Physical Sciences and Mathematics Commons^™

Acidity Studies Of Deuterated Acids And Bases Commonly Used As Buffers In Nmr Studies, Rose M. Mcconnell, Walter E. Godwin, Brant Stanley, M. Shane Green

Journal of the Arkansas Academy of Science

Structure based drug development is currently considered to be an important strategy for drug discovery. This strategy requires that critical knowledge of the three dimensional binding site on receptor molecules be known. NMR studies are frequently employed to ascertain important structural data on individual proteins as well as complexes of proteins with ligands. Deuterium labeled acids and bases are frequently used as buffers in deuterium oxide solutions for NMR studies on the structural conformations of bioactive molecules. Since pH is an important factor in any study of the conformational and stereochemical aspects of biologically active molecules, deuterated buffers are an …

Artificial Neural Networks Used To Predict Electrical Properties Of Polymers, Sanjay K. Mitra, Qing Luo, Jerry A. Darsey

Journal of the Arkansas Academy of Science

The ability to predict properties of molecules prior to their synthesis can be of great importance in optimizing their design. Substantial savings in time as well as cost can be achieved if some desired properties can be predicted prior to the synthesis of the molecule. The outer orbitals of a molecule are primarily responsible for many different properties of the molecules. These outer orbital parameters can be utilized by an intelligent computing system like an Artificial Neural Network to extract necessary knowledge about the properties of the molecule. An Artificial Neural Network was trained to extract electrical parameters of several …

New Studies Of Polyfuran And Polymers Of 3-Substituted Furan Rings, Rose M. Mcconnell, Walter E. Godwin, Bradley Phillips

Journal of the Arkansas Academy of Science

No abstract provided.

Reductive Dechlorinatin Of A 2-Chloronicotinic Acid Under Finkelstein Conditions, Frank L. Setliff, Leslie B. Coop

Journal of the Arkansas Academy of Science

No abstract provided.

Dichlorobis[1-Methyl-3-(Prop-2-Enyl)Imidazole-2(3h)-Thione-S]Zinc(Ii), Daniel J. Williams, Tuan A. Ly, Jeffrey W. Mudge, William T. Pennington, George L. Schimek

Faculty Articles

The title compd. is monoclinic, space group P21/n, with a 14.0082(8), b 10.803(1), c 14.581(1) Å, and β 116.625(8)°; Z = 4, dc = 1.50; R = 0.043,Rw = 0.044 for 1935 reflections. The crystal structure shows a discrete mol. structure with tetrahedral geometry around the Zn ion. The mean Zn-Cl and Zn-S distances are 2.259(7) and 2.372(4) Å, resp. Bond angles around the Zn ion range from 102.8(1) to 113.7(1)°. Ring distances and angles in the ligand compare favorably with literature values of analogous compds., and the mean C-S bond distance of 1.71(1) Å is close to the av. …

Dichlorobis[1,3-Dimethylimidazole-2(3h)-Selone-Se]Cobalt(Ii), Daniel J. Williams, Timothy Jones, Edward D. Rice, Kerri J. Davis, John A. Ritchie, William T. Pennington, George L. Schimek

Faculty Articles

The crystal structure of the title compound, [CoCl₂(C₅H₈N₂Se)₂], shows a discrete molecular structure with tetrahedral geometry around the cobalt ion. The mean Co-Cl and Co-Se distances are 2.277 (3) and 2.456 (3) Å, respectively. Bond angles around the Co atom range from 101.1 (1) to 120.0 (1)°. Ring distances and angles in the ligand compare favorably with the literature values of analogous compounds, and show significant increases from values observed in the uncoordinated selone. However, the mean C-Se bond distance of 1.88 (2) Å shows no significant difference from the …

Characterization Of Iron Oxides And Atmospheric Corrosion Of Steel, Sei Jin Oh

Physics Theses & Dissertations

The study of corrosion behavior was performed using three different analytical techniques, which provided information on the formation, development and layering of iron oxides on the corrosion products as a function of atmospheric conditions, exposure time and type of steel. In particular, the protective layer formed on weathering steel was investigated as a function of different amounts of alloying elements in the steel, atmospheric conditions and exposure times. Combined together, the results provided a better understanding of the atmospheric corrosion behavior of steel, and formed a part of database of the atmospheric corrosion characteristics.

Accurate characterization of the iron oxides …

Correlation Of Dynamic Dielectric Properties To Reaction Kinetics And Changing Mechanical Properties Of Epoxy Resins During Cure, Yunfei Wang

Dissertations, Theses, and Masters Projects

The principal objective of this paper is to describe how complex impedance, obtained from frequency dependent dielectric sensing technique, can be used as an effective diagnostic tool for in situ real-time investigation in the fabrication of thermoset structures.;Two epoxy systems (Pr500 from 3M and My720 from Ciba Geigy) with different functionality are characterized in terms of their dielectric, thermal, and rheological behavior. It is observed that there is a one to one relationship between Tg and conversion which is independent of cure temperature. The chemical kinetics of the reaction is satisfactorily described by an autocatalyzed reaction mechanism. The chemical rate …

The Synthesis Of Reflective And Electrically Conductive Polyimide Films Via An In Situ Self-Metallization Procedure Using Silver(I) Complexes, Robin Elaine Southward

Dissertations, Theses, and Masters Projects

Optically reflective polyimide films have been prepared by the incorporation of silver(I) acetate and a {dollar}\beta{dollar}-diketone solubilizing agent, hexafluoroacetylacetone (HFAH), into a dimethylacetamide solution of the poly(amic acid) formed from {dollar}3,3\sp\prime,4,4\sp\prime{dollar}-benzophenonetetracarboxylic acid dianhydride (BTDA) and {dollar}4,4\sp\prime{dollar}-oxydianiline {dollar}(4,4\sp\prime{dollar}-ODA). Optically reflective and conductive polyimide films have been prepared by replacing the {dollar}\beta{dollar}-diketone (HFAH), with the less substituted {dollar}\beta{dollar}-diketone, trifluoroacetylacetone (TFAH). The former system has been both cast directly from the poly(amic acid) resin and cast from the poly(amic acid) resin onto a fully imidized {dollar}\rm BTDA/4,4\sp\prime{dollar}-ODA base (forming a metallized topcoat). Thermal curing of the silver(I)-containing poly(amic acid) leads to imidization with …

Crystal Structure Of (Μ-Tranis-4,4'-Dinitro-2,2'-Biimidazolato-N,N: N'',N''') Bis[Bis(Triphenylphosphine Copper(I))] N,N-Dimethylformamide, [C42h37cun4o3p2]2, R. G. Baughman, C. A. Hester, Harvest L. Collier

Chemistry Faculty Research & Creative Works

No abstract provided.

Varietal Differences In The Total And Enantiomeric Composition Of Theanine In Tea, K. Helen Ekborg-Ott, Andre Taylor, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Theanine is the main amino acid component in tea. It usually constitutes between 1 and 2% of the dry weight of the tea leaves. It is as prevalent in tea as all other free amino acids combined. Both enantiomers of theanine were found to have a similar sweet taste, with little or no aftertaste. It was found that black and half-green teas (except for Formosa Oolong) contained as much, or more, theanine as green teas. No correlation was found between the absolute concentration of theanine in tea and its enantiomeric composition. An inverse correlation was found between certain grades of …

Characterization Of Epoxy-Amine Systems And Nylon-11 And Pvdf Degradation, Wendy Raquel Mahler

Dissertations, Theses, and Masters Projects

No abstract provided.

Development Of Supercritical Fluid Extraction (Sfe) For The Determination Of Polychlorinated Biphenyls In Tissues Of Aquatic Biota, Michael O. Gaylor

Dissertations, Theses, and Masters Projects

No abstract provided.

The Selective Oxidation Of Beta-Cyclodextrin On The Secondary Face, Christine Evelyn Heath

Dissertations, Theses, and Masters Projects

No abstract provided.

A Niobium(V) Complex With Mixed O,S-Donor Ligands. Synthesis, Structure And Properties Of The Anion Tris(2-Mercapto-4-Methylphenolato)Niobate(V), Paul Challen, Diane Peapus, Karen Magnes

Paul R. Challen

Reaction of Nb(OEt)5 with 2-mercapto-4-methylphenol (mmpH2) in the presence of triethylamine gave the mononuclear tris complex (Et3NH)[Nb(mmp)3] which was structurally characterized. The coordination geometry around the niobium is between octahedral and trigonal prismatic, with a twist angle of 41.5°. The mercaptophenolate ligands are arranged around the metal in a “propeller” fashion. (Et3NH)[Nb(mmp)3] was characterized by IR, 1H NMR and UV-vis spectroscopies, and cyclic voltammetry. A reversible reduction wave found at −1.03 V is for reduction to the NbIV complex.

Voltammetric Studies Of Mn@C82, Mark Anderson, Harry Dorn, Paul Burbank, James Gibson

Mark R. Anderson

The voltammetry for a series of related endohedral metallofullerenes is reported. It is found that as additional metal atoms are inserted into the fullerene cage, the first reduction of the metallofullerenes shifts to more negative potentials. This is consistent with more charge being transferred to the fullerene cage from the additional metal atom; however, the magnitude of the shift is much smaller than expected.

Direct Measurement Of Diffuse Double-Layer Forces At The Semiconductor/Electrolyte Interface Using An Atomic Force Microscope, Kai Hu, Fu-Ren F. Fan, Allen J. Bard, Andrew C. Hillier

Andrew C. Hillier

The forces between a silica probe and an n-type TiO2 single-crystal electrode were measured using an atomic force microscope in an aqueous electrolyte solution. These interactions were a strong function of the solution pH, the presence of specifically adsorbed anions, and the TiO2 electrode potential. For a series of pH values, a strong electrostatic repulsion was seen at high pH and decreased as the pH was reduced. At pH values below 5.5, the interaction became attractive. A series of force measurements between SiO2 and n-type TiO2 showed a repulsive interaction when TiO2 was held at negative electrode potentials, which transformed …

Nickel Catalyzed Cyclizations Of Alkynyl-Etones And Their Application To The Formal Synthesis Of Pentalenic Acid, Kevin Schlosser

Honors Theses

Pentalenic acid is a very important molecule because it is a biosynthetic intermediate of pentalenolactone, which has antibiotic effects on Grampositive/ negative bacteria and pathogenic fungi. These effects are due to its ability to inhibit glyceraldehyde 3-phosphate dehydrogenase.1 However, the total synthesis of pentalenic acid is very lengthy.2 This project will begin the process of finding a more convenient route to pentalenic acid. Previously in this laboratory there have been experiments conducted in the cyclization of enones with nickel (0)3 It is hypothesized that this method can be used to shorten the preparation of pentalenic acid. As illustrated by the …

International Symposium On Macromolecular Architecture, Otto Vogl, Jane C. Vogl, Tatsuki Kitayama

Otto Vogl

No abstract provided.

Polymer Science In Vietnam, Otto Vogl, Dang Van Luyen, Dang Mai-Huong

Otto Vogl

No abstract provided.

45. Minoru Imoto, Otto Vogl, Tatsuro Ouchi

Otto Vogl

No abstract provided.

The Biodegradation Characteristics Of Proposed Fuel Systems Icing Inhibitors (Fsii), Charles E. Meshako

Theses and Dissertations

The biodegradation characteristics of three fuel system icing ihhibitors (FSII) were evaluated. FSII are jet fuel additives that partition into water readily and are present in the water drained from storage tank bottoms in concentrations approaching 40%. These concentrations raise concerns as to the disposal and handling of these wastes. The current FSII, DiEGME was evaluated along with two new candidates, dipropylene glycol and glycerol formal. DiEGME appeared to be moderately but not completely biodegradable. It is likely that much of it would be removed in a wastewater treatment plant. Dipropylene glycol only showed signs of degradation after more than …

Elucidation Of Vancomycin's Enantioselective Binding Site Using Its Copper Complex, Usha B. Nair, Samuel S.C. Chang, Daniel W. Armstrong, Yasir Y. Rawjee, Drake S. Eggleston, James V. Mcardle

Chemistry Faculty Research & Creative Works

Vancomycin forms a stable complex with Cu2+ in neutral aqueous solutions. The enantioselectivity of native vancomycin was compared to that of the copper-vancomycin complex using capillary electrophoresis (CE). There were significant differences in their enantioselectivities. This can be attributed to the fact that copper ion coordinates with some of the same functional groups in vancomycin that are essential for chiral recognition and enantioresolution. An amine moiety that provides one of the more important enantioselective interactions was identified. This chiral interaction site was illustrated using a color-coded, space-filling model of the X-ray crystal structure of the copper-vancomycin complex. Successful enantioselective interactions …

Inhomogeneity In Gelation And Nonuniversality Of Sol-To-Gel Transitions Studied By A Computer Simulation Model, Yi-Min Liu, R.B. Pandey

Faculty Publications

No abstract provided.

The Effect Of Chromium Compounds On The Mutagenic Rate Of Benzo[A]Pyrenediolepoxide In Human Fibroblasts, Yordanos Tesfai

Masters Theses

Cancer researchers are interested in identifying the environmental causes and synergistic influences of different chemical carcinogens in order to decrease the risk of cancer. There are numerous studies which have investigated the effect of individual carcinogens but relatively few in which a well defined mixture of chemicals have been used. The present study was performed to examine the effect of chromium compounds on benzo[a]pyrene diolepoxide (BPDE) induced cytotoxicity and mutagenicity in human fibroblasts. Cytotoxicity was measured by the ability to fonn colonies while selection of 6-thioguanine resistant mutants were used to study mutagenesis in human fibroblasts.

Our results indicate that …

Side Chain Effect On Micellarly Catalyzed Hydrolysis Of Hydroxamic Acids In Perfluorooctanoic Acid Environment, A.C. Menik Fernando

Masters Theses

The side chain effect on micellar catalysis of hydroxamic acids with perfluorooctanoic acid as the reactive counterion surfactant in aqueous acetonitrile solution has been demonstrated in this thesis.

The rate constant-surfactant concentration profiles were used to estimate the critical micelle concentration and the second order rate constant for hydrolysis in the aqueous bulk phase.

The pseudo-phase ion exchange model satisfactorily explains the surfactant effect. The second order rate constants in the aqueous bulk phase show a direct relationship with steric substituent constants. The major influence of the change in micellar catalysis is the location in the micelle where the substrate …

Mass Transport Of Volatile Organic Compounds Between The Saturated And Vadose Zones, Monte S. Harner

Theses and Dissertations

Volatile organic compounds (VOCs) dissolved in the saturated zone are transported into the vadose zone primarily by gaseous phase diffusion. If the saturated zone is remediated, VOCs present in the vadose zone may become a secondary source of contamination for the groundwater. The amount of VOCs that remain in the vadose zone is dependent on site hydrology, soil properties, and the chemical properties of the contaminants. The purpose of this study was to determine what conditions caused VOC concentrations in the vadose zone to significantly recontaminate the saturated zone. A one-dimensional numerical model was developed to investigate the transport of …

Rapid Method For Determination Of Iodine Numbers Of Vegetable Oils, Ondrej Hendl

Masters Theses

There is a great deal of interest by the public about the total unsaturation of fats and oils used in commercial products as an indication of nutritional value. Dealers in fats and oils are extremely interested in characterizing these products. The unsaturation is a guide to the expected stability of food additives, such as edible oils and foods in which they are used. Unsaturation is typically evaluated as an iodine number (IN), calculated for these additives based on their consumption of iodine through addition across the carbon-carbon double bonds. The classical titration method can typically take 45 minutes.

The investigation …

Modeling Marine Exposure To Polychlorinated Biphenyls From Sunken Ships, Charles N. Wendt

Theses and Dissertations

In the past, the U.S. Navy has routinely conducted SINKing EXercises (SINKEX) for training, weapon effectiveness tests, and economic disposal of aging assets. Recent concern over polychlorinated biphenyl (PCB) chemicals aboard such target vessels has resulted in a suspension of SINKEX. The U.S. Navy has approximately 200 vessels currently requiring such disposal. Environmental legislation and health concerns preclude selling such vessels to foreign governments or scrapping. This work attempted to model the fate and transport of these PCBs by examining their transport to coastal water and their accumulation in the marine food chain. The model includes biodegradation, upwelling, partitioning of …

A Chemical Pathway To The Formation Of Chlorinated Compounds During Combustion, Xiaodong Yang

Masters Theses & Specialist Projects

Two reactions, the Deacon reaction and the chlorination of phenol, which are the postulated starting steps for the formation of chlorinated dioxins during the incineration of the refuse derived fuel, were investigated in this work. Reactions were conducted in a tube furnace, and the products were trapped and analyzed by gas chromatography/mass spectroscopy. It was shown that the Deacon reaction was favored at higher temperatures. The chlorination of phenol in vapor phase was found to begin at temperatures as low as 250°C and to be favored at higher temperatures. The ortho and para positions in the phenol ring are the …