Physical Sciences and Mathematics Commons^™

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 …

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 …

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 …

Reactions Of Chlorine And Some Of Its Oxygen Derivatives With Phenol, Lizhuo Zhang

Masters Theses

Chlorine is widely used in industry. It is also the most commonly used disinfectant in water treatment plants. Since the amount of chlorine used is increasing each year, environmental and health concerns arise due to its reactivity with various of organic compounds. Many chlorinated organic compounds are toxic and as a result other non-chlorinating compounds, such as chlorine dioxide, might be potential substitutes in the future, especially in water treatment plants.

Previous studies have indicated that chlorinated organic compounds are not formed when chlorine dioxide is used as a disinfectant. Furthermore no reaction occurs between chlorite and phenol in the …

A Hplc Method To Assay Mycotoxins - Fumonisin, Ochratoxin And Zearalenone, Nalini Sadagopan

Masters Theses

A HPLC method to quantitate the mycotoxins Fumonisin B1 (FB1), Ochratoxin A(OA), and Zearalenone (ZON) was developed and validated. Mycotoxins are secondary metabolites of fungi like Fusarium, Asperigillus and Penicillium that contaminate crops. They have a wide array of chemical structures which facilitate their analytical detection.

The analytical method consists of reverse phase chromatography and fluorescence detection. Sample cleanup was performed using SAX and C18 cartridges prior to analysis on the HPLC.

The method developed for FB1 is unique in that it is more sensitive, accurate, and reproducible than the existing methods. Automation is one of the salient features that …

An Investigation On Nonenzymatic Autoxidation Of Phenolic Compounds In Natural Waters, Lei Jiang

Masters Theses

The nonenzymatic autoxidation of the phenolic compounds chlorogenic acid in aqueous solution was studied. The study demonstrated that the oxidation rate of chlorogenic acid was strongly dependent on pH. The higher the pH, the faster the rate of oxidation. The involvement of phenolate ions and radicals in oxidation reactions are two possible reasons for the pH dependency. The presence of a trace amounts of reducible transition metal ions, such as copper(II), dramatically increases the oxidation rate of chlorogenic acid. Light also increases the oxidation rate of chlorogenic acid. However, the photochemical reaction was a much slower process.

The TLC and …

Synthesis And Characterization Of Bifunctional Silica Gel Surfaces, Alufelwi Maxwell Tshavhungwe

Masters Theses

Bifunctional silica surfaces consisting of various combinations of the following organofunctional silanes were synthesized and characterized using diffuse reflectance infrared spectroscopy: hexamethyldisilazane, octyldimethylmethoxysilane, phenyldimethylethoxysilane, (3-aminopropyl) -dimethylmethoxysilane, ( 2 - cyanoethyl)triethoxysilane, and trimethylmethoxysilane.

The relative amounts of organosilanes loaded on a silica surface were obtained from band area ratios of IR bands. Ratios of organosilanes bonded to the same silica surface were calculated from normalized band areas of the isolated silanol peak. In reactions in which surface coverage was incomplete, the relative amount of inaccessible silanols was determined from the band area ratio of the silanol peak. Comparisons of organosilane loading …

Mechanistic Studies On Malate Dehydrogenase From Escherichia Coli, S. Kirk Wright

Masters Theses

Kinetic studies and chemical modification studies were performed on malate dehydrogenase from Escherichia coli (eMDH). Chemical modification studies using diethylpyrocarbonate and iodoacetic acid, along with log V/K profiles indicate that one ionizing group with a pK_a between 7.9 and 8.5 acts as a general acid/base in the catalytic mechanism. Log V profiles suggest that malate binds to the correctly protonated form of the enzyme. These results imply that a histidine residue is required for catalysis.

A primary deuterium kinetic isotope effect of 1.43 (±0.14) was observed on V/K using malate-2-d, while no isotope effect was measured on V_{max …}