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Articles 151 - 169 of 169
Full-Text Articles in Physical Sciences and Mathematics
Monitoring Metal Containing Particulates Distribution On A College Campus Using Dandelion (Taraxacum Officinale) Leaves As Receptors., Suresh Chandra Regmi
Monitoring Metal Containing Particulates Distribution On A College Campus Using Dandelion (Taraxacum Officinale) Leaves As Receptors., Suresh Chandra Regmi
Electronic Theses and Dissertations
This study aims to determine the distribution of particulates carrying heavy metals at selected sites on a college campus using dandelion leaves as collectors. As a comparison, sites far away from the campus surrounding Bristol Motor Speedway Car Racing Stadium were also monitored. To reduce the probability of memory effects from the long-term atmospheric deposition or absorption of metals from soil a seasonal plant, dandelion, was used to monitor the metal contents. The metals monitored are cadmium, calcium, copper, chromium, iron, lead, and zinc. Fourteen sites were monitored and samples were collected once a week initially (growing time of the …
Synthesis Towards Fulminic Acid And Its Derivatives In 1, 3-Dipolar Cycloaddition Reactions., Ophilia Ndi Toh
Synthesis Towards Fulminic Acid And Its Derivatives In 1, 3-Dipolar Cycloaddition Reactions., Ophilia Ndi Toh
Electronic Theses and Dissertations
A new approach to fulminic acid cycloadditions has been developed. At reduced temperatures, fulminic acid is generated in situ and undergoes 1, 3-diploar cycloaddition reactions with dipolarophiles to form isoxazolines and/or its dimers. This procedure represents a novel, safe general method for the one-step generation of fulminic acid, which complements existing potentially explosive protocols.
Contraction-Expansion Protocols., Nadine Katia Njoya
Contraction-Expansion Protocols., Nadine Katia Njoya
Electronic Theses and Dissertations
An approach to a new class of compounds known as bridgehead dienone is described. The route is based on a tandem contraction-expansion event in which the contraction triggers the expansion. The two steps involved are a palladium-catalyzed Favorskii contraction and a cis-divinyl cyclopropanone rearrangement. Progress towards these goals is reported.
Characterization Of Commercial Pectin Preparations By Spectroscopic And Chromatographic Techniques., Daniel Wayne Dixon
Characterization Of Commercial Pectin Preparations By Spectroscopic And Chromatographic Techniques., Daniel Wayne Dixon
Electronic Theses and Dissertations
Pectin has a long history as a food additive. However, elucidation of its fine structural and property relationships remains elusive. Recent research has focused on pectin's ability to complex with divalent heavy metals to aid in characterizing it. Commercial pectins of unknown composition were obtained from local grocers. Purified pectin samples from orange peel, lemon peel, and apple pomace, each of low and high levels of methyl esterification and of unknown distribution pattern were also purchased. Instead of metal complexation, several highly absorbing dyes such as Ruthenium Red, Nile Blue, and Acridine Orange were used to complex with the pectins …
A Computational Chemistry Study Of Spin Traps., Jacob Fosso-Tande
A Computational Chemistry Study Of Spin Traps., Jacob Fosso-Tande
Electronic Theses and Dissertations
Many defects in physiological processes are due to free radical damage: reactive oxygen species, nitric oxide, and hydroxyl radicals have been implicated in the parthenogenesis of cancer, diabetes mellitus, and rheumatoid arthritis. We herein characterize the phenyl-N-ter-butyl nitrone (PBN) type spin traps in conjunction with the most studied dimethyl-1-pyrroline-N-oxide (DMPO) type spin traps using the hydroxyl radical. In this study, theoretical calculations are carried out on the two main types of spin traps (DMPO and PBN) at the density functional theory level (DFT). The energies of the optimized structures, hyperfine calculations in gaseous and aqueous phases of the spin traps …
Determination Of Cholesterol In Foods By Flow Injection Analysis With Perroxyoxalate Chemiluminescence., Abisake Feleke
Determination Of Cholesterol In Foods By Flow Injection Analysis With Perroxyoxalate Chemiluminescence., Abisake Feleke
Electronic Theses and Dissertations
Cholesterol is an important biological molecule with many important functions. However, high serum cholesterol is a health hazard. Thus analysis of cholesterol is important and many analytical techniques have been developed. The objectives of the proposed research are to develop an economical, rapid method for the determination of total cholesterol with good selectivity and enhanced sensitivity. For evaluation of proposed flow injection analysis with peroxyoxalate chemiluminescence (FIA-POCL) method, figures of merit such as accuracy, precision, and linear dynamic range will be assessed. The proposed procedure was then applied to the determination of total cholesterol in foods. The procedure was linear …
Polyaniline And Its Derivatives For Environmental Analysis., Atogho Jude Abia
Polyaniline And Its Derivatives For Environmental Analysis., Atogho Jude Abia
Electronic Theses and Dissertations
Electrooxidation has been used to deposit thin film polyaniline as well as its derivative - thin film poly (ortho-phenylenediamine) (POPD) and poly (meta-phenylenediamine) (PMPD) on carbon electrodes, which are subsequently used to monitor the environmental heavy metal ions (Hg2+, Pb2+ ,Cd2+) through a rather unusual "blocking" of anodic stripping for these metals. Using Hg2+ as a model, its cyclic voltammogram for a modified glassy carbon electrode with the resultant polymer shows an enhanced cathodic peak that increases linearly with the analyte ion concentration. POPD also exhibits unique selective detection for organic species. Acetaminophen and …
Reversed-Phase Hplc Determination Of Citral In Locally Grown Lemon Grass Harvested At Different Season., Mahmoud Al-Shaer
Reversed-Phase Hplc Determination Of Citral In Locally Grown Lemon Grass Harvested At Different Season., Mahmoud Al-Shaer
Electronic Theses and Dissertations
A simple HPLC procedure for the quantitative determination of citral, the major fragrant component in the lemon grass, has been developed. The procedure involves a C-8 stationary phase using a 90:10 methanol: water pH 5 mobile phase containing 0.25% 1-octanesulfonic acid and an UV detector (set at 233 nm). The lemon grass leaves were harvested fresh at different times of the year and were soaked in methanol for 48 hours without any mechanical assistance to extract the citral and other methanol soluble components. The method showed good reproducibility with relative standard deviation of 2.8% and 10.8% for two different sets …
Cell Toxicity And Uptake Of Rrr-Alpha-Tocopheryl Polyethylene Glycol 1000 Succinate (Tpgs) By Various Cell Ines In Vitro., Christelle Komguem Kamga
Cell Toxicity And Uptake Of Rrr-Alpha-Tocopheryl Polyethylene Glycol 1000 Succinate (Tpgs) By Various Cell Ines In Vitro., Christelle Komguem Kamga
Electronic Theses and Dissertations
This research focused on investigating and comparing the cytotoxicity and cellular uptake of RRR-alpha-tocopheryl polyethylene glycol succinate (TPGS, with that of alpha-tocopheryl succinate (α-TS). Both TPGS and α-TS are water-soluble forms of vitamin E with important clinical applications. Cytotoxicity assays with RAW 264.7 and LNCaP cells incubated overnight with TPGS or α-TS at concentrations ≥ 12.4 μM suggest that α-TS is more cytotoxic than TPGS. Macrophages were found to be more sensitive than LNCaP cells when treated with similar concentrations of α-TS. For both cell lines, most of the TPGS or α-TS taken up remained esterified after 24 hours. Our …
Potential Energy Surface Around The Tropylium Ion., Kenneth Wayne Bullins
Potential Energy Surface Around The Tropylium Ion., Kenneth Wayne Bullins
Electronic Theses and Dissertations
The formation of the tropylium ion, C7H7+, in the mass spectrum of toluene is a chemical process that has been studied extensively in the past. The advances in computational power of personal computers have made the investigation of the pathway to form this ion and its subsequent decomposition feasible at a fairly high level of theory. The calculations that we performed were at the HF/6-31G (d, p) and the B3LYP/6-311++G (2d) levels. This work will show areas of the potential energy surface around the highly symmetric tropylium ion to give a glance of possible mechanisms …
Cell Toxicology Study Of Rrr-Alpha-Tocopheryl Polyethylene Glycol 1000 Succinate (Tpgs)., Clarisse Sornsay Muenyi
Cell Toxicology Study Of Rrr-Alpha-Tocopheryl Polyethylene Glycol 1000 Succinate (Tpgs)., Clarisse Sornsay Muenyi
Electronic Theses and Dissertations
This research focused on the cytotoxic properties of RRR-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) in transformed and cancerous cell lines. We used RAW264.7 macrophage and prostate cancer (LNCaP) cell lines in this study. TPGS caused cell death and decreased cell viability in a dose and time dependent manner. Cell death was evaluated fluorimetrically by employing the nucleic acid-binding fluorophore; propidium iodide. A colorimetric 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate cell viability. Cell death can occur through necrosis or apoptosis. Our results suggested that TPGS triggered apoptotic cell death. Induction of apoptosis, as measured by caspase …
Electrochemical Remedy And Analysis For The Environment Based On The New Polymer-Dna Composite Material., Noor Feuza Hussain
Electrochemical Remedy And Analysis For The Environment Based On The New Polymer-Dna Composite Material., Noor Feuza Hussain
Electronic Theses and Dissertations
In this work a new material, the conducting polymer-DNA composite, has been reported for the first time due to its promise in micro extraction, transfer, and release of cations under controlled potential conditions by using electrochemically assisted solid phase micro extraction (SPME). The Polypyrrole/DNA composite can be formed easily by oxidation of pyrrole monomers in the presence of chromosomal DNA by electropolymerization. Environmental significant pollutants such as Cd, Pb, Hg, Co, Zn, Cu, and Bi metal ions can be extracted from the aqueous solution and are able to be transferred to another medium defined as the release solution where the …
Kinetics And Mechanism Of The Catalysis Of The Decomposition Of Hydrogen Peroxide By Schiff Base Complexes Of Copper(Ii)., Timothy Kum Beng
Kinetics And Mechanism Of The Catalysis Of The Decomposition Of Hydrogen Peroxide By Schiff Base Complexes Of Copper(Ii)., Timothy Kum Beng
Electronic Theses and Dissertations
Spectroscopic studies have been used to describe the mechanism of the decomposition of hydrogen peroxide by solutions of a dimeric Cu(II) complex of a dissymetric Schiff base, [CuSALAD]2.H2O, and imidazole or methyl substituted imidazoles, B, which form monomeric CuSALAD.B2 complexes, in aqueous ethanol solvent. Freezing point depression and vapor pressure lowering studies were carried out to confirm the dimeric nature of the [CuSALAD]2.H2O complex that had been previously reported. The stoichiometry of the [CuSALAD]2.H2O-imidazole equilibrium was extensively studied pointing to a 1:4 stoichiometry. The CuSALAD.B2 adducts …
Determination Of Lactose By Reversed-Phase High Performance Liquid Chromatography., Danessa Leann Sexton
Determination Of Lactose By Reversed-Phase High Performance Liquid Chromatography., Danessa Leann Sexton
Electronic Theses and Dissertations
Lactose is the common disaccharide found in dairy products. It can, however, be a source of discomfort for those whom are lactose intolerant. Therefore, it is necessary to accurately, reliably, and efficiently determine the lactose content of foods. The goal of this research was to develop a reversed-phase HPLC method with UV detection for the determination of lactose. Aminobenzoic acid was used to prepare a derivative, making detection possible in the 300-360 nm region. The stationary phase is a C8 column, with 85% methanol 15% water mixture at pH 5 as the mobile phase. A linear response of peak area …
Synthesis Of Chiral Surfactants For Enantioselective Organic Synthesis., Kalyan Mondal
Synthesis Of Chiral Surfactants For Enantioselective Organic Synthesis., Kalyan Mondal
Electronic Theses and Dissertations
The first step of the synthesis of the hydrocarbon-based chiral surfactant (2) involved the methylation of (S)-leucinol to give (2S)-N-hexadecyl-N,N-dimethyl-(1-hydroxy-4-methyl-1-pentyl)-2-ammonium bromide (2.92g, 67%). The chiral surfactant was synthesized by reacting (2S)-N,N-dimethyl-2-amino-4-methyl-1-pentanol (1) with bromohexadecane (2.06g, 71%). The functionalized styrene for the polymer supported chiral catalyst (6) was synthesized by reacting (1) with 4-vinylbenzyl chloride. The polymerization was carried out with 10% of the functionalized monomer (5) (1.26g, 70.2%), 5% cross-linking agent divinylbenzene, and 85% of styrene with AIBN as the initiator. The structure of each of the products was confirmed by using FTIR and NMR spectroscopy. The activity of the …
Spectroscopic Examination Of The Catalytic Decomposition Of Hydrogen Peroxide By A Copper (Ii) Complex Of A Dissymmetric Schiff Base And An Imidazole Derivative., John D. Davis Jr.
Spectroscopic Examination Of The Catalytic Decomposition Of Hydrogen Peroxide By A Copper (Ii) Complex Of A Dissymmetric Schiff Base And An Imidazole Derivative., John D. Davis Jr.
Electronic Theses and Dissertations
Previous studies involving copper (II) complexed with a dissymmetric Schiff base and imidazole derivatives had identified catalase activity of these complexes towards H2O2. Reactions such as this are of great interest due to the important role of copper-based complexes in biological systems. Our research has been conducted to add to the base of knowledge regarding the efforts of other researchers to investigate copper complexes that exhibit similar reactivity as copper-based proteins towards dioxygen. The copper complex chosen for this study contained a tri-dentate Schiff base adduct which, when complexed with an imidazole derivative, limited the manner …
Theoretical Study On The Mechanism Of Removing Nitrogen Oxides Using Isocyanic Acid., Taraneh Nowroozi-Isfahani
Theoretical Study On The Mechanism Of Removing Nitrogen Oxides Using Isocyanic Acid., Taraneh Nowroozi-Isfahani
Electronic Theses and Dissertations
The mechanism of RAPRENOx 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 …
Synthesis And Use Of Chiral Surfactants., Xiaoye Yang
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. …
A Characterization Of Extractable, Hydroxylated Fatty Acid Bearing Components In Legionella Pneumophila, Jonathan R. Lane
A Characterization Of Extractable, Hydroxylated Fatty Acid Bearing Components In Legionella Pneumophila, Jonathan R. Lane
Electronic Theses and Dissertations
Extraction of the lipids of Legionella pneumophila yields phases unlike those produced from other Gram-negative bacteria. A viscous interface forms between the aqueous (wash) and organic phases. More than half of the hydroxylated fatty acids were found distributed between the aqueous phase and the interfacial material, fractions in which such constituents have not been reported in other Gram-negative species. It was further observed that after the material from the aqueous/interfacial phase was dissolved in methanol or chloroform/methanol (2:1 (V/V)), the addition of acetone would create a white, flocculent precipitate. Analyses showed that the supernatant contained fatty acids that were nonhydroxylated …