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Thesis (M.S.)--University of Nevada, Reno, 2005. / "August, 2005." Includes bibliographical references. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2005]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

Thesis (M.S.)--University of Nevada, Reno, 2004. / "December 2004." Includes bibliographical references (leaves 59-63). Online version available on the World Wide Web.

This thesis is to study on the preparation of iron nano-particles by electrochemical method in aqueous solution. The resultant particles are stabilized as a colloidal suspension by the use of cationic surfactants. The advantages include those high yield, low cost, and simple control of particle size by adjustment of the current density. It is revealed that current density, distance between electrodes, temperature, and surfactant concentration of aqueous solution play important roles on the preparation of nano-particles. The morphology, structure, composition, and optical properties of nano-particles are studied by Ultraviolet-Visible spectrophotometer (UV/Vis spectrophotometer), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The effect of particle size on the magnetic properties of nano-particles has been studied using superconducting quantum interference device (SQUID). According to the experimental results, the greater imposed current density is applied, the smaller the particle size is obtained. The absorption spectra of the particles exhibit that the characteristic peak of surface plasmon band is at 264 nm. The maghemite (£^-Fe2O3) phase is clearly confirmed by X-ray diffraction and TEM analysis. From the hysteresis loop studies, particles are paramagnetic at room temperature and they exhibited super-paramagnetic phenomenon. They become ferromagnetic at low temperature. The increase of the coercive force is due to the reduction of thermal vibration.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaf 115). Available also in a digital version from Dissertation Abstracts.

This work is concerned with an alternative method for metal ion removal from aqueous solutions - surfactant enhanced ultrafiltration. Surfactant monomers aggregate above a certain concentration, specific to the surfactant, to form micelles. Anionic surfactant micelles will attract and bind metal cations. Free metal ions and surfactant monomers pass freely through an ultrafiltration membrane, but if the micelle-metal ion complex is sufficiently large it is rejected. Research reported in this thesis has been carried out on well defined aqueous solutions containing only one type of metal ion together with the natural surfactant lecithin. Lecithin is a food grade by-product of the soybean processing industry and it was chosen because it is non-toxic, biodegradable, abundant and inexpensive. It has a high molecular weight of about 750 Daltons and forms large size micelles. The main aim was to identify the basic mechanisms which influence the permeate flux and rejection levels of the process. The project was carried out in three stages. Stage one was the characterisation of the feed solution which included the determination of the critical micelle concentration using surface tension measurements, measurement of micelle size and zeta potential using a Malvern zeta sizer and visualisation of the micelle shape using scanning electron microscopy of freeze fractured lecithin solution droplet. In the second stage filtration experiments were carried out at a wide range of lecithin concentrations, metal ion concentrations and operating conditions. The experiments were run for 5 hours, by which stage a steady state condition was reached in all cases. Permeate samples were taken after I, 3 and 5 hours. Permeate flux was monitored throughout the experiment. The following properties were monitored for the feed solution at the beginning and the end of each experiment and for all permeate samples: lecithin concentration, copper concentration, pH, conductivity. In the 3 stage Electron Dispersive Analysis by X-ray (EDAX), Scanning Electron Microscopy (SEM) and a X-ray Photoelectron Spectrum Technique (XPS) were employed to investigate any membrane feed solution interactions. The results of the 3 stages were used to identify the basic mechanisms which control the permeate flux levels and the extent of component rejection in lecithin enhanced ultrafiltration.

Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 170-178).

The work described herein falls into three major categories: synthesis of model glycolipids, NMR studies on'model glycolipid'micelles, and application of 2D-NMR spectroscopy in spectral assignment. Three synthetic routes, namely the glycosidation reaction, reductive amination reaction, and amide bond formation have been investigated in relation to their efficiency and convenience in coupling carbohydrates with aliphatic chains. The reaction of amide bond formation was found to be a superior method over the others for the preparation of long alkyl chain derivatives. ¹H-NMR spectroscopy has been utilized to study and detect the micelle formation by the model glycolipids. The studies described illustrate that the ¹H spin-lattice relaxation rate (R-₁) is well suited for the determination of critical micelle concentration providing it is sufficiently high. The contrasting behaviour of R-₁ of the anomeric proton (H-1) of n-octyl β-D-glucoside in relation to that of H-2 and w-CH₃ upon micellization, has been tentatively attributed to the conformational changes accompanying micelle formation. The observed upfield shift of the ¹³C resonances of the alkyl chain has been explained as being due to the increased proportion of trans conformers in the micellar state. The question of the downfield ¹³C shift observed for the sugar resonances has been discussed. Study of N-alkyllactobionamides with ¹H-NMR proved to be difficult due to their extremely low critical micelle concentrations. Application of 2D J-resolved spectroscopy and spin-echo correlated spectroscopy (SECSY) in spectral assignment of unprotected sugar derivatives has been demonstrated. Using above techniques, complete assignment of the sugar region of n-octyl β-D-glucoside and N-hexyllactobionamide has been achieved. / Science, Faculty of / Chemistry, Department of / Graduate