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Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Telecomunicações). Universidade do Porto. Faculdade de Engenharia. 2010

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Kristi L. Kiick, Dept. of Materials Science & Engineering. Includes bibliographical references.

Isoelectric focusing is one of the most important techniques in protein separations. Preparative-scale isoelectric separations often use buffering membranes (isoelectric membranes), but there are no good known methods for the characterization of their pI values. Therefore, UV-absorbing carrier ampholyte mixtures (UVCAs) have been synthesized, analytically characterized, and utilized for the characterization of the pI value of a buffering membrane. To synthesize the UVCAs, addition of a UV-absorbing electrophile, 3-phenoxypropyl bromide (PhOPrBr), to a pentaethylenehexamine (PEHA) carrier ampholyte backbone, resulted in an intermediate that was subsequently reacted with increasing amounts of acrylic acid (up to 8 equiv) and itaconic acid (up to 2 equiv) via Michael’s addition. The intermediates and final products were characterized by 1H-NMR and full-column imaging capillary isoelectric focusing techniques. An optimal blended mixture of selected UVCAs was first desalted and purified by isoelectric trapping and its composition verified by full-column imaging isoelectric focusing. The mixture of UVCAs possessed a broad pI distribution from approximately pH 3 – 10. By isoelectric trapping, the mixture was separated into two subfractions with a polyacrylamide-based isoelectric membrane of known pI as the separation membrane and poly(vinyl) alcohol-based buffering membranes as the restriction membranes. The pI of the most basic UV-active carrier ampholyte in the anodic fraction was determined to be 4.4 and the pI of the most acidic UV-active carrier ampholyte in the cathodic fraction was determined to be 4.4, confirming that the pH of the polyacrylamide-based isoelectric membrane was pH 4.4.

Abstract¡G We measured time-resolved PL of Zn1-XCdXSe epilayer and ZnSe/Zn0.91Cd0.09Se MQW by Upconversion experiment. The Zn1-XCdXSe epilayer was growth with four kind of Cadmium compositions (X=0.08¡B0.32¡B0.60 and 0.84). The thickness of the Zn1-XCdXSe epilayer is around 0.5£gm. The ZnSe/Zn0.91Cd0.09Se MQW of well width thickness varies from 5nm¡B10nm¡B15nm to 20nm . From carrier recombination mechanism ,We get the two sample relative temperature dependence of radiative¡Bnonradiative recombination lifetime and quantum efficiency , From nonradiative recombination lifetime formula , we can get trap concentration and capture cross section. At low temperature the two samples recombination process is dominated by radiative recombination process. The two samples increase nonradiative recombination process and decrease quantum efficiency with increasing temperature. At high temperature the two samples recombination process is dominated by nonradiative recombination process.

Isoelectric focusing is one of the most important techniques in protein separations. Preparative-scale isoelectric separations often use buffering membranes (isoelectric membranes), but there are no good known methods for the characterization of their pI values. Therefore, UV-absorbing carrier ampholyte mixtures (UVCAs) have been synthesized, analytically characterized, and utilized for the characterization of the pI value of a buffering membrane. To synthesize the UVCAs, addition of a UV-absorbing electrophile, 3-phenoxypropyl bromide (PhOPrBr), to a pentaethylenehexamine (PEHA) carrier ampholyte backbone, resulted in an intermediate that was subsequently reacted with increasing amounts of acrylic acid (up to 8 equiv) and itaconic acid (up to 2 equiv) via Michael’s addition. The intermediates and final products were characterized by 1H-NMR and full-column imaging capillary isoelectric focusing techniques. An optimal blended mixture of selected UVCAs was first desalted and purified by isoelectric trapping and its composition verified by full-column imaging isoelectric focusing. The mixture of UVCAs possessed a broad pI distribution from approximately pH 3 – 10. By isoelectric trapping, the mixture was separated into two subfractions with a polyacrylamide-based isoelectric membrane of known pI as the separation membrane and poly(vinyl) alcohol-based buffering membranes as the restriction membranes. The pI of the most basic UV-active carrier ampholyte in the anodic fraction was determined to be 4.4 and the pI of the most acidic UV-active carrier ampholyte in the cathodic fraction was determined to be 4.4, confirming that the pH of the polyacrylamide-based isoelectric membrane was pH 4.4.

published_or_final_version / Physiology / Master / Master of Philosophy