lacking both RNase L and the dsRNA-activated protein kinase (PKR), i.e., the two best-characterized mediators of dsRNA-triggered antiviral responses. In contrast, activation of both MKK4 and JNK by dsRNA was greatly reduced in …

Enantioselective Complexation Of Amino Acids By 6a-Deoxy-6a-Hydroxyethylamino- Β -Cyclodextrin And Its Metallo-Derivatives In Aqueous Solution, Nicole Van Hoof, Noel Russell, Mary Mcnamara, Raphael Darcy

Articles

Enantioselectivity towards several amino acids by metallo-6A-deoxy-6A-hydroxyethylamino-β-cyclodextrins (metallo- β CDea’s) was investigated by potentiometric titration of the various amino acid/metallo- β CDea systems with NaOH solution. It was shown that the cyclodextrin derivative is capable of distinguishing between enantiomers of amino acid species in the presence of certain metal ions (Co, Ni, Cu and Zn). Ni- β CDea complexes show the most enantioselectivity,whereas for Cu and Co2C-_CDea complexes less selectivity is observed. As expected, Zn- β CDea complexes exhibit no enantioselectivity. Stability and selectivity, however, do not go hand in hand, since the most stable complexes are formed …

Ground-State Properties And Excited-State Reactivity Of 8-Quinolate Complexes Of Ruthenium(Ii), Dean Johnston

Chemistry Faculty Scholarship

In an effort to explore new systems with highly reducing excited states, we prepared a series of Ru(II) complexes of the type Ru(L)(2)quo(+) (L = bpy (2,2'-bipyridine), phen (1,10-phenanthroline), dmphen (4,7-dimethyl-1,10-phenanthroline), tmphen (3,4,7,8-tetramethyl-1,10-phenanthroline); quo(-) = 8-quinolate) and investigated their photophysical and redox properties. The absorption and emission spectra of the Ru(L)(2)quo(+) are significantly red-shifted relative to those of the parent complexes Ru(L)(3)(2+), with emission maxima in the 757-783 nm range in water. The Ru(L)(2)quo(+) systems are easily oxidized with E(1/2)(Ru(III/II)) values ranging from +0.62 to +0.70 V vs NHE, making the emissive Ru --> phen MLCT (metal-to-ligand charge transfer) excited …

Versatile Apparatus For Measuring Kinetics Of Gaseous Reactions By A Relative Method, Edmond W. Wilson Jr., Holly A. Sawyer, Amber A. Sawyer

Journal of the Arkansas Academy of Science

It is important that accurate, reproducible values for the rates of chemical reactions occurring in the atmosphere be obtained. The value of accurate kinetics measurements is to improve the accuracy of mathematical models used to forecast the state of the atmosphere. We describe a versatile, robust apparatus for obtaining atmospheric reaction rate values and their temperature dependencies by a relative method. This relative method has the advantage over absolute methods in that errors due to impurities and adsorption on walls of the reaction apparatus are minimized. In addition, relative values serve as an important verification for absolute values. The apparatus …

Hammett Correlations Of The Amide Proton Chemical Shift In A Series Of 1-Tosyl-3-(4-Substituted Phenyl)Ureas, Frank L. Setliff, Melody K. Harrison

Journal of the Arkansas Academy of Science

No abstract provided.

Cisplatin Interstrand Cross-Linking Of Defined Sequence Nucleosomal Dna, Erin Elizabeth Wilkes

Honors Theses

DNA interstrand cross-linking agents have been recognized for many years to be powerful antitumor chemotherapeutics. While the interactions between free DNA and many anticancer drugs have been explored extensively, there is less infonnation available about these interactions with nucleosomal DNA. Nitrogen mustards have been reported to exhibit relatively similar cross-linking sites and efficiencies of binding in free and nucleosomal DNA, but mitomycin C exhibits markedly reduced cross-linking near the center of nucleosomal DNA. This current study focuses on cisplatin interstrand cross-linking of the 154 base pair 55 rRNA gene fragment of Xenopus borealis reconstituted with histones from chicken erythrocytes. The …

A Catechol Approach To Natural Product Synthesis, Michelle E. Weber

Honors Theses

This research has focused on the total synthesis of the iron--chelating natural product 1-(2,3-hydroxyphenyl)-4-methoxy-I-butanone. An extract of the iron-cleficient fungus Gleophyllwn lraebeum, this molecule is thought to bind to Fe3+ in a hexacoordinate system to aid in transport through cell walls in order to help regulate iron levels in such iron-deficient fungi. Since the proposed structure of the molecule is based only on the spectral data of a very small sample, our hope is to synthesize and confirm its structure as the extract of the brown rot fungus. We have developed a relatively short retrosynthesis for our work on this …

Interactions Of Ti(Iv) And Sn(Iv) Organometallic Complexes With Double-Stranded Dna, Katherine Macdonald Davies

Honors Theses

In order to understand further the interactions that exist between specific organometallic complexes and DNA, reactions of double-stranded calf-thymus DNA with bis(cyclopentadienyl)titanium dichloride [Cp₂TiC1₂] (TDC), bis(t-butylcyclopentadienyl)titanium dichloride [(C₄H₉Cp)₂TiC1₂] (r-butyl TDC), bis(i-propylcyclopentadienly)titanium dichloride [(C₃H₆Cp)2TiCl₂ a-propyl mc), bis(pentamethylcyclopentadienyl) titanium dichloride [(Cp"₂TiC1₂ (pentarnethyl TDC), triphenyltin chloride (Ph₃SnCl), diphenylrin dichloride (Ph₂SnC1₂) , and triphenyltin acetate (Ph₃SnOAc) were performed. The goal of this research is to establish how the fundamental structure and composition of these compounds determine the effecti veness of their DNA interactions. Each metal compound was incubated with calf thymus DNA at several metal: DNA ratios and reactions were maintained at 37°C at …

Trimethyl(Trifluorovinyl)Silane, Roxana M. Trifu, George L. Gould

Faculty Publications

No abstract provided.

Studies Of Tryptophans In Membrane- Spanning "Walp" Peptides By Deuterium Nmr Spectroscopy, Nichole Reed

Inquiry: The University of Arkansas Undergraduate Research Journal

WALP pep tides of sequence acetyl-Gly-Trp-Trp-(Leu-Ala)-Trp-Trp-Ala-ethanolamine insert into lipid bilayers as membrane-spanning a-helices and modulate the lipid phase behavior as functions of n and the lipid acyl chain length. A key feature of the WALP peptides is the positioning of tryptophan (Trp) indole rings at the membrane/water interface. For the examples WALP19 with n = 6.5 and WALP23 with n = 8.5, we have labeled individual indoles with deuterium and incorporated the labeled peptides in oriented, hydrated bilayers of Dimyristoyl-phosphatidylcholine (DMPC). Deuterium NMR spectra from these samples show sharp resonances when the membrane normal is aligned either parallel (Beta = …

Isolation Of Curcumin From Tumeric, Ram Mohan, Andrew Anderson, Matthew Mitchell

Scholarship

No abstract provided.

High-Performance Liquid Chromatographic Determination Of Oxytetracycline Residue In Cured Meat Products, Hami̇de Z. Şenyuva, Tuncel Özden, Deni̇z Yurtsever Sarica

Turkish Journal of Chemistry

The development of a sensitive automated method for residue control of oxytetracycline (OTC) in cured meat (soudjouk) is described. The principle steps involve the extraction of OTC from cured meat in the presence of citric acid with nitric acid, methanol and de-ionized water, and then the determination by HPLC. In HPLC, Hypersil BDC C18 column was used and OTC was separated at 24 ^{o}C using a mobile phase of H_2O (pH=2.10 with H_2SO_4): ACN (85:15, v/v) at a flow rate of 1.5 ml/min. A variable wavelength detector was set at 360 nm. The detection limit of the method was calculated …

Beyond The Dipole Approximation: Angular-Distribution Effects In The 1s Photoemission From Small Molecules, Dennis W. Lindle, Oliver Hemmers, H. Wang, P. Focke, I. A. Sellin, J. D. Mills, J. A. Sheehy, P. W. Langhoff

Environmental Studies Faculty Publications

Over the past two decades, the dipole approximation has facilitated a basic understanding of the photoionization process in atoms and molecules. Recent experiments on the 1s inner shells of small molecules at relatively low photon energies (⩽ 1000 eV) show strong nondipole effects. They are significant and measurable at energies close to threshold, in conflict with a common assumption that the dipole approximation is valid for photon energies below 1 keV.

Double Cysteine Mutations In Staphylococcal Nuclease: The Effect Of Artificially Introduced Disulfide Bonds On Protein Structure And Stability, Anna Terry

Inquiry: The University of Arkansas Undergraduate Research Journal

Since a protein's function depends on its structure, basic research in protein structure facilitates the solution of many practical problems, such as the synthesis of more effective medicines. With this larger goal in sight, the purpose of this research project is to understand better the chemical principles that underlie protein structure and stability. Disulfide bonds are a potentially stabilizing feature of many proteins. They may form between cysteine residues in close proximity to one another if the orientation is favorable. Often found in proteins produced by organisms that grow at high temperatures, disulfide bonds may anchor side chains together, making …

Polybutadiene Cross-Linked With Various Diols – Effect On Thermal Stability, Fawn Marie Uhl, Michael A. Mckinney, Charles A. Wilkie

Chemistry Faculty Research and Publications

The relationship between cross-linking and thermal stability as related to polybutadiene is the focus of current research. Cross-linked polybutadienes have been prepared using various diols as the cross-linking agent. Cross-linked polymers have been characterized by gel content, swelling ratios, infrared spectroscopy, and thermal analysis. These polymers are not highly cross-linked, as seen by gel content and swelling ratios, and cross-linking does not have a large effect on the onset temperature of the degradation. Nonetheless, extensive formation of a non-volatile residue occurs.

Research Reports Andean Past 6, Tamara L. Bray, Cristobal Landazuri, Cesar Veintimilla, Earl H. Lubensky, Allison Paulsen, Hector Neff, Michael Glascock, Ralph Rowlett, Steven Velasquez, Jessica Coats, Pamela J. Hale, Julia Anne Wagner, Gene Keay, Jessica Aberle, Ronald D. Lippi, Izumi Shimada, Julie Farnum, Jack Rossen, Daniel H. Sandweiss, Daniel Belknap, Stacy H. Schafer Rogers, Jeffrey N. Rogers, Kate Pechenkina, Richard L. Burger, Lucy Salazar Burger, Robert A. Benfer Jr., Neil Duncan, Bernardino Ojeda, Deborah Pearsall, Lawrence Kuznar, Joe Vradenburg, Krzysztof Makowski Hanula, Mercedes Delgado Agurto, Donald A. Proulx, Ana Nieves, Henry Falcon Amado, Miriam Gavilan Roayza, David Johnson, Frances A. Riddell, Richard Brooks, Anna Noah, Alina Aparicio, Sheilagh Brooks, Sandra Asmussen, J. Arthur Freed, Marie Cottrell, Lidio Valdez, William Fowlks, Zasha Trivisonno, Frances Durocher, John Schaller, Nathan Parker, Dwight Wallace, Julio Manrique, Grace Katterman, Oscar Bendezu, Catherine Julien, Margaret Enrile, Juan Segura, Harold W. Borns Jr., Sarah Osgood Brooks, Rolando Paredes, Maria Del Carmen Sandweiss, Heather Mcinnis, Trevor Ott, Osvaldo Chozo, Miguel Cabrera, Arturo Santos, Ted Mcclure, Ben Tanner, Fred Andrus, Julissa Ugarte, David Sanger, Dolores Piperno, Elizabeth Reitz, Howard Melville, Bruce Smith, Richard C. Sutter, Christine A. Hastorf, Matt Bandy, Lee Steadman, Kate Moore, William Whitehead, Jose Luis Paz, Melissa Goodman Elgar, Ian Hodder, Donald Johnson, John Southon, Susan D. De France, David W. Steadman, Deborah Blom, Claudia Rivera, Sonia Alconini, Sigrid Arnott, Emily Dean, David Kojan, Rene Ayon, Franz Choque, Mario Montano Aragon

Andean Past

No abstract provided.

Electroanalysis Using Differential Pulse Methods And Stripping Techniques., Enda Howard

Masters

Application of a differential pulse waveform to a microelectrode or a rotating disk electrode results in a peaked response for amperometric redox reactions. Based on these observations models were proposed and tested for these methods. Simulations of the models were carried out by inputting the relevant equations into Microsoft Excel. The microelectrode study revealed a good correlation between one model and the numerical derivative of the current following a linear sweep potential waveform. Experimentally the derivative can be obtained numerically following a linear sweep. The alternative differential pulse waveform requires more sophisticated equipment and the response can be affected by …