Chemistry Commons^™

Alkyl Nitrates In Dickson During The Sos 1999 Field Campaign, Mei Ma

Masters Theses

Measurements of alkyl nitrates were performed during the Southern Oxidants Study (SOS) 1999 Summer Field Campaign in Dickson, TN from June 10 to July 15, 1999. The developed GC-ECD method was tested and used successfully. Nine alkyl nitrates were measured and six alkyl nitrates were quantified. The measured alkyl nitrates expect methyl nitrate showed higher mixing ratios under northeasterly and southeasterly wind, which brought anthropogenic sources to the measurement site, and lower mixing ratios when wind came from northwest and southwest, which brought NOx and clean air, respectively. The contribution of the measured alkyl nitrates to the total oxidized nitrogen …

A Qualitative Investigation Of The Polymerization Process In The Ihss Humic Substances Extraction Procedure Using Model Phenolic Compounds, Roger J. Germay

Masters Theses

Achard (1786) extracted peat with alkali and reported obtaining dark compounds now called humic substances. These are complex, high molecular weight, polyphenolic compounds naturally occurring in soil, in fresh-water and in marine environments. They are biodegradation products of plant materials.

The International Humic Substances Society (IHSS) adapted Achard's method to separate humic substances into three fractions: (1) humic acids (HA), soluble only at high pH; (2) fulvic acids (FA), water-soluble at any pH; and (3) humin, insoluble at any pH. The IHSS method involves contact of soil with 0.1N.NaOH solution, followed by acidification with HCl.

In this study, 0.01 N. …

Synthesis And Use Of Chiral Surfactants., Xiaoye Yang

Electronic Theses and Dissertations

It has been previously shown that micelles formed from surfactants with chiral head groups serve to induce a chiral reaction medium, leading to enhanced enantioselectivities in the reaction products. This utilization of chiral surfactants will offer an economical alternative to traditional chial solvents while simultaneously reducing organic waste. We have successfully dimethlated S-leucinol in an 85% yield, and have synthesized a hydrocarbon-based surfactant with this molecule as a head group. We have also formed polymeric surfactants that have polydimethylsiloxane as the hydrophobic portion with the (S)-dimethylleucinol as a head group. Tests of the solubility of these surfactants have been conducted. …

Hydrogen-Induced Embrittlement Of Candidate Target Materials For Applications In Spallation-Neutron-Target Systems, Brendan O'Toole, Ajit K. Roy

Transmutation Sciences Materials (TRP)

The purpose of this project is to evaluate the effect of hydrogen on cracking of candidate target materials for applications in spallation-neutron-target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The test materials will undergo appropriate thermal treatments prior to being hydrogen-charged by potentiostatic cathodic polarization technique in a simulated aqueous environment at different temperatures of interest. The specimens, upon completion of testing, will be metallographically examined. Further, the scanning electron microscopy (SEM) will be used to determine the extent and nature of cracking in the specimens tested. The thrust of the proposed …

Theoretical Study On The Mechanism Of Removing Nitrogen Oxides Using Isocyanic Acid., Taraneh Nowroozi-Isfahani

Electronic Theses and Dissertations

The mechanism of RAPRENO_x reactions - RAPid REduction of Nitrogen Oxides using Isocyanic acid - proposed by Robert A. Perry¹ in an attempt to help control the emission of nitrogen oxides pollutant into the atmosphere, has been re-investigated theoretically. The study of reaction mechanisms was carried out using Chemist software². All mathematically possible elementary steps have been evaluated and the chemically reasonable ones have been considered to propose new sets of reaction mechanisms. Density Functional Theory (B3LYP/6-31 G**) calculations using Gaussian 98³ were made in order to study the relative energies of all species and …

Magnetic And Conversion Electron Mössbauer Spectral Study Of Amorphous Thin Films Of Dyₓfe₁₀₀₋ₓ And Dy₂₀Fe80-YCoY, Karl Fleury-Frenette, Jacques P. Delwiche, Fernande Grandjean, Denis Vandormael, Gary J. Long

Chemistry Faculty Research & Creative Works

Amorphous thin films of Dy_xFe_100-x and Dy₂₀Fe_80-yCo_y, with various x and y values and of ~40 nm thickness, have been prepared by sputtering on polyimide films. Their magnetization curves and the Mössbauer spectra indicate that at 295 K the iron moments are preferentially oriented parallel to the film in Dy₂Fe₉₈ and that Dy₆Fe₉₄ is paramagnetic. The Dy_xFe_100-x thin films, where x is 17, 20, 24, 29, 32, 35, and 37, show perpendicular magnetic anisotropies and moderate coercive fields of at most 150 …

Physicochemical Characteristics Of Some Locally Manufactured Edible Vegetable Oils Marketed In Dar Es Salaam, F N Ngassapa, O C Othman

Tanzania Journal of Science

The physicochemical properties (refractive index, saponification value, Free Fatty Acid (FFA) value, iodine value, acid value, peroxide value and tocopherol content) of seven edible vegetable oils manufactured in Tanzania, were assessed using standard procedures of the Association of Official Analytical Chemists (AOAC). Also determined were the levels of these properties with respect to shelf storage of the products. When compared with standard values recommended by the Codex Alimentarius Commission of FAO/WHO and with other published results, the locally produced vegetable oils were found to be of fair quality but of poor storage stability.

The Geochemistry Of Banded Iron Formations In The Sukumaland Greenstone Belt Of Geita, Northern Tanzania: Evidence For Mixing Of Hydrothermal And Clastic Sources Of The Chemical Elements, M A H Maboko

Tanzania Journal of Science

Major and trace element compositions of samples of Banded Iron Formations (BIF) from the Neoarchaean Sukumaland Greenstone Belt of Geita in northern Tanzania reveal that the BIF precipitated from hydrothermal solutions. Fe-Ti-Al-Mn systematics suggest that the hydrothermal deposits have been contaminated, by up to 20% by weight, with detrital material having a composition similar to modern deep-sea pelagic clays. SiO2 and Fe2O3 contents are 48.2 to 88.5% and 8.9 to 49.1% respectively. Al2O3 contents lie between 0.33 and 2.1% and show no correlation with either Fe2O3 or SiO2. Al2O3 is, however, positively correlated with Ti, Ga, Hf, Rb,Th, Zr and …

43rd Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 43rd annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 29 - August 2, 2001.

Structural And Functional Imaging With Carbon Nanotube Afm Probes, J. H. Hafner, Chin Li Cheung, A. T. Woolley, C. M. Lieber

Barry Chin Li Cheung Publications

Atomic force microscopy (AFM) has great potential as a tool for structural biology, a field in which there is increasing demand to characterize larger and more complex biomolecular systems. However, the poorly characterized silicon and silicon nitride probe tips currently employed in AFM limit its biological applications. Carbon nanotubes represent ideal AFM tip materials due to their small diameter, high aspect ratio, large Young’s modulus, mechanical robustness, well-defined structure, and unique chemical properties. Nanotube probes were first fabricated by manual assembly, but more recent methods based on chemical vapor deposition provide higher resolution probes and are geared towards mass production, …

Cyp83b1 Is The Oxime-Metabolizing Enzyme In The Glucosinolate Pathway In Arabidopsis, Carsten Horslev Hansen, Liangcheng Du, Peter Naur, Carl Erik Olsen, Kristian B. Axelsen, Alastair J. Hick, John A. Pickett, Barbara Ann Halkier

Liangcheng Du Publications

CYP83B1 from Arabidopsis thaliana has been identified as the oxime-metabolizing enzyme in the biosynthetic pathway of glucosinolates. Biosynthetically active microsomes isolated from Sinapis alba converted p-hydroxyphenylacetaldoxime and cysteine into S-alkylated p-hydroxyphenylacetothiohydroximate, S-(p-hydroxyphenylacetohydroximoyl)-L-cysteine, the next proposed intermediate in the glucosinolate pathway. The production was shown to be dependent on a cytochrome P450 monooxygenase. We searched the genome of A. thaliana for homologues of CYP71E1 (P450ox), the only known oxime-metabolizing enzyme in the biosynthetic pathway of the evolutionarily related cyanogenic glucosides. By a combined use of bioinformatics, published expression data, and knock-out phenotypes, we identified the …

Intrasteric Inhibition Of Atp Binding Is Not Required To Prevent Unregulated Autophosphorylation Or Signaling By The Insulin Receptor, Mark Frankel, Ararat J. Ablooglu, Joseph W. Leone, Elena Rusinova, J. B. A. Ross, Robert L. Heinrikson, Ronald A. Kohanski

Chemistry and Biochemistry Faculty Publications

Receptor tyrosine kinases may use intrasteric inhibition to suppress autophosphorylation prior to growth factor stimulation. To test this hypothesis we made an Asp1161Ala mutant in the activation loop that relieved intrasteric inhibition of the unphosphorylated insulin receptor (IR) and its recombinant cytoplasmic kinase domain (IRKD) without affecting the activated state. Solution studies with the unphosphorylated mutant IRKD demonstrated conformational changes and greater catalytic efficiency from a 10-fold increase in kcat and a 15-fold-lower K_{m ATP} although K_{m peptide} was unchanged. Kinetic parameters of the autophosphorylated mutant and wild-type kinase domains were virtually identical. The Asp1161Ala mutation increased the …

Quorum Sensing In The Dimorphic Fungus Candida Albicans Is Mediated By Farnesol, Jacob M. Hornby, Ellen C. Jensen, Amber C. Lisec, Joseph J. Tasto, Brandon Jahnke, Richard Shoemaker, Patrick Dussault, Kenneth W. Nickerson

Patrick Dussault Publications

The inoculum size effect in the dimorphic fungus Candida albicans results from production of an extracellular quorum-sensing molecule (QSM). This molecule prevents mycelial development in both a growth morphology assay and a differentiation assay using three chemically distinct triggers for germ tube formation (GTF): L-proline, N-acetylglucosamine, and serum (either pig or fetal bovine). In all cases, the presence of QSM prevents the yeast-to-mycelium conversion, resulting in actively budding yeasts without influencing cellular growth rates. QSM exhibits general cross-reactivity within C. albicans in that supernatants from strain A72 are active on five other strains of C. albicans and vice versa. …

Nature Of Oxygen At Rocksalt And Spinel Oxide Surfaces, Marjorie Langell, J.G. Kim, D. L. Pugmire, W. Mccarroll

Marjorie A. Langell Publications

The chemical environment of oxygen in cobalt-containing metal oxides with compositions M _xM′_{( x – 1)} O and M _xM′_{(3x – 1)} O₄ (M,M′ = Mn,Ni,Co) has been studied by Auger, x-ray and ultraviolet photoelectron, and high resolution electron energy loss spectroscopies. While there is a single type of lattice oxygen in the bulk structure of simple rocksalt and spinel oxides, the nature of oxygen at the surface of the spinel oxides is considerably more complex. Photoemission from core oxygen states in these materials often shows multiple peaks and satellite structure which have been …

Relativistic Effects On Interchannel Coupling In Atomic Photoionization: The Photoelectron Angular Distribution Of Xe, Oliver Hemmers, S. T. Manson, M. M. Sant'anna, P. Focke, H. Wang, I. A. Sellin, Dennis W. Lindle

Environmental Studies Faculty Publications

Measurements of the photoelectron angular-distribution asymmetry parameter β for Xe 5s photoionization have been performed in the 80–200 eV photon-energy region. The results show a substantial deviation from the nonrelativistic value of β=2 and provide a clear signature of significant relativistic effects in interchannel coupling.

Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations With Weak Carbon Nucleophiles, M. Azad Hossain, Myung-Jong Jin, William A. Donaldson

Chemistry Faculty Research and Publications

The reaction of acyclic tricarbonyl(pentadienyl)iron(1+) cations with allyl trimethylsilane or with excess furan leads to (E,E-diene)iron complexes. Attack of these weak nucleophiles on the transoid form of the pentadienyl cation is presumably faster than attack on the more stable cisoid form.

Complex Effects Arising In Smoke Plume Simulations Due To Inclusion Of Direct Emissions Of Oxygenated Organic Species From Biomass Combustion, Sherri A. Mason, Richard J. Field, Robert J. Yokelson, Michael A. Kochivar, Mark R. Tinsley, Darold E. Ward, Wei Min Hao

Chemistry and Biochemistry Faculty Publications

Oxygenated volatile organic species (oxygenates), including HCOOH, H₂CO, CH₃OH, HOCH₂CHO (hydroxyacetaldehyde), CH₃COOH, and C₆H₅OH, have recently been identified by Fourier transform infrared measurements as a significant component of the direct emissions from biomass combustion. These oxygenates have not generally been included in the hydrocarbon-based initial emission profiles used in previous photochemical simulations of biomass combustion smoke plumes. We explore the effects of oxygenates on this photochemistry by using an established initial emission hydrocarbon profile and comparing simulation results obtained both with and without addition of the above six …

Shape Imprinting Due To Variable Disulfide Bonds In Polyacrylamide Gels, Andrew B. Greytak, Alexander Y. Grosberg, Toyoichi Tanaka

Faculty Publications

Through the use of variable disulfide crosslinkers, we have created polyacrylamide gels whose shape can be altered after polymerization. N,N'-bisacryloylcystamine is incorporated as a crosslinker, along with a smaller amount of a permanent crosslinker. After polymerization, the disulfide bonds are cleaved into thiols through reduction. By reoxidizing the thiols with the gel held in a new macroscopic shape, a new set of disulfide bonds is formed, and the gel is forced to adopt the new shape. Retension of the new shape improves with greater distortion from the original shape, as well as with increased concentration of variable …

Jno2 At High Solar Zenith Angles In The Lower Stratosphere, R. S. Gao, L. A. Del Negro, W. H. Swartz, R. J. Salawitch, S. A. Lloyd, M. H. Proffitt, D. W. Fahey, Stephen G. Donnelly Ph.D., J. A. Neuman, R. M. Stimpfle, T. P. Bui

Chemistry Faculty Publications

In situ measurements of NO, NO2, O3, HO2, C1O, pressure, and temperature have been made at high solar zenith angles (SZA, 70° - 93°) in the lower stratosphere. These measurements are used to derive the photolysis rate of NO2, JNO2, using a time-dependent method. The resultant JNO2 values and the results of a multiple-scattering actinic flux model show a linear relationship throughout the SZA range. The difference of the two sets of JNO2 values of about 11% suggests that the model scattering calculation is very accurate at high SZA conditions near sunrise and sunset.

Quantification Of Benzo[A]Pyrene-Guanine Adducts In In Vitro And In Vivo Tissue Samples By Lc Tandem Mass Spectrometry, Po-Chang Chiang

Dissertations

No abstract provided.

Surface Modification Of Diamond And Determination Of Kinetics And Mechanism Of Modification Reactions, Humera Farooq

Masters Theses

A series of photochemically modified diamond surfaces were prepared. Surface functional groups added included, chlorine, bromine, methoxy, amine, methylamine, dimethylarnine and trimethylammonium chloride. Photochemically chlorinated and brominated diamond surfaces were used as synthetic intermediates. The modified diamond surfaces were characterized by Diffuse Reflectance Infrared Spectroscopy (DRIFT) and X-ray Photoelectron Spectroscopy (XPS).

The study was mainly focused on understanding the kinetic processes and reaction mechanism of modified surfaces. The observed rate constants for surface hydrogen loss and HCl (g) evolution were found to be identical. Similar rate constants were observed for amine substitution and consumption of ammonia.

The study of action …

Molecular Dynamics Simulation Of Supersaturated Vapor Nucleation In Slit Pore. Ii. Thermostatted Atomic-Wall Model, K.T. Kholmurodov, K. Yasuoka, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Molecular dynamics simulations of nucleation of a supersaturated Lennard-Jones vapor in slit nanopores are carried out. In this study we extend a previous work [K. Yasuoka, G. T. Gao, and X. C. Zeng, J. Chem. Phys. 112, 4279 (2000)] in that the walls of the slit are treated as actual atomic walls serving as both the confining solid surfaces and a thermostat. The walls are fixed in place in a fcc lattice structure and wall atoms are subjected to a stiff biharmonic potential thereby bounded to lattice sites. The two walls of the slit have an identical surface [fcc (100)], …

Cross-Linking Of Polystyrene By Friedel-Crafts Chemistry: Reaction Of P-Hydroxymethylbenzyl Chloride With Polystyrene, Hongyang Yao, Michael A. Mckinney, Caroline Dick, John J. Liggat, C.E. Snape, Charles A. Wilkie

Chemistry Faculty Research and Publications

p-Hydroxymethylbenzyl chloride was found to be an effective cross-linking agent for polystyrene. The reaction was found to occur by Friedel–Crafts alkylation between the benzyl alcohol/chloride functional groups in the additive and phenyl ring in polystyrene. The reaction was studied by TGA–IR to monitor the evolution of hydrogen chloride and water, and the structure of the resultant gel was analyzed by solid state NMR and elemental analysis. The potential application in flame-retardancy was evaluated using Cone calorimetry.

Coating Of Aluminum Powder With Polymers In Supercritical Carbon Dioxide, Li Yuan

Theses

Eleven polymers were used to produce coatings (2-20 nm) on the surface of an aluminum powder to modify its properties. The polymers studied are polyisobutylene (PIB), poly (vinylidene fluoride) (PVF), poly (methyl methacrylate) (PMMA), polystyrene (PS), poly(ethylene terephthalate) (PETP), poly(4-vinylbiphenyl) (PVB), poly(4-vinylpyridine) (PVP), poly(4-bromo styrene) (PBS), poly (vinylidene fluorideco-hexafluoropropylene) (PVFH), poly (styrene-co-methyl methacrylate) (PSMMA), poly (vinyl chloride-co-vinyl acetate) (PVCVA). Supercritical carbon dioxide was used as a solvent and as a transport medium. Coated aluminum powders exhibit enhanced resistance to the dissolution in basic solutions. The protective properties of the polymeric films were quantified based on the dissolution rate. Polymeric films …

Performance Of Proton Exchange Membranefuel Cell With Co/H2 Fuel, Hong-Mei Yu, Zhong-Jun Hou, Bao-Lian Yi, Ke-Wan Bi, Jing-Xin Zhang, Zhi-Yin Lin, Ming Han

Journal of Electrochemistry

Fuel of proton exchange membrane fuel cell(PEMFC) mostly comes from reformatecontains CO which will poison the fuel cell electrocatalyst. The effect of CO on the performance of PEMFC was studied in this paper. The results of the experiment show that when CO is fed inPEMFC ,the cell voltage will be decreased violently,then it will become steady with some vibration. The poison will become more serious with higher CO content and weaker at higher temperature. The adsorption of CO on the electrocatalyst is reversible. The PtRu electrocatalyst is moresuitable for the electrocatalysis of CO/H₂ than Pt electrocatalyst.

Atmospheric Corrosion Of Steels In China, Cai-Feng Liang

Journal of Electrochemistry

Data of eight year atmospheric exposures of 17 steels at 7 sites in China were analyzed. The result showed that the most detrimental pollution is sulfur dioxide and chloride ion for corrosion of carbon steels and low alloy weathering steels. This is in accordance with the common knowledge.The effect of sulfur dioxide is serious in the first few years and becomes weak obviously in the later years. The environment factor of humid hot is much more important in long run than the ordinarily acknowledged humidity, pollution for non weathering steels,although it is not obvious in the beginning. If pollution were …

Properties Of Metallized Polyo-Toluididemembrane Modified Electrode, Li-Zong Dai, Yi-Ting Xu, Hui-Huang Wu

Journal of Electrochemistry

The platinum particles were electrodeposited on poly(o-toluidide), POT, modified electrode, and the surface configuration and crystal orientation of Pt particles were investigated by SEM and XRD. At the same time the oxidation of isopropanol on platinized POT modified electrode was studied. The results indicate that Pt particles deposite towards preferred-orientation; moreover the increase in polymer electroactivity due to proton doping affects the dimension and graininess of deposited Pt particles. At the metallized polymer electrode the oxidation of isopropanol can occur in POT electroactive potential region, however at the more positive than 0.70 V (SCE) potential where POT loses redox activity …

Galvanic Corrosion Of Tin-W Electro-Couple During Tungsten Chemical Mechanical Polishing, Xuan Cheng, Chang-Jian Lin

Journal of Electrochemistry

Chemical mechanical polishing (CMP) is a process whereby mechanicaland chemical forces are combined to remove material from a wafer and polish it to a flatsurface. Tungsten CMP is an important prcess to gain the global planarity of siliconwafers with tungsten (W) plugs. Tungsten is actually deposited on a thin adhesive layerof titanium nitride (TiN) on silicon. When close to the final stage of polishing, TiN and W will be simultaneously exposed to the polishing chemistry, forming a galvaniccouple. The corrsion of TiN and W couple will result in different polish rate.

Electrochemical Behavior Of Tinicu Shape Memry Alloy In Simulated Body Fluid, Cheng-Hao Liang, Hong-Yan Sui

Journal of Electrochemistry

The study of TiNiCu shape memory alloys (SMA) in Hank's simulated body fluidwas carried out. The results showed that narrow passive range was found in acid environment andactive anodic dissolution was discovered at 100~150 mV vs SCE on anodic polarization cure ofTiNiCu SMA. Temperature had little effect on anodic polarization. With the decrease of pH andthe increase of Cl^- concentration ,pitting corrosion potential (E_b) shifted negatively. The electrochemical capability of TiNiCu SMA was inferior to that of TiNi SMA. Observations by means ofXRD and SEM indicate that TiNiCu SMA is not in single crystal structure, which caused …

Study Of The Oxidation Dynamics Of Tizro2 Metal-Ceramics, Wen-Chao Li, Li-Dong Teng

Journal of Electrochemistry

The oxidation dynamics of hot-pressed Ti-ZrO₂ metal-ceramics with the compositionof 50 vol.% Ti and 50 vol.% ZrO₂ has been studied.Thermodynamic analysis shows that Ticould react with O₂ but not with N₂ in the oxidizing process of TiZrO₂ composites at 0.1 MPa air. The oxidation dynamic behavior of Ti-ZrO₂ composites is analogous to that of pure Ti. Theactivation energy for the oxygen diffusion in Ti-ZrO₂ composites is higher than that in Ti solutions, for the presence of ZrO₂ restrains the oxygen diffusion in Ti-ZrO₂ composites. At early stagethe oxidation of Ti-ZrO_{2 …}